JP6580932B2 - Method for producing barium titanate powder - Google Patents

Description

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

  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.

  As one method for producing the perovskite type barium titanate powder, a so-called solid phase method is known in which barium carbonate and titanium dioxide are mixed and the resulting mixture is fired. This solid phase method has a problem that it is difficult to obtain a fine perovskite-type barium titanate powder having high tetragonal properties.

  As a method for increasing the tetragonal property of perovskite-type barium titanate obtained by the solid-phase method, it is possible to raise the firing temperature when producing a perovskite-type barium titanate by firing a mixture containing barium carbonate and titanium dioxide. Although it is conceivable, if the firing temperature is raised, particle growth and particle condensation occur, making it difficult to refine the perovskite-type barium titanate.

  For this reason, for example, the following Patent Document 1 describes a method for producing a perovskite-type barium titanate having a fine particle and a high c / a ratio by calcining a mixture containing barium carbonate and titanium dioxide in steam or the like. Has been.

  Patent Document 2 below proposes a method for producing fine barium titanate by firing a raw material containing Ba and Ti in a firing atmosphere containing heated air containing water vapor.

  In Patent Document 3 below, a perovskite-type barium titanate powder having fine and high tetragonal properties is obtained by calcining a mixed powder containing barium carbonate and titanium dioxide in the presence of humidified air in a firing furnace. There has been proposed a method of manufacturing.

JP 2005-314153 A JP 2012-116728 A JP 2009-209001 A

  Various methods for producing perovskite-type barium titanate powder by solid-phase method as in the prior art have been studied. However, perovskite-type titanate having fine and high tetragonal properties is further industrially advantageous. There has been a need for a method of producing barium powder.

  Accordingly, an object of the present invention is to provide a method for producing a perovskite-type barium titanate powder that is fine and has high tetragonality by an industrially advantageous method in the solid phase method.

  As a result of intensive studies in view of the above circumstances, the present inventors have found that when a raw material mixture containing barium carbonate and titanium dioxide is fired, if a large amount of carbon dioxide is present in the firing atmosphere, the perovskite-type barium titanate powder Perovskite type barium titanate powder having a low ferroelectric property because the ratio of c axis to a axis (c / a), which is an index of tetragonal crystal, is low. Producing a perovskite-type barium titanate powder that is fine and has high tetragonality even at the same firing temperature if the carbon dioxide gas concentration in the atmosphere during firing is reduced, Furthermore, when baking is performed with a large amount of superheated steam in the atmosphere, the carbon dioxide gas is effectively absorbed by the superheated steam, so that the carbon dioxide gas in the atmosphere during baking is used. Since degree can be reduced, it found that perovskite barium titanate powder with high tetragonality be fine and and the same firing temperature can be obtained, and have completed the present invention.

That is, the present invention is a raw material mixture containing barium carbonate and titanium dioxide while supplying superheated steam 200 to 1200 ° C. to the sintering atmosphere, and fired at 600 to 1200 ° C., to obtain a powdered barium perovskite titanate The present invention provides a method for producing a perovskite-type barium titanate powder characterized by having a firing step.

  According to the present invention, it is possible to produce a perovskite-type barium titanate powder that is fine and has high tetragonality by an industrially advantageous method. The perovskite-type barium titanate powder produced by the method for producing a perovskite-type barium titanate powder of the present invention is used as a raw material for functional ceramics for electronic parts such as piezoelectrics, optoelectronic materials, dielectrics, semiconductors, and sensors. Useful.

1 is a schematic end view showing a firing furnace for carrying out an embodiment of a method for producing a perovskite-type barium titanate powder of the present invention.

  A method for producing the perovskite barium titanate powder of the present invention will be described with reference to FIG. FIG. 1 is a schematic view showing an end view of a firing furnace for carrying out an embodiment of the method for producing the perovskite-type barium titanate powder of the present invention.

