JP6573653B2 - Method for producing perovskite-type barium titanate powder - Google Patents

Description

  The present invention relates to a method for producing a perovskite-type barium titanate powder, and in particular, a perovskite-type barium titanate powder useful as a raw material for functional ceramics such as piezoelectrics, optoelectronic materials, dielectrics, semiconductors, and sensors. It relates to a manufacturing method.

  Perovskite-type barium titanate powder has been conventionally used as a raw material for functional ceramics such as piezoelectric bodies and multilayer ceramic capacitors. However, in recent years, multilayer ceramic capacitors have been required to have an increased number of layers and a higher dielectric constant in order to increase the capacity. For this reason, the perovskite-type barium titanate powder, which is the raw material, is fine and has a high squareness. It is desired to have crystallinity.

  One method for producing a perovskite barium titanate powder is to calcine a complex organic acid salt containing Ba atoms and Ti atoms. For example, an oxalate method in which a solution containing barium chloride and titanium chloride is contacted with an aqueous oxalic acid solution to obtain barium titanyl oxalate, and then the barium titanyl oxalate is calcined and deoxalated. Is representative. Although the perovskite-type barium titanate powder obtained by this oxalate method is characterized by a uniform composition, as an improvement study of other properties, an attempt to obtain a finer and higher tetragonal crystallinity Has been done.

For example, the following Patent Document 1 discloses fine oxalic acid obtained by simultaneously mixing a water-soluble barium salt, a water-soluble titanium salt and an aqueous solution of oxalic acid, and intensively crushing the resulting gel in a short time. There has been proposed a method in which a crystal of barium titanyl (BaTiO (C ₂ O ₄ ) · 4H ₂ O) is calcined at 700 to 900 ° C.

  Patent Documents 2 and 3 below propose a method in which barium titanyl oxalate is wet-pulverized to obtain fine barium titanyl oxalate, and then calcined the barium titanyl oxalate obtained. .

  Further, in Patent Document 4 below, a mixed aqueous solution of barium chloride aqueous solution and titanium chloride aqueous solution is added to the oxalic acid aqueous solution to precipitate barium titanate oxalate, and then aged, washed, filtered and dried to obtain barium titanate. A step of producing an oxalate; a step of primary calcination of the produced barium titanate oxalate, followed by primary pulverization to produce a fine barium titanate powder; and a secondary calcining of the fine barium titanate powder, A method including a step of secondary grinding has been proposed.

  However, in the above method, a perovskite-type barium titanate powder that is fine to some extent and highly tetragonal to some extent can be obtained. However, a perovskite-type fine and highly tetragonal in an industrially advantageous manner. There is a need for a method of producing barium titanate powder.

  Therefore, in Patent Document 5, in a method for producing a perovskite-type barium titanate powder by calcining a complex organic acid salt containing Ba atoms and Ti atoms in a calcining furnace, the calcining is performed with water adjusted in temperature. A method for producing a perovskite-type barium titanate powder is disclosed, which is performed while introducing humidified air that has been humidified through air into a firing furnace. In Patent Document 5, a perovskite-type barium titanate powder having a small average particle diameter and high tetragonality is obtained.

JP-A 61-146710 JP 2004-123431 A JP 2002-53320 A JP 2003-212543 A Japanese Patent No. 5119008

  According to the method of Patent Document 5, a perovskite-type barium titanate powder having characteristics of a small average particle size and high tetragonality can be obtained. However, there has been room for studying the characteristics of the perovskite-type barium titanate powder used as a raw material in order to further increase the capacity and dielectric constant of multilayer ceramic capacitors. Specifically, it was necessary to obtain a perovskite-type barium titanate powder having not only a small average particle size but also a narrow particle size distribution width and a uniform particle size.

  Accordingly, an object of the present invention is to provide a method for producing a perovskite-type barium titanate powder having not only fine and high tetragonal properties but also a uniform particle size, using a complex organic acid salt, in an industrially advantageous manner. There is to do.

The above problems are solved by the present invention described below.
That is, the present invention (1) bakes a complex organic acid salt containing Ba atoms and Ti atoms in a baking furnace while introducing humidified air having a dew point of 45 ° C. or higher and lower than 100 ° C. into the baking furnace. A firing step for obtaining a fired product,
Crushing the fired product to obtain a tetragonal perovskite-type barium titanate powder having a c-axis to a-axis ratio (c / a) of 1.004 or more in X-ray diffraction analysis ;
Having
A method for producing a perovskite-type barium titanate powder is provided.

