JP7555945B2 - Barium titanate particles, their manufacturing method, and dispersion of barium titanate particles - Google Patents

Description

The present invention relates to barium titanate particles having a perovskite structure.

Barium titanate particles are used in dielectric materials for electronic components and optical materials with high refractive index and excellent transparency. Barium titanate particles have a high dielectric constant and are therefore used in multilayer ceramic capacitors (MLCCs). MLCCs have a structure in which electrode layers and dielectric layers are alternately stacked. The electrode layers contain 80-300 nm Ni particles and barium titanate particles as a co-material. In the electrode layers, barium titanate particles are packed around the Ni particles. This increases the temperature at which the Ni particles sinter together. In other words, the sintering retardation effect of the Ni particles is obtained. This makes the temperature at which the Ni particles sinter together closer to the temperature at which the dielectric layer sinters. This reduces the difference in shrinkage rate between the electrode layer and the dielectric layer during firing, resulting in an MLCC with fewer cracks (see, for example, Patent Document 1).

On the other hand, in order to improve the dielectric constant of barium titanate particles, it is known to give the barium titanate particles a perovskite structure and further make the axial length of the c-axis of the crystal lattice longer than the axial length of the a-axis, i.e., to give the barium titanate particles a tetragonal crystal system (see, for example, Patent Document 2).

JP 2005-63707 A JP 2004-300027 A

In the barium titanate particles of Patent Document 2, the c-axis length of the perovskite structure is longer than the a-axis length, so the dielectric constant is high. However, since the barium titanate particles are sintered after being powdered, the particle size and crystallite size tend to become large. Therefore, the density of the barium titanate particles packed around the Ni particles tends to be low, making it difficult to obtain a sintering retardation effect. The greater the difference between the temperature at which the dielectric layer is sintered and the temperature at which the Ni particles are sintered, the more likely cracks are to occur in the MLCC.
An object of the present invention is to provide barium titanate particles having a high sintering retardation effect and a method for producing the same.

Therefore, in the present invention, in the barium titanate particles having a perovskite structure, the atomic ratio of barium to titanium, Ba/Ti, is set to 0.9 to 1.1, and the crystallite size is set to 5 to 25 nm. The atomic ratio of barium to titanium, Ba/Ti, may be 0.95 to 1.05.
Furthermore, the ratio c/a of the length of the c-axis to the length of the a-axis of the crystal lattice in the perovskite structure is preferably 1.005 or less.
In such a dispersion of barium titanate particles containing barium titanate particles and an organic solvent, the water content is preferably less than 3% by weight.
In addition, a method for producing barium titanate particles includes the steps of mixing barium hydroxide and an alkyl cellosolve, adding titanium alkoxide so that the atomic ratio of barium to titanium, Ba/Ti, is in the range of 0.9 to 1.1, adding water, and heating.

FIG. 2 is a structural diagram of a cyclic hydrocarbon group (R ₆ ).

The barium titanate particles having a perovskite structure according to the present invention have an atomic ratio Ba/Ti of barium to titanium in the range of 0.9 to 1.1. This makes it difficult for impurities such as crystals other than the perovskite structure to be generated. The crystallite diameter of the barium titanate particles is 5 to 25 nm. Therefore, the crystallinity of the barium titanate particles is high, and the particle diameter is small. Since such barium titanate particles enter the gaps between the Ni particles in the electrode layer, the barium titanate particles are present around the Ni particles at a high density. Therefore, the sintering retardation effect of Ni is high. Note that if the crystallite diameter is larger than 25 nm, the viscosity of the dispersion of the barium titanate particles described below is high. When the crystallite diameter is 5 to 25 nm, the particle diameter measured by a transmission electron microscope is also 5 to 25 nm.
The atomic ratio of barium to titanium, Ba/Ti, may be 0.95 to 1.05.
Furthermore, the ratio of the lengths of the c-axis and a-axis of the crystal lattice in the perovskite structure (axial ratio c/a) is preferably 1.005 or less. This makes the barium titanate particles closer to cubic crystals. As a result, the sintering retardation effect of Ni is enhanced.

