JP7579052B2 - Alkaline earth metal titanate composition, its manufacturing method, and paste containing same - Google Patents

Description

The present invention relates to a composition of alkaline earth metal titanate.

Alkaline earth metal titanate particles, which have a small average particle size and a uniform particle size distribution, are suitable for use as dielectric materials for electronic components and optical materials with a high refractive index and excellent transparency. In particular, crystalline alkaline earth metal titanates such as barium titanate are known as high dielectric materials and are used in electronic components such as multilayer ceramic capacitors (MLCCs). MLCCs have a structure in which dielectric layers and electrode layers are stacked in multiple stages, and in order to increase capacity, the dielectric layers and electrode layers must be made thin and multi-layered. Therefore, thin-film electrode layers (internal electrodes) are required to have low resistance, be free of cracks, and have excellent adhesion to the dielectric layer.

The internal electrodes of MLCCs are produced by printing using a paste containing conductive particles (nickel particles, etc.). This electrode paste contains not only conductive particles, but also 50-100 nm barium titanate particles as a co-material to increase the sintering temperature. This allows the sintering temperature of the electrode layer to be close to that of the dielectric layer (1000-1200°C). As a result, stress concentration in the electrode layer is alleviated, reducing the occurrence of cracks.

In recent years, in order to further reduce the thickness of electrode layers, there is a demand for a barium titanate dispersion with small particles of 30 nm or less and high dispersibility. A method for preparing barium titanate is known in which an alkyl cellosolve solution of barium hydroxide is mixed with titanium alkoxide and hydrolyzed (see, for example, Patent Document 1). This manufacturing method produces barium titanate with a small average particle size and excellent dispersibility.

It is also known that the dispersion stability of barium titanate particles can be improved by surface treating them with an organic silane (see, for example, Patent Document 2).

JP 2012-240904 A Japanese Patent Application Publication No. 09-202864

However, the particles obtained by the method described in Patent Document 1 have a low hydrophobic surface, so they tend to aggregate and a smooth film cannot be obtained. Furthermore, these particles have a high crystallinity and therefore a high charge. Therefore, when used as a common material for the internal electrodes of MLCCs, the mixing stability with conductive particles (Ni particles, etc.) is low. In other words, the stability of the electrode paste is also low. Furthermore, the sintering retardation effect of the electrode layer cannot be obtained during the firing process, and the difference with the sintering temperature of the dielectric layer becomes large. As a result, residual stress becomes large, cracks occur, and good reliability cannot be obtained.

In addition, the barium titanate particles described in Patent Document 2 are surface-treated with an organic silane, which results in a relatively stable coating material. However, after film formation, it is difficult to completely remove the silica even when fired at high temperatures of 1000°C or higher. Therefore, when these particles are used in internal electrodes, the remaining silane can cause a decrease in electrical conductivity and a decrease in the dielectric constant of the dielectric layer.

Nano-sized barium titanate particles produced by the oxalic acid method or solid phase method are generally available on the market. These particles are 20 nm or larger, which is larger than the gaps between conductive particles, and therefore are unlikely to exist between the particles. Even if these particles are used as co-materials for conductive particles smaller than 100 nm, sufficient sintering prevention effects cannot be obtained.

The object of the present invention is to obtain an alkaline earth metal titanate composition that is excellent as a co-material for electrode materials. In other words, the object is to realize an alkaline earth metal titanate composition that can form a smooth electrode layer with few cracks.

The alkaline earth metal titanate composition of the present invention has an atomic ratio of alkaline earth metal to titanium (alkaline earth metal/Ti) of 0.95 to 1.05, the dried product obtained by drying the composition at 300°C contains 0.5 to 10% carbon components, and the crystallinity of the dried product measured by X-ray diffraction is 50% or less. When such a composition is made into an electrode paste for MLCC together with conductive particles and a solvent, the composition and conductive particles are well dispersed and mixed, and the dispersion is stably maintained. Therefore, the sintering retardation effect of the electrode layer is sufficiently obtained, and a smooth electrode layer with few cracks can be formed.

In addition, by coordinating an organic compound to the alkaline earth metal titanate, the dispersibility is further improved. In addition, by containing 0.1 to 10 mol % of at least one element belonging to Group 2A, Group 3A, lanthanoids, actinoids, Group 4A, Group 5A, Group 7A, Group 8, Group 1B, Group 2B, Group 3B, or Group 4B in the alkaline earth metal titanate composition, the sintering temperature of the electrode layer can be increased.

