JP3190320B2 - Method for manufacturing electron emission material film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to various discharge lamps such as fluorescent lamps, cathode ray tube electrodes, plasma displays, and the like.
The present invention relates to a method for manufacturing an electron emission material film that can be used for an electrode of a fluorescent display tube or the like.

[0002]

2. Description of the Related Art In recent years, social demands for energy saving and resource saving have been increasing, and in response to this, energy saving of light sources and displays for general lighting has been actively promoted. For example, the replacement of incandescent light bulbs with bulb-type fluorescent lamps with higher energy efficiency and longer life, and the replacement of cathode ray tubes with liquid crystal displays with lower energy consumption are progressing rapidly. Along with that,
Fluorescent lamps are rapidly being used for light bulb-type fluorescent lamps and as backlight light sources for liquid crystal displays. Similarly, for cathode ray tubes such as cathode ray tubes, plasma displays, and fluorescent display tubes, there is a demand for electrodes having high energy efficiency and capable of saving energy.

Conventionally, BaO has been used as an electrode of a fluorescent lamp.
Oxide electrodes containing as a main component are generally used. Such an electrode is described in, for example, JP-A-59-75553. However, an oxide electrode containing BaO as a main component has good electron emission properties, but has high specific resistance. Therefore, when a large electron emission current is to be obtained, the temperature becomes high. As a result, the vapor pressure increases and the amount of evaporation increases, resulting in a problem that the life is shortened. Also, B
In the case of an oxide electrode containing aO as a main component, it is necessary to apply a current to a tungsten coil coated with a carbonate of Ba to convert the carbonate into an oxide, and to perform decarboxylation at that time. However, when this electrode is applied to a fluorescent lamp having a thin tube, decarboxylation tends to be insufficient, and as a result, carbon dioxide gas remains in the lamp bulb, causing unstable discharge or an extremely high luminance maintenance ratio. The problem is that it becomes worse.

Further, US Pat. No. 2,686,274 describes a rod-shaped electrode obtained by reducing a ceramic such as Ba ₂ TiO ₄ into a semiconductor. The electrode has problems that it is susceptible to thermal shock, easily deteriorated by sputtering with Hg ions or rare gas ions, and has a small usable current density.

With respect to such a conventional fluorescent lamp electrode, the present inventors have proposed an electrode having a structure in which a ceramic semiconductor is housed in a cylindrical container having one end opened and one end closed. Various improvements have been made to the electrodes and to the discharge lamp using the electrodes (Japanese Patent Publication No.
No. 103627, Japanese Patent No. 2628312, Japanese Patent No. 2773174, Japanese Patent No. 2754647, Japanese Unexamined Patent Application Publication No.
-43546, JP-A-6-267404,
JP-A-9-129177, JP-A-10-1218
9, JP-A-6-302298, JP-A-7-302
No. 142031, JP-A-7-262983,
JP-A-10-3879). These electrodes have characteristics that they have good sputtering resistance and are hard to evaporate, so they are hardly deteriorated and have a long life. However, further improvements in sputtering resistance and resistance to evaporation are desired.

In addition to electrodes for discharge lamps such as fluorescent lamps, various electrodes utilizing discharge by hot cathode operation or cold cathode operation, for example, electrodes used in cathode ray tubes, electron microscopes, plasma displays, field emission displays, etc. However, there is a problem of deterioration due to evaporation and ion sputtering, and improvement of the life is desired.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method capable of mass-producing an electron-emitting material film having little evaporation during discharge and high resistance to ion sputtering at low cost.

[0008]

The above object is achieved by the following (1).
This is achieved by the present invention of (11). (1) A first component comprising at least one of Ba, Sr and Ca, and a second component comprising at least one of Ta, Zr, Nb, Ti and Hf as metal element components, and an oxynitride perovskite is provided. A method for producing an electron-emitting material containing the metal element component, wherein the object to be fired is fired in a nitrogen gas-containing atmosphere in a state where carbon is disposed in proximity to the object, thereby producing the oxynitride perovskite. An oxynitride generating step of obtaining an electron-emitting material by crushing the electron-emitting material obtained in the oxynitride generating step to obtain an electron-emitting material powder, and a slurry containing the electron-emitting material powder. A method for producing an electron-emitting material film by forming a coating film by using the method and heat-treating the coating film to obtain an electron-emitting material film. (2) An oxynitride perovskite containing a first component composed of at least one of Ba, Sr and Ca and a second component composed of at least one of Ta, Zr, Nb, Ti and Hf as metal element components. A method for producing an electron-emitting material containing the metal element component, wherein the object to be fired is fired in a nitrogen gas-containing atmosphere in a state where carbon is disposed in proximity to the object, thereby producing the oxynitride perovskite. A method for producing an electron-emitting material film, comprising: an oxynitride generation step of obtaining an electron-emitting material by causing the film to be used as the object to be fired in the oxynitride generation step. (3) The method for producing an electron emission material film according to (1) or (2), wherein the oxygen partial pressure in the nitrogen gas-containing atmosphere is 0 to 5.0 × 10 ³ Pa. (4) A nitrogen gas flow is used as the nitrogen gas-containing atmosphere, and in a space near the object to be fired in the nitrogen gas flow, the nitrogen gas flow rate per unit area in a cross section perpendicular to the flow direction of the gas flow is 0.0001 to 5 m. / s, the method for producing an electron-emitting material film according to any one of the above (1) to (3). (5) In the oxynitride generation step, the electron-emitting material according to any one of (1) to (4) above, wherein carbon is mixed in the object to be fired so that carbon is arranged close to the object to be fired. Manufacturing method of membrane. (6) In the oxynitride generation step, any one of the above (1) to (5), in which carbon is arranged close to the object to be fired by using a firing furnace at least partially constituted of carbon. The method for producing an electron-emitting material film described above. (7) In the oxynitride generation step, the object to be fired is housed in a container at least partially composed of carbon, whereby carbon is disposed close to the object to be fired. 6) The method for producing an electron emission material film according to any one of the above. (8) The method for producing an electron-emitting material film according to any one of (1) to (7), wherein the oxynitride is generated from a firing target containing a composite oxide in the oxynitride generation step. (9) When the first component is represented by M ^I and the second component is represented by M ^II , the oxynitride perovskite is represented by M ^I M ^II O ₂ N
The method for producing an electron-emitting material film according to any one of the above (1) to (8), including a type crystal. (10) The method for producing an electron-emitting material film according to any one of the above (1) to (9), wherein the electron-emitting material containing the second component carbide and / or nitride is produced. (11) a first component M ^I, when the second component expressed respectively _{^{M II, M I 4 M II}} 2 O 9 type crystals, M ^I M ^II ₂ O ₆ type crystals, M ^I M ^II O ₃ type _{^{crystal, M I 5 M II 4 O}} 15 type crystal, M ^I ₇ M
^II ₆ O ₂₂ type crystals and M ^I ₆ M ^II M ^II ₄ above the electron emission material comprising at least one O ₁₈ type crystal is produced (1) -
(10) The method for producing an electron emission material film according to any one of (10) and (10).