The crystal structure and crystallite size can be measured using an X-ray diffraction measurement device, Rigaku's RINT-Ultima. The crystal structure can be identified using analysis software, PDXL. The crystallite size can be calculated from the half-width β (rad) by measuring the half-width at Miller indices (110) near 2θ=31.5° using Scherrer's formula "D=Kλ/βcosθ". Here, D is the crystallite size (Å), K is the Scherrer constant, λ is the X-ray wavelength (1.7889 Å), and θ is the reflection angle.
From the results of X-ray diffraction measurement using PDXL, the lengths of the a-axis and c-axis of the perovskite structure can be specified. The axial ratio c/a is preferably 1.003 or less, and more preferably 1.001 or less. The smaller the axial ratio c/a, the higher the sintering retardation effect of Ni.

It is preferable that the barium titanate particles contain at least one element (hereinafter referred to as an additive element) selected from group 2, group 3, lanthanoid, actinoid, group 4, group 5, group 6, group 7, group 8, group 9, group 10, group 11, group 12, group 13, and group 14. This enhances the sintering retardation effect. It is more preferable that the additive element is contained in an amount of 0.1 to 10 mol % when the composition formula of barium titanate, BaTiO _3, is 100 mol %. This makes it easier to obtain the sintering retardation effect of Ni. Furthermore, even if the additive element is contained in this range, no peaks other than those of the perovskite structure are observed.

A paste for printing the electrode layer can be prepared using a dispersion of barium titanate particles. The dispersion of barium titanate particles contains barium titanate particles and an organic solvent. The water content of the dispersion is preferably less than 3% by weight. If the water content is low, the viscosity of the paste is unlikely to increase even if a binder such as ethyl cellulose is added to the dispersion. If the viscosity of the paste is high, it is difficult to apply the paste evenly, and cracks are likely to occur in the electrode layer during firing. Furthermore, if the water content of the dispersion is 3% by weight or less, the dispersion is unlikely to aggregate.

The amount of water adsorbed to the solid content of the dispersion (adsorbed water content) is preferably 5 parts by mass or more per 100 parts by mass of the solid content. If the amount of adsorbed water is within this range, the barium titanate particles in the dispersion will have many hydroxyl groups on their surfaces. The solid content is obtained by drying the dispersion at 200°C for 3 hours. The amount of adsorbed water is the amount of water adsorbed to the solid content when the solid content is exposed to conditions of 25°C and 90% RH for 1 hour.

It is preferable that the barium titanate particles are not surface-treated. This tends to lower the viscosity of the paste. In particular, if the water content of the dispersion is 3% or less, the viscosity of the paste tends to be even lower. If the barium titanate is surface-treated with an organic acid surface treatment agent such as linoleic acid or oleic acid, the viscosity of the paste may increase. However, the barium titanate particles may be surface-treated with a surface treatment agent as long as the viscosity of the paste does not increase.

It is preferable that the organic solvent has an OH group. In other words, it is preferable that the organic solvent is highly hydrophilic. This makes it easier to reduce the viscosity of the dispersion or paste. When the organic solvent has an OH group, if the amount of adsorbed water is 5 parts by mass or more per 100 parts by mass of solids, the viscosity of the dispersion is easier to reduce.

It is preferable that the organic solvent has at least one of an ester bond, an ether bond, and a ketone group in addition to an OH group. This makes the organic solvent more hydrophilic. In particular, the presence of an ether bond provides high hydrophilicity.