  The present invention (2) provides the method for producing a perovskite-type barium titanate powder according to (1), wherein the dew point of the humidified air is 50 to 90 ° C.

Further, the present invention (3) is characterized in that the humidified air is prepared by passing air through water whose temperature is adjusted, and humidifying the air, (1) or (2 ) perovskite-type barium titanate A method for producing a powder is provided.

  Moreover, this invention (4) provides the manufacturing method of the perovskite-type barium titanate powder in any one of (1)-(3) characterized by baking the said complex organic acid salt at 500-1200 degreeC. Is.

  The present invention (5) provides the method for producing a perovskite-type barium titanate powder according to any one of (1) to (4), wherein the complex organic acid salt is a carboxylate. .

  The present invention (6) provides the method for producing a perovskite-type barium titanate powder according to any one of (1) to (5), wherein the complex organic acid salt is an oxalate salt or a citrate salt. To do.

  According to the present invention, a method for producing a perovskite-type barium titanate powder having not only fine and high tetragonal properties but also a uniform particle size is provided by using an organic acid salt in an industrially advantageous manner. Can do.

It is the schematic which shows the example of a form of a baking furnace.

The method for producing a perovskite-type barium titanate powder of the present invention is a composite organic material containing Ba atoms and Ti atoms in a firing furnace while introducing humidified air having a dew point of 45 ° C. or more and less than 100 ° C. into the firing furnace. A firing step of firing the acid salt to obtain a fired product;
Crushing the fired product to obtain a perovskite-type barium titanate powder;
Having
Is a method for producing a perovskite-type barium titanate powder.

  The manufacturing method of the perovskite-type barium titanate powder of the present invention includes a baking step of baking a composite organic acid salt containing Ba atoms and Ti atoms in a baking furnace to obtain a baking product, and a baking obtained by performing the baking step And crushing the product to obtain a perovskite-type barium titanate powder.

  In the firing step according to the method for producing the perovskite-type barium titanate powder of the present invention, a composite organic acid salt containing Ba atoms and Ti atoms, which are raw materials for firing (hereinafter, also simply referred to as “composite organic acid salt”). Is not particularly limited as long as a double salt of Ba and Ti is formed, for example, formate, oxalate, acetate, propionate, succinate, malate, tartrate, Carboxylates such as citrates and lactates, or complex salts containing two or more of these carboxylic acids, for example, complex salts of carboxylic acids containing both oxalic acid and lactic acid (see, for example, Japanese Patent Application No. 2007-40018) ) And the like. Examples of the complex organic acid salt include barium titanyl oxalate, barium titanyl citrate, barium titanyl succinate, and the like. Of these, oxalate and citrate are preferable as the complex organic acid salt in that a complex organic acid salt having a Ba / Ti atomic ratio of about 1 can be easily produced and the production cost is reduced. .

  The content ratio of Ba atoms and Ti atoms in the composite organic acid salt is 0.99 to 1.01, preferably 0.995 to 1.005, as a molar ratio of Ba atoms to Ti atoms (Ba / Ti). . When the molar ratio of Ba atom to Ti atom (Ba / Ti) is in the above range, fine and highly tetragonal perovskite barium titanate can be obtained.

  The composite organic acid salt may contain Ca atoms and / or Sr atoms as a partial substitute for the Ba atoms of the A site element of the perovskite-type barium titanate powder to be produced. As a partial substitute for the Ti atom, Zr atom may be contained. In this case, the amount of substitution of Ca atoms and / or Sr atoms as a partial substitution of Ba atoms is not particularly limited, but is preferably less than 50 mol% with respect to Ba atoms. Further, the amount of substitution of Zr atoms as a partial substitution of Ti atoms is not particularly limited, but is preferably less than 50 mol% with respect to Ti atoms. The mixing ratio of Ti and Zr (B site element) to Ba, Ca and / or Sr (A site element) is 0.99 to 1.01, preferably 0.995, in terms of molar ratio (A site element / B site element). It is preferable to set it to -1.005.

  The average particle size of the complex organic acid salt is not particularly limited, but the average particle size determined by the laser diffraction scattering method is preferably 200 μm or less, particularly preferably 100 μm or less, and it is fine and highly tetragonal perovskite. This is preferable in that type barium titanate is obtained.