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The oxynitride contained in the electron-emitting material according to the present invention has a low vapor pressure and a low electric resistance. For this reason, a larger electron emission current can flow than the conventional electrode material containing BaO as a main component, and electrode deterioration due to evaporation is small.
Further, the electrode deterioration is reduced as compared with the electrode composed of a Ba-Zr-Ta-based composite oxide described in the above-mentioned Japanese Patent Application Laid-Open No. 9-129177. Therefore, when applied to an electrode that performs a hot cathode operation, a higher luminance than that of a conventional electrode is obtained, and the electrode life is significantly prolonged.

In addition, the oxynitride is hardly consumed even by ion sputtering. Therefore, even in a cold cathode operation in which ion sputtering is intensified due to a large cathode drop voltage, wear is small and a long life is realized.

The oxynitride having a perovskite structure is disclosed in Journal of Materials Science, 29, (1994), pp4
686-4693. In this document, the oxynitride is manufactured by baking at 1000 ° C. in an ammonia gas flow, but the oxynitride thus manufactured is evaluated only as a dielectric.
Since oxynitride is a stable compound even in a reducing atmosphere, it is suitable for a multilayer ceramic capacitor having an internal electrode made of a base metal.

Japanese Patent Application Laid-Open No. 63-252920 (corresponding to US Pat. No. 4,964,016) discloses a conductive perovskite represented by the formula AB (O, N) _3. I have. In the above formula, the element A is IA
A metal selected from the group IV and IIA metals, yttrium and lanthanoids, wherein the element B is a group IVA to I
Shows a metal selected from Group B transition metals. In that publication,
This conductive perovskite is manufactured by firing a mixed oxide of metal A and metal B at about 700 to 900 ° C. in an ammonia gas flow. This publication proposes to use this conductive perovskite for the electrodes of a ceramic capacitor, and there is no description or suggestion that the invention is applied to an electron emission material. The composition of the conductive perovskite described in the publication overlaps with the composition of the oxynitride contained in the electron-emitting material of the present invention. However, this publication does not specifically disclose oxynitride perovskites having the composition defined by the present invention. Also,
If the composition defined in the present invention is used and baked in an ammonia gas stream under the conditions described in the publication, the specific resistance becomes too high, so that favorable characteristics as an electron-emitting material cannot be obtained.

As described above, an oxynitride having a perovskite structure itself is known, but the use of the oxynitride as an electron-emitting material is a completely new proposal by the present inventors. It has not been known at all that the above effects are realized when an object is used for an electrode. That is, the oxynitride contained in the electron-emitting material according to the present invention has not been known as an electron-emitting material.

Hereinafter, the electron-emitting material according to the present invention will be described in detail.

Electron Emitting Material The electron emitting material of the present invention comprises Ba, Sr and Ca.
A first component comprising at least one of the following: Ta, Zr, N
b, a second component comprising at least one of Ti and Hf is included as a metal element component. The first component is a low work function electron emission component. The second component is a component necessary for lowering the resistance and increasing the melting point of the electron-emitting material. A preferred element of the first component is Ba, and Ba preferably accounts for 50 to 100 atomic%, particularly 70 to 100 atomic% of the first component. The preferred element of the second component is T
a and / or Zr, especially Ta, and preferably occupies 50 to 100 at%, especially 70 to 100 at% of the second component.

The electron emission material according to the present invention contains an oxynitride having a perovskite structure, that is, an oxynitride perovskite (oxynitride perovskite). When the first component is represented by M ^I and the second component is represented by M ^II , the oxynitride preferably contains at least M ^I M ^II O ₂ N type crystal. In this crystal, the ratio between oxygen and nitrogen is not limited to 2: 1. The actual product, due to the presence of oxygen and nitrogen defects,
The one represented as _{^{M I M II O 2+ δN 1-}} δ '. Here, δ and δ ′ are preferably −0.5 to 0.95,
More preferably, it is 0 to 0.7. When δ and δ ′ are in such ranges, the effect of suppressing evaporation and evaporation of the electron-emitting material is enhanced. In addition,
M ^I M ^II O ₂ N type crystal can also be represented as ^{M I M II (O, N} ) 3 type crystal.

The electron-emitting material of the present invention may contain an oxide in addition to the oxynitride perovskite. As the oxide for ^{_{example, M I 4 M II 2 O}} 9 type crystals,
M ^I M ^II ₂ O ₆ type crystals, M ^I M ^II O ₃ type ^{_{crystal, M I 5 M II 4 O}} 15
Type ^{_{crystals, M I 7 M II 6 O}} 22 type crystals and ^{_{M I 6 M II M II 4}} O 18
At least one kind of complex oxide such as a type crystal is included.
^{_{Incidentally, M I 6 M II M II}} 4 The O ₁₈ type crystal, for example, Ba ₆
ZrTa ₄ O ₁₈ is mentioned.

The electron-emitting material, in addition to the oxynitride, the carbide and / or nitride, may especially contain M ^II carbide such as TaC. This carbide or nitride is contained as a result of part of the second component becoming carbide or nitride in the process of producing the electron-emitting material, as described later. Since these carbides and nitrides are substances having a high melting point and high conductivity, even if they are contained, the electron emission characteristics and the sputtering resistance are not impaired at all. In the second component, for example, Ta is likely to be carbide, and Zr is likely to be nitride.