  In the embodiment using the firing furnace 1 shown in FIG. 1, first, an alumina container containing a raw material mixture 5 containing barium carbonate and titanium dioxide is placed in a firing furnace 1 covered with an alumina fiber board, and a lid 2 is placed. Close. Next, the inside of the firing furnace 1 is preheated. Next, while supplying the superheated steam 11 from the superheated steam supply pipe 7 into the firing furnace 1, the temperature in the firing furnace 1 is raised to a predetermined firing temperature, and after reaching the predetermined firing temperature, the firing furnace 1. While superheated steam 11 is supplied inside, baking is performed while maintaining the temperature. When the raw material mixture 5 is fired, barium carbonate and titanium dioxide react to generate barium titanate powder, and carbon dioxide gas is generated. The generated carbon dioxide gas is absorbed by surrounding superheated water vapor and becomes superheated water vapor 12 containing carbon dioxide gas, so that the superheated water vapor 12 containing carbon dioxide gas is discharged from the exhaust pipe 4. That is, in the embodiment using the firing furnace 1 shown in FIG. 1, firing is performed while supplying superheated steam 11 to the atmosphere and discharging superheated steam 12 containing carbon dioxide gas from the atmosphere.

  At this time, since the superheated steam 11 is continuously supplied into the firing furnace 1, the atmosphere to which the raw material mixture 5 is exposed is an atmosphere in which a large amount of superheated steam exists. In the embodiment shown in FIG. 1, the inside of the firing furnace 1 is not sealed and firing is performed in an open system, so that a little air exists in the atmosphere, but the superheated steam 11 is continuously supplied to the atmosphere. As a result, the abundance of air in the atmosphere can be greatly reduced. Moreover, it can also be set as a perfect superheated steam atmosphere by adjusting the supply amount of superheated steam. In other words, by firing while supplying superheated steam to the atmosphere, the firing atmosphere of the raw material mixture containing barium carbonate and titanium dioxide is changed to a superheated steam atmosphere or a completely superheated steam atmosphere with a very small amount of air. Can be fired.

  If carbon dioxide gas generated by firing is present around the generated barium titanate powder, the tetragonality is adversely affected. However, in the embodiment using the firing furnace 1 shown in FIG. Therefore, carbon dioxide gas is absorbed by superheated water vapor. Therefore, in the embodiment using the firing furnace 1 shown in FIG. 1, adverse effects caused by carbon dioxide gas can be prevented. Further, in the embodiment using the firing furnace 1 shown in FIG. 1, since the air present in the atmosphere is very small, a side reaction caused by carbon dioxide can be prevented.

  The method for producing a perovskite barium titanate powder according to the present invention comprises calcining a raw material mixture containing barium carbonate and titanium dioxide at 600 to 1200 ° C. while supplying superheated steam to a firing atmosphere. It is a manufacturing method of the perovskite type barium titanate powder characterized by having a baking process which obtains powder.

  The firing step according to the method for producing the perovskite-type barium titanate powder of the present invention is a step of firing a raw material mixture containing barium carbonate and titanium dioxide to obtain a perovskite-type barium titanate powder.

Barium carbonate related to the firing step is not particularly limited as long as it is industrially available. BET specific surface area of barium carbonate, in that the high perovskite barium titanate tetragonality is obtained a fine, preferably ^{10 m} 2 / g or more, particularly preferably 30 to 50 m ² / g. The average particle size obtained by scanning electron microscope (SEM) observation of barium carbonate is preferably 0.1 μm or less, and preferably 0.03 to 0.03 in that perovskite-type barium titanate having fine and high tetragonal properties can be obtained. 0.05 μm.

  In addition, in this invention, an average particle diameter is calculated | required by scanning electron microscope (SEM) observation, and shows the average value of 1000 samples arbitrarily extracted with the SEM image of scanning electron microscope observation (SEM).

Titanium dioxide related to the firing step is not particularly limited as long as it is industrially available. BET specific surface area of titanium dioxide, in that the high perovskite barium titanate tetragonality is obtained a fine, preferably ^{5 m} 2 / g or more, particularly preferably 8~50m ² / g. The average particle diameter determined by scanning electron microscope (SEM) observation of titanium dioxide is preferably 0.1 μm or less, particularly preferably 0.03 to 0.05 μm.

