CN100484879C - Manufacturing method of perovskite barium titanate powder - Google Patents

Abstract

Provided is a method for manufacturing perovskite-type barium titanate powder having a small mean particle diameter of <=1 [mu]m, little dispersion in particle diameter, a Ba to Ti molar ratio of about 1 with little dispersion in the ratio, high purity and excellent crystallinity. The method for manufacturing perovskite-type barium titanate powder includes: a first step of washing barium titanyl oxalate having a mean particle diameter of 50 to 300 [mu]m with water; a second step of obtaining barium titanyl oxalate having a mean particle diameter of 0.05 to 1 [mu]m by slurrying and wet-grinding the washed barium titanyl oxalate; and a third step of calcining the obtained barium titanyl oxalate having a mean particle diameter of 0.05 to 1 [mu]m at 700 to 1,200[deg.]C.

Description

Manufacturing method of perovskite type barium titanate powder

technical field

The present invention relates to a method for producing perovskite-type barium titanate powder, in particular perovskite-type titanate useful as a raw material for functional ceramics such as piezoelectrics, photoelectric materials, dielectrics, semiconductors, and sensor elements Manufacturing method of barium powder.

Background technique

Perovskite-type barium titanate powder is currently used as a raw material for functional ceramics such as piezoelectric bodies and laminated ceramic capacitors. However, in recent years, laminated ceramic capacitors have been required to increase the number of laminations or to increase the permittivity in order to increase the capacity. For this reason, the perovskite-type barium titanate powder used as a raw material is required to be finer than 1 μm. , The fluctuation of particle size is small, the molar ratio of Ba to Ti (hereinafter also referred to as "Ba/Ti molar ratio") is about 1, and its fluctuation is small, high purity, and excellent crystallinity.

As a method for producing perovskite-type barium titanate powder, for example, it is proposed in JP-A-61-146710 that a water-soluble barium salt, a water-soluble titanium salt, and an aqueous solution of oxalic acid are mixed at the same time, and the obtained gel A method in which fine barium titanyl oxalate (BaTiO(C ₂ O ₄ )·4H ₂ O) crystals obtained by crushing with strong stirring for a short period of time are calcined at 700-900°C. In addition, Clabaugh, WS et al. proposed that an aqueous solution of TiCl ₄ and BaCl ₂ was dropped in an aqueous solution of H ₂ C ₂ O ₄ at about 80°C while vigorously stirring to obtain barium titanyl oxalate, which was then calcined, A method for producing BaTiO ₃ with a primary particle size distribution of 0.3 to 1.5 μm and a Ba/Ti molar ratio of 0.987 to 1.003.

【Patent Document 1】

JP-A-61-146710 Bulletin (Page 1)

【Non-Patent Document 1】

Clabaugh, W.S., et al. "Precipitation of Barium Titanyl Oxalate Tetrahydrate for Conversion to Barium Titanate of High Purity" (Journal of Research of the National Bureau of Standards), (USA), 1956, Volume 56 (Vol56), Number 5 (No.5), p.289-291.

However, using the perovskite-type barium titanate powder obtained by the method described in JP-A-61-146710, a considerable amount of chlorine enters the crystal during the production process, so even if it is washed, it is difficult to remove the chlorine. The content is sufficiently reduced to several hundreds of ppm or less, but there is a problem that the purity is insufficient, and the fluctuation of the composition tends to increase due to washing. In addition, in the method proposed by Clabaugh, W.S. et al., there are fine particles with an average particle size of 1 μm or less, small fluctuations in particle size, a Ba/Ti molar ratio of about 1, small fluctuations, and excellent crystallinity. The problem of perovskite barium titanate powder.

Contents of the invention

Therefore, an object of the present invention is to provide a perovskite whose average particle size is 1 μm or less, fine, has small particle size fluctuations, and has a Ba/Ti molar ratio of about 1, and has small fluctuations, high purity, and excellent crystallinity. The manufacture method of type barium titanate powder.

The inventors of the present invention have found, as a result of repeated in-depth research under such actual conditions, that if the barium titanyl oxalate having a specific particle size characteristic is cleaned, impurities such as chlorine can be easily removed. The final barium titanyl oxalate is wet pulverized to a specific particle size, and then calcined to obtain fine particles with an average particle size of 1 μm or less, with small fluctuations in particle size, and a Ba/Ti molar ratio of about 1, with small fluctuations. , high purity, excellent crystallinity perovskite barium titanate powder, thus completing the present invention.