The presence of each crystal in the electron-emitting material depends on the X-ray
We can confirm by occasion. Electron discharge in the present invention
A typical X-ray diffraction pattern of the starting material is shown in FIG. Figure
The pattern shown in FIG. 5 is substantially M^IM^II
O_TwoElectron-emitting material consisting of a single phase of N-type crystal
You. The electron emission material in the present invention is M^IM^IIO_TwoN type knot
Preferably, the main component is a crystal, and it is substantially this crystal
More preferably, it is composed of a metal. However, as mentioned above
Contains carbides and / or nitrides
No problem. Note that M^IM^IIO_TwoN-type crystal is the main component
Means the maximum of each crystal in the X-ray diffraction pattern.
When comparing the large peak intensities, M^IM^IIO_TwoCrystals other than N
Has a maximum peak intensity of M^IM^IIO_TwoMaximum peak strength of N-type crystal
Means less than 50%, preferably less than 30% of the
To taste. However, for example, BaZrO _ThreeAnd Ba_FiveTa_FourO_Fifteen
And two types where the maximum peak positions almost match, or
If more oxides are formed at the same time,
Using the intensity of the large peak in the eye,^IM^IIO_TwoN-type crystal
Is compared with the maximum peak.

In the electron-emitting material, when the molar ratio of the first component is X and the molar ratio of the second component is Y with respect to the total of the first component and the second component, preferably 0.8 ≦ X / Y ≦ 1.5, more preferably 0.9 ≦ X / Y ≦ 1.2. If X / Y is too small, the first component will be depleted early due to discharge, and the sputtering resistance will be insufficient. On the other hand, if X / Y is too large, the electron-emitting material is likely to be evaporated and scattered by sputtering during discharge. Therefore, in any case, for example, when the present invention is applied to a discharge lamp, the brightness is easily reduced due to blackening of the tube wall.

The electron emission material comprises a first component and a second component
Metal element components other than the above may be contained. like this
As a metal element component, an element M (M is Mg, Sc,
Y, La, V, Cr, Mo, W, Fe, Ni and Al
At least one). Element M has a sintering tendency
It is added as needed for the above. In electron emission materials
The content of the element M in the oxide is preferably 10
It is at most 5 mass%, more preferably at most 5 mass%. element
If the content of M is too large, the melting point of the electron-emitting material becomes low.
, The steam pressure during high temperature use increases and the
Becomes shorter. On the other hand, the effect of the addition of element M is fully exhibited
In order to achieve this, the content of the element M should be 0.5% by mass or more.
Is preferred. The content in terms of oxide and
Is an oxide having a stoichiometric composition, that is, MgO, Sc_Two
O_Three, Y_TwoO_Three, La_TwoO_Three, V_TwoO_Five, Cr _TwoO_Three, MoO_Three,
WO_Three, Fe_TwoO_Three, NiO and Al_TwoO_ThreeConverted to
Content.

The element M is substituted with a part of M ^I or a part of M ^{II in} the oxynitride, or is not substituted, and is substituted with the oxynitride as an oxide, nitride, carbide, or the like. It is in a mixed state. The fact that a part of M ^I or a part of M ^{II in} the oxynitride crystal is replaced with another metal element can be confirmed by a shift of a peak in X-ray diffraction and a change in a peak intensity ratio. it can.

The resistivity at room temperature of the electron-emitting material in the present invention is usually so 10 ^-6 to 10 ³ [Omega] m, not a dielectric. And operating temperature (typically 90
(0 to about 1400 ° C., and about 700 to 1000 ° C. for a cold cathode). That is, even when the temperature becomes high due to the flow of a large discharge current, the consumption is small because the vapor pressure is low.

Method for producing electron-emitting material The above-mentioned Journal of Materials Science, 29, (1994), pp4686-
As shown in 4693, the above-mentioned oxynitride can be obtained by mixing raw material compounds such as oxides and carbonates, followed by firing in an ammonia stream.

However, when calcination is performed in an ammonia gas stream, since strongly alkaline ammonia is contained in the exhaust gas, it is necessary to pay attention to the corrosion resistance of the manufacturing apparatus. It is necessary to arrange a trap using sulfuric acid or the like at the exhaust port.
Therefore, it is not suitable for mass production, and equipment costs increase.

Therefore, the present inventors have searched for a production method capable of producing oxynitride perovskite without using an ammonia gas flow, and as a result, it has been found that at least the material to be fired containing the raw material powder and carbon are placed in close proximity to each other. It has been found that calcination in an atmosphere containing nitrogen gas can produce oxynitride perovskite. In this method, since a stable and easy-to-use nitrogen gas can be used, the problem of the method using the ammonia gas flow is solved. This method is completely novel as a method for producing oxynitride perovskite, and is the method proposed by the present inventors for the first time. In addition,
The material to be fired in this method may be the raw material powder itself, a coating film containing the raw material powder, or a molded product of the raw material powder. In addition, the raw material powder in this case may be an oxide and / or a starting material that generates an oxide by firing, or may be an intermediate product obtained by firing this to generate a composite oxide.

In this method, the means for arranging the object to be fired and the carbon in close proximity is not particularly limited. For example, a firing furnace at least partially composed of carbon may be used, or a bulk, granular, The object to be fired is baked in a state in which powdered carbon is put, or the object to be fired is mixed with granular or powdered carbon and fired, or the object to be fired is at least partially made of carbon. Or firing in
More than one species may be used in combination. Among these, it is easy to make the raw material powder in the object to be fired substantially uniformly contact the carbon, and the object to be fired is easily exposed to a nitrogen gas stream. A method in which powdered carbon is mixed and fired is preferred. However, when baking a relatively thin coating film, the carbon powder need not be dispersed in the coating film. When the coating film is thin, sufficient carbon can be supplied from the firing furnace or container to the raw material powder in the coating film, and when the carbon powder is dispersed in the thin coating film, the carbon powder becomes denser and flatter. This is because there is a possibility that it may have an effect on the operation.

