JP7102462B2 - Barium titanyl oxalate, its production method and barium titanate production method - Google Patents

Description

The present invention relates to barium oxalate titanyl oxalate, which is useful as a raw material for functional ceramics such as dielectrics, piezoelectric materials, optelectronic materials, semiconductors, and sensors, and a method for producing the same.

Conventionally, barium titanate has been produced by a solid phase method, a hydrothermal synthesis method, an alkoxide method, an oxalate method, or the like.

In the solid-phase method, the constituent raw material powders and the like are mixed and the mixture is produced by a dry method of heating at a high temperature. Therefore, the obtained powder forms an agglomerate having an irregular shape and has desired characteristics. High temperature firing is required to achieve this. Further, the hydrothermal synthesis method has an advantage that the characteristics of the powder are good, but the synthesis process is complicated, the productivity is inferior because an autoclave is used, and the price of the produced powder is high, which is not industrially advantageous. Similarly, the alkoxide method is difficult to handle as a starting material, is expensive, and is not industrially advantageous.

Compared to the hydrothermal synthesis method and the alkoxide method, barium titanate obtained by the oxalate method can be produced at a lower cost with a uniform composition, and compared to barium titanate produced by the solid phase method. It is characterized by a uniform composition. In the conventional oxalate method, a titanium source such as titanium tetrachloride, a barium source such as barium chloride, and oxalic acid are reacted in a solvent such as water to obtain barium titanyl oxalate, and then the barium oxalate is obtained. A method of firing titanium is common (see, for example, Patent Documents 1 to 3).

Special Table 2005-500239 Japanese Unexamined Patent Publication No. 2010-202610 Japanese Unexamined Patent Publication No. 2013-63867

However, since barium titanyl oxalate obtained in the above patent document produces barium titanate at a firing temperature of 700 ° C. or higher, the degree of crystallization is low at the time of production of barium titanate, but some grains. It is growing. When such barium titanyl oxalate is fired at a high temperature, even high crystals become large particles, and there is a problem that the characteristics as a raw material for functional ceramics cannot be satisfied.

Therefore, an object of the present invention is to provide barium titanate oxalate, which can obtain barium titanate having a small particle size and high crystals, and to provide a method for industrially advantageously producing the barium titanyl oxalate. It is in.

As a result of intensive studies in view of the above circumstances, the present inventors have shortened the mixing time of the solution containing the titanium compound and the barium compound (solution B) with the solution containing oxalic acid (solution A). , Fine barium titanate oxalate can be obtained, and when such fine barium titanate oxalate is fired, carbon dioxide gas can be easily released during thermal decomposition, and the temperature at which barium titanate is generated can be lowered. By generating barium titanate at a low temperature, barium titanate can be highly crystallized at a lower temperature than before, and thus the grain growth of barium titanate can be suppressed. They have found that barium titanate can be obtained and have completed the present invention.

That is, the present invention (1) provides barium titanyl oxalate, which is characterized in that the temperature at which the weight loss rate reaches 99% with respect to the weight loss rate at 1000 ° C. is 600 to 700 ° C. in thermogravimetric analysis. Is.

Further, the present invention (2) is a barium titanate having a specific surface area of 15 to 20 m ² / g and a c / a of 1.030 to 1.0055 by a heating test at 700 ± 10 ° C. in the air for 2 hours. It provides barium titanate oxalate (1), which is characterized by being converted to.

Further, the present invention (3) provides barium titanyl oxalate according to (1) or (2), wherein the average particle size is 1.0 μm or less.

Further, in the present invention (4), barium titanyl oxalate is produced by mixing a solution containing oxalic acid (solution A) and a solution containing a titanium compound and a barium compound (solution B) and reacting them. It is a method for producing barium titanyl oxalate to be produced.
First, the liquid A is filled in the reaction vessel, and then the liquid B is mixed with the liquid A while stirring the liquid A in the reaction vessel.
The time from the start to the end of mixing the B solution with the A solution is within 10 seconds.
The solvent of the liquid A is an organic solvent and the solvent of the liquid B is water.
The present invention provides a method for producing barium titanyl oxalate, which is characterized by the above.

Further, in the present invention ( 5 ), the solvent of the solution A is methanol, ethanol, propanol, butanol, diethyl ether, 1,3-butylene glycol, ethylene glycol, propylene glycol, dipropylene glycol, glycerol, N, N-. The present invention provides a method for producing barium titanyl oxalate ( 4 ), which is one or more selected from the group consisting of dimethylformamide and acetone.