That is, the present invention provides a method for producing perovskite-type barium titanate powder, which is characterized by comprising: a first step of washing barium titanyl oxalate with an average particle diameter of 50 to 300 μm with water; washing the washed oxalic acid After the barium titanyl oxalate is made into a slurry, wet pulverization is carried out to obtain the second process of barium titanyl oxalate with an average particle size of 0.05-1 μm; and, calcining the oxalic acid oxide with an average particle size of 0.05-1 μm The third process of titanium barium.

In addition, the aforementioned wet pulverization treatment is preferably performed in an organic solvent, and the organic solvent is more preferably ethanol.

Description of drawings

FIG. 1 is a schematic diagram illustrating X-ray diffraction curves of a and b used in Mathematical Formula 1. FIG.

FIG. 2 is an X-ray diffraction diagram around 2θ=44° to 46° of barium titanate obtained in Example 1. FIG.

3 is an X-ray diffraction diagram around 2θ=44 to 46° of barium titanate obtained in Comparative Example 1. FIG.

Detailed ways

[Manufacturing method of perovskite type barium titanate powder]

(first process)

The first step of the production method of the perovskite type barium titanate powder of the present invention is to wash the barium titanyl oxalate (BaTiO(C ₂ O ₄ )·4H ₂ O) with a specific particle size with water to remove the Process for impurities such as chlorine in barium particles. The barium titanyl oxalate used in the present invention has an average particle diameter of usually 50 to 300 μm, preferably 100 to 200 μm. If the average particle size is within this range, the crystal grains are large, so Ba and Ti are less eluted when washed with water, and impurities such as chlorine can be effectively removed, so it is optimal. Furthermore, the barium titanyl oxalate particles are golden rice sugar-like particles, but in the present invention, the average particle diameter of the so-called barium titanyl oxalate means the tip of the protrusions to the golden rice sugar-like particles observed with a scanning electron microscope (SEM). The largest diameter is included as the particle diameter of one golden rice candy-shaped particle, the summed average of the particle diameters for a plurality of golden rice candy-shaped particles.

If the average particle diameter of barium titanyl oxalate is within the above range, if it is washed with water, it is easy to reduce the content of impurities such as chlorine entering the barium titanyl oxalate particles to hundreds of ppm levels, and the obtained perovskite type When washing the barium titanate powder, the elution of Ba and Ti is small, and the Ba/Ti molar ratio tends to be about 1 in the range of 0.998 to 1.002, so it is preferable.

On the other hand, if the average particle size of barium titanyl oxalate is less than 50 μm, even if it is washed with water, it is difficult to reduce impurities such as chlorine entering the particles to hundreds of ppm levels, and due to the elution of Ba and Ti, it is obtained The Ba/Ti molar ratio of the perovskite-type barium titanate is difficult to fall within the range of 0.998 to 1.002, which is not preferable. In addition, when the average particle diameter exceeds 300 μm, the crushing efficiency is lowered, and the fluctuation of the particle diameter after wet crushing tends to increase in the second step described later, which is not preferable.

In addition, the barium titanyl oxalate used in the first step usually has a Ba/Ti molar ratio of 0.998 to 1.002. If the Ba/Ti molar ratio of barium titanyl oxalate is within this range, the Ba/Ti molar ratio of the obtained perovskite-type barium titanate is 0.998～1.002 which is about 1 perovskite-type barium titanate, Therefore it is preferable.

The water used for cleaning is determined not to contaminate the barium titanyl oxalate with ions and the like, so ion-exchanged water, pure water, ultrapure water, and the like are preferable. In addition, in order to improve the cleaning effect, after the initial cleaning with industrial water, etc., it can be washed with ion-exchanged water, etc.

The cleaning method in the first step is not particularly limited, but it is preferable to perform cleaning using repulp or the like because the cleaning effect is good. The so-called repulping is a method of discarding the supernatant, adding pure water, and then washing. In addition, if the concentration of chlorine contained in the barium titanyl oxalate is sufficiently washed to be 500 ppm or less, preferably 200 ppm or less, high-purity perovskite-type barium titanate powder can be easily obtained, which is preferable.

After cleaning, drying is carried out as required to obtain washed barium titanyl oxalate. In the present invention, the physical properties of the barium titanyl oxalate after washing are usually 50 to 300 μm, preferably 100 to 200 μm in average particle size. In addition, the Ba/Ti molar ratio is usually 0.998 to 1.002. In addition, the washed barium titanyl oxalate has a chlorine content of usually 500 ppm or less, preferably 200 ppm or less. In addition, the number of times of washing is not limited to one, and may be repeated several times so that the chlorine content of the barium titanyl oxalate after washing falls within the above-mentioned range.