  The complex organic acid salt is produced by a known method. The oxalate is recovered by, for example, bringing an aqueous solution containing titanium chloride and barium chloride into contact with an aqueous oxalic acid solution to precipitate the oxalate, performing an aging reaction if necessary, and then performing solid-liquid separation by a conventional method. If necessary, it is manufactured by washing, drying, pulverizing and the like. As an oxalate, it manufactures by the method described in Unexamined-Japanese-Patent No. 2006-321722, Unexamined-Japanese-Patent No. 2006-321723, Unexamined-Japanese-Patent No. 2006-348026, Unexamined-Japanese-Patent No. 2004-123431 etc., for example. Examples include complex organic acid salts.

  The citrate is collected, for example, by adding a solution of barium chloride to a citric acid solution of titanium, precipitating the citrate, performing an aging reaction if necessary, and then solid-liquid separation by a conventional method. Manufactured by washing, drying, grinding, etc. Examples of the citrate include complex organic acid salts produced by the method described in US Pat. No. 3,231,328.

  In addition, a complex salt of carboxylic acid containing both oxalic acid and lactic acid reacts, for example, by contacting a solution containing a titanium component, a barium component and a lactic acid component with a solution containing an oxalic acid component in a solvent containing alcohol. (See International Publication WO2008 / 102785 pamphlet).

  When grinding | pulverizing complex organic acid salt, there is no restriction | limiting in particular, It can carry out with a wet method or a dry process. For example, when performing by a wet method, the method of carrying out the grinding | pulverization process by charging the slurry containing complex organic acid salt in a wet grinding apparatus is mentioned. Examples of the wet pulverizer include a ball mill and a bead mill. As the solvent used for the preparation of the slurry, those inert to the complex organic acid salt are used. For example, water, methanol, ethanol, propanol, butanol, toluene, xylene, acetone, methylene chloride, ethyl acetate, Examples include dimethylformamide and diethyl ether. Among these, as the solvent used for preparing the slurry, methanol, ethanol, propanol, butanol, toluene, xylene, acetone, methylene chloride, ethyl acetate, dimethylformamide and diethyl ether are preferable. The solvent used for preparing the slurry may be a single type or a combination of two or more types. In addition, you may dry the whole slurry with a spray dryer after a wet process. Moreover, when performing by a dry method, the method of grind | pulverizing complex organic acid salt using dry grinders, such as a jet mill, a pin mill, a roll mill, a hammer mill, a pulverizer, is mentioned.

  In order to obtain a high-purity perovskite-type barium titanate powder, a high-purity organic acid salt is preferable.

  And in the baking process which concerns on the manufacturing method of the perovskite type barium titanate powder of the present invention, while introducing humidified air having a dew point of 45 ° C. or more and less than 100 ° C. into the baking furnace, Bake.

  In the firing step, the dew point of the humidified air introduced into the firing furnace is 45 ° C. or higher and lower than 100 ° C., preferably 50 to 90 ° C. When the dew point of the humidified air is in the above range, perovskite-type barium titanate having high tetragonality and fine particle size is obtained.

  The method for preparing the humidified air is not particularly limited as long as the dew point of the humidified air falls within the above range.For example, the humidified air can be prepared by passing air through water adjusted in temperature. The humidified air can be prepared by mixing water vapor with the air.

Table 1 shows the relationship between the dew point (° C.) and the amount of saturated water vapor (humidity 100%) (g) contained in 1 m ² of dry air.

  The amount of humidified air introduced into the firing furnace varies depending on the capacity of the firing furnace and is appropriately selected depending on the firing furnace, but the amount of humidified air introduced into the firing furnace per unit capacity of the firing furnace is preferably 0.3 L / (min · L (capacity of firing furnace)) or more, particularly preferably 0.5 to 3 L / (minute · L (capacity of firing furnace)). The amount of humidified air introduced into the firing furnace per unit capacity of the firing furnace is the amount of humidified air introduced per unit time (L / min) into the firing furnace, the capacity of the firing furnace (L). Calculated by dividing by. For example, when a firing furnace having a capacity of 10 L is used, the amount of humidified air introduced into the firing furnace per unit capacity of the firing furnace is preferably 0.3 L / (min · L (capacity of the firing furnace). )) Or more, and particularly preferably 0.5 to 3 L / (minute · L (capacity of firing furnace)), the amount of humidified air introduced into the firing furnace per unit time is preferably 3 L / minute or more. Particularly preferably, it is 5 to 30 L / min. The amount of humidified air introduced into the firing furnace per unit capacity of the firing furnace is in the above range, so that the carbon dioxide generated in the firing furnace can be efficiently absorbed in the production reaction to the perovskite-type barium titanate. And it is preferable at the point which can prevent that the temperature in a furnace falls with humidified air.