The method for producing an alkaline earth metal titanate composition according to the present invention comprises a first step of mixing an alkaline earth metal hydroxide with a titanium alkoxide so that the atomic ratio of the alkaline earth metal to titanium (alkaline earth metal/Ti ratio) is in the range of 0.95 to 1.05, and a second step of adjusting the water content so that the ratio (M _H /M _T ) of the number of moles of titanium (M _T ) to the number of moles of water (M _H ) contained in the titanium alkoxide is in the range of 0.1 to 8, and then performing hydrolysis.

The alkaline earth metal titanate composition according to the present invention has an atomic ratio of alkaline earth metal to titanium (alkaline earth metal/Ti) of 0.95 to 1.05. The dried product obtained by drying this composition at 300°C contains 0.5 to 10% carbon components. This carbon component is derived from titanium alkoxide. The crystallinity of the dried product measured by X-ray diffraction is 50% or less. That is, the composition is formed using a precursor of alkaline earth metal titanate with a low degree of crystallinity. Such a composition has low crystallinity and therefore low charge. Therefore, when this composition is mixed with conductive particles, solvent, and binder components with high charge to form an electrode paste, high dispersibility and excellent stability are obtained. That is, the composition and conductive particles are well dispersed in the paste, and this dispersion can be stably maintained. The electrode layer formed using such a paste has high smoothness and does not crack due to firing. The sintering temperature of the electrode layer is close to the sintering temperature of the dielectric layer, so stress concentration is prevented and cracks are suppressed. The reason why the electrode layer has a high sintering retardation effect is not clear, but it can be assumed that the thermal energy during firing is first consumed in crystallizing the alkaline earth metal titanate, which has low crystallinity, and then consumed in sintering the electrode particles. Therefore, the alkaline earth metal titanate composition of the present invention has a higher sintering retardation effect on the electrode layer than conventional co-materials. The degree of crystallinity is more preferably 5 to 30%. In an alkaline earth metal titanate composition with a degree of crystallinity of less than 5%, there is a risk that the condensation reaction will not be completed when titanium alkoxide and alkaline earth metal salt are mixed.

In addition, if the atomic ratio of alkaline earth metal to titanium (alkaline earth metal/Ti) is in the range of 0.95 to 1.05, there is almost no elution of Ti components or alkaline earth metal components into the dispersion liquid. Because the amount of these eluted components is small, it is possible to obtain MLCC with good electrical properties.

The carbon content of the dried product obtained by drying the composition at 300°C is preferably 0.5 to 10%. This carbon content is derived from titanium alkoxide. Since such a composition contains alkoxy groups, it has a low charge and is highly hydrophobic. Therefore, the composition has high mixing stability with the conductive particles, solvent, and binder components, and is less likely to aggregate. Furthermore, the paste is also highly stable. Therefore, the resulting electrode layer has high smoothness and is less likely to crack during firing. On the other hand, if it is less than 0.5%, the surface charge is high, the mixing stability is low, and the paste stability is also low. Therefore, the resulting electrode layer has poor smoothness and may crack during firing. If it exceeds 10%, it means that the composition has hardly reacted, and the Ti component and alkaline earth metal component are easily eluted. Therefore, even if an electrode paste is prepared using this composition, the sintering retardation effect may not be obtained.

Furthermore, it is preferable that an organic compound is coordinated to the alkaline earth metal titanate. This further improves dispersibility. Even if an organic compound is coordinated to alkaline earth metal titanate that does not contain a carbon component derived from an alkoxide, it is difficult to improve dispersibility in conductive particles, binder components, solvents, etc. Even if an electrode paste is prepared and an MLCC is produced, the film may have poor smoothness and be non-uniform, causing cracks during firing. Examples of organic compounds include carboxylic acids and β-diketones. When carboxylic acids are coordinated, a peak appears in the range of 165 to 167 ppm when C ¹³ NMR is measured.

Furthermore, it is preferable that the alkaline earth metal titanate composition contains 0.1 to 10 mol% of at least one element belonging to Group 2A, Group 3A, Lanthanoid, Actinoid, Group 4A, Group 5A, Group 7A, Group 8, Group 1B, Group 2B, Group 3B, or Group 4B. Possible forms of this element contained in the alkaline earth metal titanate include substitution and mixing, but it is preferable that it exists as a crystal after the composition is fired. By including this element in the composition, the sintering temperature of the electrode layer becomes higher and approaches the sintering temperature of the dielectric layer, thereby reducing cracks during the production of the MLCC.