(second process)

The second step is a step of slurrying the barium titanyl oxalate washed in the first step, and then performing a wet pulverization treatment to obtain barium titanyl oxalate having an average particle diameter within a specific range.

As the solvent used in the preparation of the above slurry, a solvent inert to barium titanyl oxalate is used, for example, water, methanol, ethanol, propanol, butanol, toluene, xylene, acetone, methylene chloride , ethyl acetate, dimethylformamide and diethyl ether, etc. Among them, if organic solvents such as methanol, ethanol, propanol, butanol, toluene, xylene, acetone, dichloromethane, ethyl acetate, dimethylformamide and diethyl ether are used and the elution of Ba and Ti is less If the solvent is used, the perovskite-type barium titanate powder with high crystallinity can be obtained, so it is preferable. In particular, the use of ethanol is particularly preferable because perovskite-type barium titanate powder excellent in crystallinity can be produced inexpensively at a low temperature range of about 800 to 950°C. The above solvents may be used alone or in combination of two or more.

In the second step, pulp is prepared first. The washed barium titanyl oxalate was mixed and uniformly dispersed in the above-mentioned solvent to obtain a slurry. The concentration of the slurry is not particularly limited as long as it can be wet pulverized, but it is usually 10 to 70% by weight, preferably 30 to 50% by weight, and the pulverization efficiency is high at this concentration.

Next, a wet pulverization process is performed using this slurry. As a method of wet pulverization treatment, for example, a method of putting the slurry in a wet pulverization apparatus and performing pulverization treatment is mentioned. As a wet pulverization apparatus, a ball mill, a bead mill, etc. are mentioned, for example.

The wet pulverization treatment is performed until the average particle diameter of the barium titanyl oxalate obtained from a scanning electron microscope (SEM) is usually 0.05 to 1 μm, preferably 0.05 to 0.8 μm. If the average particle size is less than 0.05 μm, pulverization is technically difficult and handling becomes difficult, so it is not preferable. In addition, when the average particle diameter exceeds 1 μm, the fluctuation of the particle diameter of the obtained perovskite-type barium titanate tends to be large, which is not preferable.

Examples of the material of the beads loaded into the wet pulverization apparatus during the pulverization process include zirconia, alumina, silica, zeolite, silicon carbide, silicon nitride and the like. Among them, zirconia is most preferable because there is little contamination of impurities during wet pulverization.

The above-mentioned beads have a diameter of usually 0.3 to 5 mm, preferably 0.3 to 2 mm. If the diameter is within this range, the grinding efficiency is good, which is preferable.

After the wet pulverization treatment, the obtained fine barium titanyl oxalate powder or slurry is dried as it is. If the drying method is a method that can recover the solvent, it can reduce the production cost, so it is preferable. In addition, if it is carried out using a spray dryer or the like that can completely dry the slurry after the wet pulverization treatment, the eluted components can be included again in the Barium titanyl oxalate powder is therefore most preferred.

In addition, in the slurry before the wet pulverization treatment or the slurry after the wet pulverization treatment in the second step, a subsidiary component element-containing compound may be added and mixed as necessary. By adding and mixing a compound containing subcomponent elements in this way, a solid-solution perovskite-type barium titanate powder can be obtained in a state where the subcomponent elements are dispersed approximately uniformly on the particle surface. For example, the perovskite-type barium titanate can be adjusted to The dielectric constant of the ceramic after powder ceramization, etc., is therefore desirable.

Examples of compounds containing subcomponent elements include rare earth elements selected from the group consisting of Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. , Ba, Li, Bi, Zn, Mn, Al, Si, Ca, Sr, Co, Ni, Cr, Fe, Mg, Ti, V, Nb, Mo, W and Sn at least one element compound.

The subcomponent element-containing compound may be either inorganic or organic, and examples include oxides, hydroxides, chlorides, nitrates, oxalates, carboxylates, and alkoxides containing the above-mentioned elements. In addition, when the subcomponent element-containing compound is a compound containing Si element, in addition to the above-mentioned oxides, silica sol, sodium silicate, or the like may be used. Furthermore, when the element of the compound containing the subsidiary element element is a metal element, if an alkoxide is used as the compound containing the subsidiary element element, the perovskite-type titanic acid in which the subsidiary element element is particularly uniformly dispersed on the particle surface can be obtained. Barium powder is therefore preferred. The aforementioned subcomponent element-containing compounds may be used singly or in combination of two or more kinds.

