JP7796396B2 - Composite and manufacturing method thereof - Google Patents

Description

The present invention relates to a composite with excellent structural stability and a method for producing the same.

In recent years, with the advancement of the IoT society, materials with various excellent properties, such as mechanical strength, thermal conductivity, and electrical and chemical properties, have been developed, and the development of devices that combine multiple materials is progressing. It is expected that further novel materials and devices will continue to be developed in the future. For example, at the bonding interface between materials with different chemical properties, such as oxide and nitride, or at the bonding interface between materials with high reactivity to each other, it is necessary to suppress chemical reactions and element diffusion, prevent material decomposition and degradation, and maintain the original performance of the materials. Therefore, even in the development of new devices, it is necessary to suppress insufficient mechanical strength at the bonding interface between different materials, and to suppress material degradation and decomposition due to element diffusion that occurs during device manufacturing and operation. To solve these problems, intermediate layers and manufacturing methods tailored to each device or material combination are being developed.

For example, Patent Document 1 discloses a metal/ceramic bonded body used as a thermistor, in which a composite ceramic containing SiC is bonded to a surface layer made of an Fe-Cr-Al alloy, and the intermediate layer is made of Cr or a Cr alloy to prevent oxidation and peeling of the surface layer.

Patent Document 2 discloses a diffusion prevention layer that, when bonding a substrate made of a piezoelectric material such as lithium tantalate or lithium niobate to a support substrate such as sapphire with an intervening layer provided in a surface acoustic wave device, prevents oxygen contained in the intervening layer or support substrate from diffusing into the piezoelectric material such as lithium tantalate or lithium niobate through heat treatment.

Patent Document 3 discloses a method for manufacturing a metallized ceramic substrate in which a conductor layer is formed on a ceramic substrate directly or indirectly by firing conductive metal particles, thereby bonding the ceramic substrate and the conductor layer with high adhesion.

JP 2019-182667 A JP 2020-36212 A JP 2008-109062 A

The object of the present invention is to provide a composite with excellent structural stability, which includes an intermediate layer (stabilizing layer) between two materials that suppresses defects such as chemical reactions and element diffusion that may occur when two parts containing inorganic materials with different compositions are bonded together, and a method for producing the composite.

As a result of extensive research, the inventors discovered that the above-mentioned objectives can be achieved by interposing a compound represented by the following general formula (1) between the two material portions (stabilizing layer), leading to the completion of the present invention.

[1] A composite comprising: a first material portion containing a first inorganic material; a second material portion containing a second inorganic material having a different composition from the first inorganic material; and a stabilizing layer disposed between the first material portion and the second material portion,
The stabilizing layer comprises a compound (A) represented by the following general formula (1):
M ¹ ₂ M ² O ₄ (1)
(In the formula, ^M1 and ^M2 are different elements, ^M1 is at least one selected from Al, Fe, and Ga, and ^M2 is at least one selected from Cu, Mg, Zn, Fe, Mn, and Co.)

[2] The composite described in [1] above, wherein the first inorganic material contains a nitride and the second inorganic material contains an oxide (excluding the compound (A)).

[3] The composite described in [1] above, wherein the first inorganic material contains a silicon compound (excluding silicon nitride) or silicon, and the second inorganic material contains an oxide (excluding compound (A)).

[4] The composite according to any one of [1] to [3] above, wherein the compound (A) is Al ₂ CuO ₄ .

[5] The composite described in any one of [1] to [4] above, wherein the stabilization layer includes a reinforcing layer containing an inorganic compound (excluding compound (A)).

[6] The composite described in [5] above, wherein the inorganic compound contained in the reinforcing layer includes copper oxide.

[7] A method for producing the composite according to any one of [1] to [4] above,
A method for producing a composite, comprising forming a film containing compound (A) on the surface of the first material part to form a laminate, and then forming the second material part on the surface of the film containing compound (A) in the laminate.

[8] The composite manufacturing method described in [7] above, wherein the laminate is obtained by applying a paste containing the raw materials for manufacturing the compound (A) and a dispersion medium to the surface of the first material part, then heating the formed coating film to remove the dispersion medium, and then further increasing the temperature to generate the compound (A) and form the compound (A)-containing film.

According to the composite of the present invention, when two material portions (first material portion and second material portion) containing inorganic materials of different compositions are bonded together, a stabilization layer is provided between the first material portion and the second material portion to suppress defects such as chemical reactions and element diffusion that occur between the two different materials, resulting in excellent structural stability. In particular, there are no defects at the stabilization layer-side interface in the first material portion and the stabilization layer-side interface in the second material portion, resulting in excellent structural stability. For example, when the first inorganic material contains a nitride, a silicon compound, or silicon, and the second inorganic material contains an oxide other than compound (A), chemical reactions and element diffusion that may occur between the first inorganic material and the second inorganic material when they are directly bonded can be suppressed.
In the composite of the present invention, even when the stabilizing layer includes a reinforcing layer containing an inorganic compound other than the compound (A), the structural stability is excellent.
According to the method for producing a composite of the present invention, a composite having the above-mentioned effects can be produced efficiently.

FIG. 1 is a schematic cross-sectional view showing a first embodiment of the composite of the present invention. FIG. 2 is a schematic cross-sectional view showing a second embodiment of the composite of the present invention. FIG. 2 is a schematic cross-sectional view showing a third embodiment of the composite of the present invention. 1 shows an X-ray diffraction pattern of a stabilizing film (Al ₂ CuO ₄ film) formed on the surface of a silicon nitride substrate in a laminate obtained before producing a composite (C1) in Example 1. 1 is an X-ray diffraction pattern of a conductive oxide sintered film in a composite (C1) obtained in Example 1. 1 is a cross-sectional SEM image of the composite (C1) obtained in Example 1. 1 is an X-ray diffraction pattern of a conductive oxide sintered film in a composite (D1) obtained in Comparative Example 1. 1 is an X-ray diffraction pattern of a conductive oxide sintered film in a composite (C2) obtained in Example 2. 1 is an X-ray diffraction pattern of a conductive oxide sintered film in a composite (D2) obtained in Comparative Example 2. 1 is an X-ray diffraction pattern of a conductive oxide sintered film in a composite (C3) obtained in Example 3. 1 is a cross-sectional SEM image of the composite (C3) obtained in Example 3. 1 shows an X-ray diffraction pattern of a SmBa ₂ Cu ₃ O _y sintered film in a composite (C4) obtained in Example 4. 1 shows an X-ray diffraction pattern of the sintered surface of a composite (D3) obtained by sintering a SmBa ₂ Cu ₃ O _y printed film in Comparative Example 4. 10 is an X-ray diffraction pattern of a stabilizing film (Al ₂ O ₃ -containing Al ₂ CuO ₄ film) formed on the surface of a silicon nitride substrate in a laminate obtained before producing a composite (C5) in Example 5. 1 is an X-ray diffraction pattern of a conductive oxide sintered film in a composite (C5) obtained in Example 5. 1 is a cross-sectional SEM image of the composite (C6) obtained in Example 6. 1 is an X-ray diffraction pattern of a conductive oxide sintered film in a composite (C6) obtained in Example 6. 1 is an X-ray diffraction pattern of a conductive oxide sintered film in a composite (D4) obtained in Comparative Example 4. 10 is an X-ray diffraction pattern of a stabilizing film (Al ₂ CoO ₄ film) formed on the surface of a silicon nitride substrate in a laminate obtained before producing a composite (C7) in Example 7. 10 is an X-ray diffraction pattern of a stabilizing film (Al ₂ MgO ₄ film) formed on the surface of a silicon nitride substrate in a laminate obtained before producing a composite (C8) in Example 8. 10 is an X-ray diffraction pattern of a stabilizing film (Al ₂ ZnO ₄ film) formed on the surface of a silicon nitride substrate in a laminate obtained before producing a composite (C9) in Example 9. 10 is an X-ray diffraction pattern of a stabilizing film (Fe ₂ CoO ₄ film) formed on the surface of a silicon nitride substrate in a laminate obtained before producing a composite (C10) in Example 10. 11 is an X-ray diffraction pattern of a stabilizing film (Fe ₂ CuO ₄ film) formed on the surface of a silicon nitride substrate in a laminate obtained before producing a composite (C11) in Example 11. 10 is an X-ray diffraction pattern of a stabilizing film (Fe ₂ MgO ₄ film) formed on the surface of a silicon nitride substrate in a laminate obtained before producing a composite (C12) in Example 12. 10 is an X-ray diffraction pattern of a stabilizing film (Fe ₂ ZnO ₄ film) formed on the surface of a silicon nitride substrate in a laminate obtained before producing a composite (C13) in Example 13. 10 is an X-ray diffraction pattern of a stabilizing film (Ga ₂ CoO ₄ film) formed on the surface of a silicon nitride substrate in a laminate obtained before producing a composite (C14) in Example 14. 15 is an X-ray diffraction pattern of a stabilizing film (Ga ₂ CuO ₄ film) formed on the surface of a silicon nitride substrate in a laminate obtained before producing a composite (C15) in Example 15. 16 is an X-ray diffraction pattern of a stabilizing film (Ga ₂ MgO ₄ film) formed on the surface of a silicon nitride substrate in a laminate obtained before producing a composite (C16) in Example 16. 10 is an X-ray diffraction pattern of a stabilizing film (Ga ₂ ZnO ₄ film) formed on the surface of a silicon nitride substrate in a laminate obtained before producing a composite (C17) in Example 17. 1 is an X-ray diffraction pattern of a conductive oxide sintered film in a composite (D5) obtained in Comparative Example 5. 10 is an X-ray diffraction pattern of a stabilizing film (Al ₂ CuO ₄ film) formed on the surface of a gallium nitride thin film on a sapphire substrate in a laminate obtained before producing a composite (C18) in Example 18. 19 is an X-ray diffraction pattern of a stabilizing film (Ga ₂ ZnO ₄ film) formed on the surface of a gallium nitride thin film on a sapphire substrate in a laminate obtained before producing a composite (C19) in Example 19.

The composite of the present invention comprises a first material part containing a first inorganic material, a second material part containing a second inorganic material having a different composition from the first inorganic material, and a stabilizing layer containing compound (A) disposed between the first material part and the second material part.

1 to 3 show cross-sectional structures of essential parts of a composite body of the present invention, which comprises a first material part, a second material part, and a stabilizing layer, but the present invention is not limited to these.
1 shows a composite 1 of a first embodiment having a structure in which a stabilizing layer 14 and a second material part 12 are bonded in that order onto a first material part 10. The stabilizing layer 14 may be a layer consisting of only the compound (A), or may be a layer consisting of the compound (A) and another compound (described later). In the present invention, the stabilizing layer 14 may be a single layer as shown in FIG. 1, or, although not shown, may have a structure in which multiple layers containing different compounds (A) are stacked.
Fig. 2 shows a composite 2 of a second embodiment having a structure in which a stabilizing layer 24 and a second material part 22 are bonded in this order onto a first material part 20. The stabilizing layer according to the present invention may include a reinforcing layer that does not contain compound (A) (described later), and the stabilizing layer 24 in Fig. 2 is composed of a stabilizing main agent layer 26 that contains compound (A) and reinforcing layers 28, 28 that sandwich the stabilizing main agent layer 26 on both sides.
FIG. 3 shows a composite body 3 of a third embodiment having a structure in which a stabilizing layer 34 and a second material portion 32 are bonded between first material portions 30, 30 arranged on one surface side and the other surface side.

The materials that make up the first material part, second material part, and stabilization layer are described below.

In the present invention, the first inorganic material and the second inorganic material are materials that contain completely different substances, or that contain a common substance but have different compositions.

In the present invention, the combination of the first inorganic material and the second inorganic material is not particularly limited, and the first inorganic material and the second inorganic material can be, for example, a nitride and a non-nitride; silicon or a silicon-containing compound and an oxide; an acidic material that reacts with a base to form a salt; and a basic material that reacts with an acid to form a salt, respectively.

Examples of nitrides include silicon nitride, aluminum nitride, gallium nitride, boron nitride, titanium nitride, lithium nitride, zinc nitride, and iron nitride.

Examples of non-nitrides containing oxides include metal elements (Pt, Au, Ag, W, Mo, Nb, or Ta), conductive oxides containing Ru (RuO ₂ , CaCu ₃ Ru ₄ O ₁₂ , SrRuO ₃ , CaRuO ₃ , Ca ₂ RuO _4, etc.), superconducting copper oxides (RE _2-x Ba _x CuO ₄ , REBa ₂ Cu ₃ O _6+δ , REBa ₂ Cu ₄ O ₈ , RE ₂ Ba ₄ Cu ₇ O ₁₄ , Bi ₂ Sr ₂ CuO ₆ , Bi ₂ Sr ₂ CaCu ₂ O ₈ , Bi ₂ Sr ₂ Ca ₂ Cu ₃ O ₁₀ , HgBa _{2CuO 4+δ} , HgBa ₂ CaCu ₂ O _6+δ , HgBa ₂ Ca ₂ Cu ₃ O _8+δ , where RE is a rare earth element such as Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu), layered cobalt oxides (sodium cobaltite, calcium cobaltite), perovskite structure oxides (barium titanate, strontium titanate, barium zirconate, barium hafnate, barium stannate, or the like, or compounds in which some of the constituent elements thereof are substituted with different elements, or compounds in which some of the constituent elements are missing), metal oxides (silicon dioxide, quartz, aluminum oxide, sapphire, ferrite, titanium oxide, tin oxide, zinc oxide, copper oxide, cobalt oxide, iron oxide, gallium oxide, molybdenum oxide, hafnium oxide, rare earth oxides other than the above, etc.), and other oxides, carbides, sulfides, silicon, and the like can be mentioned.

Examples of silicon-containing compounds include silicon dioxide, quartz, silicon carbide, metal silicides ( _Cu5Si , (V, Cr, Mn) _3Si , _Fe3Si , _Mn3Si , (Mg, Ge, Sn, Pb) _2Si , (Ca, Ru, Ce, Rh, Ir, Ni) _2Si , (Ti, Zr, Hf, Th, Ce, Pu)Si, CaSi, SrSi, YSi, _Mg2Si , NiSi, _Na2Si , _WSi2 , _MoSi2 , _TiSi2 , etc.), and the like.