Next, a method for producing an alkaline earth metal titanate composition will be described. First, an alkaline earth metal hydroxide and a titanium alkoxide are mixed (first step). At this time, the atomic ratio of the alkaline earth metal to titanium (alkaline earth metal/Ti ratio) is adjusted to be in the range of 0.95 to 1.05. Water is added to this mixed solution, and the molar ratio (M _H /M _T ) of the number of moles of titanium (M _T ) contained in the titanium alkoxide to the number of moles of water (M _H ) is adjusted to be in the range of 0.1 to 8. This causes hydrolysis of the titanium alkoxide, and a dispersion of an alkaline earth metal titanate composition is obtained (second step).

In the first step, the atomic ratio of alkaline earth metal to titanium (alkaline earth metal/Ti) is set to 0.95 to 1.05. Within this range, Ti and Ba components are hardly eluted, so a dispersion of an alkaline earth titanate composition with low crystallinity and high dispersibility can be obtained.

In the second step, hydrolysis is carried out by adjusting the molar ratio of titanium to water (M _H /M _T ) to the range of 0.1 to 8. If this molar ratio exceeds 8, hydrolysis may proceed too far, resulting in a degree of crystallinity exceeding 50%. If it is less than 0.1, hydrolysis may not occur, and the desired composition may not be obtained.

Here, it is desirable to carry out aging after hydrolysis. The aging is carried out by leaving the composition to stand at a temperature in the range of 25°C to 200°C. If the temperature exceeds 200°C, the composition will crystallize too much, and there is a risk that a composition with the desired degree of crystallinity will not be obtained. A temperature of 30°C to 100°C is particularly preferable. The aging time is set in the range of 0.5 hours to 48 hours depending on the temperature conditions and the desired degree of crystallinity. If the aging time is outside of these ranges, there is a risk that a composition with the optimal degree of crystallinity will not be obtained.

In addition, if water is added to the alkaline earth metal hydroxide in the first step, hydrolysis occurs before the alkaline earth metal titanate precursor is formed when mixed with titanium alkoxide, and the desired composition cannot be obtained. Similarly, if water is added to the titanate alkoxide in the first step, hydrolysis of the titanium alkoxide occurs when mixed with the alkaline earth metal hydroxide, and the desired composition cannot be obtained. Therefore, it is necessary to keep the water content of the mixed solution obtained in the first step to 1.0% or less.

Furthermore, for the alkaline earth metal hydroxide used in the first step, it is preferable to use an "alkyl cellosolve solution of alkaline earth metal hydroxide" or an "alcohol solution of alkaline earth metal hydroxide" prepared so that the water content in the liquid is 0.5% or less. If the water content exceeds 0.5%, the alkyl cellosolve solution (or alcohol solution) will be oxidized, and there is a risk that an alkaline earth metal titanate composition will not be obtained in the second step.

Furthermore, in the first step, i.e., before the titanium alkoxide is hydrolyzed, it is preferable to add a metal salt containing at least one element belonging to Group 2A, Group 3A, Lanthanoids, Actinoids, Group 4A, Group 5A, Group 7A, Group 8, Group 1B, Group 2B, Group 3B, or Group 4B. The metal salt is preferably a salt other than an oxide. If an oxide is added, the reaction may not proceed easily in the subsequent steps. It is preferable to add a mineral acid salt or a halide salt, and hydroxides, carboxylates, and alkoxides are particularly preferable. If hydroxides or alkoxides are added, inorganic impurities are not present in the obtained composition, and a composition with very high dispersibility can be obtained.

It is further preferable to provide a step (third step) of replacing the solvent contained in the hydrolyzate obtained in the second step with an organic solvent. When conductive particles or a binder component are added to the hydrolyzate, the dispersibility of the composition and conductive particles is improved. Examples of organic solvents used in this step include alcohols, glycols, ethers, turpentines, esters, ketones, paraffin-based hydrocarbons, and mixed solvents thereof. Specific examples of organic solvents are shown in Table 1.

A paste is prepared by adding conductive particles, a binder component, and a solvent to the alkaline earth metal titanate composition described above. This paste is applied to a substrate, dried, reduced, and then heated to form an electrode layer. This electrode layer is suitable for use as an internal electrode for an MLCC. If necessary, a dispersant or leveling agent may be added, and these may be selected from those conventionally known. It is preferable to disperse the paste before application. As long as each component can be uniformly dispersed, conventionally known dispersion methods such as the three-roll method, homomixer method, and dispersion using a planetary agitator can be used.