  The firing temperature of the complex organic acid salt in the firing step is 500 to 1200 ° C, preferably 600 to 1000 ° C. If the firing temperature of the complex organic acid salt in the firing step is less than the above range, the formation reaction to the perovskite-type barium titanate does not proceed and tends to remain unreacted, and if it exceeds the above range, the perovskite produced Type barium titanate tends to cause grain growth.

  The firing time of the complex organic acid salt in the firing step is preferably 4 hours or more, particularly preferably 6 to 30 hours. The firing atmosphere of the complex organic acid salt in the firing step is an oxidizing gas atmosphere containing humidified air such as an atmosphere containing humidified air or an oxygen gas atmosphere containing humidified air. The firing pressure of the complex organic acid salt in the firing step is under atmospheric pressure.

  In the baking step, examples of the baking furnace for baking the complex organic acid salt include a batch type or continuous type electric furnace and a gas furnace, and examples thereof include a roller hearth kiln, a rotary kiln, and a pusher furnace.

  In the firing step, in order to make the powder characteristics uniform, the fired product may be pulverized and refired.

  In this way, a fired composite organic carbonate is obtained by performing the firing step. In the fired product obtained by performing the firing step, primary particles of perovskite-type barium titanate are aggregated to form secondary particles. That is, the fired product obtained by performing the firing step is secondary particles in which primary particles of perovskite-type barium titanate are aggregated.

  In the pulverization step according to the method for producing the perovskite-type barium titanate powder, the fired product obtained by firing is pulverized to obtain a perovskite-type barium titanate powder.

  In the pulverization step, the method of pulverizing the fired product obtained by firing is not particularly limited, and may be wet pulverization or dry pulverization. Examples of the wet pulverizer include a ball mill and a bead mill. Examples of the dry pulverizer include a jet mill, a pin mill, and a roll mill.

  After performing the pulverization step, washing with an acid solution of perovskite-type barium titanate powder, washing with water, drying, classification, and the like can be performed as necessary. As a drying method, a conventional method is used, but when wet pulverization is performed, for example, a method using a spray dryer can be applied.

  The average particle diameter (D50) of the perovskite-type barium titanate powder obtained by the method for producing the perovskite-type barium titanate powder of the present invention is preferably 0.330 μm or less, particularly preferably 0.010 to 0.328 μm. In addition, the D90 of the perovskite barium titanate powder obtained by the method for producing the perovskite barium titanate powder of the present invention is preferably 0.930 μm or less, particularly preferably 0.650 to 0.900 μm. Therefore, the perovskite-type barium titanate powder obtained by performing the method for producing a perovskite-type barium titanate powder of the present invention is fine and suppresses the formation of large particles. It becomes a uniform perovskite-type barium titanate powder. In the present invention, the particle size of the perovskite barium titanate powder is determined by a laser diffraction scattering method. Further, in the present invention, the average particle diameter (D50) means a particle diameter at which the volume-based cumulative distribution is 50%, means a median diameter, and D90 is a volume-based cumulative distribution of 90%. Means a particle size of

  The particle size distribution index ((D90-D10) / D50) of the perovskite-type barium titanate powder obtained by carrying out the method for producing the perovskite-type barium titanate powder of the present invention is 2.410 or less, particularly 2.405 or less. Is preferred. That is, the perovskite-type barium titanate powder obtained by the method for producing the perovskite-type barium titanate powder of the present invention has a narrow particle size distribution.

The specific surface area of the perovskite barium titanate powder obtained performed a method of manufacturing a perovskite-type barium titanate powder of the present invention, 2m 2 / ^g or more, preferably 3 to 50 m 2 / ^g.

  In the X-ray diffraction analysis of the perovskite-type barium titanate powder obtained by the method for producing the perovskite-type barium titanate powder of the present invention, the ratio (c / a) between the c-axis and the a-axis serving as a tetragonal index is preferably Is 1.004 or more, preferably 1.005 to 1.010. Therefore, the perovskite type barium titanate powder obtained by performing the method for producing the perovskite type barium titanate powder of the present invention has high tetragonality.