Examples of acidic materials that react with bases to produce salts include silicon oxide, chromium oxide, tin oxide, boron oxide, manganese oxide, and rhenium oxide.

Examples of basic materials that react with acids to produce salts include copper-containing oxides (such as superconducting copper oxide, copper oxide, and oxygen _- deficient perovskite-structure copper oxides such as _{La4BaCu5O14 +δ} ), calcium-containing compounds (such as _CaF2 , CaO, _CaCO3 , and calcium cobaltite), and sodium-containing compounds (such as _Na2O and sodium cobaltite).

In the present invention, preferred combinations of the first inorganic material and the second inorganic material are shown below.
(A) An embodiment in which the first inorganic material contains a nitride, and the second inorganic material contains an oxide (excluding compound (A)) as a non-nitride. (B) An embodiment in which the first inorganic material contains a silicon compound (excluding silicon nitride) or silicon, and the second inorganic material contains an oxide (excluding compound (A)).

In the above aspect (a), the first inorganic material is preferably a material containing at least one nitride selected from silicon nitride, aluminum nitride, gallium nitride, boron nitride, titanium nitride, lithium nitride, zinc nitride, and iron nitride, particularly preferably silicon nitride, in an amount of 80% by volume or more relative to the entire first inorganic material; and the second inorganic material is preferably a material containing at least one oxide selected from conductive oxides containing Ru and superconducting copper oxides containing rare earth elements, in an amount of 50% by volume or more relative to the entire second inorganic material. If the second inorganic material contains another oxide, copper oxide is preferred.

In the above aspect (i), the first inorganic material is preferably a material containing silicon dioxide or silicon in an amount of 50% by volume or more relative to the entire first inorganic material, and the second inorganic material is preferably a material containing at least one oxide selected from conductive oxides containing Pt, Au, Ag, W, Mo, Nb, Ta, and Ru, and superconducting copper oxides containing rare earth elements, in an amount of 50% by volume or more relative to the entire second inorganic material. If the second inorganic material contains another oxide, copper oxide is preferred.

Next, the compound (A) contained in the stabilizing layer will be described.
This compound (A) is represented by the general formula (1): M ¹ ₂ M ² O ₄ , and is composed of mutually different elements, where M ¹ is at least one trivalent element selected from Al, Fe, and Ga, and M ² is at least one divalent element selected from Cu, Mg, Zn, Fe, Mn, and Co.
The stabilizing layer may contain only one type of compound (A), or two or more types of compounds.

The compound (A) generally has a spinel structure. The bonding strength between ^M1 or ^M2 in the general formula (1) and O (oxygen) is strong, resulting in a stable crystal structure. Therefore, when such a compound (A) is contained in the stabilization layer, the effects of the present invention are fully exhibited.

In an oxide ( _A2BO4 ) having a spinel structure, the element corresponding to the A site is at least one selected from Al, Fe _, and Ga, as in the above ^M1 , and the element corresponding to the B site is at least one selected from Cu, Mg, Zn, Fe, Mn, and Co, as in the above ^M2 . Therefore, if the total number of metal elements in the A site is 2 and the total number of metal elements in the B site is 1, an oxide consisting of multiple elements can be obtained.

Since the compound (A) typically has low electrical conductivity, for example, when the first inorganic material and the second inorganic material are conductive materials, a stabilization layer containing the compound (A) can be interposed between the first material portion and the second material portion to electrically insulate the first material portion and the second material portion, thereby suppressing chemical reactions and element diffusion that occur between the different first and second inorganic materials.

In the oxide having a spinel structure represented by the general formula (1) above, a compound having lower reactivity with the material to be joined is preferably a compound in which aluminum (Al) is applied to the A site. The aluminum (Al) element is contained in alumina, sapphire, aluminum nitride, etc., which constitute ceramic substrates used in many ceramic products and electronic devices.
In this case, using a compound in which copper (Cu) is applied to the B site can suppress reaction with the first inorganic material and the second inorganic material, making it more preferable as a component constituting the stabilization layer.

The proportion of compound (A) contained in the stabilization layer (the total proportion if multiple types are present) is preferably 80% by volume or more, and more preferably 90% by volume or more, of the entire stabilization layer, in order to suppress defects such as element diffusion at the stabilization layer-side interface in the first material part and the stabilization layer-side interface in the second material part.

If the stabilization layer contains components other than compound (A), the other components are preferably components that do not react with compound (A) or decompose compound (A) at temperatures between 500°C and 1100°C, and can be, for example, at least one of metals, alloys, oxides, carbides, sulfides, etc. In the present invention, oxides and nitrides are preferred. Preferred oxides include aluminum oxide, copper oxide, magnesium oxide, etc., with copper oxide being particularly preferred.

When the stabilizing layer is composed of compound (A) and other components, the stabilizing layer may be a layer in which these are uniformly mixed, or may be a layer in which compound (A) is contained with a gradient distribution from the first material part side to the second material part side.
In addition, from the viewpoint of density, the stabilization layer is preferably a dense layer.

In the present invention, the stabilization layer may further include a reinforcing layer containing an inorganic compound other than compound (A) in addition to the portion containing compound (A). Composite 2 in Figure 2 is a preferred example of a composite including a reinforcing layer. It includes a stabilization base layer 26 containing compound (A) and reinforcing layers 28, 28 sandwiching the stabilization base layer 26 on both sides. The advantages of the present invention are difficult to obtain even if a layer containing only a compound other than compound (A), such as aluminum oxide or copper oxide, is provided between a first material portion containing a first inorganic material and a second material portion containing a second inorganic material. In the present invention, not only the first embodiment of composite 1 shown in Figure 1, which has a structure in which a stabilization layer 14 and a second material portion 12 are bonded sequentially onto a first material portion 10, but also the second embodiment of composite 2 shown in Figure 2, which includes reinforcing layers 28, 28, exhibit excellent structural stability by suppressing defects such as element diffusion at the stabilization layer-side interface of the first material portion and the stabilization layer-side interface of the second material portion.

The other inorganic compound constituting the reinforcing layer (hereinafter also referred to as "reinforcing layer inorganic compound") can be at least one of oxide, carbide, sulfide, nitride, etc. In the present invention, oxides and nitrides are preferred because they are less likely to peel and have excellent structural stability as an integrated product. Preferred oxides include copper oxide, bismuth oxide, and antimony oxide. In the two reinforcing layers shown in Figure 2, the inorganic compound contained in one reinforcing layer and the inorganic compound contained in the other reinforcing layer may be the same or different.

In the present invention, the thickness of the stabilization layer in the embodiment shown in Figures 1 and 2 is not particularly limited, but the lower limit is typically 10 nm, preferably 100 nm, and more preferably 1 μm. The upper limit is selected appropriately depending on the size of the portions where the first material portion and the second material portion face each other or the types of the first inorganic material and the second inorganic material, but is typically 1 mm. Furthermore, the thicknesses of the two reinforcing layers 28, 28 in Figure 2 may be the same or different.

1 and 2 are examples of cross sections of a main part of a composite body, and show that the layers are in contact with each other on a flat surface, but the contact is not limited to a flat surface, and may be an uneven surface.
FIG. 2 shows a structure in which a stabilizing layer 24 consisting of a stabilizing main agent layer 26 containing compound (A) and reinforcing layers 28, 28 sandwiching the stabilizing main agent layer 26 on both sides, and a second material portion 22 are bonded in this order on top of a first material portion 20; however, the reinforcing layer 28 may also be a composite provided either between the first material portion 20 and the stabilizing main agent layer 26, or between the stabilizing main agent layer 26 and the second material portion 22 (not shown).
The composite 3 in Figure 3 is a composite showing a modified example of the composite in Figure 1, and has a structure in which a second material part 32 is provided inside, and this second material part 32 is sandwiched between a stabilizing layer 34 and a first material part 30, in that order.

In the present invention, for example, composite 1 in Figure 1 can be produced by a method such as (a) forming a film or deposition portion for a stabilizing layer (hereinafter, these are also collectively referred to as "stabilizing film") on the surface of a first material portion, and then forming a second material portion on the surface of the stabilizing film in the resulting laminate, or (b) arranging raw materials for forming the stabilizing layer between the first material portion and the second material portion and integrating them. Below, we will explain the composite production method of the present invention, which corresponds to (a) above, in which a film containing compound (A) (stabilizing film) is formed on the surface of the first material portion to form a laminate, and then forming a second material portion on the surface of the compound (A)-containing film (stabilizing film) in the laminate.

Methods for forming a stabilizing film containing compound (A) on the surface of the first material part (stabilizing film formation method) include: applying a dispersion liquid obtained by dispersing particles containing compound (A) in a liquid medium (dispersion medium) such as an organic solvent to the first material part, followed by drying (desolvation), degreasing (de-dispersant) if necessary, and heat treatment (sintering if necessary); applying a dispersion liquid obtained by dispersing the manufacturing raw materials (particles, etc.) of compound (A) in a liquid medium to the first material part, followed by drying, a firing reaction, and sintering if necessary; forming a film containing compound (A) on the first material part using a vapor phase film deposition method such as sputtering, pulsed laser deposition, chemical vapor deposition, metalorganic vapor phase deposition, molecular beam epitaxy, or atomic layer deposition; and forming a stabilizing film containing compound (A) on the first material part using a chemical solution film deposition method such as metalorganic compound decomposition or sol-gel method. In this way, a method can be applied in which a stabilizing film is formed on the surface of the first material part using a compound (A) that has been prepared in advance, or a method can be applied in which a stabilizing film containing compound (A) is formed on the surface of the first material part using the manufacturing raw materials for compound (A).

Hereinafter, a method for producing Al ₂ CuO ₄ using the raw material when the compound (A) is Al ₂ CuO ₄ will be described, but Al ₂ CuO ₄ is not limited to the production method described below and may be obtained by any other production method.

When producing Al ₂ CuO ₄ , first, copper oxide (CuO, Cu ₂ O, etc.) and aluminum oxide (Al ₂ O _3, etc.) are used so as to have a composition ratio of Al ₂ CuO ₄ , and are mixed using, for example, a mortar made of various materials such as agate or alumina, or a ball mill.

The resulting raw material mixture is then fired under the conditions described below, but prior to this, it may be formed into a molded body by pressure molding, extrusion molding, sheet molding, casting molding, injection molding, etc.

The raw material mixture (molded body) is then heated under atmospheric pressure to cause a firing reaction. The heating temperature is preferably 800°C or higher, more preferably 900°C to 1000°C, and even more preferably 950°C to 1000°C. If the ratio of copper oxide and aluminum oxide to Al ₂ CuO ₄ is not based on the amount of each compound used, and one of them is used in excess, a mixture consisting of the excess raw material compound and Al ₂ CuO ₄ is obtained after firing. This is also acceptable as long as it can suppress chemical reactions and element diffusion between the first material portion and the second material portion.

When using a dispersion containing particles containing compound (A), a liquid medium, and a dispersant used in combination as needed, the dispersion can be prepared by mixing and dispersing compound (A)-containing particles, the particle size of which has been adjusted to, for example, 10 μm or less using a ball mill or the like, with terpineol, polyethylene glycol, glycerin, toluene, propylene glycol, or the like to a predetermined solids concentration, followed by stirring and dispersing the mixture to form a paste or slurry.

The method for forming a stabilizing film on the surface of the first material part using the dispersion to obtain a laminate is not particularly limited, and can be a method in which the dispersion is subjected to various film-forming methods such as screen printing, dip coating, spin coating, inkjet printing, etc. to form a coating film, and then heated for desolvation and degreasing to remove the dispersion medium, etc. After this heating, the stabilizing film can be densified by further heating at a high temperature, if necessary, for sintering.
Furthermore, a denser stabilizing film can also be obtained by the vapor phase film formation method.

In the present invention, a preferred method for forming a film containing _Al2CuO4 on the surface of the first material part is to use copper oxide (CuO, _{Cu2O, etc.} ) and aluminum oxide ( _{Al2O3 , etc.} ) in a composition ratio of _Al2CuO4 , mix them with a dispersion medium such as terpineol, polyethylene glycol, glycerin, toluene, or propylene glycol to a predetermined solid concentration, and subject the resulting dispersion (paste or slurry) to various film formation methods such as screen printing, dip coating, spin coating, or inkjet printing to form a coating film, and then heat the mixture for desolvation and degreasing to remove the dispersion medium, etc., and after this heating, further heat at a high temperature to perform firing.

To produce composite 1 having the structure of Figure 1 by forming a second material portion on the surface of the stabilizing film in the laminate obtained as described above, methods that can be used include: applying a dispersion of particles containing the second inorganic material dispersed in a liquid medium (dispersion medium) such as an organic solvent to the surface of the stabilizing film, followed by drying (desolvation), degreasing (de-dispersant) as needed, and heat treatment (sintering as needed); applying a slurry or paste of the second inorganic material's manufacturing raw materials (particles, etc.) dispersed in a liquid medium to the surface of the stabilizing film, followed by drying, firing, and sintering as needed; forming the second material portion on the surface of the stabilizing film using a vapor-phase deposition method such as sputtering, pulsed laser deposition, chemical vapor deposition, metalorganic vapor phase deposition, molecular beam epitaxy, or atomic layer deposition; or forming the second material portion on the surface of the stabilizing film using a chemical solution deposition method such as a metalorganic compound decomposition method or a sol-gel method.

Next, a preferred method for producing the composite 2 of Figure 2, i.e., a composite having a stabilizing layer 24 including reinforcing layers 28 sandwiching both sides of a stabilizing base layer 26 containing compound (A), will be described.

First, a dispersion liquid containing particles containing an inorganic compound for the reinforcing layer dispersed in a liquid medium (dispersion medium) such as an organic solvent is applied to the surface of the first material part, followed by drying (desolvation), degreasing (dedispersant) if necessary, and heat treatment (sintering if necessary) to form a film for the reinforcing layer. Next, a stabilizing base film is formed on the surface of this film using the stabilizing film formation method described in the composite manufacturing method of the present invention above. After that, a film for the reinforcing layer is formed on the surface of this stabilizing base film in the same manner as above to form a stabilizing film with a laminated structure, and then the second material part is preferably formed on the surface of this stabilizing film.