The composition contained in the paste provides a sintering retardation effect for the electrode layer. It is preferable that the composition is contained in an amount of 1 to 50% relative to the amount of conductive particles. If it is contained in an amount of less than 1%, the amount is too small and there is a risk that the sintering retardation effect for the electrode layer will not be obtained. If it is contained in an amount of more than 30%, although the sintering retardation effect will be obtained, there is a risk that the composition will remain in the electrode layer and excellent conductivity will not be obtained. It is more preferable that the composition is contained in an amount of 5 to 30% relative to the amount of conductive particles.

The conductive particles used in the paste may be any particles that provide electrical conductivity. Metal particles are preferred. Specific examples include nickel, silver, gold, copper, palladium, ruthenium, aluminum, and alloys thereof. The surfaces of the conductive particles may be oxidized. In that case, the particles are reduced by hydrogen or plasma treatment in the film-forming process. The particle size of the conductive particles is set according to the thickness of the electrode layer. The particle size is generally in the range of 3 to 500 nm. Particles with a particle size of less than 3 nm have a large specific surface area, so a large amount of dispersant must be used when forming a paste, and there is a risk of reduced electrical conductivity. If the particle size exceeds 300 nm, the particles are heavy and high dispersibility as a paste may not be obtained. The particle size is preferably 5 to 300 nm. In addition, the concentration of conductive particles in the paste is preferably 0.05 to 90%. If it is less than 0.05%, the film thickness of the electrode layer may be thin and the desired electrical conductivity may not be obtained. If it exceeds 90%, the viscosity of the paste may be high and the surface smoothness of the electrode layer may be deteriorated. It is more preferably 0.5 to 80%.

The binder component may be a known binder, such as cellulose, vinyl alcohol, styrene, acrylic, urethane, or a polymer or copolymer thereof. The concentration of the binder component in the paste is preferably 1 to 30%. If it is less than 1%, the strength of the electrode layer may be weak. If it exceeds 30%, the conductivity may decrease due to the influence of voids caused by the binder decomposed in the firing process. Solvents used in the paste include alcohols, glycols, ethers, esters, ketones, paraffin-based hydrocarbons, etc., and mixed solvents of these. The organic solvents exemplified in Table 1 above may be used.

An example using barium as an alkaline earth metal will be specifically described.

[Example 1]
First, prepare an alkyl cellosolve solution of barium hydroxide. 50 g of barium hydroxide octahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) and 315 g of 2-methoxyethanol (methyl cellosolve) were placed in a beaker and dissolved at 30 ° C. for 20 minutes. At this time, the Ba concentration of the solution was 6.0%, and the water content was 6.2%. This solution was placed in a 1-liter eggplant-shaped flask, and water was removed using a rotary evaporator at a reduced pressure of 0.015 MPa and 70 ° C. for 1 hour. As a result, a solution A (an alkyl cellosolve solution of barium hydroxide) with a Ba concentration of 16.0% and a water content of 0.5% was obtained. Next, in a glove box under a nitrogen gas atmosphere, 56.18 g of tetraisopropoxytitanium (manufactured by Matsumoto Fine Chemical Co., Ltd.: Orgatics TA-10; Ti concentration 16.88%) was mixed with 170 g of this solution A. At this time, the mixture was adjusted so that the Ba/Ti atomic ratio was 1.00.

To this mixed solution, 3.57 g of water and 171.3 g of methanol were added over a period of 1 minute while stirring. At this time, the molar ratio (M _H /M _T ) of the number of moles of Ti (M _T ) to the number of moles of water (M _H ) was adjusted to 1. The liquid temperature was maintained at 25° C. for 1 hour. As a result, tetraisopropoxytitanium was hydrolyzed, and hydrate gel B was obtained.

This hydrate gel B was heated to 80°C and aged for 1 hour. This resulted in a dispersion C of a barium titanate composition. The concentration of the composition contained in dispersion C was 11.5% as barium titanate. Using this dispersion C, the properties of the barium titanate composition were evaluated.

Furthermore, this dispersion C was subjected to solvent replacement with methyl cellosolve (2-methoxyethanol) to obtain methyl cellosolve dispersion D of a barium titanate composition. At this time, the solids concentration was adjusted to 20%. Using this dispersion D, a sample (electrode paste, MLCC) was prepared as follows, and its characteristics were evaluated. The results are shown in Table 2.

(1) Barium titanate composition Dispersion liquid C of the barium titanate composition was dried at 300°C for 2 hours to obtain a powder. The crystallinity of this powder was measured by X-ray diffraction. The crystallinity was calculated using a profile fitting method [crystallinity % = crystalline peak surface / (crystalline peak surface + amorphous peak surface)]. The crystallinity was 20%. Furthermore, the carbon content of this powder was measured using a carbon-sulfur analyzer (EMIA-320V manufactured by HORIBA). The carbon content detected from the powder of this example was 5.5%. This carbon component is derived from alkoxide (tetraisopropoxytitanium).