Examples of the furnace at least partially composed of carbon include, for example, a furnace composed of carbon at least part of a heat insulating material. In an electric furnace, only a heating element or a heating element and a heating element are used. A furnace in which the heat insulating material is made of carbon is used. As the container made of carbon, a container having at least one open end is used so as not to hinder the contact of the nitrogen gas with the object to be fired.

Further, a carbon compound can be used instead of simple carbon. For example, usually, a molded article or a coating film contains a binder made of an organic compound.However, it is also possible to form oxynitride by supplying carbon from the binder by insufficiently removing the binder during firing. it can. The oxynitride can also be generated by putting an organic compound in the raw material powder or by putting an organic compound in a furnace and firing. However, a method using carbon alone is more preferable because oxynitride can be manufactured stably and there is no fear that the characteristics of the electron-emitting material are deteriorated due to the residual organic compound.

Hereinafter, each of the methods for obtaining the electron-emitting material in the present invention as a film will be described in detail.

Method 1 for Producing Film In obtaining the electron-emitting material as a film, the oxynitride may be formed under the above-mentioned conditions, and the other steps are not particularly limited. For example, the steps shown in FIGS. Can be used. First, each step shown in FIG. 1 will be described.

[0032] In the weighing step weighing process, weighed in accordance with the final composition of the starting material.
As a compound used as a starting material, an oxide and / or a compound which becomes an oxide upon firing, for example, a carbonate, an oxalate, or the like may be used. Usually, BaCO ₃ , SrCO ₃ and It is preferable to use CaCO _3, and the compound containing the second component includes Ta ₂ O ₅ ,
It is preferable to use ZrO ₂ , Nb ₂ O ₅ , TiO ₂ and HfO ₂ . Further, as a starting material of the element M,
MgCO ₃ , Sc ₂ O ₃ , Y ₂ O ₃ , La ₂ O ₃ , V ₂ O ₅ , C
r ₂ O ₃ , MoO ₃ , WO ₃ , Fe ₂ O ₃ , NiO and Al
It is preferable to use ₂ O ₃ .

Mixing Step In the mixing step, the weighed starting materials are mixed to obtain a raw material powder. For mixing, a method such as a ball mill method, a friction mill method, and a coprecipitation method can be used. After mixing, drying is performed by a dehydration heating drying method or a freeze drying method.

In this mixing step, carbon is added to the starting materials as required. Carbon may be wet-mixed simultaneously with the mixing of the starting materials, or may be added after the starting materials are mixed and then dry-mixed. Carbon has a relatively small specific gravity,
Since it is difficult to disperse in a dispersion medium, a dispersant is added as needed when performing wet mixing. The dispersion medium may be aqueous or organic, but considering the load on the environment,
It is preferable to use an aqueous type.

The amount of carbon added is preferably 50% by mass or less, more preferably 20% by mass or less, based on the starting materials. If the addition amount is too large, a large amount of carbides and nitrides that do not contribute to electron emission tends to be generated, which is not preferable. In addition, it is not preferable because a large amount of carbon remains after firing and is likely to evaporate and gasify when used as an electron-emitting material. On the other hand, in the case where the container made of carbon and the furnace material containing carbon are not used, if the added amount of carbon is too small, it becomes difficult to generate oxynitride. Therefore, in this case, the added amount of carbon is preferably 1% by mass or more, more preferably 2% by mass, based on the starting material. The type of carbon is not particularly limited, and may be any of graphite, amorphous carbon, and the like. The average particle size of carbon in the mixture is preferably 1 mm or less, more preferably 500 μm or less. If the average particle size is too large, it is difficult to uniformly disperse in the mixture, and it is difficult to react, so that it tends to remain after firing. It is preferable that the average particle size of the carbon powder is small, but if the average particle size is too small, it becomes difficult to handle and disperse.
μm or more. In addition, a dispersant may be used to improve the dispersibility of the carbon powder. Further, the specific value of the average particle diameter of carbon in the mixture may be appropriately determined according to the thickness of the coating film, the density required for the coating film, and the like.

Slurry Preparation Step In the slurry preparation step, a mixture of starting materials is slurried. When performing wet mixing in the mixing step,
It is preferable that the mixing step also serves as a slurry preparation step. The dispersion medium used for slurrying may be aqueous or organic as described in the mixing step.

In the slurry preparation step, a binder is added as required. The type of the binder is not particularly limited, and for the organic dispersion medium, for example, ethyl cellulose, may be appropriately selected from various ordinary binders such as polyvinyl butyral, and for the aqueous dispersion medium, for example, polyvinyl alcohol, cellulose, A water-soluble acrylic resin or the like may be used.

The solids concentration in the slurry or the viscosity of the slurry, may be suitably determined depending on the film forming method, usually, the slurry viscosity is preferably set to 0.01 to 10 ⁵ mPa · s about .

The coating film-forming step In this step, a coating film is formed on the substrate surface using a prepared slurry. The base material is not particularly limited, and may be any of various metals and ceramics.

The method for forming a coating film is not particularly limited, and may be appropriately selected from various methods such as a printing method, a doctor blade method, and a spraying method according to a required coating film thickness and the like.

[0041] In the oxynitride forming step oxynitride forming step as the coating film of the baked product, a nitrogen gas-containing atmosphere, preferably calcined in a nitrogen stream, an electron-emitting material containing oxynitride perovskite obtain. At this time, as described above, a furnace or a vessel at least partially composed of carbon is used, carbon is disposed in the furnace, or both are used as necessary. The firing temperature is preferably 800 to 2000 ° C, more preferably 1 to 2000 ° C.
100-1700 ° C. If the firing temperature is too low, oxynitrides are less likely to be generated, and if the firing temperature is too high, the amount of carbides and nitrides generated increases, and in any case, the performance as an electron-emitting material tends to be insufficient. Also,
If the firing temperature is too high, the material to be fired may be melted. The firing time (temperature holding time) may be generally about 0.5 to 5 hours. By this firing, an oxynitride having a perovskite structure is generated. Further, at this time, in addition to the oxynitride, carbide and / or nitride of the second component may be simultaneously generated, and particularly, carbide is easily generated.