Further, the present invention ( 6 ) is characterized in that the titanium compound in the liquid B is titanium tetrachloride and the barium compound is barium chloride. It provides a manufacturing method.

Further, the present invention ( 7 ) provides a method for producing barium titanyl oxalate according to any one of (4) to ( 6 ), wherein the mixing temperature of the liquid B with the liquid A is 40 ° C. or lower. Is what you do.

Further, the present invention ( 8 ) is characterized in that the average particle size of barium titanyl oxalate produced is 1.0 μm or less, which is a method for producing barium titanyl oxalate according to any one of (4) to ( 7 ). It is to provide.

Further, the present invention ( 9 ) provides a method for producing barium titanate, which comprises firing barium titanyl oxalate obtained by any of the production methods (4) to ( 8 ).

According to the present invention, it is possible to provide barium titanyl oxalate, which can obtain barium titanate having a smaller particle size and higher crystals than conventional barium titanate oxalate when fired at the same temperature. Further, according to the present invention, it is possible to provide a method for industrially advantageously producing the barium titanyl oxalate.

It is a measurement result of thermogravimetric analysis of barium titanyl oxalate obtained in Example 1 and Comparative Example 1. It is an SEM photograph of barium titanyl oxalate obtained in Example 1. It is an SEM photograph of barium titanate obtained in Example 1. It is an SEM photograph of barium titanyl oxalate obtained in Comparative Example 1. It is an SEM photograph of the fired product obtained in Comparative Example 1.

In thermogravimetric analysis, the barium titanyl oxalate of the present invention has a temperature at which the weight loss rate reaches 99% with respect to the weight loss rate of 1000 ° C. at 600 to 700 ° C., preferably 610 to 690 ° C., particularly preferably 615 to 685. Barium titanyl oxalate, characterized by a temperature of ° C. The weight loss rate of 1000 ° C. in the thermogravimetric analysis refers to the weight loss rate at the time when the analysis temperature in the thermogravimetric analysis is 1000 ° C. Further, the temperature at which the weight loss rate reaches 99% with respect to the weight loss rate of 1000 ° C. in the thermogravimetric analysis means that the weight loss rate with respect to the start of analysis is 99% of the weight loss rate at the analysis temperature of 1000 ° C. Refers to the temperature at which it reaches.

In the thermal weight analysis, the temperature at which the weight loss rate reaches 99% with respect to the weight loss rate at 1000 ° C. is the temperature at which the thermal decomposition of barium titanyl oxalate occurs and the conversion to barium titanate ends, that is, barium titanate oxalate. Refers to the temperature at which barium titanate is produced from. Regarding the weight loss measured by thermogravimetric analysis of barium titanate oxalate, when the temperature of the sample to be measured was raised from room temperature to 10 ° C./min, some weight loss was confirmed, and then at around 700 ° C. It can be confirmed that the weight loss is no longer confirmed, and finally barium titanate is thermally decomposed. The weight loss of the conventional barium titanate oxalate disappears at 700 to 720 ° C., and it can be confirmed that barium titanate is obtained in this temperature range. However, the barium titanyl oxalate of the present invention cannot be confirmed to lose weight at 600 to 700 ° C., preferably 610 to 690 ° C., particularly preferably 615 to 685 ° C. Barium titanate can be obtained. The reason for this is that the average particle size of barium titanyl oxalate obtained by the method for producing barium titanyl oxalate of the present invention, which will be described later, is preferably 1.0 μm or less, particularly preferably 0.01 to 0.5 μm. The present inventors consider that the fine particles make it easy for carbon dioxide gas to escape during thermal decomposition and change to barium titanate at a lower temperature than in the prior art.