(2) Electrode Paste 50 g of methyl cellosolve dispersion D of barium titanate composition, 40 g of Ni particles having a particle size of 200 nm (NFP301SD manufactured by JFE Mineral Co., Ltd.), and 10 g of ethyl cellulose powder were mixed and primarily dispersed using Thinky Corporation's Awatori Rentaro (registered trademark) AR-250. Further, secondary dispersion was performed using a three-roll mill (HHC type manufactured by Inoue Seisakusho Co., Ltd.) to prepare an electrode paste. The composition of this paste is shown in Table 2.

Furthermore, the dispersibility of this paste was evaluated by dropping the paste onto a glass plate and visually judging whether or not there were any aggregates according to the following criteria.
⊚: Almost no aggregates were observed. ◯: A small amount of aggregates were observed.
Δ: A small amount of aggregates is present.
x: A large amount of aggregates is present.
XX: The particles and the solvent are separated.

(3) Smoothness of the electrode layer An electrode layer was prepared by applying one layer of the electrode paste and drying it at 600° C. for 1 hour. The thickness of the electrode layer (single layer) was 600 nm. The surface of the electrode layer was measured with an atomic force microscope (AFM) to determine the surface roughness Ra within a range of 20 μm.

(4) Multilayer ceramic capacitors (MLCCs)
The above-mentioned electrode paste was used to form the internal electrodes of the MLCC. First, the electrode paste was screen-printed on a barium titanate ceramic sheet (thickness = 4.0 μm) to form a pattern. Then, it was dried at 600 ° C for 1 hour. Furthermore, a pattern of the dielectric layer paste was formed on this by screen printing. Then, it was dried at 600 ° C for 1 hour. This was repeated to laminate 20 layers. Then, it was reduced at 1200 ° C for 2 hours under a nitrogen gas atmosphere containing 3% H _2. Then, it was heated at 1000 ° C for 3 hours under a nitrogen gas atmosphere. In this way, the MLCC was produced. The dielectric layer paste used here was prepared as follows. That is, 90 g of barium titanate (manufactured by Sakai Chemical Industry Co., Ltd.: BT-01, average particle size = 300 nm) and 10 g of ethyl cellulose-based powder were added to 56.5 g of terpineol-based solvent, and the primary dispersion was performed using Awatori Rentaro. Then, the secondary dispersion was performed using a three-roll mill.

<Number of cracks>
The MLCC was cut vertically, and a cross-sectional photograph was taken at 100,000 magnifications using a scanning electron microscope (SEM). Cracks present in each layer within a 100 μm square area were confirmed and counted in the cross-sectional photograph.

<Charge/discharge characteristics>
The number of charge/discharge cycles when a direct current voltage of 200 V was applied was used to evaluate the battery as follows.
◎: Charge/discharge cycles of 10,000 or more are possible. ○: Charge/discharge cycles of 5,001 to less than 10,000 are possible. △: Charge/discharge cycles of 1,001 to 5,000 are possible. ×: Charge/discharge cycles of less than 1,000 are possible.

[Example 2]
In this example, the aging conditions for hydrate gel B in Example 1 were changed to 40° C. and 1 hour. Except for this, a sample was prepared in the same manner as in Example 1 and evaluated.

[Example 3]
In this example, the aging conditions for hydrate gel B in Example 1 were changed to 80° C. and 2 hours. Except for this, a sample was prepared in the same manner as in Example 1 and evaluated.

[Example 4]
Dispersion liquid C of the composition was prepared in the same manner as in Example 1. 2.3 g of acetylacetone was added to 100 g of this dispersion liquid and stirred at 25° C. for 15 hours. As a result, acetylacetone (an organic compound) was coordinated to barium titanate. The amount of coordinated acetylacetone was 20% relative to barium titanate. After this, samples were prepared and evaluated in the same manner as in Example 1.

[Example 5]
Dispersion liquid C of the composition was prepared in the same manner as in Example 1. 0.23 g of oleic acid (concentration 99%) was added to 100 g of this dispersion liquid and stirred at 25° C. for 15 hours. Furthermore, the dispersion liquid was subjected to solvent replacement with 500 g of ethanol using an ultra-thinning membrane. As a result, an ethanol dispersion liquid of barium titanate (solid concentration 20%) was obtained. After this, samples were prepared and evaluated in the same manner as in Example 1.