  In order to obtain high-purity perovskite-type barium titanate powder, barium carbonate and titanium dioxide are preferable as the purity is higher. The particle shape of barium carbonate and titanium dioxide is not particularly limited, and may be acicular, spherical, granular, or indefinite.

  The raw material mixture containing barium carbonate and titanium dioxide, which is the firing raw material for the firing step, is obtained by mixing barium carbonate, titanium dioxide and other raw materials used as necessary, and the raw materials are mixed uniformly. The better. The mixing ratio of barium carbonate and titanium dioxide is such that the molar ratio of Ba to Ti (Ba / Ti) is 0.99 to 1.01, preferably 0.995 to 1.005 in terms of atoms. When the molar ratio of Ba to Ti (Ba / Ti) is less than 0.99, titanium is rich and perovskite-type barium titanate with high tetragonality cannot be obtained. On the other hand, when it exceeds 1.01, it becomes barium-rich and tetragonal. Highly crystalline perovskite barium titanate cannot be obtained.

  The barium titanate obtained by performing the firing step is a perovskite type complex oxide in which the A site element is Ba and the B site element is Ti. The barium titanate obtained by performing the firing step may be a perovskite-type barium titanate in which the A site element is only Ba and the B site element is only Ti, or the Ba atom of the A site element Is partially substituted with either Ca or Sr or both of Ca and Sr, partially substituted Ti atom of B site element with Zr, or partially Ba atom of A site element May be substituted with either Ca or Sr or both of Ca and Sr, and a part of the Ti atom of the B site element may be substituted with Zr.

  In the method for producing perovskite-type barium titanate of the present invention, a perovskite-type titanic acid in which a part of the Ba atom of the A-site element is substituted with Ca or Sr, or a part of the Ti atom of the B-site element is substituted with Zr. In order to obtain barium, the raw material mixture may contain a compound having a Ca atom, a compound having a Sr atom, or a compound having a Zr atom together with barium carbonate and titanium oxide. When a part of the Ba atom is substituted with either Ca or Sr or both of Ca and Sr, the content of the compound having a Ca atom or the compound having a Sr atom in the raw material mixture is not particularly limited. In terms of conversion, the content is preferably such that the total ratio of Ca atoms and Sr atoms to Ba atoms is less than 50 mol%. When substituting a part of Ti atoms with Zr, the content of the compound having Zr atoms in the raw material mixture is not particularly limited, but the content is such that the ratio of Zr atoms to Ti atoms is less than 50 mol% in terms of atoms. An amount is preferred. The mixing ratio of the compound having barium carbonate, the compound having Ca atom and the compound having Sr atom and the compound having titanium oxide and Zr atom is the B site with respect to the sum of Ba atom, Ca atom and Sr atom as A site element in terms of atom. The total molar ratio of Ti atoms and Zr atoms as elements is 0.99 to 1.01, preferably 0.995 to 1.005. In addition, examples of the compound having a Ca atom, the compound having an Sr atom, and the compound having a Zr atom include carbonates, oxides, organic acid salts, and the like of these atoms, and physical properties are not particularly limited. From the viewpoint of dispersibility in the raw material mixture, fine ones are preferable.

  The mixing method of barium carbonate and titanium dioxide is that a strong shearing force by wet method or dry method acts so that barium carbonate and titanium dioxide and other raw materials used as necessary are uniformly mixed in the above ratio. And a method using mechanical means.

  The wet method is performed using apparatuses such as a ball mill, a bead mill, a disperser mill, a homogenizer, a vibration mill, a sand grind mill, an attritor, and a powerful stirrer. In the dry method, the high-speed mixer, super mixer, turbo sphere mixer, Henschel mixer, nauter mixer, ribbon blender and the like are used. Among these, in the present invention, it is preferable to prepare a raw material mixture by a wet method from the viewpoint of obtaining a uniform raw material mixture and obtaining a dielectric having a high dielectric constant.

  Examples of the solvent used in the wet method include water, methanol, ethanol, propanol, butanol, toluene, xylene, acetone, methylene chloride, ethyl acetate, dimethylformamide, and diethyl ether. Among these, alcohols such as methanol, ethanol, propanol, and butanol are preferable because those having a small change in composition can be obtained and a dielectric ceramic having a high dielectric constant can be obtained.