In the present invention, a composite comprising a first material portion, a second material portion, and a stabilizing layer disposed therebetween suppresses problems such as chemical reactions and element diffusion that may occur between the first and second inorganic materials, which are different from each other in the past. Therefore, the composite can be widely used as an article with excellent structural stability without degrading the properties of the first and second inorganic materials. For example, the composite is considered useful for components of various electronic devices, heat-generating components, and the like, which have a bonded interface between materials with different chemical properties or a bonded interface between highly reactive materials, such as a combination of a nitride with a non-nitride such as an oxide or metal, a combination of a silicon-containing compound with an oxide, or a combination of an acidic material that reacts with a base to produce a salt with a basic material that reacts with an acid to produce a salt.

Next, the present invention will be explained in more detail using examples, but these are merely illustrative and do not limit the present invention.

Example 1
In this example, a paste containing CuO particles and _Al2O3 particles (a stabilization layer _{forming material containing Al2CuO4 )} was printed on a silicon _nitride ( _Si3N4 ) substrate, which has high thermal conductivity and is expected to be a heat dissipation substrate for next-generation power _{semiconductors} , and the paste was heated and sintered to form an _Al2CuO4 film. Then, a conductive oxide layer forming material containing conductive _{oxide CaCu3Ru4O12 ,} which has a _perovskite crystalline structure and is known to have metallic electrical conductivity, and _{CuO ,} a sintering aid that promotes sintering, was printed on the surface of the Al2CuO4 film and sintered by heating. A composite (hereinafter referred to as "composite (C1)") was produced in which a stabilization layer containing a compound represented by general formula (1) according to the present invention was interposed between the substrate and the conductive oxide layer, and the composite was evaluated.

First, we will explain the stabilization layer-forming material printed on the surface of a silicon nitride substrate. CuO particles and _{Al2O3 particles} were mixed so that the CuO content was 32 volume % to obtain a 32 volume % CuO-containing _Al2O3 mixed powder. Next, the resulting mixed powder was mixed with a dispersion medium mainly composed of terpineol to obtain _a 32 volume % CuO _- containing _Al2O3 paste, which is the stabilization layer-forming material.

The resulting paste (stabilizing layer forming material) was then applied to the surface of the silicon nitride substrate by screen printing using a rubber squeegee and a stainless steel mesh screen to form a paste film.

Next, the obtained paste film was heated in air at 200°C for 30 minutes to remove the dispersion medium, and then further heated to 1000°C in air for 3 hours to react and sinter _CuO and _Al2O3 , thereby obtaining a laminate in which the sintered film was adhered closely to the surface of the silicon nitride substrate.

The sintered film of the obtained laminate was subjected to X-ray diffraction measurement (ray source: CuKα) using a fully automatic multipurpose X-ray diffractometer "SmartLab" (model name) manufactured by Rigaku Co., Ltd. The X-ray diffraction pattern is shown in FIG.
According to this, the diffraction pattern had diffraction peaks of Al ₂ CuO ₄ in addition to the diffraction peaks of silicon nitride constituting the substrate, and it was found that the substrate had a spinel structure.

Then, a conductive oxide layer-forming material was screen-printed on the surface of the sintered film ( _{Al2CuO4 film} ) of the laminate. This conductive oxide layer-forming material was a _CaCu3Ru4O12 paste containing 30 _% by volume of CuO, which was obtained by mixing _{CaCu3Ru4O12 particles} and _CuO particles synthesized by a solid-state reaction method so that the CuO content was ₃₀ % by volume, and mixing _this with a dispersion medium mainly _{containing terpineol} .

Next, the obtained _CaCu3Ru4O12 paste (conductive oxide layer forming material) containing 30 _% by volume of CuO was applied by screen printing to the surface of the _Al2CuO4 film formed on the silicon nitride substrate using a _{rubber squeegee} and a stainless steel mesh screen to form a conductive paste film.

The resulting conductive paste film was then heat-treated in air at 200°C for 30 minutes to remove the dispersion medium, and then further heated and sintered in air at 1000°C for 12 hours to produce a composite (C1 ₎ having, in order, _four layers of _Al2CuO and _twelve layers of _CaCu3Ru4O containing 30% by volume of CuO on the surface of the silicon nitride substrate.

The X-ray diffraction pattern of the sintered film of CaCu ₃ Ru ₄ O ₁₂ containing 30% by volume of CuO in the obtained composite (C1) is shown in FIG.
This shows that most of the _CaCu3Ru4O12 is sintered without decomposition. In Fig. 5, a peak attributable to _RuO2 is observed, but _the amount is extremely _small . This _RuO2 is not the result of a reaction between _{CaCu3Ru4O12 and Al2CuO4} , but _is also produced, for example, when _{a CaCu3Ru4O12 film} is directly formed on a sinterable aluminum oxide substrate _and then heated at _a high temperature for sintering.

The cross section of the obtained composite (C1) was observed using a scanning electron microscope "JSM-6335FM" (model name) manufactured by JEOL Ltd. The photographed image is shown in FIG.
According to this, an Al ₂ CuO ₄ layer 62 and a sintered film 63 of CaCu ₃ Ru ₄ O ₁₂ containing 30 volume % CuO are formed in this order on the surface of a silicon nitride substrate 61. The thickness of the Al ₂ CuO ₄ layer 62 measured from Fig. 6 was 13.5 µm.

(Comparative Example 1)
The same procedure as in Example 1 was carried out except that the Al ₂ CuO ₄ layer was not formed, and an attempt was made to form a 30 volume % CuO-containing CaCu ₃ Ru ₄ O ₁₂ sintered film on the surface of a silicon nitride substrate, thereby obtaining a composite (hereinafter referred to as "composite (D1)").

The X-ray diffraction pattern of the sintered film of CaCu ₃ Ru ₄ O ₁₂ containing 30% by volume of CuO in the obtained composite (D1) is shown in FIG.
According to this, no peaks reflecting CaCu ₃ Ru ₄ O ₁₂ are observed, and it is understood that all of CaCu ₃ Ru ₄ O ₁₂ has decomposed, and RuO ₂ has been produced.

The present inventors speculate as follows about the cause of the decomposition of CaCu ₃ Ru ₄ O ₁₂ in the composite (D1).

One reason is that when sintered in air at 1000°C for 12 hours, silicon nitride deprives _{CaCu3Ru4O12 of oxygen at the interface between the silicon nitride and CaCu3Ru4O12 , oxidizing it} and changing it to silicon dioxide, and at this time, _{CaCu3Ru4O12 , which} has lost oxygen, is unable to maintain _its crystal structure and decomposes. In other words, when there is an interface between a nitride such as silicon nitride and an oxide, when heat treatment such as high-temperature sintering is performed in air, the oxygen constituting the oxide is deprived by the nitride, and the oxide is unable to maintain its crystal structure and decomposes.

One reason for this is that silicon constituting the silicon nitride of the substrate and Ca and Cu constituting _CaCu3Ru4O12 undergo a chemical reaction during sintering in air at 1000°C for 12 hours, forming _impurities such as _{CaCuSi4O10 .} At this time, _CaCu3Ru4O12 , which has lost its Ca and Cu, _is unable to maintain its crystalline structure and _decomposes . In other words, because silicon can react with various elements to form compounds, in the case of an interface between a silicon-containing material and an oxide, when _heat treatment such as high-temperature sintering is performed in air, the silicon reacts with the elements constituting the oxide, and the oxide, which has lost its constituent elements, is unable to maintain its crystalline structure and decomposes.

Furthermore, at the interface between a material containing silicon, an acidic material that reacts with bases to produce silicates, and a basic material containing Ca, which reacts with hydrochloric acid to produce calcium chloride, or Cu, which reacts with nitric acid to produce copper nitrate, this is a highly reactive combination of materials, and the oxide, which has lost its constituent elements due to this reaction, is unable to maintain its crystalline structure and decomposes.

On the other hand, in Example 1, in which an Al ₂ CuO ₄ layer was interposed between a silicon nitride substrate and a sintered film of CaCu ₃ Ru ₄ O ₁₂ containing 30% CuO by volume, which is a conductive oxide, was formed, CaCu ₃ Ru ₄ O ₁₂ did not decompose. Therefore, the following phenomena, as in Comparative Example 1, are considered to occur: (1) when there is an interface between a nitride (silicon nitride) and an oxide, oxygen constituting the oxide is taken by the nitride when heat treatment such as high-temperature sintering is performed in the atmosphere, and the oxide is unable to maintain its crystal structure and decomposes; (2) when there is an interface between a silicon-containing material and an oxide, elements constituting the oxide react with silicon, and the oxide that has lost its constituent elements is unable to maintain its crystal structure and decomposes when heat treatment such as high-temperature sintering is performed in the atmosphere; and (3) when there is an interface between an acidic material and a basic material, the oxide that has lost its constituent elements due to the reaction is unable to maintain its crystal structure and decomposes because of a combination of _highly reactive materials. ₄ was found to be suppressed.

Example 2
A composite (hereinafter referred to as "composite ( _C2 )") having, in order, _{an Al2CuO4} layer and a _{CaCu3Ru4O12 layer} containing 30 volume % CuO on the surface of the silicon dioxide substrate was produced by the same procedure as in Example ₁ , except that a silicon dioxide (SiO2) substrate was used instead of the silicon _nitride substrate. The X-ray diffraction pattern of the 30 volume % CuO-containing _{CaCu3Ru4O12 sintered} film in the obtained composite (C2) is shown in Figure 8.
This shows that most of the _CaCu3Ru4O12 was sintered without decomposition. In Fig. 8, a peak attributable to _RuO2 is observed, but _the amount is extremely small. This _RuO2 is not the result of a reaction _{between CaCu3Ru4O12 and Al2CuO4} , but _is also produced, for example, when _{a CaCu3Ru4O12 film} is directly formed on a sinterable aluminum oxide substrate _and then heated at _a high temperature for sintering.

(Comparative Example 2)
The same procedure as in Example 2 was carried out except that the Al ₂ CuO ₄ layer was not formed, and an attempt was made to form a 30 volume % CuO-containing CaCu ₃ Ru ₄ O ₁₂ sintered film on the surface of a silicon dioxide substrate, thereby obtaining a composite (hereinafter referred to as "composite (D2)").

The X-ray diffraction pattern of the sintered film of CaCu ₃ Ru ₄ O ₁₂ containing 30% by volume of CuO in the obtained composite (D2) is shown in FIG.
According to this, peaks reflecting CaCu ₃ Ru ₄ O ₁₂ were observed, but peaks reflecting RuO ₂ were also observed, so it is believed that part of CaCu ₃ Ru ₄ O ₁₂ had decomposed.

The present inventors speculate as follows about the cause of decomposition of CaCu ₃ Ru ₄ O ₁₂ in the composite (D2).

One reason is that silicon that constitutes silicon dioxide and Ca and Cu that constitute _CaCu3Ru4O12 undergo a chemical reaction during sintering in air at 1000°C for 12 hours, forming _impurities such as _{CaCuSi4O10 .} At this time, _CaCu3Ru4O12 , which has lost its Ca _and Cu, is unable to maintain its crystalline structure and decomposes. In _other words, because silicon can react with various elements to form compounds, when there is an interface between a silicon-containing material and an oxide, during heat treatment such as high-temperature sintering in air, the _silicon reacts with the elements that constitute the oxide, and the oxide that has lost its constituent elements is unable to maintain its crystalline structure and decomposes.

One reason is that the interface between a silicon-containing material, such as silicon dioxide, which is an acidic material that reacts with bases to produce silicates, and a basic material that contains calcium, which reacts with hydrochloric acid to produce calcium chloride, or copper, which reacts with nitric acid to produce copper nitrate, is a highly reactive combination of materials, and the oxide loses its constituent elements as a result of this reaction, making it unable to maintain its crystalline structure and causing it to decompose.

On the other hand, in Example 2, in which an Al ₂ CuO ₄ layer was interposed between a silicon dioxide substrate and a sintered film of CaCu ₃ Ru ₄ O ₁₂ containing 30 volume % CuO, which is a conductive oxide, was formed, CaCu ₃ Ru ₄ O ₁₂ did not decompose, which shows that the following phenomenon, as seen in Comparative Example 2: (1) when there is an interface between a silicon-containing material and an oxide, when heat treatment such as high-temperature sintering is performed in the atmosphere, the elements constituting the silicon and the oxide react, and the oxide that has lost the constituent elements is unable to maintain its crystal structure and decomposes; and _{( 2} ) when there is an interface between an acidic material and a basic material, when a combination of highly reactive materials is used, the oxide that has lost the constituent elements is unable to maintain its crystal structure and decomposes due to the reaction.

Example 3
In this example, the same operations as in Example 1 were carried out except that an Al ₂ CuO ₄ layer was formed on the surface of the silicon nitride substrate by pulsed laser deposition, and an Al ₂ CuO ₄ layer and a sintered film of a conductive oxide material, CaCu ₃ Ru ₄ O _12, containing 30 volume % CuO, were formed on the surface of the silicon nitride substrate, thereby obtaining a composite (hereinafter referred to as “composite (C3)”).

The target material used in the pulsed laser deposition method was an Al2CuO4 sintered body obtained by mixing CuO particles and _{Al2O3 particles} so that the molar ratio of Al element to Cu element was Al _: Cu = 2: ₁ , pressurizing the obtained mixed powder, and then heating it in air at 1000°C for ₁₂ hours to react and sinter the CuO and _Al2O3 .

Using a closed vapor deposition system, an _Al2CuO4 film was formed on the surface of a silicon nitride substrate placed in the system by the following method. Specifically, using a _fourth -harmonic Nd:YAG laser with a wavelength of 266 nm, the laser was irradiated onto _{an Al2CuO4} sintered compact target in a vacuum at room temperature, vapor-depositing _Al2CuO4 to obtain a laminate with _{an Al2CuO4} film on the surface of the silicon nitride substrate. This laminate was then heated in air at 1000°C for 1 hour to obtain _a laminate with an _{Al2CuO4 sintered} film.
Thereafter, the same operation as in Example 1 was carried out using a CaCu ₃ Ru ₄ O ₁₂ paste containing 30% by volume of CuO (conductive oxide layer forming material), to obtain a composite (C3).