[Example 6]
Dispersion liquid C of the composition was prepared in the same manner as in Example 1. 1.16 g of linoleic acid (concentration 99%) was added to 100 g of this dispersion liquid and stirred at 50° C. for 15 hours. Furthermore, 50 g of terpineol was added to this dispersion liquid and concentrated with a rotary evaporator to obtain a terpineol dispersion liquid of barium titanate (solid concentration 40%). After this, samples were prepared and evaluated in the same manner as in Example 1.

[Example 7]
As in Example 1, an alkyl cellosolve solution of barium hydroxide and tetraisopropoxytitanium were mixed. To this solution, 1.22 g of calcium hydroxide (99%-molecular weight 76.08) manufactured by Kanto Chemical Co., Ltd. was added so that the content was 8 mol% relative to the obtained barium titanate composition. To this mixed solution, 3.57 g of water and 171.3 g of methanol were added over 2 hours while stirring. At this time, the molar ratio (M _H /M _T ) of the number of moles of Ti (M _T ) to the number of moles of water (M _H ) was adjusted to be 1. During the addition, the liquid temperature was maintained at 25°C. As a result, tetraisopropoxytitanium was hydrolyzed, and hydrate gel B was obtained.

This hydrate gel B was heated to 80°C and aged for 1 hour. This resulted in a dispersion of Ca-containing barium titanate. The concentration of the composition contained in the dispersion was 11.7% as Ca-containing barium titanate. 0.6 g of linoleic acid (concentration 99%) was added to 100 g of this dispersion and stirred at 25°C for 15 hours. It was then concentrated in the same manner as in Example 6 to obtain a terpineol dispersion of the Ca-containing barium titanate composition (solid concentration 40%). After this, samples were prepared and evaluated in the same manner as in Example 1.

[Example 8]
Instead of the calcium hydroxide used in Example 7, 1.87 g of magnesium diethoxide (97%, molecular weight 114.2) manufactured by Kanto Chemical Co., Ltd. was added. Except for this, hydrate gel B was prepared and aged in the same manner as in Example 7. As a result, a dispersion of Mg-containing barium titanate was obtained. The concentration of the composition contained in the dispersion was 11.7% as Mg-containing barium titanate.

1.18 g of linoleic acid (concentration 99%) was added to 100 g of this dispersion and stirred at 25°C for 15 hours. It was then concentrated in the same manner as in Example 6 to obtain a terpineol dispersion of a Mg-containing barium titanate composition (solids concentration 40%). After this, samples were prepared and evaluated in the same manner as in Example 1.

[Example 9]
Instead of the calcium hydroxide used in Example 7, 1.96 g of strontium hydroxide (anhydrous, molecular weight 121.63) manufactured by Mitsuwa Chemical Co., Ltd. was added. Except for this, hydrate gel B was prepared and aged in the same manner as in Example 7. As a result, a dispersion of Sr-containing barium titanate was obtained. The concentration of the composition contained in the dispersion was 11.9% as Sr-containing barium titanate.

2.4 g of linoleic acid (concentration 99%) was added to 100 g of this dispersion and stirred at 25°C for 15 hours. It was then concentrated in the same manner as in Example 6 to obtain a terpineol dispersion of a Sr-containing barium titanate composition (solids concentration 40%). After this, samples were prepared and evaluated in the same manner as in Example 1.

[Example 10]
As in Example 1, an alkyl cellosolve solution of barium hydroxide and tetraisopropoxytitanium were mixed. To this solution, 9.29 g of yttrium tristearate (molecular weight 937.9) manufactured by Mitsuwa Chemical Co., Ltd. was added so that the content was 5 mol% relative to the obtained barium titanate composition. To this mixed solution, 3.57 g of water and 171.3 g of methanol were added over 2 hours while stirring. At this time, the molar ratio (M _H /M _T ) of the number of moles of Ti (M _T ) to the number of moles of water (M _H ) was adjusted to be 1. In addition, the liquid temperature was maintained at 25°C during the addition. As a result, tetraisopropoxytitanium was hydrolyzed to obtain a hydrate gel B. The hydrate gel B was heated to 80°C and aged for 1 hour. As a result, a dispersion of Y-containing barium titanate was obtained. The concentration of the composition contained in the dispersion was 12.1% as Y-containing barium titanate.

1.22 g of oleic acid (concentration 99%) was added to 100 g of this dispersion, and the mixture was stirred at 25°C for 15 hours. The mixture was then concentrated in the same manner as in Example 6 to obtain a terpineol dispersion of a Y-containing barium titanate composition (solid concentration 40%). After this, samples were prepared and evaluated in the same manner as in Example 1.