  In the case of mixing by a wet method, a dispersant can be added to a slurry containing various raw materials as necessary for the purpose of improving dispersibility. After mixing by a wet method, the whole slurry can be dried by a spray dryer as desired.

  In addition, mixing by these wet methods or dry methods is not limited to the method using the illustrated mechanical means. In addition, the raw materials can be mixed while adjusting the particle size of the raw material mixture using a device such as a jet mill that can simultaneously perform mixing and pulverization.

  In the firing step, the raw material mixture containing barium carbonate and titanium dioxide is fired. The firing temperature in the firing step is 600 to 1200 ° C, preferably 700 to 1000 ° C. If the firing temperature is less than the above range, a solid phase reaction that changes to perovskite-type barium titanate does not occur and tends to remain unreacted. On the other hand, if it exceeds the above-mentioned range, the generated perovskite-type barium titanate Because it causes grain growth, it is not possible to obtain a fine one. The firing time in the firing step is 4 hours or more, preferably 6 to 30 hours. Moreover, in a baking process, after baking once at 600-1200 degreeC, Preferably 700-1000 degreeC, after grind | pulverizing a baked material and granulating as needed, it is further 600-1200 degreeC, Preferably it is 700- Firing may be performed at 1000 ° C. Further, in order to make the powder characteristics uniform, once fired ones may be pulverized and fired again.

  Examples of the firing furnace used in the firing step 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, the raw material mixture containing barium carbonate and titanium dioxide is fired at 600 to 1200 ° C., preferably 700 to 1000 ° C., while carbon dioxide generated by reaction from the firing atmosphere while supplying superheated steam to the firing atmosphere. It is performed while discharging superheated steam.

Superheated steam refers to colorless and transparent H ₂ O gas obtained by further heating saturated steam at 100 ° C. under normal pressure. Since superheated steam maintains a saturated state of water in air at high temperatures, carbon dioxide generated during the production of barium titanate is effectively superheated by firing while supplying superheated steam to the firing atmosphere. The reaction can proceed without lowering the firing temperature while being absorbed by water vapor. In addition, since most of the fired atmosphere is superheated steam, side reactions due to the presence of carbon dioxide in the air can be suppressed.

  Since superheated steam is obtained by further heating saturated steam at 100 ° C. at normal pressure, the method of firing while supplying superheated steam to the firing atmosphere can perform the reaction under atmospheric pressure, There is no need to carry out in a firing furnace.

  In the firing step, the temperature of the superheated steam supplied to the firing atmosphere is preferably 200 to 1200 ° C, particularly preferably 300 to 1000 ° C. If the temperature of the superheated steam is less than the above range, the firing temperature is difficult to decrease.If the temperature exceeds the above range, the firing temperature can be prevented from decreasing, but the energy for generating the superheated steam increases. Manufacturing cost increases.

  As a method for generating superheated steam, saturated steam obtained by heating water to 100 ° C. or higher is heated directly or indirectly by a fuel such as oil or gas, or heating means such as infrared rays, electromagnetic waves, or microwaves. The method of heating with is mentioned. Examples of such superheated steam generation means include Tokuden Corporation UPSS series, Fuji Electric Co., Ltd. IHSS series, Nippon Thermoelectric Co., Ltd. superheated steam generator, Shinthermal Industry Co., Ltd. Can be mentioned.

  The amount of superheated steam supplied to the firing atmosphere is appropriately selected, but is preferably 5 L / min or more per kg of the raw material mixture, more preferably 10 to 200 L / min per kg of the raw material mixture, and particularly preferably per kg of the raw material mixture. 15 to 100 L / min. When the amount of superheated steam supplied to the firing atmosphere is in the above range, carbon dioxide generated in the firing furnace in the solid phase reaction is efficiently absorbed, and the furnace temperature is prevented from being lowered by the superheated steam. be able to. Although it is the time to introduce superheated steam into the firing furnace, at least before the perovskite-type barium titanate is generated by the solid-state reaction between barium carbonate and titanium dioxide, it is possible to introduce superheated steam into the firing furnace. This is preferable in that it effectively absorbs carbon dioxide gas generated in the reaction process and can suppress the occurrence of adverse effects due to carbon dioxide gas.