The temperature at which the weight loss rate of barium titanyl oxalate of the present invention reaches 99% with respect to the weight loss rate of 1000 ° C. is 600 to 700 ° C., preferably 610 to 690 ° C., particularly preferably 615 to 685. By being at ° C., barium titanate can be produced in a temperature range of 600 to 700 ° C., preferably 610 to 690 ° C., particularly preferably 615 to 685 ° C. Therefore, the barium titanyl oxalate of the present invention can generate barium titanate at a low temperature, so that barium titanate can be highly crystallized at a lower temperature than before. In the barium titanyl oxalate of the present invention, barium titanate can be highly crystallized at a lower temperature than before, so that the grain growth of barium titanate can be suppressed. Barium is obtained. Therefore, according to the barium titanate oxalate of the present invention, finer and higher crystal barium titanate can be obtained as compared with the conventional barium titanyl oxalate when fired at the same temperature. On the other hand, when the temperature at which the weight loss rate reaches 99% with respect to the weight loss rate at 1000 ° C. exceeds 700 ° C., the temperature at which barium titanate is produced from barium titanate oxalate rises, so that for subsequent high crystallization. The heating temperature also becomes high, and as a result, the particle size of barium titanate becomes large.

The thermogravimetric analyzer used for the thermogravimetric analysis of barium titanyl oxalate is not particularly limited, and examples thereof include TGA / DSC 1 manufactured by METTLER TOLEDO Co., Ltd.

The barium titanyl oxalate of the present invention has a specific surface area of 15 to 20 m ² / g and a c / a of 1.0030 to 1.0055 by a heating test at 700 ± 10 ° C. for 2 hours in the air. It is preferably barium titanyl oxalate that is converted to. The specific surface area of barium titanate obtained by heating the barium titanyl oxalate of the present invention in the air at 700 ± 10 ° C. for 2 hours is particularly preferably 16 to 19 m ² / g. The c / a of barium titanate obtained by heating the barium titanyl oxalate of the present invention in the air at 700 ± 10 ° C. for 2 hours is particularly preferably 1.0035 to 1.0050. Since the specific surface area of barium titanate produced by the heating test at 700 ± 10 ° C. in the air for 2 hours is in the above range and c / a is in the above range, the height after barium titanate is produced in the firing process is high. Even if grain growth occurs due to heating for crystallization, finer and higher crystal barium titanate can be obtained as compared with the conventional barium titanate oxalate. Regarding the heating test of barium titanyl oxalate, the measurement target sample was held for 2 hours in a heating device whose temperature was adjusted to 700 ± 10 ° C., and the heating test was performed. After cooling, the measurement target sample after the heating test was BET. Specific surface area analysis and X-ray diffraction analysis by the method are performed to determine the specific surface area and c / a of the sample to be measured after the heating test.

The average particle size of barium titanyl oxalate of the present invention is preferably 1.0 μm or less, more preferably 0.005 to 1.0 μm, and particularly preferably 0.01 to 0.5 μm. When the average particle size of barium titanyl oxalate is in the above range, barium titanate can be produced at a low temperature. In the present invention, the average particle size of barium titanyl oxalate is obtained by arbitrarily measuring 200 particles by a scanning electron microscope (SEM) photograph and using the average value as the average particle size.

Further, the barium titanyl oxalate of the present invention is a barium oxalate capable of producing barium titanate when heated in a temperature range of 600 to 700 ° C., preferably 610 to 690 ° C., particularly preferably 615 to 685 ° C. Barium titanyl.

Hereinafter, the production method of the present invention will be described based on the preferred embodiment thereof.
In the method for producing barium oxalate titanyl oxalate of the present invention, a solution containing oxalic acid (solution A) and a solution containing a titanium compound and a barium compound (solution B) are mixed and reacted to cause oxalic acid. A method for producing barium titanyl oxalate, which produces barium titanyl.
First, the liquid A is filled in the reaction vessel, and then the liquid B is mixed with the liquid A while stirring the liquid A in the reaction vessel.
The time from the start to the end of mixing the B solution with the A solution is within 10 seconds.
It is a method for producing barium titanyl oxalate, which is characterized by the above.

The liquid A according to the method for producing barium titanyl oxalate of the present invention is a solution containing oxalic acid. The concentration of oxalate ion in the liquid A is not particularly limited, but is preferably 0.1 to 7.0 mol / L, and particularly preferably 0.6 to 5.0 mol / L.

The solvent of the liquid A includes an aqueous solvent, an organic solvent, or a mixed solvent thereof, and is preferably an organic solvent from the viewpoint of obtaining fine particles of barium oxalate titanyl oxalate. The organic solvent is not particularly limited as long as it is hydrophilic and inactive with respect to the raw material, and is limited to methanol, ethanol, propanol, butanol, diethyl ether, 1,3-butylene glycol, ethylene glycol, propylene glycol, and di. One or more selected from the group consisting of propylene glycol, glycerol, N, N-dimethylformamide and acetone can be used. In the case of a mixed solvent of water and an organic solvent or a mixed solvent of a plurality of organic solvents, the mixing ratio thereof is appropriately selected.