The carbon powder mixed with the raw material powder is
Since it is consumed by reacting by baking in a nitrogen gas-containing atmosphere, it does not substantially remain in the electron emission material film if the mixing amount is appropriate. Therefore, after firing, it is not necessary to remove the carbon powder from the electron emission material film. However, for example, when a relatively large amount of carbon powder having a large particle diameter is used, the removal operation may be performed as necessary. .

As the nitrogen gas-containing atmosphere, nitrogen 1
It is most preferable that the content be 00%, but an inert gas such as Ar, a reducing gas such as CO or H _2, or a gas containing carbon as a component (for example, benzene or carbon monoxide) may be contained. . However, even in that case, nitrogen is 50% of the whole
It is preferable to occupy the above. A gas containing carbon as a constituent component is generally more difficult to handle than nitrogen, and it is difficult to stably generate an oxynitride perovskite.

When firing in a nitrogen stream, the flow rate of nitrogen gas per unit area near the object to be fired, ie, the nitrogen per unit area in a space near the object to be fired in a cross section perpendicular to the direction of flow of the nitrogen gas flow The gas flow rate is 0.0
It is preferably at least 001 m / s, particularly preferably at least 0.001 m / s. By supplying nitrogen gas to the object to be fired at such a flow rate, oxynitride can be easily and quickly generated in the object to be fired. The flow rate may be set within a range in which the material to be fired is not scattered, and there is no specific upper limit, but it is not usually necessary to set the flow rate to more than 5 m / s.

Since the above oxynitride is easily decomposed when heated in an atmosphere containing an oxygen gas, the firing atmosphere is preferably maintained at a low oxygen partial pressure. Since the ease of decomposition of the oxynitride varies depending on the heating temperature, the oxygen partial pressure may be appropriately controlled according to the firing temperature, but preferably 5.0.
× 10 ³ Pa (0.05 atm) or less, more preferably 1.
The pressure is 0 × 10 ³ Pa (0.01 atm) or less, more preferably 0.1 × 10 ³ Pa (0.001 atm) or less. The preferable lower limit of the oxygen partial pressure is not particularly limited, and the oxygen partial pressure may be zero. However, when a normal firing apparatus is used, the oxygen partial pressure in the firing atmosphere is generally 0.1 Pa or more.

Method 2 for Producing Film The method shown in FIG. 2 is different from the method shown in FIG. 1 in that oxynitride perovskite is generated before forming a coating film. When carbon powder is contained in the coating film in the method shown in FIG. 1, carbon in the coating film reacts at the time of firing, so that dimensional accuracy and density of the electron emission material film may be affected by consumption of carbon. On the other hand, in the method shown in FIG. 2, since the coating is formed after the carbon is consumed in the oxynitride generation step provided before the coating is formed, there is no need to worry about the influence of carbon consumption. Hereinafter, each step will be described.

[0047] performed in the same manner as the weighing process shown in weighing Scheme 1.

Mixing Step The mixing step is performed in the same manner as in the mixing step shown in FIG.

Oxynitride Formation Step In this method, the mixture of the starting materials and the carbon, which is optionally added, is prepared in the form of a powder or, if necessary, for ease of handling. Firing is performed under the same conditions as in the oxynitride generation step shown in FIG. 1 to obtain an electron emission material containing oxynitride perovskite.

[0050] In the pulverization step grinding process, grinding the electron emission material obtained by oxynitride forming step, obtaining an electron-emitting material powder. In this grinding,
A ball mill or airflow pulverization may be used. By providing the pulverizing step, the particle size of the electron-emitting material can be reduced and the particle size distribution can be narrowed, so that the electron-emitting property can be improved and its variation can be reduced. Therefore, it is preferable to provide a pulverizing step.

[0051] In addition the use of slurry preparation step the electron-emitting material is performed similarly to the slurry preparation step shown in FIG. If wet pulverization is used in the pulverization step provided immediately before, the pulverization step can also serve as a slurry preparation step.

[0052] carried out in the same manner as the coating film forming step shown in the film forming process diagram 1.

Heat Treatment Step In the heat treatment step, the coating film is dried and, if a binder is added, the binder is removed. Heat treatment is 8
It may be performed at 0 ° C. or higher, usually at 150 to 2000 ° C. for about 0.5 to 20 hours. Although the coating film may be sintered and densified by this heat treatment, it may be preferable that the electron emission material film is not a dense sintered body. In that case, processing conditions under which the particles do not sinter, for example, 0.5 to 5 at 1600 ° C. or less.
It is preferable to set it to about time.

The atmosphere at the time of the heat treatment may be appropriately determined so as not to decompose the oxynitride perovskite already generated. In other words, when the heat treatment is performed at a relatively low temperature, the heat treatment may be performed in an oxidizing atmosphere such as in air, but when the heat treatment is performed at a relatively high temperature, the heat treatment may be performed using a neutral gas such as nitrogen gas or an inert gas such as Ar. It is preferable to use a non-oxidizing atmosphere. In this case, the oxygen partial pressure in the atmosphere is preferably in the range described in the description of the oxynitride generation step. When heat treatment is performed at a higher temperature, carbon is disposed close to the coating film, as in the case of the oxynitride generation step, and
The heat treatment is preferably performed in a nitrogen gas-containing atmosphere.
That is, it is only necessary to use a container or a furnace at least partly made of carbon, arrange carbon in the furnace, or use them together. The preferable conditions in the nitrogen gas-containing atmosphere at this time are the same as the preferable conditions for the nitrogen gas-containing atmosphere described in the description of the oxynitride generation step.

[0055] The method shown in the production method 3 Figure 3 of the membrane, M ^I ₅ M in the composite oxide generation step
^The difference from the method shown in FIG. 1 is that once a composite oxide such as ^II ₄ O ₁₅ is generated, a powder containing this composite oxide is used as a raw material powder. In the method shown in FIG. 1, the starting material powder is slurried to form a coating film on the surface of the base material, and oxynitride is generated in the coating film, so that the coating film and the base material react during firing. As a result, the characteristics of the electron emission material film may be deteriorated. In contrast, the method shown in FIG.
Once the composite oxide is formed and the coating film containing the powder containing the composite oxide is baked, the coating film and the substrate hardly react. Therefore, when the reaction with the base material is extremely disliked, the method shown in FIG. 3 is effective. Hereinafter, each step shown in FIG. 3 will be described.