The X-ray diffraction pattern of the sintered film of CaCu ₃ Ru ₄ O ₁₂ containing 30% by volume of CuO in the obtained composite (C3) is shown in FIG.
This shows that most of _{the CaCu3Ru4O12} was sintered without decomposition. In Fig. 10, as in Fig. 5 of Example 1, a peak derived from _RuO2 is observed, but the amount is extremely small _. Therefore, even in the method of forming a 30 volume % CuO-containing _{CaCu3Ru4O12 sintered} film on _{an Al2CuO4} film formed on a silicon nitride substrate by pulsed laser deposition, it is found that the following phenomena are suppressed by the _Al2CuO4 constituting the stabilizing layer: (1) when there is an interface between a nitride such as silicon nitride and an oxide, when heat treatment such as high-temperature sintering is performed in the atmosphere, the oxygen constituting the oxide is taken by the nitride, and the oxide is unable to maintain its crystal structure and decomposes; (2) when there is an interface between a silicon-containing material and an oxide, when heat treatment such as high-temperature sintering is performed in the atmosphere, the elements constituting the oxide react with the silicon, and the oxide that has lost its constituent elements is unable to maintain its crystal structure and decomposes; and (3) when there is an interface between an acidic material and a basic material, when the combination of highly reactive materials causes the oxide that has lost its constituent elements due to the _reaction , is unable to maintain its _crystal structure and decomposes.

Furthermore, the cross section of the obtained composite (C3) was observed, and the image shown in FIG. 11 was obtained.
According to this, an Al ₂ CuO ₄ layer 82 and a sintered film 83 of CaCu ₃ Ru ₄ O ₁₂ containing 30 volume % CuO are formed in this order on the surface of a silicon nitride substrate 81. The thickness of the Al ₂ CuO ₄ layer 82 measured from FIG. 11 was 1.9 μm.

Example 4
In this example, the stabilizing layer-forming material used in Example 1 (a paste containing CuO particles and _{Al2O3 particles} ) was printed on a silicon dioxide ( _SiO2 ) substrate, followed by heat sintering to form an _{Al2CuO4 film} . Then, a paste (copper oxide superconducting layer-forming material ₎ containing particles of _{SmBa2Cu3Oy ,} which has an oxygen-deficient layered perovskite crystal structure and is known as a copper oxide superconducting material, was printed on the surface of the _Al2CuO4 film, followed by heat sintering to produce a composite (hereinafter referred to as "composite ( _C4 )") in which a stabilizing layer containing a compound represented by general formula (1) according to the present invention was interposed between the substrate and the copper oxide superconducting layer, and the composite was then evaluated.

First, the stabilizing layer-forming material (paste containing CuO particles and _{Al2O3 particles} ) was screen-printed on the surface of a silicon dioxide substrate to form a paste film in the same manner as in Example 1. Then, heating and firing were carried out to obtain a laminate in which the sintered film was adhered closely to the surface of the silicon dioxide substrate.

Then, a copper oxide superconducting layer-forming material was screen-printed on the surface of the sintered film ( _{Al2CuO4 film} ) of the laminate. This copper oxide superconducting layer-forming material was a _{SmBa2Cu3Oy paste} obtained by mixing _{SmBa2Cu3Oy particles} synthesized by a solid-state reaction method with a dispersion medium mainly composed of _{terpineol .}

Next, the obtained _{SmBa2Cu3Oy paste} (copper oxide superconducting layer forming material) was _applied by screen printing to the surface of the _Al2CuO4 film formed on the silicon dioxide substrate using a rubber squeegee and _a stainless steel mesh screen to form a paste film.

The resulting paste film was then heat-treated in air at 200°C for 30 minutes to remove the dispersion medium, and then further heated to 950°C in air for 12 hours for sintering, producing a composite (C4) having _{an Al2CuO4} layer and _{a SmBa2Cu3Oy layer} , successively, on the surface of a silicon dioxide substrate.

The X-ray diffraction pattern of the SmBa ₂ Cu ₃ O _y sintered film in the obtained composite (C4) is shown in FIG.
According to this, although there are peaks that are thought to be _{due to} the _{decomposition of} some _SmBa2Cu3Oy to _{form Sm2CuO4 ,} it is clear that the majority of _SmBa2Cu3Oy is sintered without decomposition. Note that the amount of _Sm2CuO4 is extremely small compared to the _amount of _{remaining SmBa2Cu3Oy} .

(Comparative Example 3)
The same procedure as in Example 4 was carried out except that the Al ₂ CuO ₄ layer was not formed, and an attempt was made to form a SmBa ₂ Cu ₃ O _y sintered film on the surface of a silicon dioxide substrate, thereby obtaining a composite (hereinafter referred to as "composite (D3)").

The X-ray diffraction pattern of the SmBa ₂ Cu ₃ O _y sintered film in the obtained composite (D3) is shown in FIG.
According to this, peaks due to Sm ₃ Ba ₃ Cu ₆ O _14.1 and Sm ₂ CuO ₄ were detected, which indicates that the copper oxide superconducting material SmBa ₂ Cu ₃ O _y decomposed to produce the decomposition products Sm ₃ Ba ₃ Cu ₆ O _14.1 and Sm ₂ CuO ₄ .

The present inventors speculate as follows about the cause of decomposition of SmBa ₂ Cu ₃ O _y in the composite (D3).

One reason is that silicon constituting the silicon dioxide of the substrate and Ba and Cu constituting _SmBa2Cu3Oy undergo a chemical reaction to form _Cu3.17Si , _{Ba2SiO4 , etc.} during sintering in air at 950°C for ₁₂ hours, and _SmBa2Cu3Oy , which has lost its Ba and Cu, is unable to maintain its crystal structure _{and decomposes} . In other words, because silicon can react with various elements to form compounds, in cases where there is an interface between a silicon-containing material and an oxide, when heat treatment such as high-temperature sintering is performed in air, the silicon reacts with the elements constituting the oxide, and the oxide, which has lost its constituent elements, is unable to maintain its crystal structure and decomposes.

One reason is that the interface between a silicon-containing material, such as silicon dioxide, which is an acidic material that reacts with bases to produce silicates, and a basic material that contains Ba, which reacts with acids to produce barium salts, or Cu, which reacts with nitric acid to produce copper nitrate, is a highly reactive combination of materials, and the oxide loses its constituent elements as a result of this reaction, making it unable to maintain its crystalline structure and causing it to decompose.

On the other hand, in Example 4, in which an Al ₂ CuO ₄ layer was interposed between a silicon dioxide substrate and a SmBa ₂ Cu ₃ O _y sintered film, which is a copper oxide superconducting material, was formed, SmBa ₂ Cu ₃ O _y did not decompose, which shows that the following phenomena, as seen in Comparative Example 3: (1) when there is an interface between a silicon-containing material and an oxide, when heat treatment such as high-temperature sintering is performed in the atmosphere, elements constituting the silicon and the oxide react, and the oxide that has lost the constituent elements is unable to maintain its crystal structure and decomposes; and ( _{2 )} when there is an interface between an acidic material and a basic material, when a combination of highly reactive materials is used, the oxide that has lost the constituent elements is unable to maintain its crystal structure and decomposes.

Example 5
In this example, a stabilizing layer-forming material (a paste containing CuO particles and _{Al2O3 particles} ) different from that used in Example 1 etc. was printed on a silicon nitride substrate, followed by heat sintering to form _{an Al2O3 -} containing _Al2CuO4 film. Thereafter, the conductive oxide layer-forming material containing _{CaCu3Ru4O12 and CuO} used in Example 1 was printed on the surface of this _{Al2O3 -} containing _Al2CuO4 film, followed by heat sintering to produce a composite (hereinafter referred to as _" composite (C5)") in which a stabilizing layer containing the compound represented by general formula ( ₁ ) according to the present invention and aluminum oxide ( _Al2O3 ) was interposed between the substrate and the conductive oxide layer, and the composite was evaluated.

First, we will explain the stabilization layer-forming material printed on the surface of a silicon nitride substrate. CuO particles and _{Al2O3 particles} were mixed so that the CuO content was 20 volume % to obtain a 20 volume % _CuO -containing _Al2O3 mixed powder. Next, the resulting mixed powder was mixed with a dispersion medium mainly composed of terpineol to obtain a 20 volume % CuO _- containing _Al2O3 paste, which is the stabilization layer-forming material.

Thereafter, the obtained Al ₂ O ₃ paste containing 20% by volume of CuO (stabilizing layer forming material) was applied to the surface of the silicon nitride substrate by screen printing using a rubber squeegee and a stainless steel mesh screen to form a paste film.

Next, the obtained paste film was heated in air at 200°C for 30 minutes to remove the dispersion medium, and then further heated to 1000°C in air for 3 hours to react and sinter _CuO and _Al2O3 , thereby obtaining a laminate in which the sintered film was adhered closely to the surface of the silicon nitride substrate.

The X-ray diffraction pattern of the sintered film of the resulting laminate is shown in FIG.
According to this, it was found that the diffraction pattern had, in addition to the diffraction peaks of silicon _nitride constituting the substrate, diffraction peaks of _Al2CuO4 produced by the reaction of _CuO and _Al2O3 , and diffraction peaks _{of Al2O3} that remained uninvolved in the reaction. In other words, it was found that the sintered film contained _Al2CuO4 formed by the reaction of _CuO particles and _{Al2O3 particles} during sintering, and _{Al2O3 .} As described above, this sintered film is called an " _{Al2O3 -} containing _{Al2CuO4 film} ."

Thereafter, the conductive oxide layer forming material used in Example 1 was screen printed on the surface of the sintered film of the above laminate (Al ₂ O ₃ -containing Al ₂ CuO ₄ film).
That is, the conductive oxide layer forming material was applied to the surface of the Al ₂ O ₃ -containing Al ₂ CuO ₄ film by screen printing using a rubber squeegee and a stainless steel mesh screen to form a conductive paste film.

The resulting conductive paste film was then heat-treated in air at 200°C for 30 minutes to remove the dispersion medium, and the temperature was further increased to 1000°C for 12 hours for sintering, producing a composite (C5) having, on the surface of the silicon nitride substrate, an _{Al2O3 -} containing _{Al2CuO4 layer} and a _{30% by volume CuO-containing CaCu3Ru4O12 layer ,} in that order.

The X-ray diffraction pattern of the sintered film of CaCu ₃ Ru ₄ O ₁₂ containing 30% by volume of CuO in the obtained composite (C5) is shown in FIG.
This shows that most of the CaCu ₃ Ru ₄ O ₁₂ is sintered without decomposition. Also, in Fig. 15, a peak derived from RuO ₂ is observed, but it is only a very small amount. Therefore, even when the stabilization layer contains other materials in addition to Al ₂ CuO ₄ , which is the compound represented by the general formula (1) according to the present invention, it is found that the following phenomena are suppressed by Al 2 CuO 4 constituting the stabilization layer: (1) when there is an interface between a nitride (silicon nitride) and an oxide, oxygen constituting the oxide is taken by the nitride when heat treatment such as high-temperature sintering is performed in the atmosphere, causing the oxide to be unable to maintain its crystal structure and to decompose; (2) when there is an interface between a silicon-containing material and an oxide, elements constituting the oxide react with silicon, causing the oxide from which the constituting elements have been taken to be unable to maintain its crystal structure and to decompose when heat treatment such as high-temperature sintering is performed in the atmosphere; and (3) when there is an interface between an acidic material and a basic _material , due to the combination of highly reactive materials, the oxide from which the constituting elements have been taken to be unable to maintain its _crystal structure and to decompose.

Example 6
In this example, a composite (hereinafter referred to as "composite (C6)") was produced and evaluated, which had, on the surface of a silicon nitride substrate, a reinforcing layer containing _CuO , a stabilizing layer containing _Al2CuO4 , which is a compound represented by general formula (1) according to the present invention, a reinforcing layer containing CuO, _and a conductive oxide _layer containing _CaCu3Ru4O12 , in that order.

To form the two reinforcing layers, a CuO paste was used, obtained by mixing CuO particles with a dispersion medium whose main component is terpineol.

First, the CuO paste was applied to the surface of the silicon nitride substrate by screen printing using a rubber squeegee and a stainless steel mesh screen to form a paste film for the reinforcing layer.

Next, the resulting reinforcing layer paste film was heated in air at 200°C for 30 minutes to remove the dispersion medium. The temperature was then further increased to 1,020°C in air for 3 hours for sintering, forming a first reinforcing film made of CuO on the surface of the silicon nitride substrate.

Thereafter, the stabilizing layer forming material used in Example 1, Al ₂ O ₃ paste containing 32% by volume of CuO, was applied to the surface of the first reinforcing film made of CuO by screen printing using a rubber squeegee and a stainless steel mesh screen to form a paste film.

Next, the obtained paste film was heated in air at 200°C for 30 minutes to remove the dispersion medium, and then further heated to 1000°C in air for 12 hours to react and sinter _CuO and _Al2O3 , thereby obtaining a laminate in which an _{Al2CuO4 sintered} film was adhered to the surface of the first reinforcing film.

Thereafter, a CuO paste for forming a reinforcing layer was applied to the surface of the sintered film (Al ₂ CuO ₄ film) of the laminate by screen printing in the same manner as described above, and a paste film was formed by heating and sintering to form a second reinforcing film made of CuO.

Next, the same operation as in Example ₁ was carried out using _{a CaCu3Ru4O12} paste containing 30% by volume of CuO (conductive oxide layer-forming material), to obtain a composite (C6) (see Figure 16). That is, Figure 16 is a cross-sectional image of the composite (C6) taken by SEM, and it can be seen that the composite (C6) is a stable laminated structure having, on the surface of a silicon nitride substrate 131, a reinforcing layer ₁₃₂ containing CuO derived from the first reinforcing film, a stabilizing layer 133 containing _Al2CuO4 , a reinforcing layer ₁₃₄ containing CuO derived from the second reinforcing film, and a conductive oxide layer ₁₃₅ containing _CaCu3Ru4O12 , in that order.