[Example 11]
Instead of the yttrium tristearate used in Example 10, 0.92 g of nickel hydroxide (molecular weight 92.71) manufactured by Taiyo Co., Ltd. was added. Except for this, hydrate gel B was prepared and aged in the same manner as in Example 10. This resulted in a dispersion of Ni-containing barium titanate. The concentration of the composition contained in the dispersion was 11.7% as Ni-containing barium titanate.

1.18 g of oleic acid (concentration 99%) was added to 100 g of this dispersion, and the mixture was stirred at 25°C for 15 hours. The mixture was then concentrated in the same manner as in Example 6 to obtain a terpineol dispersion of a Ni-containing barium titanate composition (solids concentration 40%). After this, samples were prepared and evaluated in the same manner as in Example 1.

[Example 12]
Instead of the yttrium tristearate used in Example 10, 3.98 g of erbium chloride octahydrate (molecular weight 381.73) manufactured by Taiyo Co., Ltd. was added. A hydrate gel B was prepared and aged in the same manner as in Example 10 except for this. Thus, a dispersion of Er-containing barium titanate was obtained. The concentration of the composition contained in the dispersion was 12.5% as Er-containing barium titanate.

1.26 g of oleic acid (concentration 99%) was added to 100 g of this dispersion, and the mixture was stirred at 25°C for 15 hours. The mixture was then concentrated in the same manner as in Example 6 to obtain a terpineol dispersion of an Er-containing barium titanate composition (solids concentration 40%). After this, samples were prepared and evaluated in the same manner as in Example 1.

[Example 13]
As in Example 1, the alkyl cellosolve solution of barium hydroxide and tetraisopropoxytitanium were mixed. 2.3 g of stannous chloride dihydrate (molecular weight 225.72) manufactured by Mitsuwa Chemical Co., Ltd. was added to this solution so that the content was 5 mol% relative to the obtained barium titanate composition. 3.57 g of water and 171.3 g of methanol were added to this solution over 2 hours while stirring. At this time, the molar ratio (M _H /M _T ) of the number of moles of Ti (M _T ) to the number of moles of water (M _H ) was adjusted to 1. During the addition, the liquid temperature was maintained at 25°C. As a result, tetraisopropoxytitanium was hydrolyzed, and hydrate gel B was obtained.

This hydrate gel B was heated to 80°C and aged for 1 hour. This resulted in a dispersion of Sn-containing barium titanate. The concentration of the composition contained in the dispersion was 12.2% as Sn-containing barium titanate. 1.23 g of oleic acid (concentration 99%) was added to 100 g of this dispersion and stirred at 25°C for 15 hours. It was then concentrated in the same manner as in Example 6 to obtain a terpineol dispersion of the Sn-containing barium titanate composition (solid concentration 40%). Thereafter, samples were prepared and evaluated in the same manner as in Example 1.

[Example 14]
As in Example 1, an alkyl cellosolve solution of barium hydroxide and tetraisopropoxytitanium were mixed. 4.55 g of indium chloride hydrate (molecular weight 284.32 99%) manufactured by Kojundo Chemical Co., Ltd. was added to this solution so that the content was 5 mol% relative to the obtained barium titanate composition. 3.57 g of water and 171.3 g of methanol were added to this solution over 2 hours while stirring. At this time, the molar ratio (M _H /M _T ) of the number of moles of Ti (M _T ) to the number of moles of water (M _H ) was adjusted to be 1. During the addition, the liquid temperature was maintained at 25°C. As a result, tetraisopropoxytitanium was hydrolyzed to obtain a hydrate gel B. The hydrate gel B was heated to 80°C and aged for 1 hour. As a result, a dispersion of In-containing barium titanate was obtained. The concentration of the composition contained in the dispersion was 12.6% as In-containing barium titanate. 1.27 g of oleic acid (concentration 99%) was added to 100 g of this dispersion and stirred at 25° C. for 15 hours. The mixture was then concentrated in the same manner as in Example 6 to obtain a terpineol dispersion of an In-containing barium titanate composition (solid concentration 40%). After this, samples were prepared and evaluated in the same manner as in Example 1.