Alternatively, the organic solvent preferably has a hydrophobic structure together with the OH group. Here, the hydrophobic structure refers to a cyclic structure or a chain structure in which two or more carbon atoms from the terminal are continuously bonded to each other by carbon-carbon bonds. Examples of the cyclic structure include a cyclic hydrocarbon group (R ₆ ) which is a monovalent substituent obtained by removing a hydrogen atom from any carbon atom of a cycloalkane, a cycloalkene (cycloolefin), an aromatic ring, etc. R ₆ may be any of a three-membered ring, a four-membered ring, a five-membered ring, a six-membered ring, and a seven-membered ring. The structure of the six-membered ring R ₆ is illustrated in FIG. 1. In FIG. 1, (a) is a six-membered aromatic ring, (b) is a six-membered cycloalkene, and (c) is a six-membered cycloalkane. In the structure of R ₆ , some of the carbon atoms may be replaced by heteroatoms such as oxygen, nitrogen, and sulfur atoms. In this case, the number of hydrogen atoms bonded to the heteroatom may increase or decrease depending on the number of bonds to which the heteroatom can be bonded. In the structure of R ₆ , R ₁ to R ₅ can be selected from hydrophilic groups such as hydrogen groups, OH groups, and carboxy groups, and hydrophobic groups such as methyl groups, ethyl groups, isopropyl groups, and t-butyl groups. _{R 1} to R ₅ may be the same or different. R ₁ to R ₅ are preferably four hydrogen groups and one methyl group. This increases the compatibility of the organic solvent with the binder. The organic solvent having a cyclic structure can be represented by R ₆ -R ₇ (wherein R ₇ has a structure containing elements such as carbon, hydrogen, nitrogen, and oxygen). The OH group is preferably included in R _7. This increases the compatibility of the organic solvent with the binder and the barium titanate particles.

Examples of the chain structure include a linear structure such as an alkyl group, and a branched structure such as an isopropyl group or a tert-butyl group. The organic solvent having a chain structure can be expressed by the rational formula R ₃ -CR ₄ R ₅ -CH _3. In this rational formula, the methyl group (-CH ₃ ) is the terminal. The carbon atom bonded to the terminal methyl group is the second carbon atom from the terminal. That is, the carbon atom of the methyl group and the carbon atom bonded to the methyl group are continuously carbon-carbon bonded from the terminal. Here, R ₃ , R ₄ and R ₅ have a structure containing elements such as carbon, hydrogen, nitrogen and oxygen. R ₃ , R ₄ and R ₅ may be bonded to each other to form a cyclic structure. It is considered that the compatibility between the organic solvent and the binder is increased when the organic solvent has a hydrophobic structure. When the organic solvent has a hydrophobic structure and an OH group, the organic solvent enhances the compatibility between the binder and the barium titanate particles. Therefore, the paste is less likely to aggregate. The number of carbon atoms bonded in succession from the end of the chain structure is preferably 5 or less. This increases the hydrophilicity of the organic solvent. The number of carbon atoms bonded in carbon-carbon bonds is more preferably 4 or less. When the organic solvent has an ether bond, it is preferable that an alkyl group is bonded to the oxygen atom of the ether bond. The number of carbon atoms in this alkyl group is preferably 3 to 5.

The solubility parameter (SP value) of the organic solvent is preferably 8.5 or more. If it is 8.5 or more, the hydrophilicity of the organic solvent increases.

The boiling point of the organic solvent under atmospheric pressure is preferably 300°C or less. This makes the carbon chain of the organic solvent shorter than that of an organic solvent with a boiling point higher than 300°C. Therefore, the viscosity of the dispersion liquid is reduced. In addition, the viscosity of the printing paste is also reduced, so that the printing paste is easily applied uniformly during printing. The boiling point of the organic solvent under atmospheric pressure is preferably 200 to 300°C. This makes it easier to dry the paste uniformly with the Ni particles and barium titanate particles dispersed when applying and drying the paste. Therefore, the sintering retardation effect of the Ni particles is enhanced. In addition, cracks are less likely to occur in the MLCC. If an organic solvent with a boiling point of 200 to 300°C has an OH group, the dispersion liquid and the Ni particles are easily mixed. Therefore, the paste is less likely to aggregate. If the paste is less likely to aggregate, the paste is more likely to dry uniformly, so the printability is improved. In terms of boiling point and hydrophobic structure, the organic solvent is preferably butyl carbitol.
The viscosity of the organic solvent is preferably 100 mPa·s or less at atmospheric pressure and 25° C. This reduces the viscosity of the dispersion liquid, and also reduces the viscosity of the printing paste.