The X-ray diffraction pattern of the sintered film of CaCu ₃ Ru ₄ O ₁₂ containing 30% by volume of CuO in the obtained composite (C6) is shown in FIG.
According to this, the X-ray diffraction pattern is very similar to that of the composite (C1) obtained in Example 1, _and it can be seen _that even in a structure in which a reinforcing layer containing CuO is adjacent to a conductive oxide _layer containing _CaCu3Ru4O12 , most of _CaCu3Ru4O12 is sintered without decomposition. Also in Figure ₁₇ , peaks derived from _RuO2 are seen, but only in very small amounts. Therefore, it can be seen that even in the composite (C6) having not only a stabilization layer containing Al ₂ CuO ₄ but also a reinforcing layer between the silicon nitride substrate and the stabilization layer containing Al ₂ CuO ₄ and between the stabilization layer and the conductive oxide layer, it is possible to prevent the following phenomena: (1) when an interface between a nitride (silicon nitride) and an oxide is present, oxygen constituting the oxide is taken by the nitride, and the oxide is unable to maintain its crystal structure and decomposes when heat treatment such as high-temperature sintering is performed in the atmosphere; (2) when an interface between a silicon-containing material and an oxide is present, silicon reacts with elements constituting the oxide, and the oxide that has lost its constituent elements is unable to maintain its crystal structure and decomposes when heat treatment such as high-temperature sintering is performed in the atmosphere; and (3) when an interface between an acidic material and a basic material is present, the oxide that has lost its constituent elements due to the reaction is unable to maintain its crystal structure and decomposes because of a combination of highly reactive materials.

Furthermore, to confirm the effectiveness of the reinforcing layer of composite (C6), a test was conducted in which adhesive tape was attached to and removed from the surface of the conductive oxide layer. No interfacial peeling was observed, demonstrating that composite (C6) is a strongly integrated product.

(Comparative Example 4)
In this example, a composite (hereinafter referred to as "composite (D4)") was prepared by sequentially forming a CuO layer and a conductive oxide layer containing CaCu ₃ Ru ₄ O ₁₂ on the surface of a silicon nitride substrate.
The CuO layer was formed using the same CuO paste as in Example 6. The conductive oxide layer was formed using the same _CaCu3Ru4O12 paste (conductive oxide layer-forming material) containing ₃₀ % by volume of CuO as in Example ₁ .

First, the CuO paste was applied to the surface of a silicon nitride substrate, and then the same operation as in Example 6 was carried out to form a CuO film.
Next, the CaCu ₃ Ru ₄ O ₁₂ paste containing 30% by volume of CuO was applied to the surface of the CuO film, and then the same operation as in Example 1 was carried out to form a conductive oxide sintered film, thereby obtaining a composite (D4).

The X-ray diffraction pattern of the conductive oxide sintered film in the obtained composite (D4) is shown in FIG.
This shows _that no diffraction peaks reflecting _CaCu3Ru4O12 contained in the conductive oxide layer-forming material are observed, but diffraction peaks reflecting _RuO2 are observed, which indicates that all of this _CaCu3Ru4O12 has decomposed. Therefore, it is clear that when only CuO _is present, _it does not exert its effect as _a stabilizing layer that suppresses the chemical reaction that occurs between the silicon _nitride substrate and the conductive oxide material _{CaCu3Ru4O12 .}

Example 7
In this example, a paste containing _{Co3O4 particles} and _{Al2O3 particles} (a material for forming a stabilizing layer containing _{Al2CoO4 )} was printed on a silicon _nitride substrate, followed by heat sintering to form an _Al2CoO4 film. Then, _CaCu3Ru4O12 containing 30% by volume of CuO was printed on the surface of this _{Al2CoO4 film} , followed by heat sintering to produce a _composite (hereinafter referred to as _" composite (C7)") in which a stabilizing layer containing the compound represented by general formula (1) according to the present invention was interposed between the substrate and the conductive oxide layer, and the composite was evaluated.

First, we will explain the stabilization layer-forming material printed on the surface of a silicon nitride substrate. _{Co3O4 particles} and _{Al2O3 particles} were mixed so that the _Co3O4 content was 44 mass% to obtain a 44 mass% _{Co3O4 -} containing _Al2O3 mixed powder. The resulting mixed powder was then mixed with a dispersion medium primarily composed of terpineol to obtain _a 44 mass% _{Co3O4 -} containing _{Al2O3 paste} , which is the stabilization layer _- forming material.

The resulting paste (stabilizing layer forming material) was then applied to the surface of the silicon nitride substrate by screen printing using a rubber squeegee and a stainless steel mesh screen to form a paste film.

Next, the obtained paste film was heated in air at 200°C for 30 minutes to remove the dispersion medium, and then further heated to 1000°C in air for 2 hours to react and sinter _{Co3O4 and Al2O3} , thereby obtaining a laminate in _which the sintered film was adhered closely to the surface of the silicon nitride substrate.

The X-ray diffraction pattern of the sintered film of the resulting laminate is shown in FIG.
According to this, the diffraction pattern had diffraction peaks of Al ₂ CoO ₄ in addition to the diffraction peaks of silicon nitride that constitutes the substrate, and it was found that the substrate had a spinel structure.

Thereafter, _{a CaCu3Ru4O12 paste} containing 30% by volume of CuO (a conductive oxide layer forming material) was applied by screen printing to the surface of the _Al2CoO4 film formed on the silicon _nitride substrate using a rubber squeegee and a stainless steel mesh screen to form a conductive paste film.

The resulting conductive paste film was then heat-treated in air at 200°C for 30 minutes to remove the dispersion medium, and then further heated and sintered in air at 1000°C for 2 hours to produce a composite (C7 ₎ having, in order on the surface of a silicon nitride substrate, _four layers of _Al2CoO and _twelve layers of _CaCu3Ru4O containing 30% by volume of CuO.

The X-ray diffraction pattern (not shown) of the sintered film of the resulting composite (C7) containing ₃₀ % CuO by volume _{, CaCu3Ru4O12} , showed that most of the _CaCu3Ru4O12 was sintered without decomposition. Furthermore, _a peak attributable _{to RuO2} was observed, but only in trace amounts. This _RuO2 is not the result of a reaction _{between CaCu3Ru4O12} and _Al2CoO4 , but is also produced, for example, by forming _{a CaCu3Ru4O12} film directly on a sinterable aluminum oxide substrate and _then heating and sintering _it at a high temperature _.

(Example 8)
In this example, a paste containing MgO particles and Al ₂ O ₃ particles (a material for forming a stabilizing layer containing Al ₂ MgO ₄ ) was printed on a silicon nitride substrate, followed by heat sintering to form an Al ₂ MgO ₄ film. Then, CaCu ₃ Ru ₄ O ₁₂ containing 30% by volume of CuO was printed on the surface of this Al ₂ MgO ₄ film, followed by heat sintering to produce a composite (hereinafter referred to as "composite (C8)") in which a stabilizing layer containing the compound represented by general formula (1) according to the present invention was interposed between the substrate and the conductive oxide layer, and the composite was evaluated.

First, we will explain the stabilization layer-forming material printed on the surface of a silicon nitride substrate. MgO particles and _{Al2O3 particles} were mixed so that the MgO content was 28 mass% to obtain a 28 mass% MgO-containing _Al2O3 mixed powder. Next, the resulting mixed powder was mixed with a dispersion medium mainly composed of _terpineol to obtain a ₂₈ mass% MgO-containing _Al2O3 paste, which is the stabilization layer-forming material.

The resulting paste (stabilizing layer forming material) was then applied to the surface of the silicon nitride substrate by screen printing using a rubber squeegee and a stainless steel mesh screen to form a paste film.

Next, the obtained paste film was heat-treated in air at 200°C for 30 minutes to remove the dispersion medium, and then the temperature was further increased to 1100°C for 2 hours in air to react and sinter the _MgO and _Al2O3 , thereby obtaining a laminate in which the sintered film was adhered closely to the surface of the silicon nitride substrate.

The X-ray diffraction pattern of the sintered film of the resulting laminate is shown in FIG.
According to this, the diffraction pattern had diffraction peaks of Al ₂ MgO ₄ in addition to the diffraction peaks of silicon nitride that constitutes the substrate, and it was found that the substrate had a spinel structure.

Thereafter, _{a CaCu3Ru4O12 paste} containing 30% by volume of CuO (a conductive oxide layer forming material) was applied by screen printing to the surface of the _Al2MgO4 film formed on the silicon nitride substrate using a rubber squeegee and a stainless steel _mesh screen to form a conductive paste film.

The resulting conductive paste film was then heat-treated in air at 200°C for 30 minutes to remove the dispersion medium, and then further heated and sintered in air at 1000°C for 2 hours to produce a composite (C8 ₎ having, in order on the surface of a silicon nitride substrate, _four layers of _Al2MgO and _twelve layers of _CaCu3Ru4O containing 30% by volume of CuO.

The X-ray diffraction pattern (not shown) of the sintered film of the resulting composite (C8) containing ₃₀ % CuO by volume _{, CaCu3Ru4O12} , showed that most of the _CaCu3Ru4O12 was sintered without decomposition. Furthermore, _a peak attributable _{to RuO2} was observed, but only in trace amounts. This _RuO2 is not the result of a reaction _{between CaCu3Ru4O12} and _Al2MgO4 , but is also produced, for example, by forming _{a CaCu3Ru4O12} film directly on a sinterable aluminum oxide substrate and _then heating and sintering _it at a high temperature _.

Example 9
In this example, a paste containing ZnO particles and Al ₂ O ₃ particles (a material for forming a stabilizing layer containing Al ₂ MgO ₄ ) was printed on a silicon nitride substrate, followed by heat sintering to form an Al ₂ ZnO ₄ film. Then, CaCu ₃ Ru ₄ O ₁₂ containing 30% by volume of CuO was printed on the surface of this Al ₂ ZnO ₄ film, followed by heat sintering to produce a composite (hereinafter referred to as "composite (C9)") in which a stabilizing layer containing the compound represented by general formula (1) according to the present invention was interposed between the substrate and the conductive oxide layer, and the composite was evaluated.

First, we will explain the stabilization layer-forming material printed on the surface of a silicon nitride substrate. ZnO particles and _{Al2O3 particles} were mixed so that the ZnO content was 44 mass% to obtain a 44 mass% ZnO-containing _Al2O3 mixed powder. The resulting mixed powder was then mixed with a dispersion medium primarily composed of terpineol to obtain a ₄₄ mass% ZnO _- containing _Al2O3 paste, which is the stabilization layer-forming material.

The resulting paste (stabilizing layer forming material) was then applied to the surface of the silicon nitride substrate by screen printing using a rubber squeegee and a stainless steel mesh screen to form a paste film.

Next, the obtained paste film was heated in air at 200°C for 30 minutes to remove the dispersion medium, and then further heated to 1000°C in air for 2 hours to react and sinter the _ZnO and _Al2O3 , thereby obtaining a laminate in which the sintered film was adhered closely to the surface of the silicon nitride substrate.

The X-ray diffraction pattern of the sintered film of the obtained laminate is shown in FIG.
According to this, the diffraction pattern had diffraction peaks of Al ₂ ZnO ₄ in addition to the diffraction peaks of silicon nitride that constitutes the substrate, and it was found that the substrate had a spinel structure.

Thereafter, _{a CaCu3Ru4O12 paste} containing 30% by volume of CuO (a conductive oxide layer forming material) was applied by screen printing to the surface of the _Al2ZnO4 film formed on the silicon _nitride substrate using a rubber squeegee and a stainless steel mesh screen to form a conductive paste film.

The resulting conductive paste film was then heat-treated in air at 200°C for 30 minutes to remove the dispersion medium, and then further heated and sintered in air at 1000°C for 2 hours to produce a composite (C9 ₎ having, in order on the surface of a silicon nitride substrate, _four layers of _Al2ZnO and _twelve layers of _CaCu3Ru4O containing 30% by volume of CuO.

The X-ray diffraction pattern (not shown) of the sintered film of the resulting composite (C9) containing ₃₀ % CuO by volume _{, CaCu3Ru4O12} , showed that most of the _CaCu3Ru4O12 was sintered without decomposition. Furthermore, _a peak attributable _{to RuO2} was observed, but only in trace amounts. This _RuO2 is not the result of a reaction _{between CaCu3Ru4O12} and _Al2ZnO4 , but is also produced, for example, by forming _{a CaCu3Ru4O12} film directly on a sinterable aluminum oxide substrate and _then heating and sintering _it at a high temperature _.

Example 10
In this example, a paste containing _{Co3O4 particles} and _{Fe2O3 particles} (a material for forming a stabilization layer containing _{Fe2CO4 )} was printed on a silicon nitride substrate, and the paste was heated and sintered to form _{an Fe2CoO4} film. Then, _CaCu3Ru4O12 containing 30% by volume of CuO was printed on the surface of the _{Fe2CoO4 film} , and the _paste was heated and sintered to produce a composite ₍ hereinafter referred to as "composite (C10)") in which a stabilization layer containing the compound represented by general formula (1) according to the present invention was interposed between the substrate and the conductive oxide layer, and the composite was evaluated.

First, we will explain the stabilization layer-forming material printed on the surface of a silicon nitride substrate. _{Co3O4 particles} and _{Fe2O3 particles} were mixed so that the _Co3O4 content was 33 mass% to obtain a 33 mass% _{Co3O4 -} containing _Fe2O3 mixed powder. The resulting mixed powder was then mixed with a dispersion medium primarily composed of terpineol to obtain _a 33 mass% _{Co3O4 -} containing _{Fe2O3 paste} , which is the _{stabilization} layer-forming material.

The resulting paste (stabilizing layer forming material) was then applied to the surface of the silicon nitride substrate by screen printing using a rubber squeegee and a stainless steel mesh screen to form a paste film.

The resulting paste film was then heated in air at 200°C for 30 minutes to remove the dispersion medium, and then heated further to 1000°C for 2 hours in air to react and _{sinter Co3O4} and _Fe2O3 , resulting in a laminate in _which the sintered film was adhered closely to the surface of the silicon nitride substrate.