As a method of adding and mixing the subcomponent element-containing compound to the slurry before the wet pulverization treatment, for example, preparing a solution in which the subcomponent element-containing compound is dissolved in the above-mentioned solvent or dispersing the subcomponent element-containing compound in A slurry in the above solvent, a method of mixing the solution or slurry with a slurry of barium titanyl oxalate before wet pulverization treatment; a method of directly adding and mixing a compound containing an auxiliary component element to the slurry of barium titanyl oxalate before wet pulverization treatment ; A method of preparing a slurry by simultaneously mixing the washed barium titanyl oxalate obtained in the first step, the compound containing an accessory element element, and the above-mentioned solvent, and the like. In addition, as a method of adding and mixing an accessory element-containing compound to the barium titanyl oxalate slurry after the wet pulverization treatment, for example, a solution in which the accessory element-containing compound is prepared in advance in the above-mentioned solvent, and the A method of mixing the solution with a wet pulverized barium titanyl oxalate slurry; a method of directly adding and mixing a compound containing an auxiliary component element to the wet pulverized barium titanyl oxalate slurry. Among them, the former method is preferable since dispersion becomes easy.

The amount of the compound containing the subcomponent element can be arbitrarily set in accordance with the desired dielectric properties, but the cumulative amount of elements in the compound containing the subcomponent element is, for example, generally It is 0.01 to 10 parts by weight.

(third process)

The third step is a step of calcining the barium titanyl oxalate powder having an average particle size of 0.05 to 1 μm obtained in the above second step at a predetermined temperature. Through this step, a perovskite type barium titanate powder is obtained.

Calcination conditions, the calcination temperature is 700-1200°C, preferably 800-1100°C. The reason why the calcination temperature is set within the above range is that if it is less than 700°C, it is difficult to obtain a single-phase perovskite-type barium titanate powder, so it is not advisable. On the other hand, if it exceeds 1200°C, the particle The fluctuation of the diameter is easy to become large, so it is not advisable. In addition, in the present invention, the calcination treatment may be performed several times as needed.

After calcination, it is appropriately cooled and pulverized as needed to obtain perovskite-type barium titanate powder. Furthermore, pulverization according to need is suitable when the perovskite-type barium titanate powder obtained by calcination is in the form of a weakly bonded block, but the particles of the perovskite-type barium titanate powder themselves have the following specific characteristics: Particles with average particle size and BET specific surface area.

That is, the perovskite-type barium titanate powder obtained after the completion of the third step has an average particle diameter of usually 0.05 to 1 μm, preferably 0.05 to 0.8 μm, as measured by a scanning electron microscope (SEM), and a BET specific surface area of 1 m ² /g or more, preferably 2 to 15 m ² /g, and a powder with little variation in particle size. In addition to the above physical properties, it is a powder with excellent crystallinity having a chlorine content of usually 500 ppm or less, preferably 200 ppm or less, and a molar ratio of Ba to Ti of 0.998 to 1.002 or approximately 1.

The perovskite-type barium titanate powder obtained in this way has an average particle diameter as fine as 0.05 to 1 μm as described above, and is a high-purity powder with low content of impurities such as chloride ions. It has small fluctuations in particle diameter and excellent crystallinity. powder.

The perovskite-type barium titanate powder of the present invention, for example, for the manufacture of laminated ceramic capacitors, is mixed and dispersed in a suitable solvent together with currently known additives, organic binders, plasticizers, dispersants, etc. In this process, the slurry is formed, and by performing sheet forming, ceramic sheets used in the manufacture of laminated ceramic capacitors can be obtained.

To manufacture a laminated ceramic capacitor from this ceramic sheet, first, a conductive paste for forming internal electrodes is printed on one surface of the ceramic sheet, and after drying, a plurality of the above-mentioned ceramic sheets are laminated and pressed together in the thickness direction to form a laminate. . Next, the laminate was heat-treated, subjected to a binder removal treatment, and then fired to obtain a fired body. Then, Ni paste, Ag paste, nickel alloy paste, copper paste, copper alloy paste, etc. are coated on the sintered body, and if baked, a laminated capacitor can be obtained.