Next, we will explain the manufacturing method of barium titanate particles and their dispersion.

First, barium hydroxide is mixed with alkyl cellosolve as a solvent to prepare mixed solution A (first step). By using barium hydroxide, the counter ions do not diffuse into the dielectric layer when the electrode layer is fired. Therefore, the performance of the MLCC is likely to be improved. Since the solvent is alkyl cellosolve, the viscosity of the dispersion is reduced. In addition, the viscosity of the paste is less likely to increase. The water content of mixed solution A is preferably 5% by mass or less. This makes it difficult for titanium alkoxide to hydrolyze when it is added as described later. Therefore, the particle size is likely to be small. Before the second step described later, mixed solution A may be decompressed or heated to reduce the water content of mixed solution A to 5% by mass or less.

Next, titanium alkoxide is added to mixed solution A to prepare mixed solution B (second step). In mixed solution B, the atomic ratio of barium to titanium, Ba/Ti, is preferably 0.95 to 1.05. In this range, crystals other than the perovskite structure are less likely to form. The atomic ratio of barium to titanium may also be 0.9 to 1.1. The titanium alkoxide is preferably added under a nitrogen atmosphere. This reduces the reaction rate of the titanium alkoxide. As a result, barium titanate particles with small particle size and crystallite size are more likely to be obtained.

The titanium alkoxide preferably has a structure of "Ti(OR) ₄ ". Here, R is a hydrocarbon group having 1 to 4 carbon atoms, or a substituted hydrocarbon group in which one or more hydrogen atoms of the hydrocarbon group have been substituted with halogen atoms. The Rs may be the same or different. Such a structure tends to increase the crystallinity of the barium titanate particles. Specific examples include titanium tetramethoxide, titanium tetraethoxide, titanium tetra n-propoxide, titanium tetraisopropoxide, titanium tetra n-butoxide, and titanium tetraisobutoxide.

Next, water is added to mixed solution B to prepare mixed solution C (third step). It is preferable that the amount of water added is equal to or greater than the molar equivalent of the titanium alkoxide. This reduces the amount of titanium alkoxide remaining in mixed solution C without hydrolyzing. This results in higher crystallinity of the barium titanate particles.

Next, mixed liquid C is heated (fourth step). It is preferable to heat at 40°C or higher for 2 to 200 hours. This step promotes maturation, and barium titanate particles are generated in the aged product. If the heating temperature is 40°C or higher, the particle size distribution tends to become uniform, although this varies depending on the concentration of the gel. Furthermore, the crystallinity improves. Also, a heating temperature of 120°C or lower is easy to handle industrially. If heated for 2 hours or more, the particle size distribution tends to become uniform. Furthermore, the crystallinity improves. If the heating time is 200 hours or less, the particle size and crystallite size tend to become small. A heating time of 5 hours or more and 100 hours or less is more preferable.

The aged product obtained in the fourth step is ultrafiltered or distilled (fifth step). When ultrafiltered or distilled, the water content of the dispersion is adjusted to less than 3% by weight. An organic solvent may be added before ultrafiltering or distilling. When the boiling point of the organic solvent is lower than that of the alkyl cellosolve, ultrafiltering is preferred. When the boiling point is higher than that of the alkyl cellosolve, distillation is preferred. The organic solvent preferably has the characteristics of the organic solvent described in the description of the dispersion above.