The liquid B according to the method for producing barium titanyl oxalate of the present invention is a solution containing a titanium compound and a barium compound. The concentration of titanium ions in the liquid B is not particularly limited, but is preferably 0.04 to 4.0 mol / L, and particularly preferably 0.2 to 3.0 mol / L. The concentration of barium ions in the liquid B is not particularly limited, but is preferably 0.08 to 6.5 mol / L, and particularly preferably 0.4 to 3.0 mol / L.

The titanium compound according to the method for producing barium titanyl oxalate of the present invention is not particularly limited, and examples thereof include titanium tetrachloride and titanium lactate. The titanium compound may be one kind or a combination of two or more kinds. As the titanium source, titanium tetrachloride is preferable.

The barium compound according to the method for producing barium titanyl oxalate of the present invention is not particularly limited, and examples thereof include barium chloride, barium carbonate, barium hydroxide, barium acetate, and barium nitrate. The barium compound may be one kind or a combination of two or more kinds. As the barium compound, one or more selected from the group consisting of barium chloride, barium carbonate and barium hydroxide is preferable, and barium chloride is particularly preferable.

In the method for producing barium oxalate titanyl oxalate of the present invention, liquid A is filled in the reaction vessel, and then liquid A is supplied to the liquid A and mixed while stirring the liquid A in the reaction vessel. Then, the reaction for producing barium titanyl oxalate is carried out.

At this time, the mixing of the liquid B into the reaction vessel filled with the liquid A is performed within 10 seconds, preferably within 8 seconds, from the start to the end of the mixing of the liquid B with the liquid A. be. When the time from the start to the end of mixing the liquid B with the liquid A is within the above range, fine particles of barium oxalate titanyl oxalate can be obtained.

The temperature at which the B solution is mixed with the A solution, that is, the temperature of the reaction solution (A solution) and the B solution in the reaction vessel when the B solution is added to the reaction vessel is preferably 40 ° C. or lower, particularly preferably. Is 5 to 30 ° C.

The amount of the B solution mixed with the A solution is such that the ratio of the total number of moles of titanium and barium in the B solution to the number of moles of oxalic acid in the A solution is preferably 0.01 to 20, particularly preferably 0.01 to 20. The amount is 0.1 to 10.

The reaction may be terminated by adding the entire amount of the B solution to the A solution to complete the mixing of the B solution with the A solution and then removing the reaction solution by filtration or the like, or to the A solution. After adding the entire amount of the liquid B and completing the mixing of the liquid B with the liquid A, the reaction liquid may be aged at a predetermined temperature for a certain period of time. When aging is performed, the aging temperature is preferably 40 ° C. or lower, particularly preferably 5 to 30 ° C., and the aging time is preferably 0.5 to 40 hours, particularly preferably 1 to 24 hours.

When the liquid B is added to the liquid A and mixed, it is preferable to add the liquid B while stirring the liquid A. Further, when aging is carried out after adding the entire amount of the liquid B to the liquid A and completing the mixing of the liquid B with the liquid A, it is preferable to carry out the aging while stirring the reaction liquid. The stirring speed is not particularly limited, but a reaction solution containing barium titanyl oxalate produced from the start of addition of solution B to solution A to the end of addition of the entire amount of solution B, and in the case of aging, until the end of aging. However, the stirring speed may be such that it always flows.

When aging is performed after adding the entire amount of solution B to solution A and completing mixing of solution B with solution A, solid-liquid separation of the reaction solution is performed by a conventional method after the completion of aging, and then solid. Rinse the minutes with water. The washing method is not particularly limited, but washing with repulp or the like is preferable in terms of high washing efficiency. After washing, the solid content is dried and, if necessary, pulverized to obtain barium titanyl oxalate.