In addition, for example, if the perovskite-type barium titanate powder of the present invention is mixed with resins such as epoxy resin, polyester resin, and polyimide resin, if it is formed into a resin sheet, a resin film, an adhesive, etc., it can be used as a printed material. Materials such as wiring boards or multilayer printed wiring boards, the same materials used to suppress the shrinkage difference between internal electrodes and dielectric layers, electrode ceramic circuit boards, glass ceramic circuit boards, and circuit surrounding materials are used.

In addition, the perovskite-type barium titanate powder obtained in the present invention can be suitably used as a catalyst used in reactions such as degassing and chemical synthesis, or as a surface modification material for printing colorants that impart antistatic and cleaning effects use.

In addition, barium titanyl oxalate used in the first step of the method for producing perovskite-type barium titanate powder of the present invention can be produced, for example, using the following method for producing barium titanyl oxalate.

[Manufacturing method of barium titanyl oxalate]

At a specific temperature, liquid A formed by dissolving titanium tetrachloride and barium chloride in water is contacted with liquid B formed by dissolving oxalic acid in water, and after aging, it can be produced by solid-liquid separation. In the first process The specific particle size of barium titanyl oxalate used.

Titanium tetrachloride, barium chloride, and oxalic acid that can be used in this method are not particularly limited if they are industrially available, but in order to obtain high-purity barium titanyl oxalate or perovskite type barium titanate For powder, it is preferable to use one with less impurity content.

For the reaction operation, first, liquid A obtained by dissolving titanium tetrachloride and barium chloride in water, and liquid B obtained by dissolving oxalic acid in water were prepared. Liquid A is an aqueous solution containing titanium tetrachloride and barium chloride, but the dissolving order of titanium tetrachloride and barium chloride is not particularly limited, they can be dissolved at the same time, or one can be dissolved and then the other can be dissolved.

In liquid A, the molar ratio (Ba/Ti) of Ba in barium chloride to Ti in titanium tetrachloride is usually 1.0 to 1.5, preferably 1.0 to 1.2. If it is such a molar ratio, the Ba of barium titanyl oxalate The /Ti molar ratio is easily 0.998 to 1.002, which is preferable.

In addition, the concentration of _barium chloride in liquid A is usually 1 to 10% by weight, preferably 5 to 8% by weight in terms of BaCl2 concentration. If it is such a concentration, titanyl oxalate can be obtained in high yield. Barium is therefore preferred. In addition, the concentration of _titanium tetrachloride in liquid A is usually 1 to 10% by weight, preferably 5 to 8% by weight in terms of TiCl4 concentration. If it is such a concentration, oxalic acid oxygen can be obtained in high yield. Titanium barium is therefore preferred.

In addition, the concentration of oxalic acid in the liquid B is usually 5 to 70% by weight, preferably 10 to 40% by weight. Such a concentration is preferable because barium titanyl oxalate can be obtained in high yield.

As a contact method of liquid A and liquid B, the method of adding liquid B with stirring liquid A, or the method of adding liquid A to liquid B with stirring are mentioned. The amount of liquid B added to the above liquid A or the amount of liquid A added to liquid B, and the molar ratio (oxalic acid/Ti) of oxalic acid in liquid B to Ti in liquid A (oxalic acid/Ti) can be added if they are usually 2.1 to 2.3. Barium titanyl oxalate is obtained in high yield and is therefore preferred. In addition, the stirring speed is not particularly limited as long as the slurry containing barium titanyl oxalate generated from the addition to the end of the reaction always shows fluidity.

In the present invention, the particle size of the barium titanyl oxalate produced tends to be large by either making the addition time of liquid A or liquid B supplied continuously or intermittently to the reaction system longer, or by increasing the temperature of addition. For this reason, in the present invention, the contact of the A liquid and the B liquid, the addition temperature of another solution added in the A liquid or the B liquid, is usually 50～90°C, preferably 50～70°C, the addition time Be more than 0.5 hour, preferably more than 1 hour, carry out continuously at a certain speed, if so, the barium titanyl oxalate obtained just becomes the Ba/Ti molar ratio is about 1, and the stable quality titanyl oxalate of little fluctuation Barium is also preferable because it can obtain an average particle diameter within the above-mentioned range in a short time in the aging reaction described later. Furthermore, the temperature of another solution added to the A liquid or B is not particularly limited, but if it is within the same range as the above-mentioned addition temperature, the reaction operation becomes easy, so it is preferable.

After the contact of liquid A and liquid B is completed, aging reaction is performed. If such an aging reaction is carried out, the reaction is terminated as the crystal grain growth of the produced barium titanyl oxalate is accelerated, so it is possible to obtain a compound having an average particle diameter within the above range, a Ba/Ti molar ratio of 0.998 to 1.002, and a composition The fluctuation of barium titanyl oxalate is small.