[0056] performed in the same manner as the weighing process shown in weighing Scheme 1.

Mixing Step The mixing step is performed in the same manner as in the mixing step shown in FIG. 1 except that carbon is not added.

The composite oxide forming step The raw material powder is fired in an oxidizing atmosphere such as air to obtain M ^I ₅
An intermediate product containing a complex oxide such as M ^II ₄ O ₁₅ is produced. Examples of the complex oxide contained in the intermediate product include at least one of the complex oxides that can be contained in the electron-emitting material produced according to the present invention. It is preferable that the intermediate product obtained by this calcination is substantially composed of only the composite oxide. The firing temperature is preferably 800 to 1700 ° C, more preferably 800 to 1700 ° C.
1500 ° C, more preferably 900 to 1300 ° C. If the firing temperature is too low, M ^I ₅ M ^II ₄ O composite oxide such as ₁₅ is hardly generated. On the other hand, if the firing temperature is too high, sintering proceeds and it becomes difficult to grind, and the composite oxide may be melted or decomposed. The firing time may be about 0.5 to 5 hours. This baking may be performed in a powder state, or may be performed in a state in which the powder is molded for easy handling. Note that the composite oxide generation step may be performed in a reducing atmosphere. The above-mentioned composite oxide can be produced even by firing in a reducing atmosphere. However,
Since it is necessary to control the atmosphere in order to obtain a reducing atmosphere, and since the performance of the electron emission material finally obtained does not depend on the firing atmosphere in the composite oxide generation step, firing in air is usually performed. preferable.

Pulverization Step The pulverization step is performed in the same manner as in the pulverization step shown in FIG. 1, but carbon is mixed as necessary, as in the mixing step shown in FIG.

[0060] In addition the use of slurry preparation step the intermediate product is carried out similar to the slurry preparation step shown in FIG.

[0061] carried out in the same manner as the coating film forming step shown in the film forming process diagram 1.

Oxynitride Generation Step An oxynitride perovskite is generated in the same manner as in the oxynitride generation step shown in FIG.

Method 4 for Producing Film The method shown in FIG. 4 differs from the method shown in FIG. 3 in that an oxynitride generation step is provided before the coating film is formed to generate an oxynitride perovskite. Alternatively, it can be said that the method differs from the method shown in FIG. 2 in that once the composite oxide is generated in the composite oxide generation step, the powder containing the composite oxide is used as the raw material powder. Therefore, there is no need to worry about the influence of carbon consumption on the dimensional accuracy and density of the coating film even in the method shown in FIG. Hereinafter, each step will be described.

[0064] performed in the same manner as the weighing process shown in weighing Scheme 3.

Mixing Step The mixing step is performed in the same manner as in the mixing step shown in FIG.

Composite Oxide Generation Step A composite oxide is generated in the same manner as the composite oxide generation step shown in FIG.

First crushing step The first crushing step is performed in the same manner as in the crushing step shown in FIG.

Oxynitride Generation Step The oxynitride generation step shown in FIG. 3 is performed to obtain an electron emission material containing an oxynitride.

Second pulverizing step The pulverizing step is performed in the same manner as in the pulverizing step shown in FIG. 3, except that carbon is not added.

[0070] In addition the use of slurry preparation step the electron-emitting material is performed similarly to the slurry preparation step shown in FIG.

Coating Film Forming Step The coating film forming step is performed in the same manner as the coating film forming step shown in FIG.

Heat treatment step is performed in the same manner as the heat treatment step shown in FIG.

Electrodes The electron emitting material of the present invention is suitable for electrodes for various discharge lamps such as fluorescent lamps. In that case, it can be used both as an electrode for hot cathode operation and as an electrode for cold cathode operation.

In the case where the electron-emitting material of the present invention is used as a film, for example, it may be applied to the surface of a base material such as a linear body (a coil-shaped or double-coiled filament) or a plate-shaped body.
An electrode can be formed by forming an electron emission material film. As the base material, for example, W, Mo, Ta, Ni, Z
r, various metals such as Ti, or alloys containing at least one of these, or ZrO ₂ , Al ₂ O ₃ , Mg
Ceramics such as O, AlN, Si ₃ N ₄ or ceramics containing at least one of them (SIALON etc.)
Can be used. In addition, a coating film containing an oxynitride-containing powder or a raw material powder in which oxynitride is generated by firing and a coating film containing a conductive material are laminated by a printing method or a sheet method, and this is fired. To form a stacked electrode.

When the electron-emitting material according to the present invention is used as a film, the thickness of the film is usually about 5 to 1000 μm. The average particle size of the electron emitting material particles in the electron emitting material film is preferably 0.05 to 20 μm, and more preferably 0.1 to 10 μm. In order to further reduce the average particle size in the film, fine particles that are difficult to handle must be used. In addition, such fine particles are likely to aggregate into secondary particles, so that the particle size distribution is widened and it is difficult to form a uniform coating film. On the other hand, if the average particle size in the film is too large, the particles of the electron-emitting material tend to fall off, and the workability during coating is also poor, and the electron-emitting properties are also poor.

The electron-emitting material in the present invention is not only an electrode for various discharge lamps such as a fluorescent lamp, but also an electrode for an electron gun of a cathode ray tube, an electrode of a plasma display, an electrode of a field emission display, an electrode of a fluorescent display tube, an electron microscope. It can also be used as an electron emission material such as an electrode. In each of these cases, the effect of the present invention, that is, the longevity of the electrode and the improvement of the characteristics are realized.