  The perovskite-type barium titanate powder obtained by the production method of the perovskite-type barium titanate powder of the present invention is extremely high in purity and has functionalities for electronic parts such as piezoelectrics, optoelectronic materials, dielectrics, semiconductors, and sensors. This is a perovskite-type barium titanate powder useful as a ceramic raw material.

  In the method for producing a perovskite-type barium titanate powder according to the present invention, in the formation reaction to the perovskite-type barium titanate by firing the complex organic acid salt while introducing humidified air into the reaction furnace in the firing step. Carbon dioxide gas generated in the firing furnace can be efficiently absorbed into the humidified air, so that perovskite-type barium titanate with high tetragonality can be obtained, and the dew point of the humidified air should be in a specific range Thus, a fired product that is easily pulverized in the pulverization process, that is, secondary particles of perovskite-type barium titanate that are easily pulverized in the pulverization process. Therefore, in the method for producing a perovskite-type barium titanate powder of the present invention, a secondary step of perovskite-type barium titanate having a high tetragonality, fineness and uniform particle size is obtained after the firing step. Particles are obtained.

  In the method for producing a perovskite-type barium titanate powder according to the present invention, an auxiliary component element-containing compound is added to a composite organic acid salt that is a firing raw material in the firing step, if necessary, thereby adding an oxide of the subsidiary component element. A perovskite-type barium titanate powder can be obtained. Further, in the method for producing a perovskite-type barium titanate powder of the present invention, the auxiliary component element-containing compound is added to the fired product obtained by performing the firing step and fired, and the present invention also contains the subsidiary component element. Perovskite-type barium titanate powder can be obtained. Examples of such subcomponent elements include Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and other rare earth elements, Li, Bi Zn, Mn, Al, Si, Sr, Co, V, Nb, Ni, Cr, B, Fe, and Mg. The subcomponent element-containing compound may be either an inorganic substance or an organic substance. Examples of the subcomponent element-containing compound include oxides, hydroxides, chlorides, nitrates, oxalates, carboxylates, and alkoxides having subcomponent elements. When the subcomponent element-containing compound is a compound containing Si element, the subcomponent element-containing compound includes oxides, hydroxides, chlorides, nitrates, oxalates, carboxylates having byproduct elements, In addition to the alkoxide, silica sol, sodium silicate and the like can be mentioned.

  In addition, the combination and addition amount of these subcomponent elements are arbitrarily set according to the dielectric characteristics required for the ceramic in which the perovskite-type barium titanate powder to be produced is used. For example, the addition amount of the subcomponent element is 0.1 to 5 parts by mass of the subcomponent element in terms of atoms with respect to 100 parts by mass of the perovskite barium titanate powder.

  The perovskite-type barium titanate powder obtained by the method for producing the perovskite-type barium titanate powder of the present invention is used as a raw material for producing a multilayer capacitor. For example, first, a perovskite-type barium titanate powder obtained by performing the method for producing a perovskite-type barium titanate powder of the present invention is mixed with conventionally known compounding agents such as additives, organic binders, plasticizers, and dispersants. Then, it is dispersed to form a slurry, and a solid material in the slurry is formed to obtain a ceramic sheet. Next, a conductive paste for forming an internal electrode is printed on one surface of the ceramic sheet, and after drying, a plurality of ceramic sheets are laminated and then pressed in the thickness direction to form a laminate. Furthermore, this laminated body is heat-treated to remove the binder, and calcined to obtain a calcined body. Thereafter, an In-Ga paste, Ni paste, Ag paste, nickel alloy paste, copper paste, copper alloy paste or the like is applied to this fired body and baked, whereby a multilayer capacitor can be obtained.

  Further, the perovskite-type barium titanate powder obtained by performing the method for producing the perovskite-type barium titanate powder of the present invention is blended with a resin such as an epoxy resin, a polyester resin, a polyimide resin, etc. As an agent etc., it is used suitably for materials, such as a printed wiring board and a multilayer printed wiring board. Further, the perovskite-type barium titanate powder obtained by the method for producing the perovskite-type barium titanate powder of the present invention is a dielectric material for EL elements, and a co-material for suppressing the shrinkage difference between the internal electrode and the dielectric layer. , Substrate materials for electrode ceramic circuit boards and glass ceramic circuit boards, raw materials for circuit peripheral materials, catalysts used in reactions such as exhaust gas removal and chemical synthesis, surface modifiers for printing toner that provide antistatic and cleaning effects Etc. are suitably used.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.
<Preparation of barium titanyl oxalate>
A mixed solution in which 600 g (2.456 mol) of barium chloride dihydrate and 444 g (2.342 mol) of titanium tetrachloride were dissolved in 4100 ml of water was prepared. Next, 620 g of oxalic acid was dissolved in 1500 ml of warm water at 70 ° C. to prepare an aqueous oxalic acid solution, which was designated as solution B. The liquid B was added to the liquid A over 120 minutes with stirring while maintaining the liquid at 70 ° C., and further aged with stirring at 70 ° C. for 1 hour. After cooling, it was filtered to recover barium titanyl oxalate. Next, the recovered barium titanyl oxalate was repulped with 4.5 L of distilled water three times and washed. Next, it was dried at 105 ° C. and pulverized to obtain 1000 g of barium titanyl oxalate (BaTiO (C ₂ O ₄ ) · 4H ₂ O). The Ba / Ti molar ratio of the obtained barium titanyl oxalate was 1.00.