In this way, the barium titanyl oxalate obtained by performing the method for producing barium titanyl oxalate of the present invention has a temperature at which the weight loss rate reaches 99% with respect to the weight loss rate at 1000 ° C. in thermogravimetric analysis from 600 to. It is 700 ° C., preferably 610 to 690 ° C., particularly preferably 615 to 685 ° C. Therefore, barium titanate oxalate obtained by the method for producing barium titanyl oxalate of the present invention contains barium titanate when fired at 600 to 700 ° C., preferably 610 to 690 ° C., particularly preferably 615 to 685 ° C. The resulting barium titanyl oxalate.

The average particle size of barium titanyl oxalate obtained by the method for producing barium titanyl oxalate of the present invention is preferably 1.0 μm or less, more preferably 0.005 to 1.0 μm, and particularly preferably 0.01 to 0. It is 5.5 μm.

The composition of barium titanyl oxalate obtained by the method for producing barium titanyl oxalate of the present invention has a Ba / Ti molar ratio of 0.998 to 1.004, preferably 0.999 to 1.003.

The barium titanyl oxalate obtained by the method for producing barium titanyl oxalate of the present invention is suitably used as a raw material for producing a barium titanate-based ceramic as a dielectric ceramic material. The method for producing barium titanate of the present invention is as follows.

The method for producing barium titanate of the present invention is characterized by firing barium titanyl oxalate obtained by the method for producing barium titanyl oxalate of the present invention.

Oxalic acid-derived organic substances contained in the final product are not preferable because they impair the dielectric properties of the material and cause unstable behavior in the thermal process for ceramicization. Therefore, in the present invention, it is necessary to thermally decompose barium titanyl oxalate by firing to obtain the desired barium titanate and to sufficiently remove organic substances derived from oxalic acid. The firing conditions are such that the firing temperature is preferably 600 to 1200 ° C, more preferably 620 to 1100 ° C. If the firing temperature is less than 600 ° C., only a part of barium titanate is produced, or it is difficult to obtain single-phase barium titanate. On the other hand, when the firing temperature exceeds 1200 ° C., the variation in particle size becomes large. The firing time is preferably 0.5 to 30 hours, more preferably 1 to 20 hours. The firing atmosphere is not particularly limited, and may be any of an inert gas atmosphere, a vacuum atmosphere, an oxidizing gas atmosphere, and the atmosphere, or firing is performed in the atmosphere while introducing water vapor. You may.

The firing may be performed as many times as desired. Alternatively, for the purpose of making the powder characteristics uniform, the one that has been fired once may be crushed and then re-baked.

After firing, it is appropriately cooled and, if necessary, pulverized to obtain barium titanate powder. The pulverization performed as necessary is appropriately performed when the barium titanate obtained by firing is a brittle block, etc., but the barium titanate particles themselves have the following specific average particle size and BET specific surface area. Have. That is, the barium titanate powder obtained above has an average particle size of preferably 0.5 μm or less, more preferably 0.02 to 0.5 μm, as determined from a scanning electron micrograph (SEM). The BET specific surface area is preferably 2 to 100 m ² / g, more preferably 2.5 to 50 m ² / g. Further, the composition of barium titanate obtained by the production method of the present invention preferably has a molar ratio of Ba to Ti (Ba / Ti) of 0.998 to 1.004, particularly preferably 0.999 to 1.003. .. The c-axis / a-axis ratio, which is an index of crystallinity, is preferably 1.030 to 1.0055, preferably 1.0035 to 1.0050, in the range where the specific surface area of barium titanate is 15 m ² / g or more. Especially preferable. Since grain growth occurs when the firing temperature is high, the specific surface area is in the range of less than 15 m ² / g, but in that range, the c-axis / a-axis ratio is preferably more than 1.0055, preferably 1.0070 or more. More preferably, 1.0075 or more is particularly preferable.

Further, in the barium titanate obtained by the method for producing barium titanate of the present invention, the method for producing barium titanate of the present invention can be obtained by adding a subcomponent element-containing compound to the barium titanate for the purpose of adjusting the dielectric property and the temperature characteristic as necessary. It can be added to the resulting barium titanate to contain subcomponent elements. Examples of the subcomponent element-containing compound that can be used include rare earth elements such as 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. Examples include compounds containing elements.

The subcomponent element-containing compound may be either an inorganic substance or an organic substance. For example, oxides containing the above elements, hydroxides, chlorides, nitrates, oxalates, carboxylates, alkoxides and the like can be mentioned. When the subcomponent element-containing compound is a compound containing a Si element, silica sol, sodium silicate, or the like can be used in addition to the oxide or the like. The subcomponent element-containing compound may be used alone or in combination of two or more. The addition amount and the combination of the added compounds may be carried out according to a conventional method.