Aging conditions, the aging temperature is usually 50° C. or higher, preferably 50 to 90° C., and the aging reaction is carried out for 0.5 hour or longer, preferably 1 hour or longer. In addition, aging temperature means the temperature of the whole mixture after A liquid and B liquid contact. After the aging, the solid-liquid separation is carried out by a conventional method to obtain barium titanyl oxalate with an average particle size of usually 50-300 μm, preferably 100-200 μm.

The method for producing barium titanyl oxalate described above can be used, for example, to prepare barium titanyl oxalate having an average particle diameter of 50 to 300 μm used in the first step of the method for producing perovskite-type barium titanate powder.

【Example】

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited by these examples.

Example 1

(Manufacturing process of barium titanyl oxalate)

A liquid A was prepared by dissolving 600 g (2.456 mol) of barium chloride dihydrate and 444 g (2.342 mol) of titanium tetrachloride in 4100 ml of water. Next, an oxalic acid aqueous solution in which 620 g of oxalic acid was dissolved in 1500 ml of 70° C. warm water was prepared, and this was prepared as B liquid. While keeping liquid B at 70°C, liquid B was dripped into A over 120 minutes with stirring, and aging was performed while stirring at 70°C for 1 hour. After cooling, filter and recover the barium titanyl oxalate. Table 1 shows the physical property values of the obtained barium titanyl oxalate. The average particle diameter was calculated|required from the scanning electron microscope (SEM) photograph.

Table 1

Physical properties of barium titanyl oxalate The average particle size 120μm

(first process)

The recovered barium titanyl oxalate was repulped three times with 4.5 liters of distilled water and washed carefully. Next, drying was performed at 105° C. to obtain 1000 g of barium titanyl oxalate. Table 2 shows the physical property values of the obtained barium titanyl oxalate.

The Ba/Ti molar ratio was calculated based on the value of the fluorescent X-ray analysis. Moreover, the average particle diameter was calculated|required from the scanning electron microscope (SEM) photograph. Chloride concentration was determined by ion chromatography.

Table 2

Physical properties of barium titanyl oxalate Ba/Ti molar ratio 1.000 The average particle size 120μm Chlorine content 100ppm

(second process)

氧化锆球，进行湿式粉碎处理。接着在105℃下全量干燥湿式粉碎处理后的浆，得到平均粒径是0.7μm的草酸氧钛钡。Put the slurry formed by adding 60 g of barium titanyl oxalate prepared in the first process and 140 ml of ethanol into a ball mill with a capacity of 700 ml, and put 1070 g of

Zirconia balls are wet pulverized. Next, the whole amount of the wet pulverized slurry was dried at 105° C. to obtain barium titanyl oxalate with an average particle diameter of 0.7 μm.

(third process)

10 g of the barium titanyl oxalate sample obtained in the second step was calcined at 900° C. for 4 hours in the air to obtain a barium titanate sample.

The Ba/Ti molar ratio, BET specific surface area, crystallinity, average particle diameter, fluctuation in particle diameter, and chlorine content of the obtained barium titanate sample were determined. The results are shown in Table 3 and Table 4. In addition, an X-ray diffraction pattern of barium titanate is shown in FIG. 2 .

In addition, the Ba/Ti molar ratio was calculated based on the fluorescent X-ray analysis value. In addition, a barium titanate sample was measured with an X-ray diffractometer (manufactured by Nippon Phillips Co., Ltd., model X'PartMPD) using Cu-Kα rays as a radiation source, and the degree of crystallinity was determined according to the following calculation formula. As for the degree of crystallinity, the larger the obtained value, the better the crystallinity. Fig. 1 schematically shows how to obtain a and b in the following formula.

Crystallinity = a/b

(a: The intensity of the diffraction peak c of the lattice plane (200) near 2θ=45.38°. b: The diffraction peak d of the lattice plane (002) near 2θ=44.86° and the above-mentioned lattice plane (200) The intensity of the valley e between the diffraction peaks c of the surface). Diffraction peak c, diffraction peak d, and trough e were obtained using the mechanical conversion means of the X-ray diffraction apparatus.

When observing a sample with an electron microscope at a magnification of 20,000 times, the fluctuation in the particle diameter was evaluated as the standard deviation σ when measuring the particle diameters of 200 or more randomly selected particles. A smaller standard deviation σ indicates less variation in particle size. In addition, the chlorine content of barium titanate was measured by ion chromatography.