[Example 15]
In Example 7, 1.55 g of calcium hydroxide was added to the obtained barium titanate composition so that the content was 10 mol%. A dispersion of Ca-containing barium titanate was obtained in the same manner as above. The concentration of the composition contained in the dispersion was 11.8% as Ca-containing barium titanate. 0.59 g of linoleic acid (concentration 99%) was added to 100 g of this dispersion and stirred at 25 ° C. for 15 hours. Further, it was concentrated in the same manner as in Example 6 to obtain a terpineol dispersion of Ca-containing barium titanate composition (solid concentration 40%). After this, samples were prepared and evaluated in the same manner as in Example 1.

[Example 16]
As in Example 1, an alkyl cellosolve solution A of barium hydroxide was prepared. 54.54 g of the above-mentioned tetraisopropoxy titanium was mixed with 175.10 g of this solution in the same manner as in Example 1 so that the Ba/Ti atomic ratio was 1.03. Using this mixed solution, a dispersion C of barium titanate was prepared in the same manner as in Example 1. The concentration of the composition contained in the dispersion was 11.2% as barium titanate. Furthermore, the solvent was replaced in the same manner as in Example 1 to obtain a methyl cellosolve dispersion of the barium titanate composition (solid concentration 20%). Thereafter, samples were prepared and evaluated in the same manner as in Example 1.

[Example 17]
In Example 16, 57.32 g of tetraisopropoxytitanium was mixed with 175.10 g of an alkyl cellosolve solution of barium hydroxide so that the Ba/Ti atomic ratio was 0.980. A methyl cellosolve dispersion of a barium titanate composition (solid concentration 20%) was obtained in the same manner as in Example 16 except for this. The concentration of the composition contained in the dispersion C of barium titanate was 11.2% as barium titanate. After this, samples were prepared and evaluated in the same manner as in Example 1.

[Comparative Example 1]
In Example 1, _{when obtaining the hydrate gel B, the amount of water was set to 36.5 g so that the molar ratio (M H /} M _T ) of the number of moles of titanium (M _T ) to the number of moles of water (M H ) was 10. Furthermore, this hydrate gel B was aged at 100° C. for 24 hours. The concentration of the composition contained in the obtained dispersion was 10.8% as barium titanate. Other than this, a methyl cellosolve dispersion of the barium titanate composition (solid concentration 20%) was obtained in the same manner as in Example 1. After this, a sample was prepared and evaluated in the same manner as in Example 1. In this comparative example, the barium titanate composition was particles with an average primary particle size of 10 nm.

[Comparative Example 2]
Here, barium titanate was prepared without using titanium alkoxide. That is, TFP-NA (manufactured by Toda Kogyo Co., Ltd.) was dried at 100°C for 1 hour, and 20g of the obtained powder was stirred and mixed with 80g of methyl cellosolve. This resulted in a methyl cellosolve dispersion of barium titanate (solid concentration 20%). 2.02g of oleic acid (concentration 99%) was added to 100g of this dispersion and stirred at 50°C for 15 hours. Furthermore, 50g of terpineol was added thereto and concentrated with a rotary evaporator to obtain a terpineol dispersion of crystalline barium titanate (solid concentration 40%). In this comparative example, the barium titanate composition was particles with an average primary particle diameter of 20nm. After this, samples were prepared and evaluated in the same manner as in Example 1.

Claims (4)

1. A composition of alkaline earth metal titanate comprising:
the atomic ratio of alkaline earth metal to titanium (alkaline earth metal/Ti) is 0.95 to 1.05;
The composition is dried at 300° C. to obtain a dried product containing 0.5 to 10% carbon components;
The crystallinity of the dried product measured by X-ray diffraction is 5% or more and 22 % or less. The composition of claim 1, wherein the composition comprises an organic solvent comprising at least one of alcohols, glycols, ethers, esters, ketones, and paraffinic hydrocarbons. a first step of mixing an alkaline earth metal hydroxide and a titanium alkoxide so that the atomic ratio of the alkaline earth metal to titanium (alkaline earth metal/Ti ratio) is in the range of 0.95 to 1.05;
a second step of adjusting the moisture content so that the ratio (MH/MT) of the number of moles of titanium (MT) contained in the titanium alkoxide to the number of moles of water (MH) is within a range of 0.1 to 1, and then hydrolyzing the titanium alkoxide;
A third step of leaving the mixture at a temperature in the range of 25° C. to 200° C. for 0.5 hours to 48 hours after the second step;
A method for producing an alkaline earth metal titanate composition comprising the steps of: A paste comprising the alkaline earth metal titanate composition according to claim 1, conductive particles, a binder component, and a solvent , wherein the concentration of the conductive particles in the paste is 0.5 to 80%, the concentration of the binder component is 1 to 30%, and the composition is 5 to 30% of the amount of the conductive particles .