The X-ray diffraction pattern of the sintered film of the resulting laminate is shown in FIG.
According to this, the diffraction pattern had a diffraction peak of Fe ₂ CoO ₄ in addition to the diffraction peak of silicon nitride constituting the substrate, and it was found that the substrate had a spinel structure.

Thereafter, a _{CaCu3Ru4O12 paste} containing 30% by volume of CuO (a conductive oxide layer forming material) was applied by screen printing to the surface of the _Fe2CoO4 film formed on the silicon nitride substrate using _a rubber squeegee and a stainless steel _mesh screen to form a conductive paste film.

The resulting conductive paste film was then heat-treated in air at 200°C for 30 minutes to remove the dispersion medium, and the temperature was further increased to 950°C for 2 hours for sintering, producing a composite (C10 ₎ having, in order, _four layers of _Fe2CoO and _twelve layers of _CaCu3Ru4O containing 30% by volume of CuO on the surface of a silicon nitride substrate.

The X-ray diffraction pattern (not shown) of the sintered film of the resulting composite (C10) containing ₃₀ % CuO by volume _{, CaCu3Ru4O12} , showed that most of the _CaCu3Ru4O12 was sintered without decomposition. Furthermore, _a peak attributable _{to RuO2} was observed, but only in trace amounts. This _RuO2 is not the result of a reaction _{between CaCu3Ru4O12} and _Fe2CoO4 , but is also produced, for example, by forming _{a CaCu3Ru4O12} film directly on a sinterable aluminum oxide substrate and _then heating and sintering _it at a high temperature _.

Example 11
In this example, a paste containing CuO particles and _{Fe2O3 particles} (a material for forming a stabilization layer containing _{Fe2CuO4 )} was printed on a silicon nitride substrate, and the paste was heated and sintered to form an _Fe2CuO4 film. Then, _CaCu3Ru4O12 containing 30% by volume of CuO was printed on the surface of the _{Fe2CuO4 film} , and the _paste was heated and sintered to produce a composite ( _hereinafter referred to as _" composite (C11)") in which a stabilization layer containing the compound represented by general formula (1) according to the present invention was interposed between the substrate and the conductive oxide layer, and the composite was evaluated.

First, we will explain the stabilization layer-forming material printed on the surface of a silicon nitride substrate. CuO particles and _{Fe2O3 particles} were mixed so that the CuO content was 33% by mass to obtain a 33% by mass _CuO -containing _Fe2O3 mixed powder. Next, the resulting mixed powder was mixed with a dispersion medium mainly composed of terpineol to obtain a 33% by mass _CuO -containing _Fe2O3 paste, which is the stabilization layer-forming material.

The resulting paste (stabilizing layer forming material) was then applied to the surface of the silicon nitride substrate by screen printing using a rubber squeegee and a stainless steel mesh screen to form a paste film.

Next, the obtained paste film was heated in air at 200°C for 30 minutes to remove the dispersion medium, and then further heated to 1000°C in air for 2 hours to react and sinter _CuO and _Fe2O3 , thereby obtaining a laminate in which the sintered film was adhered closely to the surface of the silicon nitride substrate.

The X-ray diffraction pattern of the sintered film of the resulting laminate is shown in FIG.
According to this, the diffraction pattern had a diffraction peak of Fe ₂ CuO ₄ in addition to the diffraction peak of silicon nitride constituting the substrate, and it was found that the substrate had a spinel structure.

Thereafter, _{a CaCu3Ru4O12} paste containing 30% by volume of CuO (a conductive oxide layer forming material) was applied by screen printing to the surface of the _Fe2CuO4 film formed on the silicon nitride substrate using _a rubber squeegee and a stainless steel _mesh screen to form a conductive paste film.

The resulting conductive paste film was then heat-treated in air at 200°C for 30 minutes to remove the dispersion medium, and then further heated to 950°C for 2 hours for sintering, producing a composite (C11 ₎ having, in order, _four layers of _Fe2CuO and _twelve layers of _CaCu3Ru4O containing 30% by volume of CuO on the surface of a silicon nitride substrate.

The X-ray diffraction pattern (not shown) of the sintered film of the resulting composite (C11) containing ₃₀ % CuO by volume _{, CaCu3Ru4O12} , showed that most of the _CaCu3Ru4O12 was sintered without decomposition. Furthermore, _a peak attributable _{to RuO2} was observed, but only in trace amounts. This _RuO2 is not the result of a reaction between _CaCu3Ru4O12 and _Fe2CuO4 , but is also produced, for example, by forming a _CaCu3Ru4O12 film directly on a sinterable aluminum oxide substrate _{and then} heating and sintering _it at _a high temperature _.

Example 12
In this example, a paste containing MgO particles and _{Fe2O3 particles} (a material for forming a stabilizing layer containing _{Fe2MgO4 )} was printed on a silicon nitride substrate, and the paste was heated and sintered to form an _Fe2MgO4 film. Then, _CaCu3Ru4O12 containing 30 _% by volume of CuO was printed on the surface of the _{Fe2MgO4 film} , and the paste was heated and sintered to produce a composite (hereinafter referred to as _" composite ( _C12 )") in which a stabilizing layer containing the compound represented by general formula (1) according to the present invention was interposed between the substrate and the conductive oxide layer, and the composite was evaluated.

First, we will explain the stabilization layer-forming material printed on the surface of a silicon nitride substrate. MgO particles and _{Fe2O3 particles} were mixed so that the MgO content was 20 mass% to obtain a 20 mass% MgO-containing _Fe2O3 mixed powder. Next, the resulting mixed powder was mixed with a dispersion medium mainly composed of terpineol to obtain _a 20 mass% _MgO -containing _Fe2O3 paste, which is the stabilization layer-forming material.

The resulting paste (stabilizing layer forming material) was then applied to the surface of the silicon nitride substrate by screen printing using a rubber squeegee and a stainless steel mesh screen to form a paste film.

Next, the obtained paste film was heated in air at 200°C for 30 minutes to remove the dispersion medium, and then further heated to 1000°C in air for 2 hours to react and sinter the _MgO and _Fe2O3 , thereby obtaining a laminate in which the sintered film was adhered closely to the surface of the silicon nitride substrate.

The X-ray diffraction pattern of the sintered film of the obtained laminate is shown in FIG.
According to this, the diffraction pattern had a diffraction peak of Fe ₂ MgO ₄ in addition to the diffraction peak of silicon nitride that constitutes the substrate, and it was found that the substrate had a spinel structure.

Thereafter, a _{CaCu3Ru4O12 paste} containing 30% by volume of CuO (a conductive oxide layer forming material) was applied by screen printing to the surface of the _Fe2MgO4 film formed on the silicon nitride substrate using _a rubber squeegee and a stainless steel _mesh screen to form a conductive paste film.

The resulting conductive paste film was then heat-treated in air at 200°C for 30 minutes to remove the dispersion medium, and the temperature was further increased to 1000°C for 2 hours for sintering, producing a composite (C12) having, in order, _four layers of _Fe2MgO and _twelve layers of _CaCu3Ru4O containing ₃₀ % by volume of CuO on the surface of a silicon nitride substrate.

The X-ray diffraction pattern (not shown) of the sintered film of the resulting composite (C12) containing ₃₀ % CuO by volume _{, CaCu3Ru4O12} , showed that most of the _CaCu3Ru4O12 was sintered without decomposition. Furthermore, _a peak attributable _{to RuO2} was observed, but only in trace amounts. This _RuO2 is not the result of a reaction _{between CaCu3Ru4O12 and Fe2MgO4} , but is also produced, for example, by forming a _CaCu3Ru4O12 film directly on a sinterable aluminum oxide substrate and _then heating and sintering _it at a high temperature _.

Example 13
In this example, a paste containing ZnO particles and _{Fe2O3 particles} (a material for forming a stabilization layer containing _{Fe2ZnO4 )} was printed on a silicon nitride substrate, and the paste was heated and sintered to form an _Fe2ZnO4 film. Then, _CaCu3Ru4O12 containing ₃₀ % by volume of CuO was printed on the surface of the _{Fe2ZnO4 film} , and the paste was heated and sintered to produce a composite (hereinafter referred to as _" composite ( _C13 )") in which a stabilization layer containing the compound represented by general formula (1) according to the present invention was interposed between the substrate and the conductive oxide layer, and the composite was evaluated.

First, we will explain the stabilization layer-forming material printed on the surface of a silicon nitride substrate. ZnO particles and _{Fe2O3 particles} were mixed so that the ZnO content was 34 mass% to obtain a 34 mass% ZnO-containing _Fe2O3 mixed powder. The resulting mixed powder was then mixed with a dispersion medium primarily composed of terpineol to obtain a ₃₄ mass% ZnO _- containing _Fe2O3 paste, which is the stabilization layer-forming material.

The resulting paste (stabilizing layer forming material) was then applied to the surface of the silicon nitride substrate by screen printing using a rubber squeegee and a stainless steel mesh screen to form a paste film.

Next, the obtained paste film was heated in air at 200°C for 30 minutes to remove the dispersion medium, and then further heated to 1000°C in air for 2 hours to react and sinter the _ZnO and _Fe2O3 , thereby obtaining a laminate in which the sintered film was adhered closely to the surface of the silicon nitride substrate.

The X-ray diffraction pattern of the sintered film of the obtained laminate is shown in FIG.
According to this, it was found that the diffraction pattern had a diffraction peak of Fe ₂ ZnO ₄ in addition to the diffraction peak of silicon nitride constituting the substrate, and had a spinel structure.

Thereafter, a _{CaCu3Ru4O12 paste} containing 30% by volume of CuO (a conductive oxide layer forming material) was applied by screen printing to the surface of the _Fe2ZnO4 film formed on the silicon nitride substrate using _a rubber squeegee and a stainless steel _mesh screen to form a conductive paste film.

The resulting conductive paste film was then heat-treated in air at 200°C for 30 minutes to remove the dispersion medium, and the temperature was further increased to 950°C for 2 hours for sintering, producing a composite (C13 ₎ having, in order, _four layers of _Fe2ZnO and _twelve layers of _CaCu3Ru4O containing 30% by volume of CuO on the surface of a silicon nitride substrate.

The X-ray diffraction pattern (not shown) of the sintered film of the resulting composite (C13) containing ₃₀ % CuO by volume _{, CaCu3Ru4O12} , showed that most of the _CaCu3Ru4O12 was sintered without decomposition. Furthermore, _a peak attributable _{to RuO2} was observed, but only in trace amounts. This _RuO2 is not the result of a reaction _{between CaCu3Ru4O12} and _Fe2ZnO4 , but is also produced, for example, by forming _{a CaCu3Ru4O12} film directly on a sinterable aluminum oxide substrate and _then heating and sintering _it at a high temperature _.

Example 14
In this example, a paste containing _{Co3O4 particles} and _{Ga2O3 particles} (a material for forming a stabilization layer containing _{Ga2CoO4 )} was printed on a silicon nitride substrate, and the paste was heated and sintered to form _{a Ga2CoO4} film. Then, _CaCu3Ru4O12 containing 30% by volume of CuO was printed on the surface of the _{Ga2CoO4 film} , and the _paste was heated and sintered to produce a composite ₍ hereinafter referred to as "composite (C14)") in which a stabilization layer containing the compound represented by general formula (1) according to the present invention was interposed between the substrate and the conductive oxide layer, and the composite was evaluated.

First, we will explain the stabilization layer-forming material printed on the surface of a silicon nitride substrate. _{Co3O4 particles} and _{Ga2O3 particles} were mixed so that the _Co3O4 content was 30 mass% to obtain a 30 mass% _Co3O4 -containing _Ga2O3 mixed powder. The resulting mixed powder was then mixed with a dispersion medium primarily composed of terpineol to obtain _a 30 mass% _{Co3O4 -} containing _{Ga2O3 paste ,} which is the stabilization layer _- forming material.

The resulting paste (stabilizing layer forming material) was then applied to the surface of the silicon nitride substrate by screen printing using a rubber squeegee and a stainless steel mesh screen to form a paste film.

Next, the obtained paste film was heated in air at 200°C for 30 minutes to remove the dispersion medium, and then further heated to 1000°C in air for 2 hours to react and sinter _{Co3O4 and Ga2O3} , thereby obtaining a laminate in _which the sintered film was adhered closely to the surface of the silicon nitride substrate.

The X-ray diffraction pattern of the sintered film of the obtained laminate is shown in FIG.
According to this, the diffraction pattern has diffraction peaks of Ga ₂ CoO ₄ in addition to diffraction peaks of silicon nitride constituting the substrate, and it was found that the substrate has a spinel structure.

Thereafter, _{a CaCu3Ru4O12 paste} containing 30% by volume of CuO (a conductive oxide layer forming material) was applied by screen printing to the surface of the _Ga2CoO4 film formed on the silicon _nitride substrate using a rubber squeegee and a stainless steel mesh screen to form a conductive paste film.

The resulting conductive paste film was then heat-treated in air at 200°C for 30 minutes to remove the dispersion medium, and the temperature was further increased to 1000°C for 2 hours for sintering, producing a composite ( _C14 ) having, in order on the surface of a silicon nitride substrate, _four layers of _Ga2CoO and _twelve layers of _CaCu3Ru4O containing 30% by volume of CuO.

The X-ray diffraction pattern (not shown) of the sintered film of the resulting composite (C14) containing ₃₀ % CuO by volume _{, CaCu3Ru4O12} , showed that most of the _CaCu3Ru4O12 was sintered without decomposition. Furthermore, _a peak attributable _{to RuO2} was observed, but only in trace amounts. This _RuO2 is not the result of a reaction _{between CaCu3Ru4O12} and _Ga2CoO4 , but is also produced, for example, by directly forming a _CaCu3Ru4O12 film on a sinterable aluminum oxide substrate and _then heating and sintering _it at _a high temperature _.