In order to make barium titanate contain a sub-component element, for example, barium titanate and a sub-component element-containing compound may be uniformly mixed and then fired. Alternatively, barium titanyl oxalate and a subcomponent element-containing compound may be uniformly mixed and then calcined.

When, for example, a multilayer ceramic capacitor is produced using barium titanate obtained by the method for producing barium titanate of the present invention, first, a powder of barium titanate, including subcomponent elements, is added conventionally known. It is mixed and dispersed in an appropriate solvent together with a compounding agent such as an agent, an organic binder, a plasticizing agent, and a dispersant to form a slurry, and sheet molding is performed. As a result, a ceramic sheet used for manufacturing a multilayer ceramic capacitor is obtained. To manufacture a multilayer ceramic capacitor from the ceramic sheet, first, a conductive paste for forming an internal electrode is printed on one surface of the ceramic sheet. After drying, a plurality of the ceramic sheets are laminated and pressure-bonded in the thickness direction to form a laminated body. Next, this laminated body is heat-treated to perform a binder removal treatment, and then fired to obtain a fired body. Further, Ni paste, Ag paste, nickel alloy paste, copper paste, copper alloy paste and the like are applied to the fired body and baked to obtain a multilayer ceramic capacitor.

Further, the barium titanate powder obtained by the method for producing barium titanate of the present invention is blended with a resin such as an epoxy resin, a polyester resin or a polyimide resin to form a resin sheet, a resin film, an adhesive or the like. Then, in addition to being able to be used as a material for a printed wiring board, a multilayer printed wiring board, etc., a common material for suppressing the shrinkage difference between the internal electrode and the dielectric layer, an electrode ceramic circuit board, a glass ceramic circuit board, and a circuit periphery It can also be used as a material and a dielectric material for inorganic EL.

Further, the barium titanate obtained by the method for producing barium titanate of the present invention is used for surface modification of catalysts used in reactions such as exhaust gas removal and chemical synthesis, and printing toners that impart antistatic and cleaning effects. It is preferably used as a material.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples.

(1) Thermogravimetric analysis of barium titanyl oxalate Using the thermogravimetric measuring device TGA / DSC 1 manufactured by METTLER TOLEDO Co., Ltd., a temperature of 30 mg of a sample is raised from 30 ° C. to 1200 ° C. in an air stream of 50 mL / min. It was measured at 10 ° C./min.
(2) Average particle size of barium titanate oxalate and barium titanate 200 particles were arbitrarily measured by a scanning electron microscope (SEM) photograph, and the average value was taken as the average particle size.
(3) Specific surface area of barium titanate Obtained by the BET method.
(4) c / a value of barium titanate Using Cu—Kα ray as a radiation source, the c-axis to a-axis ratio c / a was measured by an X-ray diffractometer (D8 ADVANCE manufactured by Bruker).

(Example 1)
25.0 g of oxalic acid dihydrate was dissolved in 100 g of ethylene glycol to prepare 120 mL of a solution (solution A) containing an oxalic acid component having oxalic acid of 2.21 mol / L. Separately, 64.4 g of titanium tetrachloride and 32.0 g of barium chloride are dissolved in 210 g of pure water, and the titanium component and barium component having titanium tetrachloride of 0.59 mol / L and barium chloride of 0.63 mol / L are dissolved. 270 mL of a solution (solution B) containing the above was prepared.
Then, the solution B was added in 2 seconds while stirring the solution A, and then the solution was held for 3 hours and then solid-liquid separated to obtain a precipitate. After washing this precipitate, it was dried to obtain barium titanyl oxalate. The physical characteristic values of the obtained barium titanyl oxalate are as shown in Table 1. Moreover, the result of having measured the weight loss rate of the obtained barium titanyl oxalate by thermal analysis is shown in FIG. As a result, the weight loss rate at 680 ° C. was 44.90%, which was 99.16% with respect to the weight loss rate at 1000 ° C. of 45.28%.
The obtained barium titanate oxalate was calcined at 700 ° C. for 2 hours to obtain barium titanate. The physical characteristics of the obtained barium titanate are as shown in Table 1.