The dispersion liquid prepared by this manufacturing method has a low water content. Therefore, the viscosity of the paste is less likely to increase. In addition, the particle size and crystallite size of the barium titanate particles in the dispersion liquid are small, and the crystallinity is high. Furthermore, since the crystal system of the barium titanate particles is close to a cubic system, when used in the electrode layer, the sintering retardation effect of Ni is enhanced.

It is also preferable to add a metal salt containing at least one selected from Groups 2, 3, lanthanoids, actinoids, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, and 14 before the fourth step. By adding such a metal salt, the sintering retardation effect is enhanced. In addition, the metal salt makes it difficult for crystals other than the perovskite structure to form. Furthermore, by adding the metal salt before the fourth step, the metal salt is dispersed in the barium titanate gel. Therefore, the sintering retardation effect is likely to be enhanced.

Examples of the present invention are described below in detail. Preparation conditions for each example and comparative example are shown in Table 1.

[Example 1]
<Preparation of Dispersion>
50 g of barium hydroxide octahydrate (manufactured by Fuji Film 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. The Ba concentration of this solution was 6.0% by weight, and the water content was 6.2% by weight. This solution was placed in a ¹ dm3 eggplant-shaped flask and distilled using a rotary evaporator to obtain mixed solution A. The distillation conditions were a temperature of 70°C, a reduced pressure of 0.015 MPa, and 1 hour. The Ba concentration of mixed solution A was 16.0% by weight, and the water content was 0.5% by weight.

In a glove box under a nitrogen gas atmosphere, 170 g of mixed solution A was mixed with 56.18 g of tetraisopropoxytitanium (Orgatix (registered trademark) TA-10, manufactured by Matsumoto Fine Chemical Co., Ltd., Ti concentration 16.88 wt%) to prepare mixed solution B.

A mixture of 57.1 g of water and 171.2 g of methanol was added over 1 minute. During the addition, the mixture was stirred while maintaining the temperature at 25°C. The resulting hydrate gel was heated to 80°C and aged for 96 hours. The aged product was ultrafiltered to obtain a dispersion containing 40% by mass of barium titanate.

The dispersions were measured as follows. The measurement results for each example and comparative example are shown in Table 2.

<Moisture content measurement>
The measurement was performed using a benchtop coulometric moisture meter, Model CA-200 (manufactured by Mitsubishi Chemical Analytech Co., Ltd.).

<Measurement of adsorbed water amount>
30 g of the dispersion was dried at 200°C for 3 hours and cooled in a desiccator to obtain a dry powder. The dry powder was left to stand for 1 hour in a thermohygrostat (PL-3J manufactured by Espec Corp.) adjusted to 25°C and 90 RH%. The amount of adsorbed water was calculated from the change in weight before and after.

<X-ray diffraction measurement>
The dispersion liquid was dried at 400°C to obtain a powder of barium titanate particles. X-ray diffraction measurement was performed on this powder using a Rigaku RINT-Ultima. X-ray diffraction measurement was also performed in the examples and comparative examples described below. In the X-ray diffraction measurement, no X-ray diffraction peaks other than those of the perovskite structure were observed except for Comparative Example 1.

<Viscosity measurement>
A binder liquid was prepared by dispersing 3 g of ethyl cellulose powder in 74 g of terpineol (manufactured by Yasuhara Chemical Co., Ltd.). 4.5 g of this binder liquid was mixed with 3 g of the dispersion liquid to obtain a paste for viscosity measurement. Using a rheometer RS3000 (HAAKE Co., Ltd.), dynamic viscosity measurements were performed in the range of dγ/dt = 0.1 to 1000 s ^-1 , and the value when dr/dt = 40 s ^-1 was taken as the viscosity.