Example 2 and 3

In the third step, except that the calcining temperature of the barium titanyl oxalate sample is specified as 920° C. (Example 2) or 940° C. (Example 3), it is produced in the same manner as in Example 1 to obtain a barium titanate sample. The Ba/Ti molar ratio, BET specific surface area, crystallinity, average particle size, fluctuation in particle size, and chlorine content were determined. The results are shown in Table 3 and Table 4.

Comparative example 1

(Manufacturing process and first process of barium titanyl oxalate)

The production process of barium titanyl oxalate and the first step were carried out in the same manner as in Example 1 to obtain 1000 g of barium titanyl oxalate samples with physical properties shown in Table 2.

(process after the first process)

200 g of this barium titanyl oxalate sample was calcined at 900° C. for 4 hours in the air to obtain a barium titanate sample.

氧化锆球，进行湿式粉碎处理。接着在105℃下全量干燥湿式粉碎处理后的浆，得到钛酸钡试样。Next, 60 g of the obtained barium titanate sample and 140 ml of ethanol were added into a ball mill with a capacity of 700 ml to form a slurry, and 1070 g of

Zirconia balls are wet pulverized. Next, the entire amount of the wet pulverized slurry was dried at 105° C. to obtain a barium titanate sample.

For the obtained barium titanate samples, the Ba/Ti molar ratio, BET specific surface area, crystallinity, average particle diameter, fluctuation in particle diameter, and chlorine content were determined in the same manner as in Example 1. The results are shown in Table 3 and Table 4. In addition, an X-ray diffraction pattern of the obtained barium titanate is shown in FIG. 2 .

Comparative example 2-4

In the process after the first process, except that the calcining temperature of the barium titanyl oxalate sample is specified as 920 ° C (comparative example 2), 940 ° C (comparative example 3) or 1000 ° C (comparative example 4), the same as the comparative example 1 was produced in the same manner to obtain a barium titanate sample, and the Ba/Ti molar ratio, BET specific surface area, crystallinity, average particle diameter, fluctuation in particle diameter, and chlorine content were determined. The results are shown in Table 3 and Table 4.

table 3

Calcination temperature (℃) Ba/Ti molar ratio BET specific surface area (m²/g) Crystallinity Example 1 900 1.000 5.7 2.4 Example 2 920 1.000 4.6 3.2 Example 3 940 1.000 3.6 4.2 Comparative example 1 900 1.000 5.4 — Comparative example 2 920 1.000 4.5 — Comparative example 3 940 1.000 4.3 — Comparative example 4 1000 1.000 4.1 0.5

Table 4

Average particle size (μm) Standard deviation of particle size fluctuation σ Chlorine content (ppm) Example 1 0.39 0.12 85 Example 2 0.43 0.13 84 Example 3 0.48 0.11 81 Comparative example 1 0.44 0.25 89 Comparative example 2 0.48 0.26 87 Comparative example 3 0.53 0.24 85 Comparative example 4 0.60 0.25 81

From the results of Table 3 and Table 4, the following facts are known. That is, as can be seen from Examples 1 to 3, the barium titanate obtained by the production method of the present invention is fine particles with a particle diameter of 1 μm or less, high purity, good crystallinity, and little fluctuation in particle diameter. In addition, as can be seen from Comparative Examples 1 to 4, barium titanate with good crystallinity cannot be obtained unless the second step of the present invention is performed without heat treatment at a high temperature of 1000° C. or higher. In addition, as can be seen from Comparative Examples 1 to 4, when the second step of the present invention is not performed, titanyl oxalate remains in the barium titanate even if the pulverization treatment is performed after calcination, because there are many coarse particles or fine particles. In addition, even if the barium skeleton is pulverized, there are many coarse particles or fine particles, so the fluctuation in particle size is large. In addition, the diffraction peak of the 002 plane near 2θ = 44.86° was not detected by X-ray diffraction analysis, and the crystallization Poor sex.

Example 4

(Manufacturing process and first process of barium titanyl oxalate)

The production process of barium titanyl oxalate and the first step were carried out in the same manner as in Example 1 to obtain 1000 g of barium titanyl oxalate samples with physical properties shown in Table 2.

(second process)

氧化锆球，进行湿式粉碎处理。140 ml of ethanol and yttrium butoxide were added to a ball mill with a capacity of 700 ml. The amount of yttrium butoxide added was 1% by weight in terms of yttrium oxide relative to the barium titanate produced. Then, put 60g of barium titanyl oxalate and 1070g of barium titanyl oxalate prepared in the first process into the ball mill

Zirconia balls are wet pulverized.