[0077] The discharge lamp Figure 6 shows a configuration example of a discharge lamp of cold cathode operation. It should be noted that only the vicinity of the pipe end is shown in FIG. Conventionally, it is common to use a metal tubular body made of Ni or the like for the cold cathode. When an emitter is used, the tubular body is used as an electrode substrate, and the peripheral surface is made of, for example, BaO. The coating film of the emitter is provided. When the present invention is applied to a cold cathode discharge lamp, a coating containing the above-mentioned electron-emitting material may be provided on the surface of the electrode substrate instead of the conventional emitter coating. As a constituent material of the electrode substrate, in addition to Ni, for example, a high melting point metal such as W, Ti, Zr, Mo, and Ta, or an alloy containing at least one of these can be preferably used.

This discharge lamp shown in FIG. 6 has a phosphor 9 on its inner surface.
A is applied and has a hermetically sealed valve 9. A rare gas is sealed in the valve 9. A lead wire 5 is inserted through an end of the bulb 9. The end of the lead wire 5 present in the valve 9 has a stem 9 for closing the valve end.
An internal introduction line 6A is provided through B. A conductive pipe 7 serving as an electrode substrate is connected to the internal introduction line 6A. On the inner peripheral surface of the conductive pipe 7, an electron emission material film 2A is formed. This discharge lamp has a structure in which mercury is supplied into a bulb during a sealing process.

The electrode using the electron-emitting material according to the present invention is applicable not only to the discharge lamp having the above structure. For example, the invention can be applied to various types of discharge lamps already proposed by the present inventors in the above publications.

[0080]

EXAMPLE 1 Samples of the electron emission material films shown in Table 1 were prepared by the following procedure using the method shown in FIG.

First, Ba was selected as the first component, and Ta and Zr were selected as the second component.
aCO ₃ and Ta ₂ O ₅ were prepared.

Then, Ba: Ta: Zr = 1: 0.8:
The starting material was weighed so as to be 0.2, and the starting material, water and polyvinyl alcohol were wet-mixed by a ball mill for 20 hours to obtain a slurry.

Using this slurry, a coating film was formed on the surface of the plate-like substrate by a printing method. Table 1 shows the base material and the thickness of the coating film. SIALON shown in Table 1
Is an oxynitride sintered body containing Al and Si as metal element components.

Next, the coating film was subjected to an oxynitride generation treatment. In this treatment, the substrate on which the coating film is formed is placed in a carbon container having an open top surface, a gap is provided between the substrate and the container, and a carbon lid is placed thereon.
After firing for an hour, an electron emission material film sample was obtained. Nitrogen gas was supplied so that the flow rate of nitrogen gas per unit area in a section perpendicular to the flowing direction of the nitrogen gas flow in the space near the coating film in the furnace was 0.001 m / s. Table 1 shows the oxygen partial pressure in the firing atmosphere.

For each sample shown in Table 1, the product was examined by X-ray diffraction. As a result, the peak of the peak and TaC all samples oxynitride perovskite (M ^I M ^II O ₂ N type crystals) were observed. Table 1 shows the relative evaluation of the peak intensity of each sample.

[0086]

[Table 1]

Table 1 shows that oxynitride perovskites can be produced according to the present invention.

For comparison, Japanese Patent Application Laid-Open No.
Based on the method described in JP-A-129177, an electrode sample was prepared in the following procedure. First, the mixture of the starting materials used in the production of Sample No. 4 was molded at a pressure of 100 MPa, and then fired at 1100 ° C. for 2 hours in the atmosphere. The obtained fired body, wet pulverization, drying, granulation into granules,
The granules were compression molded to obtain a molded body. Then, after filling the above-mentioned granules into this compact, the above-mentioned compact is completely buried in carbon powder, and 1600 ° C. while flowing nitrogen gas.
For 2 hours. Nitrogen gas was supplied such that the flow rate of nitrogen gas per unit area in a section perpendicular to the direction of flow of the nitrogen gas in the space near the compact in the furnace was 0.00005 m / s. The oxygen partial pressure in the firing atmosphere is
The pressure was 20 Pa (0.0002 atm).

The product of this electrode sample was confirmed by performing X-ray diffraction in the same manner as described above.
Except aC), it was a single phase of the composite oxide ^{_{(M I 5 M II 4 O}} 15 type crystal).

Example 2 An electron emission material film sample shown in Table 2 was produced by the following procedure using the method shown in FIG.

After the starting materials used in Example 1 were weighed and mixed in the same manner as in Example 1, the starting materials were further weighed to a value of 0.1.
01 μm carbon powder was mixed. The weight ratio of carbon to the starting material was 5% by mass.

The obtained mixture was used to prepare a mixture having a diameter of 15 mm and a thickness of 10 mm.
It was formed into a cylindrical shape of mm. The obtained molded product was subjected to an oxynitride generation treatment. In this treatment, the molded body was placed in a carbon-made container without a lid, and fired under the same conditions as in the firing of the coating film in Example 1, except that the oxygen partial pressure in the firing atmosphere was set to the value shown in Table 2.

The obtained fired body was mixed with a binder (acrylic resin) and a solvent (α terpineol) to form a slurry, and this slurry was printed on the surface of a plate-like substrate to obtain a coating film. Table 2 shows the base material and the thickness of the coating film.
Shown in In addition, the viscosity of the slurry was appropriately selected from the range of 7000 to 100000 mPa · s in order to adjust the thickness of the coating film.

Next, the substrate on which the coating film was formed was heat-treated at 400 ° C. for 2 hours in a nitrogen stream to obtain an electron emission material film sample. For these samples, Example 1
The analysis by X-ray diffraction was performed in the same manner as described above. as a result,
Oxynitride perovskite in all samples (M ^I M ^II
O ₂ N-type crystal) and TaC peak were observed. Table 2 shows the relative evaluation of the peak intensity of each sample.

[0095]

[Table 2]

From the comparison between Table 2 and Table 1, it can be seen that in the method shown in FIG. 2, the amount of oxynitride perovskite in the electron emission material film is not affected by the thickness of the coating film. On the other hand, in the method of generating oxynitride in the coating film, TaC is generated near the surface of the film, so that the content of the electron-emitting material near the surface of the electron-emitting material film is slightly reduced.