<Evaluation of printability>
The paste for viscosity measurement was applied to a glass plate and dried at 200° C. The aggregates and smoothness in the dried film were visually confirmed to evaluate the printability.
◎: No agglomerates, excellent smoothness ○: Almost no agglomerates, excellent smoothness △: Almost no agglomerates, some problems with smoothness ×: Many agglomerates or problems with smoothness

<Preparation of electrode paste>
50 g of dispersion (amount of barium titanate in the dispersion is 10 g), 40 g of Ni nanoparticles (manufactured by JFE Mineral Co., Ltd.: NFP301SD) having a particle diameter of 200 nm, and 10 g of ethyl cellulose powder were mixed and primarily dispersed using Thinky Corporation's Awatori Rentaro (registered trademark) AR-250. Furthermore, a paste for electrodes was prepared by secondary dispersion using a three-roll machine (manufactured by Inoue Seisakusho Co., Ltd.: HHC type). The concentration of the paste for electrodes was 60% by weight. For the examples and comparative examples described later, paste for electrodes was similarly prepared and measured and evaluated.

<Preparation of Dielectric Layer Paste>
90 g of barium titanate (BT-01, average particle size = 300 nm, manufactured by Sakai Chemical Industry Co., Ltd.) and 10 g of ethyl cellulose powder were added to 56.5 g of terpineol solvent, and the mixture was subjected to primary dispersion using a foaming mixer. A paste for the dielectric layer was prepared by secondary dispersion using a three-roll mill.

<Preparation of Multilayer Ceramic Capacitor (MLCC)>
The electrode paste was screen-printed on a barium titanate ceramic sheet (thickness = 4.0 μm). This was dried at 600 ° C for 1 hour. The dielectric layer paste was screen-printed on top of this. This was dried at 600 ° C for 1 hour. These steps were repeated to stack a total of 20 layers. This stack was reduced at 1200 ° C for 2 hours in a nitrogen gas atmosphere containing 3% _H2 . It was then heated at 1000 ° C for 3 hours in a nitrogen gas atmosphere.

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

<Evaluation of aggregation>
The electrode paste was dropped onto a glass plate and the presence or absence of aggregates was visually determined.

In the following examples and comparative examples, each sample was prepared, measured, and evaluated in the same manner as in Example 1.

[Example 2]
A dispersion was obtained in the same manner as in Example 1, except that the mixture in Example 1 was changed to a mixture of 71.3 g of water and 214.0 g of methanol.

[Example 3]
A dispersion was obtained in the same manner as in Example 1, except that the mixture in Example 1 was changed to a mixture of 2.46 g of nickel acetate tetrahydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 57.1 g of water, and 171.3 g of methanol.

[Example 4]
A dispersion was obtained in the same manner as in Example 1, except that the mixture in Example 1 was changed to a mixture of 0.85 g of magnesium acetate tetrahydrate (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.), 57.1 g of water, and 171.3 g of methanol.

[Example 5]
When the barium hydroxide octahydrate of Example 1 was dissolved in 2-methoxyethanol, 1.79 g of tin methoxide (manufactured by Alfa Aesar) was added. Except for this, a dispersion was prepared in the same manner as in Example 1.

[Example 6]
When the barium hydroxide octahydrate of Example 1 was dissolved in 2-methoxyethanol, 2.02 g of calcium methoxide (manufactured by Strem Chemicals) was added. A dispersion was obtained in the same manner as in Example 1, except that 178 g of this solution was used.

[Example 7]
A dispersion was obtained in the same manner as in Example 1 except that 0.67 g of tantalum methoxide (manufactured by Strem Chemicals) was added when dissolving the barium hydroxide octahydrate of Example 1 in 2-methoxyethanol.

[Example 8]
A dispersion was obtained in the same manner as in Example 1, except that the mixture in Example 1 was changed to a mixture of 0.92 g of nickel hydroxide hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 57.1 g of water, and 171.2 g of methanol.

[Example 9]
When the barium hydroxide octahydrate of Example 1 was dissolved in 2-methoxyethanol, 0.67 g of dysprosium isopropoxide (manufactured by Fuji Film Wako Chemicals Co., Ltd.) was added. Otherwise, a dispersion was obtained in the same manner as in Example 1.