Next, the entire amount of the slurry after the wet pulverization treatment was dried at 105° C. to obtain barium titanyl oxalate having yttrium adhered to the surface with an average particle diameter of 0.7 μm.

(third process)

10 g of barium titanyl oxalate with yttrium attached to the surface was calcined at 1100° C. for 4 hours in the air to obtain a barium titanate sample in which yttrium oxide was solid-dissolved.

For this barium titanate sample, the Ba/Ti molar ratio, BET specific surface area, crystallinity, average particle diameter, fluctuation in particle diameter, chlorine content, and yttrium content were determined in the same manner as in Example 1. In addition, the amount of Y was determined by an ICP (inductively coupled plasma) analysis method. The results are shown in Table 5.

Example 5

(preparatory process and first process)

The preparatory step and the first step were carried out in the same manner as in Example 1 to obtain 1000 g of a barium titanyl oxalate sample with the physical properties shown in Table 2.

(second process)

氧化锆球，进行湿式粉碎处理。接着，在105℃下全量干燥湿式粉碎处理后的浆，得到氧化钇和平均粒径为0.7μm的草酸氧钛钡的混合物。In a ball mill with a capacity of 700ml, put 60g of the barium titanyl oxalate sample obtained in the first process, 0.6g of yttrium oxide (average particle size 0.1μm), 140ml of ethanol and 1070g of

Zirconia balls are wet pulverized. Next, the entire amount of the wet pulverized slurry was dried at 105° C. to obtain a mixture of yttrium oxide and barium titanyl oxalate having an average particle diameter of 0.7 μm.

(third process)

Next, the obtained mixture of yttrium oxide and barium titanyl oxalate was calcined at 1100° C. for 4 hours in the atmosphere. A barium titanate sample having yttrium oxide attached to the surface was obtained.

For this barium titanate sample, the Ba/Ti molar ratio, BET specific surface area, crystallinity, average particle size, fluctuation in particle size, chlorine content, and yttrium content were determined by the same method as in Example 1. In addition, the amount of Y was determined by an ICP (inductively coupled plasma) analysis method. The results are shown in Table 5.

table 5

Example 4 Example 5 Ba/Ti molar ratio 1.000 1.000 Y₂O₃ content (weight%) 0.98 1.01 Chlorine content (ppm) 87 83 BET specific surface area (m²/g) 4.4 4.0 Average particle size (μm) 0.41 0.58 Standard deviation σ of particle size 0.08 0.13 Crystallinity 5.3 4.8

As a result of mapping the barium titanate samples containing yttrium obtained in Examples 4 and 5 using SEM-EDX (manufactured by JEOL Ltd.), no segregation of yttrium was observed in Examples 4 and 5. , evenly dispersed on the surface of the powder, but comparing Example 4 with Example 5, it can be seen that yttrium is more uniformly dispersed.

The effect of the invention

According to the manufacturing method of the perovskite-type barium titanate powder of the present invention, it is possible to manufacture fine particles with an average particle size of 1 μm or less, with small particle size fluctuations, a Ba/Ti molar ratio of about 1, and small fluctuations and high purity. Perovskite-type barium titanate powder with excellent crystallinity.

Claims (2)

1. a manufacture method of perovskite type barium titanate powder, is characterized in that, has: The first step of washing with water the barium titanyl oxalate with an average particle diameter of 50 to 300 μm, which is formed by dissolving titanium tetrachloride and barium chloride in water It is obtained by contacting liquid A and liquid B formed by dissolving oxalic acid in water at 50-90°C, aging at 50-90°C for more than 0.5 hours, and then performing solid-liquid separation; After making the washed barium titanyl oxalate into a slurry, wet pulverization treatment in ethanol to obtain the second step of barium titanyl oxalate with an average particle size of 0.05-1 μm; and The third step of calcining the barium titanyl oxalate having an average particle diameter of 0.05 to 1 μm at 700 to 1200° C. is performed. 2. the manufacture method of perovskite type barium titanate powder according to claim 1 is characterized in that, in the slurry before the wet pulverization treatment in the second step or the slurry after the wet pulverization treatment, add and mix selected from At least one of rare earth elements, Ba, Li, Bi, Zn, Mn, Al, Si, Ca, Sr, Co, Ni, Cr, Fe, Mg, Ti, V, Nb, Mo, W and Sn compound.

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