Example 3 The procedure was the same as in Example 2 up to the preparation of the slurry. However, slurries having various viscosities were prepared for adjusting the thickness of the coating film. Then, using the metal wire as a base material, the metal wire was dipped in a slurry to form a coating film. The thickness of the coating was controlled by the viscosity of the slurry and the number of dips. Table 3 shows the base material and the thickness of the coating film. Next, heat treatment was performed in the same manner as in Example 2 to obtain an electron emission material film sample. These samples were analyzed by X-ray diffraction in the same manner as in Example 1. As a result, the peak of the peak and TaC all samples oxynitride perovskite (M ^I M ^II O ₂ N type crystals) were observed. Table 3 shows the relative evaluation of the peak intensity of each sample.

[0098]

[Table 3]

Table 3 shows that an electron emission material film can be formed on the surface of the metal wire.

The slurry prepared in the same manner as in Example 3 except that the viscosity was changed to 10 mPa · s was sprayed onto a metal plate in a nitrogen atmosphere and heated by a burner at the same time. Was.

In the electron-emitting material film samples of Examples 1 to 3, the specific resistance at room temperature was 10 ⁻⁶ to 10 ³ Ωm.
Was within the range.

In the above embodiment, FIGS. 1 and 2
Although the electron emission material film was manufactured by the method shown in the above, even when the other method described in this specification was used, when the various conditions in the oxynitride generation step were made equal, the electron emission material having almost the same characteristics was obtained. A material film was obtained.

[0103]

According to the present invention, since the electron-emitting material contains the above-mentioned oxynitride, the electron-emitting material has good electron-emitting characteristics, less evaporation at a high temperature, and less consumption by ion sputtering. Few. Therefore, for example, when applied to an electrode of a discharge lamp, a discharge lamp with less blackening of the tube wall and a long life is realized. Further, the electron emission material film containing the oxynitride can be manufactured in the present invention without using ammonia gas. Therefore, there is no need to provide a production facility corresponding to ammonia gas, so that mass production becomes possible and production costs are reduced.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a manufacturing process of an electron emission material film.

FIG. 2 is a flowchart showing a manufacturing process of an electron emission material film.

FIG. 3 is a flowchart illustrating a manufacturing process of an electron emission material film.

FIG. 4 is a flowchart showing a manufacturing process of the electron emission material film.

FIG. 5 is an X-ray diffraction pattern of the electron-emitting material used in the present invention.

FIG. 6 is a cross-sectional view illustrating a configuration example of a discharge lamp that operates in a cold cathode operation.

[Explanation of symbols]

 2A Electron emitting material film 5 Lead wire 6A Internal introduction wire 7 Conductive pipe 9 Valve 9A Phosphor 9B Stem

Continued on the front page (72) Inventor Munemitsu Hamada 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDK Corporation (72) Inventor Masatada Yodogawa 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDK Corporation (72) Inventor Taku Harada 1-13-1 Nihonbashi, Chuo-ku, Tokyo Inside TDK Corporation (56) References JP-A-5-190137 (JP, A) JP-A-7-153373 (JP, A) JP-A-2000-331603 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01J 9/02

Claims (11)

(57) [Claims] 1. A first component comprising at least one of Ba, Sr and Ca, Ta, Zr, Nb, Ti and H
a second component comprising at least one of f as a metal element component, and producing an electron-emitting material containing an oxynitride perovskite. Baking in an atmosphere containing nitrogen gas in a state of being placed in proximity to generate an oxynitride perovskite to obtain an electron-emitting material; and providing an electron obtained by the oxynitride generation step. The emission material is pulverized to obtain an electron emission material powder, a coating film is formed using a slurry containing the electron emission material powder, and the coating film is heat-treated to obtain an electron emission material film. Production method. 2. A first component comprising at least one of Ba, Sr and Ca, Ta, Zr, Nb, Ti and H
a second component comprising at least one of f as a metal element component, and producing an electron-emitting material containing an oxynitride perovskite. By firing in a nitrogen gas-containing atmosphere in a state of being placed close to, an oxynitride generating step of obtaining the electron emitting material by generating the oxynitride perovskite, A method for producing an electron-emitting material film, wherein an electron-emitting material film is obtained by using the object as a firing target. 3. The method according to claim 1, wherein an oxygen partial pressure in the nitrogen gas-containing atmosphere is 0 to 5.0 × 10 ³ Pa. 4. A nitrogen gas flow is used as the nitrogen gas-containing atmosphere, and a nitrogen gas flow rate per unit area in a cross section perpendicular to a flow direction of the gas flow in a space near the object to be fired in the nitrogen gas flow is 0.0001. The method for producing an electron-emitting material film according to any one of claims 1 to 3, wherein the speed is set to 5 m / s. 5. The electron emission material film according to claim 1, wherein, in the oxynitride generation step, carbon is mixed in the object to be fired, so that carbon is arranged in proximity to the object to be fired. Manufacturing method. 6. The method according to claim 1, wherein in the oxynitride forming step, carbon is disposed in proximity to the object to be fired by using a firing furnace at least partially constituted of carbon. A method for manufacturing an electron emission material film. 7. The oxynitride generation step, wherein the object to be fired is housed in a container at least partially composed of carbon, so that carbon is arranged in proximity to the object to be fired. 6. The method for manufacturing an electron emission material film according to any one of the above items 6. 8. The method for producing an electron emission material film according to claim 1, wherein in the oxynitride forming step, the oxynitride is formed from a firing target containing a composite oxide. 9. When the first component is represented by M ^I and the second component is represented by M ^II , the oxynitride perovskite is represented by M ^I M
Method of any of the electron-emitting material film according to claim 8 including a ^II O ₂ N type crystals. 10. The method of manufacturing an electron-emitting material film according to claim 1, wherein an electron-emitting material containing the second component carbide and / or nitride is manufactured. 11. The first component M ^I, when the second component expressed respectively _{^{M II, M I 4 M II}} 2 O 9 type crystals, M ^I M ^II ₂ O ₆ type crystals, M ^I M ^II O ₃ type _{^{crystal, M I 5 M II 4 O}} 15 type crystal, an electron emission material comprising at least one M ^I ₇ M ^II ₆ O ₂₂ type crystals and _{^{M I 6 M II M II 4}} O 18 type crystals is produced The method for producing an electron-emitting material film according to claim 1.