(Examples 2 to 4)
The barium titanyl oxalate obtained in Example 1 was calcined at the temperatures shown in Table 1 to obtain barium titanate. Table 1 shows the physical property values of the obtained barium titanate.

(Comparative Example 1)
35.0 g of barium chloride dihydrate and 35.0 g of oxalic acid dihydrate are dissolved in 120 g of pure water, and the barium component and oxalic acid having a barium concentration of 1.10 mol / L and a oxalic acid concentration of 2.20 mol / L are dissolved. 120 mL of a solution (solution a) containing the components was prepared. Separately, 54.0 g of titanium tetrachloride was dissolved in pure water to prepare 260 mL of a solution (liquid b) containing a titanium component having a titanium concentration of 0.40 mol / L.
Then, the solution b was added in 90 seconds while stirring the solution a, and then the solution was held for 1 hour and then solid-liquid separated to obtain a precipitate. After washing this precipitate, it was dried to obtain barium titanyl oxalate. The physical characteristic values of the obtained barium titanyl oxalate are as shown in Table 1. Moreover, the result of having measured the weight loss rate of the obtained barium titanyl oxalate by thermal analysis is shown in FIG. As a result, the weight loss rate at 680 ° C. was 37.71%, which was 84.15% with respect to the weight loss rate at 1000 ° C. of 44.81%.
The obtained barium titanyl oxalate was calcined at 700 ° C. for 2 hours. However, it was found that barium titanate was not obtained from the measurement result of the weight loss rate of the thermogravimetric analysis.

(Comparative Examples 2 to 4)
The barium titanyl oxalate obtained in Comparative Example 1 was calcined at the temperatures shown in Table 1 to obtain barium titanate. Table 1 shows the physical characteristics of the obtained barium titanate.

As shown in Table 1, the titanium obtained in the examples was compared with the barium titanate obtained in the comparative example from the comparison of the average particle size, the BET specific surface area and the numerical values of c / a when calcined at the same temperature. It can be seen that barium acid acid is fine and highly crystalline. Further, as shown in FIG. 1, the barium titanate oxalate obtained in Example 1 was obtained as barium titanate at 700 ° C. by thermal weight analysis, but the barium titanyl oxalate obtained in Comparative Example 1 was obtained. It can be seen that barium titanate could not be obtained even at 700 ° C.

Claims (9)

Barium titanyl oxalate, characterized in that the temperature at which the weight loss rate reaches 99% with respect to the weight loss rate at 1000 ° C. is 600 to 700 ° C. in thermogravimetric analysis. It is characterized in that a specific surface area of 15 to 20 m ² / g and c / a of 1.0030 to 1.0055 are converted to barium titanate by a heating test at 700 ± 10 ° C. in the air for 2 hours. The barium titanyl oxalate according to claim 1. The barium titanyl oxalate according to claim 1 or 2, wherein the average particle size is 1.0 μm or less. A method for producing barium titanyl oxalate, which produces barium titanyl oxalate by mixing and reacting a solution containing oxalic acid (solution A) and a solution containing a titanium compound and a barium compound (solution B). And
First, the liquid A is filled in the reaction vessel, and then the liquid B is mixed with the liquid A while stirring the liquid A in the reaction vessel.
The time from the start to the end of mixing the B solution with the A solution is within 10 seconds.
The solvent of the liquid A is an organic solvent and the solvent of the liquid B is water.
A method for producing barium titanyl oxalate. The solvent of the solution A is selected from the group consisting of methanol, ethanol, propanol, butanol, diethyl ether, 1,3-butylene glycol, ethylene glycol, propylene glycol, dipropylene glycol, glycerol, N, N-dimethylformamide and acetone. The method for producing barium titanyl oxalate according to claim 4 , wherein the amount is one or more. The method for producing barium titanyl oxalate according to claim 4 or 5 , wherein the titanium compound in the liquid B is titanium tetrachloride, and the barium compound is barium chloride. The method for producing barium titanyl oxalate according to any one of claims 4 to 6 , wherein the mixing temperature of the liquid B with the liquid A is 40 ° C. or lower. The method for producing barium titanyl oxalate according to any one of claims 4 to 7 , wherein the average particle size of the barium titanyl oxalate produced is 1.0 μm or less. A method for producing barium titanate, which comprises calcining barium titanyl oxalate obtained by the production method according to any one of claims 4 to 8 .

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