  After performing the firing step, if necessary, the perovskite-type barium titanate powder after firing is washed with an acid solution, washed with water, dried, pulverized, classified, and the like to obtain a product. The drying method is not particularly limited as long as a conventional method is used, but when wet pulverization is performed, for example, a method using a spray dryer can be applied.

The perovskite-type barium titanate powder obtained by carrying out the method for producing the perovskite-type barium titanate powder of the present invention has a high tetragonality and a ratio of the c-axis to the a-axis (c / a) serving as a tetragonal index However, it is preferably 1.005 or more, particularly preferably 1.0055 to 1.010. The average particle size of the perovskite-type barium titanate powder obtained by performing the production method of the perovskite-type barium titanate powder of the present invention is an average particle size determined by observation with an electron microscope, preferably 0.5 μm or less. , particularly preferably 0.05 to 0.2 [mu] m, also, BET specific surface area is preferably ^2m 2 / g or more, particularly preferably 3 to 20 m ² / g. The perovskite-type barium titanate powder obtained by carrying out the method for producing the perovskite-type barium titanate powder of the present invention has a very high purity and is used for electronic parts such as piezoelectrics, optoelectronic materials, dielectrics, semiconductors and sensors. It is useful as a raw material for functional ceramics.

  Further, in the method for producing a perovskite-type barium titanate powder of the present invention, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd when mixing barium carbonate and titanium dioxide as necessary. , 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 containing at least one element is mixed to obtain a raw material mixture, and the resulting raw material mixture is fired in a firing step, or a raw material mixture containing barium carbonate and titanium dioxide is obtained. After that, the obtained raw material mixture was mixed with rare earth elements such as Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Li, Bi. , Mixing subcomponent element-containing compounds containing at least one element selected from n, Mn, Al, Si, Sr, Co, V, Nb, Ni, Cr, B, Fe and Mg, and firing the resulting mixture By firing in the step, perovskite-type barium titanate containing an oxide of a subcomponent element can be obtained.

  The kind and mixing amount of these subcomponent element-containing compounds are arbitrarily selected according to the dielectric properties required for the barium titanate powder for production purposes. A specific addition amount of the subcomponent element-containing compound is 0.1 to 5 parts by mass in terms of atoms in the subcomponent element-containing compound with respect to 100 parts by mass of the perovskite-type barium titanate powder. The subcomponent element-containing compound may be either an inorganic substance or an organic substance. Examples thereof include oxides, hydroxides, chlorides, nitrates, oxalates, carboxylates and alkoxides containing the above-mentioned subcomponent elements. When the subcomponent element-containing compound is a compound containing Si element, silica sol, sodium silicate, or the like is also used.

  The perovskite-type barium titanate powder obtained by the method for producing a 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 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 resulting 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 laminate is heat treated to remove the binder, and fired to obtain a fired body. Thereafter, an In—Ga paste, Ni paste, Ag paste, nickel alloy paste, copper paste, copper alloy paste or the like is applied to the fired body and baked, whereby a multilayer capacitor can be obtained.

  Further, perovskite-type barium titanate powder obtained by the method for producing a perovskite-type barium titanate powder of the present invention is blended in a resin such as an epoxy resin, a polyester resin, a polyimide resin, etc. As an agent or the like, it can be suitably used for materials such as printed wiring boards and multilayer printed wiring boards. Further, the perovskite-type barium titanate powder is a dielectric material for an EL element, a co-material for suppressing a shrinkage difference between an internal electrode and a dielectric layer, a base material and a circuit for an electrode ceramic circuit board and a glass ceramic circuit board. It is suitably used as a raw material for peripheral materials, a catalyst used in reactions such as exhaust gas removal and chemical synthesis, and a surface modifier for printing toner that imparts an antistatic effect and a cleaning effect.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.
In the examples, the average particle diameter was determined as an average value obtained from observation with a scanning electron microscope (SEM) for 1000 samples extracted arbitrarily.