Example 15
In this example, a paste containing CuO particles and _{Ga2O3 particles} (a material for forming a stabilization layer containing _{Ga2CuO4 )} was printed on a silicon nitride substrate, and the paste was heated and sintered to form a _Ga2CuO4 film. Then, _CaCu3Ru4O12 containing 30 _% by volume of CuO was printed on the surface of the _{Ga2CuO4 film} , and the _paste was heated and sintered to produce a composite (hereinafter referred to as _" composite (C15)") in which a stabilization layer containing the compound represented by general formula (1) according to the present invention was interposed between the substrate and the conductive oxide layer, and the composite was evaluated.

First, we will explain the stabilization layer-forming material printed on the surface of a silicon nitride substrate. CuO particles and _{Ga2O3 particles} were mixed so that the CuO content was 30% by mass to obtain a 30% by mass _CuO -containing _Ga2O3 mixed powder. Next, the resulting mixed powder was mixed with a dispersion medium mainly composed of terpineol to obtain a 30% by mass _CuO -containing _Ga2O3 paste, which is the stabilization layer-forming material.

The resulting paste (stabilizing layer forming material) was then applied to the surface of the silicon nitride substrate by screen printing using a rubber squeegee and a stainless steel mesh screen to form a paste film.

Next, the obtained paste film was heated in air at 200°C for 30 minutes to remove the dispersion medium, and then further heated to 1000°C in air for 2 hours to react and sinter _CuO and _Ga2O3 , thereby obtaining a laminate in which the sintered film was adhered closely to the surface of the silicon nitride substrate.

The X-ray diffraction pattern of the sintered film of the obtained laminate is shown in FIG.
According to this, the diffraction pattern had diffraction peaks of Ga ₂ CuO ₄ in addition to diffraction peaks of silicon nitride constituting the substrate, and it was found that the substrate had a spinel structure.

Thereafter, _{a CaCu3Ru4O12} paste containing 30% by volume of CuO (a conductive oxide layer forming material) was applied by screen printing to the surface of the _Ga2CuO4 film formed on the silicon nitride substrate using _a rubber squeegee and a stainless steel _mesh screen to form a conductive paste film.

The resulting conductive paste film was then heat-treated in air at 200°C for 30 minutes to remove the dispersion medium, and then further heated to 950°C for 2 hours for sintering, producing a composite (C15 ₎ having, in order on the surface of a silicon nitride substrate, _four layers of _Ga2CuO and _twelve layers of _CaCu3Ru4O containing 30% by volume of CuO.

The X-ray diffraction pattern (not shown) of the sintered film of the resulting composite (C15) containing ₃₀ % CuO by volume _{, CaCu3Ru4O12} , showed that most of the _CaCu3Ru4O12 was sintered without decomposition. Furthermore, _a peak attributable _{to RuO2} was observed, but only in trace amounts. This _RuO2 is not the result of a reaction between _CaCu3Ru4O12 and _Ga2CuO4 , but is also produced, for example, by forming a _CaCu3Ru4O12 film directly on a sinterable aluminum _oxide substrate and _then heating and sintering _it at _a high temperature _.

Example 16
In this example, a paste containing MgO particles and _{Ga2O3 particles} (a material for forming a stabilization layer containing _{Ga2MgO4 )} was printed on a silicon nitride substrate, and the paste was heated and sintered to form a _Ga2MgO4 film. Then, _CaCu3Ru4O12 containing 30 _% by volume of CuO was printed on the surface of the _{Ga2MgO4 film} , and the paste was heated and sintered to produce a composite (hereinafter referred to as _" composite ( _C16 )") in which a stabilization layer containing the compound represented by general formula (1) according to the present invention was interposed between the substrate and the conductive oxide layer, and the composite was evaluated.

First, we will explain the stabilization layer-forming material printed on the surface of a silicon nitride substrate. MgO particles and _{Ga2O3 particles} were mixed so that the MgO content was 18% by mass to obtain a _Ga2O3 mixed powder containing 18% by mass of _MgO . The resulting mixed powder was then mixed with a dispersion medium containing terpineol as the main component to obtain a stabilization layer-forming material, _{a Ga2O3} paste containing 18% by mass of MgO.

The resulting paste (stabilizing layer forming material) was then applied to the surface of the silicon nitride substrate by screen printing using a rubber squeegee and a stainless steel mesh screen to form a paste film.

Next, the obtained paste film was heated in air at 200°C for 30 minutes to remove the dispersion medium, and then further heated to 1100°C in air for 2 hours to react and sinter the _MgO and _Ga2O3 , thereby obtaining a laminate in which the sintered film was adhered closely to the surface of the silicon nitride substrate.

The X-ray diffraction pattern of the sintered film of the obtained laminate is shown in FIG.
According to this, the diffraction pattern had diffraction peaks of Ga ₂ MgO ₄ in addition to diffraction peaks of silicon nitride constituting the substrate, and it was found that the substrate had a spinel structure.

Thereafter, _{a CaCu3Ru4O12 paste} containing 30% by volume of CuO (a conductive oxide layer forming material) was applied by screen printing to the surface of the _Ga2MgO4 film formed on the silicon nitride substrate using a rubber squeegee and a stainless steel _mesh screen to form a conductive paste film.

The resulting conductive paste film was then heat-treated in air at 200°C for 30 minutes to remove the dispersion medium, and the temperature was further increased to 1000°C for 2 hours for sintering, producing a composite (C16 ₎ having, in order, _four layers of _Ga2MgO and _twelve layers of _CaCu3Ru4O containing 30% by volume of CuO on the surface of a silicon nitride substrate.

The X-ray diffraction pattern (not shown) of the sintered film of the resulting composite (C16) containing ₃₀ % CuO by volume _{, CaCu3Ru4O12} , showed that most of the _CaCu3Ru4O12 was sintered without decomposition. Furthermore, _a peak attributable _{to RuO2} was observed, but only in trace amounts. This _RuO2 is not the result of a reaction _{between CaCu3Ru4O12 and Ga2MgO4} , but is also produced, for example, by directly forming a _CaCu3Ru4O12 film on a sinterable aluminum oxide substrate and _then heating and sintering _it at a high temperature _.

(Example 17)
In this example, a paste containing ZnO particles and _{Ga2O3 particles} (a material for forming a stabilization layer containing _{Ga2ZnO4 )} was printed on a silicon nitride substrate, and the paste was heated and sintered to form a _Ga2ZnO4 film. Then, _CaCu3Ru4O12 containing ₃₀ % by volume of CuO was printed on the surface of the _{Ga2ZnO4 film} , and the _paste was heated and sintered to produce a composite (hereinafter referred to as _" composite (C17)") in which a stabilization layer containing the compound represented by general formula (1) according to the present invention was interposed between the substrate and the conductive oxide layer, and the composite was evaluated.

First, we will explain the stabilization layer-forming material printed on the surface of a silicon nitride substrate. ZnO particles and _{Ga2O3 particles} were mixed so that the ZnO content was 18% by mass to obtain a _Ga2O3 mixed powder containing 18% by mass _of ZnO. Next, the resulting mixed powder was mixed with a dispersion medium containing terpineol as the main component to obtain a stabilization layer-forming material, _{a Ga2O3} paste containing 18% by mass of ZnO.

The resulting paste (stabilizing layer forming material) was then applied to the surface of the silicon nitride substrate by screen printing using a rubber squeegee and a stainless steel mesh screen to form a paste film.

Next, the obtained paste film was heated in air at 200°C for 30 minutes to remove the dispersion medium, and then further heated to 1000°C in air for 2 hours to react and sinter the _ZnO and _Ga2O3 , thereby obtaining a laminate in which the sintered film was adhered closely to the surface of the silicon nitride substrate.

The X-ray diffraction pattern of the sintered film of the obtained laminate is shown in FIG.
According to this, the diffraction pattern has diffraction peaks of Ga ₂ ZnO ₄ in addition to diffraction peaks of silicon nitride constituting the substrate, and it was found that the substrate has a spinel structure.

Thereafter, _{a CaCu3Ru4O12} paste containing 30% by volume of CuO (a conductive oxide layer forming material) was applied by screen printing to the surface of the _Ga2ZnO4 film formed on the silicon nitride substrate using _a rubber squeegee and a stainless steel _mesh screen to form a conductive paste film.

The resulting conductive paste film was then heat-treated in air at 200°C for 30 minutes to remove the dispersion medium, and the temperature was further increased to 1000°C for 2 hours for sintering, producing a composite (C17 ₎ having, in order, _four layers of _Ga2ZnO and _twelve layers of _CaCu3Ru4O containing 30% by volume of CuO on the surface of a silicon nitride substrate.

The X-ray diffraction pattern (not shown) of the sintered film of the resulting composite (C17) containing ₃₀ % CuO by volume _{, CaCu3Ru4O12} , showed that most of the _CaCu3Ru4O12 was sintered without decomposition. Furthermore, _a peak attributable _{to RuO2} was observed, but only in trace amounts. This _RuO2 is not the result of a reaction _{between CaCu3Ru4O12} and _Ga2ZnO4 , but is also produced, for example, by directly forming a _CaCu3Ru4O12 film on a sinterable aluminum oxide substrate and _then heating and sintering _it at _a high temperature _.

(Comparative Example 5)
The same procedure as in Example 10 was carried out except that the _{Fe2CoO4 layer} was not formed, and an attempt was made to form a 30 volume % CuO-containing _{CaCu3Ru4O12 sintered} film on the surface of a silicon _nitride substrate (sintered at 950°C), thereby obtaining a composite (hereinafter referred to as "composite (D5)").

The X-ray diffraction pattern of the CaCu ₃ Ru ₄ O ₁₂ sintered film containing 30% by volume of CuO in the obtained composite (D5) is shown in FIG.
This shows that part of CaCu ₃ Ru ₄ O ₁₂ was decomposed and a relatively large amount of RuO ₂ was produced.

The present inventors speculate that the cause of partial decomposition of CaCu ₃ Ru ₄ O ₁₂ in the composite (D5) is as follows.

One reason for _{this is that during sintering in air at 950°C for 2 hours, silicon nitride deprives CaCu3Ru4O12 of oxygen at the interface between the silicon nitride and CaCu3Ru4O12 , oxidizing it and changing} it to silicon dioxide, and at this time, _{CaCu3Ru4O12 , which} has lost its oxygen, is unable to maintain its crystal structure and decomposes. In other words, when there is an interface between a nitride such as silicon nitride and an oxide, during heat treatment such as high-temperature sintering in air, the oxygen that constitutes the oxide is deprived by the nitride, and the oxide is unable to maintain its crystal structure and decomposes.

One reason for this is that silicon constituting the silicon nitride of the substrate and Ca and Cu constituting _CaCu3Ru4O12 undergo a chemical reaction during sintering in air at 950°C for two hours, forming _impurities such as _{CaCuSi4O10 .} At this time, _CaCu3Ru4O12 , which has lost its Ca and Cu, _is unable to maintain its crystalline structure and _decomposes . In other words, because silicon can react with various elements to form compounds, in the case of an interface between a silicon-containing material and an oxide, when _heat treatment such as high-temperature sintering is performed in air, the silicon reacts with the elements constituting the oxide, and the oxide, which has lost its constituent elements, is unable to maintain its crystalline structure and decomposes.

Furthermore, at the interface between a material containing silicon, an acidic material that reacts with bases to produce silicates, and a basic material containing Ca, which reacts with hydrochloric acid to produce calcium chloride, or Cu, which reacts with nitric acid to produce copper nitrate, this is a highly reactive combination of materials, and the oxide, which has lost its constituent elements due to this reaction, is unable to maintain its crystalline structure and decomposes.

On the other hand, in Example 10, in which an _Fe2CoO4 layer was interposed between a silicon _nitride substrate and a sintered film of _CaCu3Ru4O12 containing ₃₀ % by volume of CuO _, which is a conductive oxide, was formed, _CaCu3Ru4O12 did not decompose _. Therefore, it is believed that _the following phenomena, as in Comparative Example 5, occur: (1) when there is an interface between a nitride (silicon nitride) and an oxide, oxygen constituting the oxide is taken by the nitride when heat treatment such as high-temperature sintering is performed in the atmosphere, and the oxide is unable to maintain its crystal structure and decomposes; (2) when there is an interface between a silicon-containing material and an oxide, elements constituting the oxide react with silicon, and the oxide that has lost its constituent elements is unable to maintain its crystal structure and decomposes when heat treatment such as high-temperature sintering is performed in the atmosphere; and (3) when there is an interface between an acidic material and a basic material, the oxide that has lost its constituent elements due to the reaction is unable to maintain its crystal structure and decomposes because of a combination of _highly reactive materials. ₄ was found to be suppressed.

(Example 18)
In this example, a paste containing CuO particles and _Al2O3 particles (a material for forming a stabilizing layer containing _Al2CuO4 ) was printed on the surface of a gallium nitride (GaN ₎ thin film formed on a sapphire substrate, and the paste was heated and sintered to form _{an Al2CuO4} film. Then, _CaCu3Ru4O12 containing ₃₀ % by volume of _CuO was printed on the surface of _{this Al2CuO4} film, and the paste was heated and sintered to produce a composite (hereinafter referred to as "composite ( _C18 )") in which a stabilizing layer containing the compound represented by general formula (1) according to the present invention was interposed between the substrate and the conductive oxide layer, and the composite was evaluated.

First, we will explain the stabilization layer forming material printed on the surface of the gallium nitride thin film. CuO particles and Al ₂ O ₃ particles were mixed so that the CuO content was 32 volume % to obtain a 32 volume % CuO-containing Al ₂ O ₃ mixed powder. Next, the obtained mixed powder was mixed with a dispersion medium mainly composed of terpineol to obtain a 32 volume % CuO-containing Al ₂ O ₃ paste, which is the stabilization layer forming material.

The resulting paste (stabilizing layer forming material) was then applied to the surface of the gallium nitride thin film by screen printing using a rubber squeegee and a stainless steel mesh screen to form a paste film.

Next, the resulting paste film was heat-treated in air at 200°C for 30 minutes to remove the dispersion medium, and then further heated to 1000°C in air for 2 hours to react and sinter _CuO and _Al2O3 , thereby obtaining a laminate in which the sintered film was adhered closely to the surface of the gallium nitride thin film.