  In addition, about Ba / Ti molar ratio, Ba / Ti molar ratio was computed based on the value which carried out the fluorescent X ray analysis.

(Examples 1 and 2, Comparative Examples 1 and 2)
1 kg of the barium titanyl oxalate sample obtained above in the firing furnace comprising the electric batch furnace shown in FIG. 1 at a rate of 20 L / min While being introduced into the firing furnace, the temperature was raised to the temperature shown in Table 2 at a temperature elevation rate of 2.5 ° C./minute, and the firing was carried out for 6 hours. After the completion of firing, the mixture was cooled and pulverized to obtain a barium titanate powder.
The average particle diameter (D50), D90, particle size distribution index ((D90-D10) / D50), specific surface area, and c-axis to a-axis ratio (c / a) of the obtained barium titanate powder were determined. The results are shown in Table 2.

  The four surfaces inside the furnace 1 of the firing furnace shown in FIG. 1 are covered with an alumina fiber board, and a sample 3 is accommodated in a sample container 2 made of alumina in the furnace. Humidified air 6 was introduced into the furnace, and the humidified air was discharged from the outlet 8 of the discharge pipe 7 to the outside of the furnace.

<Measuring method of particle diameter D50, D90, D10>
Measurement was performed by a laser diffraction scattering method using MT3000 manufactured by Microtrack Bell.
<C / a value>
The ratio c / a between the c-axis and the a-axis was measured with an X-ray diffractometer (manufactured by Nippon Philips Co., Ltd., type X'PartMPD) using Cu-Kα rays as a radiation source.

  In Examples 1 and 2, tetragonal crystallinity was high, D90 was as small as 0.9 μm or less, and a narrow particle size distribution was obtained.

  On the other hand, in Comparative Examples 1 and 2, although tetragonality was high, D90 exceeded 0.9 μm and a wide particle size distribution was obtained.

  The present invention can produce a perovskite-type barium titanate powder that is fine, has a narrow particle size distribution, and high tetragonality. Therefore, the produced perovskite-type barium titanate powder is a piezoelectric material, optoelectronics. It is suitably used as a raw material for functional ceramics for electronic parts such as materials, dielectrics, semiconductors and sensors.

1 Furnace 2 Sample container 3 Sample 4 Introducing pipe 5 Inlet 6 Humidified air 7 Exhaust pipe 8 Outlet 9 Lid

Claims (6)

A firing step of firing a complex organic acid salt containing Ba atoms and Ti atoms in the firing furnace while introducing humidified air having a dew point of 45 ° C. or more and less than 100 ° C. into the firing furnace to obtain a fired product, ,
Crushing the fired product to obtain a tetragonal perovskite-type barium titanate powder having a c-axis to a-axis ratio (c / a) of 1.004 or more in X-ray diffraction analysis ;
Having
A method for producing a perovskite-type barium titanate powder characterized by   The method for producing a perovskite-type barium titanate powder according to claim 1, wherein the dew point of the humidified air is 50 to 90 ° C.   The method for producing a perovskite-type barium titanate powder according to claim 1 or 2, wherein the humidified air is prepared by passing air through water adjusted in temperature and humidifying the air.   The method for producing a perovskite-type barium titanate powder according to any one of claims 1 to 3, wherein the complex organic acid salt is fired at 500 to 1200 ° C.   The method for producing a perovskite-type barium titanate powder according to any one of claims 1 to 4, wherein the complex organic acid salt is a carboxylate. The method for producing a perovskite-type barium titanate powder according to any one of claims 1 to 5, wherein the complex organic acid salt is oxalate or citrate .

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