<Barium carbonate sample>
Commercially available barium carbonate having a purity of 99.5% by mass, a BET specific surface area of 30 m ² / g, and an average particle size of 0.05 μm was used.

<Titanium dioxide sample>
Commercially available titanium dioxide having a purity of 99.5% by mass, a BET specific surface area of 30 m ² / g, and an average particle size of 0.05 μm was used.
<Superheated steam>
Superheated steam was generated using UPSS-W20 manufactured by Tokuden Corporation.

(Examples 1-3)
The barium carbonate sample and the titanium dioxide sample were mixed for 6 hours using a ball mill (bead diameter: 1 mm zirconia beads, solvent: water) as a wet mixer so that the Ba / Ti molar ratio was 1.00. After the treatment, it was dried at 130 ° C. for 2 hours to obtain a dry powder.

  In the firing furnace comprising the electric batch furnace shown in FIG. 1, the dry powder 50 g was heated to the temperature shown in Table 1 at a heating rate of 2.5 ° C./min in the atmosphere, and firing was started. At the start of firing, superheated steam heated to the temperature shown in Table 1 was introduced into the firing furnace at a rate of 4 L / min and fired for 6 hours. After the completion of firing, the mixture was cooled and pulverized to obtain a barium titanate powder.

(Comparative Examples 1-3)
A dry powder was prepared in the same manner as in Example 1, and 50 g of the dry powder was heated to the temperature shown in Table 1 at a temperature increase rate of 2.5 ° C./min in an electric batch furnace and baked for 6 hours. Firing was performed in a normal atmosphere without introducing superheated steam into a firing furnace. After the completion of firing, the mixture was cooled and pulverized to obtain a barium titanate powder.

(Comparative Examples 4-6)
A dry powder was prepared in the same manner as in Example 1, and 50 g of the dry powder was heated to the temperature shown in Table 1 at a temperature increase rate of 2.5 ° C./min in an electric batch furnace and baked for 6 hours. In addition, it baked, introducing the humidified air (dew point 21 degreeC) humidified through the water heated at 30 degreeC into the baking furnace at the rate of 4 L / min with the start of baking. After the completion of firing, the mixture was cooled and pulverized to obtain a barium titanate powder.

<Evaluation of physical properties of barium titanate samples>
For the barium titanate samples obtained in Examples 1 to 3 and Comparative Examples 1 to 6, the average particle diameter, the BET specific surface area, and the ratio of c axis to a axis (c / a) serving as an index of tetragonal crystal were measured. . The results are shown in Table 2. The ratio of c axis to a axis was determined by X-ray diffraction.

  From Table 2, the barium titanate obtained by carrying out calcination by introducing superheated steam has the same c-axis as a tetragonal index compared to that obtained by calcination without introducing superheated steam at the same calcination temperature. It can be seen that the ratio of c to a axis (c / a) is high and the tetragonality is excellent.

  Since the present invention can produce a perovskite-type barium titanate powder that is fine and has high tetragonal crystallinity, the produced perovskite-type barium titanate powder includes, in particular, piezoelectric materials, optoelectronic materials, dielectric materials, It can be used as a raw material for functional ceramics for electronic parts such as semiconductors and sensors.

DESCRIPTION OF SYMBOLS 1 Firing furnace 2 Lid 4 Exhaust pipe 5 Raw material mixture containing barium carbonate and titanium dioxide 7 Superheated steam supply pipe 11 Superheated steam 12 Superheated steam containing carbon dioxide

Claims (3)

A raw material mixture containing barium carbonate and titanium dioxide is fired at 600 to 1200 ° C. while supplying superheated steam at 200 to 1200 ° C. in a firing atmosphere, and has a firing step to obtain a perovskite-type barium titanate powder. A method for producing a characteristic perovskite-type barium titanate powder. Method for producing a perovskite-type barium titanate powder of claim 1, wherein said BET specific surface area of the barium carbonate is 10 m 2 / ^g or more. The method for producing perovskite-type barium titanate according to claim 1 or 2, wherein the titanium dioxide has a BET specific surface area of 5 m ² / g or more.