The X-ray diffraction pattern of the sintered film of the obtained laminate is shown in FIG.
According to this, the diffraction pattern had diffraction peaks of Al ₂ CuO ₄ in addition to diffraction peaks of gallium nitride constituting the substrate, and it was found that the substrate had a spinel structure.

Thereafter, _{a CaCu3Ru4O12 paste} containing 30% by volume of CuO (a conductive oxide layer forming material) was applied by screen printing to the surface of the _Al2CuO4 film formed on the gallium nitride thin film using a rubber _squeegee and a stainless steel mesh screen to form a conductive paste film.

The resulting conductive paste film was then heat-treated in air at 200°C for 30 minutes to remove the dispersion medium, and then further heated and sintered in air at 1000°C for 2 hours to produce a composite (C18 ₎ having, in order, _four layers of _Al2CuO and _twelve layers of _CaCu3Ru4O containing 30% by volume of CuO on the surface of the gallium nitride thin film.

From the _X -ray diffraction pattern (not shown) of the sintered film _{of CaCu3Ru4O12} containing 30 volume % _CuO in the obtained composite (C18) _, it was found that _CaCu3Ru4O12 was sintered without decomposition. Therefore, even when a sintered film of _CaCu3Ru4O12 containing ₃₀ volume % CuO is formed on _{gallium nitride} , the _Al2CuO4 layer has the effect of suppressing the decomposition of _CaCu3Ru4O12 as a stabilizing layer, similar to that on _{silicon nitride} .

Example 19
In this example, a paste containing ZnO particles and _Ga2O3 particles (a material for forming a stabilization layer containing _Ga2ZnO4 ) was printed on the surface of a gallium nitride (GaN ₎ thin film formed on a sapphire substrate, and the paste was heated and sintered to form _{a Ga2ZnO4} film. Then, _CaCu3Ru4O12 containing ₃₀ % by volume of _CuO was printed on the surface of this _Ga2ZnO4 film, and the paste was heated and sintered to produce a composite (hereinafter referred to as "composite ( _C19 ) _" ) in which a stabilization layer containing the compound represented by general formula (1) according to the present invention was interposed between the substrate and the conductive oxide layer, and the composite was evaluated.

First, we will explain the stabilization layer-forming material printed on the surface of a silicon nitride substrate. ZnO particles and _{Ga2O3 particles} were mixed so that the ZnO content was 18% by mass to obtain a _Ga2O3 mixed powder containing 18% by mass _of ZnO. Next, the resulting mixed powder was mixed with a dispersion medium containing terpineol as the main component to obtain a stabilization layer-forming material, _{a Ga2O3} paste containing 18% by mass of ZnO.

The resulting paste (stabilizing layer forming material) was then applied to the surface of the gallium nitride thin film by screen printing using a rubber squeegee and a stainless steel mesh screen to form a paste film.

Next, the resulting paste film was heated in air at 200°C for 30 minutes to remove the dispersion medium, and then heated further to 1000°C in air for 2 hours to react and sinter the ZnO _{and Ga2O3} , resulting in a laminate in which the sintered film was adhered closely to the surface of the gallium nitride thin film.

The X-ray diffraction pattern of the sintered film of the obtained laminate is shown in FIG.
According to this, it was found that the diffraction pattern had a diffraction peak of Ga ₂ ZnO ₄ in addition to the diffraction peak of gallium nitride that constitutes the substrate, and had a spinel structure.

Thereafter, a _{CaCu3Ru4O12 paste} containing 30% by volume of CuO (a conductive oxide layer forming material) was applied by screen printing to the surface of the _Ga2ZnO4 film formed on the gallium _nitride thin film using _a rubber squeegee and a stainless steel mesh screen to form a conductive paste film.

The resulting conductive paste film was then heat-treated in air at 200°C for 30 minutes to remove the dispersion medium, and the temperature was further increased to 1000°C for 2 hours for sintering, producing a composite (C19 ₎ having, on the surface of the gallium nitride thin film, _four layers of _Ga2ZnO and _twelve layers of _CaCu3Ru4O containing 30% by volume of CuO, in that order.

From the _X -ray diffraction pattern (not shown) of the sintered film _{of CaCu3Ru4O12} containing 30 volume % _CuO in the obtained composite (C19) _, it was found that _CaCu3Ru4O12 was sintered without decomposition. Therefore, even when a sintered film of _CaCu3Ru4O12 containing 30 volume % CuO is formed on _{gallium nitride} , the _{Ga2ZnO4 layer} has the effect of suppressing the decomposition of _CaCu3Ru4O12 as a stabilizing layer, similar to that on _{silicon nitride} .

The results obtained in the above examples and comparative examples are shown in Table 1.

A comparison between Comparative Example 1 and Example 1 reveals that the stabilization layer containing Al ₂ CuO 4 as compound (A), arranged between the first inorganic material (silicon nitride substrate) and the second inorganic material (30% by volume CuO-containing CaCu _{3 Ru 4} O ₁₂₎ , suppresses chemical reactions and element diffusion that may occur between the first inorganic material and the second inorganic material, resulting in a composite with excellent structural stability without degrading the properties of the first and second inorganic materials. In this case, the first inorganic material is a nitride and the second inorganic material is a non-nitride. Furthermore, the first inorganic material is a silicon-containing compound and the second inorganic material is an oxide.

Comparison of Comparative Example 1 with Examples 7, 8, 9, 12, 14, 16 and 17 reveals that the stabilization layer containing any of Al 2 CoO 4 , Al 2 MgO 4 , Al ₂ ZnO ₄ , Fe 2 MgO 4 , Ga ₂ CoO ₄ , Ga ₂ MgO ₄ , and _{Ga 2} ZnO ₄ as the compound (A) arranged between the silicon nitride substrate ₍ first inorganic material ₎ and the CaCu ₃ Ru ₄ O ₁₂ containing 30% _CuO by _volume suppresses chemical reactions, element diffusion _, etc. that may occur between the first inorganic material and the second inorganic material, resulting in a composite with excellent structural stability without deteriorating the properties of the first and second inorganic materials. In this case, the first inorganic material is a nitride, and the second inorganic material is a non-nitride. The first inorganic material is a compound containing silicon, and the second inorganic material is an oxide.

Comparison of Comparative Example 5 with Examples 10, 11, 13, and 15 reveals that the stabilization layer containing any of _{Fe2CoO4, Fe2CuO4} , _Fe2ZnO4 , _{and Ga2CuO4} as compound (A) arranged between the silicon nitride substrate (first inorganic material) and the _CaCu3Ru4O12 ( ₃₀ % by volume CuO _- containing ₎ suppresses chemical reactions, element diffusion _, and the like that may occur between the first inorganic material and the _second inorganic material, resulting in a composite with excellent structural stability without degrading the properties of the first and second inorganic materials. In this case, the first inorganic material is a nitride, and the second inorganic material is a non-nitride. Furthermore, the first inorganic material is a silicon-containing compound, and the second inorganic material is an oxide.

A comparison between Comparative Example 2 and Example 2 reveals that the stabilization layer containing Al2CuO4 as compound (A), disposed between the first inorganic material (a _{silicon dioxide} substrate ₎ and the second inorganic material (30% by volume _{CaCu3Ru4O12 )} , suppresses chemical reactions and element diffusion that may occur between the first and second inorganic materials, resulting in a composite with excellent structural stability without degrading the properties of the first and second inorganic materials. In this case, the first inorganic material is a silicon-containing compound, and the second inorganic material is an oxide. Furthermore, the first inorganic material is an acidic material that reacts with a base to produce a salt, and the second inorganic material is a basic material that reacts with an acid to produce a salt.

Comparing Example 1 and Example 3, it can be seen that regardless of the method of forming a stabilizing film containing Al ₂ CuO ₄ as compound (A) as a stabilizing layer between the silicon nitride substrate as the first inorganic material and the CaCu ₃ Ru ₄ O ₁₂ as the second inorganic material containing 30% CuO by volume, and regardless of the thickness of the stabilizing layer, chemical reactions, element diffusion, etc. that may occur between the first inorganic material and the second inorganic material are suppressed, resulting in a composite with excellent structural stability without deteriorating the properties of the first inorganic material and the second inorganic material.

A comparison between Comparative Example 3 and Example 4 reveals that the stabilization layer containing _Al2CuO4 as _compound (A), disposed between the _silicon dioxide substrate (first inorganic material) and the _SmBa2Cu3Oy (second inorganic material ₎ , suppresses chemical reactions, element diffusion, and other reactions that may occur between the first and second inorganic materials, resulting in a composite with excellent structural stability without degrading the properties of the first and second inorganic materials. In this case, the first inorganic material is a silicon-containing compound, and the second inorganic material is an oxide. Furthermore, the first inorganic material is an acidic material that reacts with a base to produce a salt, and the second inorganic material is a basic material that reacts with an acid to produce a salt.

A comparison between Example 1 and Example 5 reveals that even when the stabilization layer contains Al 2 O ₃ in addition to Al ₂ CuO ₄ , which is compound (A), between the silicon nitride substrate as the first inorganic material and the CaCu _{3 Ru 4} O ₁₂ containing 30% CuO by volume as the second inorganic material, chemical reactions, element diffusion, etc. that may occur between the first inorganic material and the second inorganic material are suppressed, resulting in a composite with excellent structural stability without deteriorating the properties of the first inorganic material and the second inorganic material.

Comparing Example 1 and Example 6, it can be seen that even when the stabilization layer between the first inorganic material, a silicon _nitride substrate, and the second inorganic material, _CaCu3Ru4O12 , containing 30% CuO by volume, contains copper oxide (CuO ₎ as a reinforcing layer between _Al2CuO4 , _which is compound (A), and each of the first and second inorganic materials, chemical reactions, element diffusion, etc. that may occur between the first and second inorganic materials are suppressed, resulting in a composite with excellent structural stability without deteriorating the properties of the first and second inorganic materials.

A comparison between Comparative Example 4 and Example 6 shows that when only _copper oxide (CuO) contained in the stabilization layer as a reinforcing layer in Example 6 is arranged between the silicon nitride substrate as the first inorganic material and the second inorganic material _CaCu3Ru4O12 containing ₃₀ % CuO by volume, chemical reactions and element diffusion that may occur between the first inorganic material and the second inorganic material are not suppressed, and a composite with excellent structural stability is not obtained without degrading the properties of the first inorganic material and the second inorganic material. Therefore, it can be seen that in Example 6, the compound (A), _{Al2CuO4 ,} suppresses chemical reactions and element diffusion that may occur between the first inorganic material and the second inorganic material.

Comparing Example 18 with Example 1, it can be seen that the stabilization layer containing Al 2 CuO 4 as compound (A) arranged between the first inorganic material, a _gallium nitride thin film on a sapphire substrate, and the second inorganic material, CaCu ₃ Ru _{4 O 12} , containing 30% by volume of CuO, suppresses chemical reactions, element diffusion, etc. that may occur between the first inorganic material and the second inorganic material, resulting in a composite with excellent structural stability without deteriorating the properties of the first inorganic material and the second inorganic material. In this case, the first inorganic material is a nitride, and the second inorganic material is a non-nitride.

A comparison between Example 19 and Example 17 shows that the stabilization layer containing Ga ₂ ZnO ₄ as compound (A), arranged between the first inorganic material (a _gallium nitride thin film on a sapphire substrate) and the second inorganic material (30% by volume CuO-containing CaCu 3 Ru ₄ O ₁₂₎ , suppresses chemical reactions, element diffusion, etc. that may occur between the first inorganic material and the second inorganic material, resulting in a composite with excellent structural stability without deteriorating the properties of the first inorganic material and the second inorganic material. In this case, the first inorganic material is a nitride, and the second inorganic material is a non-nitride.

The composite of the present invention has a stabilizing layer that suppresses chemical reactions, element diffusion, and other reactions that may occur between two different inorganic materials when they are bonded. This allows it to be widely used as an article with excellent structural stability without degrading the properties of the first and second inorganic materials. For example, it is useful as a component of various electronic devices, heat-generating components, and the like, which have a bonded interface between materials with different chemical properties or a bonded interface between highly reactive materials, such as a combination of a nitride with a non-nitride such as an oxide or metal, a combination of a silicon-containing compound with an oxide, or a combination of an acidic material that reacts with a base to produce a salt with a basic material that reacts with an acid to produce a salt.

1, 2, 3: composites 10, 20, 30: first material parts 12, 22, 32: second material parts 14, 24, 34: stabilizing layer 26: stabilizing base layer 28: reinforcing layer

Claims (6)

A composite comprising: a first material portion including a first inorganic material; a second material portion including a second inorganic material having a different composition from the first inorganic material; and a stabilizing layer disposed between the first material portion and the second material portion,
The stabilizing layer contains a compound (A) represented by the following general formula (1):
M ¹ ₂ M ² O ₄ (1)
(In the formula, ^M1 and ^M2 are different elements, ^M1 is at least one selected from Al, Fe, and Ga, and ^M2 is at least one selected from Cu , Zn, Fe, Mn, and Co.)
A composite characterized in that the first inorganic material and the second inorganic material are a combination of the following (1) or (2):
(1) The first inorganic material includes a nitride, and the second inorganic material includes an oxide (excluding the compound (A)).
(2) The first inorganic material contains a silicon compound (excluding silicon nitride) or silicon, and the second inorganic material contains an oxide (excluding the compound (A)). 2. The composite of claim ₁ , wherein the compound (A) is _Al2CuO4 . The composite body described in claim 1 or 2, wherein the stabilizing layer includes a reinforcing layer containing an inorganic compound (excluding compound (A)). The composite according to claim 3, wherein the inorganic compound contained in the reinforcing layer includes copper oxide. A method for producing the composite of claim 1 or 2, comprising:
a compound (A)-containing film containing the compound (A) formed on a surface of the first material part to form a laminate, and then the second material part formed on a surface of the compound (A)-containing film in the laminate. The composite manufacturing method described in claim 5, wherein the laminate is obtained by applying a paste containing a raw material for manufacturing the compound (A) and a dispersion medium to the surface of the first material part, then heating the formed coating to remove the dispersion medium, and then further increasing the temperature to generate the compound (A) and form the compound (A)-containing film.