[Example 10]
A hydrolysis solution containing 57.1 g of water and 171.3 g of methanol was added to the mixed solution B obtained in Example 1 over a period of 1 minute while stirring and maintaining the temperature at 25° C. This resulted in a hydrate gel. The temperature of this hydrate gel was raised to 80° C. and aged for 96 hours. Ethanol was mixed with this aged product, and ultrafiltration was performed to obtain a dispersion containing 40% by mass of barium titanate.

[Example 11]
Mixture B was prepared in the same manner as in Example 1, except that the weight of mixture A was changed to 178 g. A dispersion was obtained in the same manner as in Example 1, except that 70 g of butyl carbitol (manufactured by Kanto Chemical Co., Ltd.) was mixed with the aged product and solvent replacement was performed using a rotary evaporator instead of ultrafiltration. The solvent replacement was performed under the conditions of a temperature of 70° C., a reduced pressure of 0.015 MPa, and one hour.

[Example 12]
A dispersion was obtained in the same manner as in Example 11, except that the weight of the mixed liquid A was changed to 170 g.

[Example 13]
A dispersion was obtained in the same manner as in Example 12, except that the solution for hydrolysis was changed to a solution of 2.46 g of nickel acetate tetrahydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 57.1 g of water, and 171.3 g of methanol.

[Example 14]
A dispersion was obtained in the same manner as in Example 12, except that the weight of mixed solution A was changed to 168 g, and 70 g of terpineol and 3.5 g of linoleic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were mixed with the aged product instead of butyl carbitol.

[Example 15]
3.5 g of linoleic acid was added to the aged product obtained in Example 11 and stirred at 50° C. for 15 hours. 70 g of butyl carbitol was added thereto and distilled with a rotary evaporator to obtain a dispersion. The distillation conditions were a temperature of 70° C., a reduced pressure of 0.015 MPa, and 1 hour.

[Example 16]
70 g of terpineol was added to the aged product obtained in Example 10. Using a rotary evaporator, distillation was carried out under the conditions of a temperature of 70° C., a reduced pressure of 0.015 MPa, and a time of 1 hour.

[Example 17]
70 g of triethanolamine was added to the aged product obtained in Example 10. Distillation was carried out using a rotary evaporator under the conditions of a temperature of 70° C., a reduced pressure of 0.015 MPa, and a time of 1 hour.

[Comparative Example 1]
A dispersion was obtained in the same manner as in Example 1, except that the weight of the barium hydroxide solution was changed to 204 g.

[Comparative Example 2]
Barium carbonate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and titanium oxide powder (manufactured by Ishihara Sangyo Kaisha, Ltd.) were weighed to give a Ba/Ti molar ratio of 1.01 and mixed using a ball mill. The mixed powder was fired at 900° C. in air, and the fired powder was further crushed using a mortar.

Claims (3)

The present invention comprises barium titanate particles having a perovskite structure and an organic solvent having a boiling point of 200 to 300° C.,
the barium titanate particles have an atomic ratio of barium to titanium, Ba/Ti, of 0.9 to 1.1;
The axial ratio c/a of the perovskite structure is 1.005 or less,
The barium titanate particles have a crystallite size of 5 to 25 nm;
The moisture content is less than 3% by weight,
The organic solvent has an OH group,
A dispersion of barium titanate particles, characterized in that when the solid content obtained by drying the dispersion at 200°C for 3 hours is exposed to conditions of 25°C and 90RH% for 1 hour, the amount of water adsorbed by the solid content is 5 parts by mass or more per 100 parts by mass of the solid content. 2. The dispersion according to claim 1 , wherein the organic solvent has a cyclic structure or a chain structure in which two or more carbon atoms from the terminal are successively carbon-carbon bonded. 3. The dispersion according to claim 1, wherein the organic solvent has an ether bond.

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