JP2013014460A - Method for producing perovskite form composite oxide and production apparatus thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a perovskite form composite oxide and its production apparatus which can obtain perovskite form composite oxide particles with high crystallinity.SOLUTION: In the production method of perovskite form composite oxides, the perovskite form composite oxide is given by the general formula ABO(wherein A includes at least one among Ba, Ca and Sr, and B includes at least Ti). The method includes a reaction process of heating a raw liquid containing at least titanium oxide powder in a hermetically sealed vessel, and adding a hydroxide of an element composing A site component to the heated raw liquid for reaction. Therefore, perovskite form composite oxide particles with high crystallinity can be obtained.

Description

  The present invention relates to an apparatus for manufacturing a perovskite complex oxide and a method for manufacturing the same, and more particularly to a method for manufacturing barium titanate, which is a perovskite complex oxide, and an apparatus for manufacturing the same.

  In recent years, with the progress of miniaturization and large capacity of multilayer capacitors and the like, dielectric elements have been made thinner. In order to manufacture this type of thin-layer multilayer capacitor, it is necessary to reduce the grain size of the dielectric ceramics to suppress the grain growth. In addition, it is required to have excellent crystallinity.

  As a method for producing a perovskite complex oxide such as barium titanate having fine particles and excellent crystallinity, for example, a method for producing a perovskite complex oxide as disclosed in Patent Document 1 and Patent Document 2 has been proposed. ing.

The method for producing a perovskite complex oxide described in Patent Document 1 is a method for producing a perovskite complex oxide represented by the general formula ABO ₃ , and includes water containing crystal water of an element constituting the A site component. It has a mixing treatment step of mixing oxide and titanium oxide powder having a specific surface area of 250 m ² / g or more, and this mixing treatment step dissolves the A site component only by water of crystallization water by performing heat treatment. A solution generation step for generating a dissolved solution and a reaction step for reacting titanium oxide powder with the solution to generate a reaction product, and the solution generation step and the reaction step are continuous. This is a method for producing a composite oxide powder.
Patent Document 1 discloses that the composite oxide powder obtained by the above-described manufacturing method is calcined.

  Further, in the method for producing a perovskite complex oxide described in Patent Document 2, a charged composition (Ba / Ti) of titanium and barium is 1. in a titanium hydroxide colloid, an aqueous barium salt solution in the presence of carboxylic acid. The barium titanate core particles are produced by adding to 0.001 to 10.10, and then the reaction solution containing the barium titanate core particles is hydrothermally treated in a temperature range of 100 ° C. to 350 ° C. to form cubic crystals. A method for producing spherical barium titanate particles, comprising obtaining spherical barium titanate particles and calcining the spherical barium titanate particles in a temperature range of 800 ° C. to 1200 ° C. to form tetragonal crystals.

  The composite oxide obtained by the production methods described in Patent Document 1 and Patent Document 2 is a cubic composite oxide having ultrafine particles and excellent crystallinity. And it is said that the tetragonal complex oxide excellent in crystallinity can be manufactured by calcining the obtained complex oxide.

Japanese Patent No. 4200197 Japanese Patent No. 4240190

However, in the cubic composite oxide obtained by the manufacturing methods described in Patent Document 1 and Patent Document 2, there is a concern that the crystallinity may not be sufficient due to residual hydroxyl groups in the lattice of the composite oxide. That is, in patent document 1, since the temperature of the whole reaction process is less than 100 degreeC, there exists a concern that a hydroxyl group may remain. Moreover, in patent document 2, since the temperature at the time of producing | generating barium titanate nucleus particle | grains is performed by less than 100 degreeC (an Example is 70 degreeC), there exists a possibility that a hydroxyl group may remain in a nucleus part.
Therefore, since the crystallinity of the cubic complex oxide is not sufficient, there is a problem that even if these are calcined and rearranged to tetragonal crystal, the crystallinity is not sufficient.

  Therefore, a main object of the present invention is to provide a method for producing a perovskite complex oxide and a production apparatus therefor, which can obtain perovskite complex oxide particles having high crystallinity.

The method for producing a perovskite complex oxide according to the present invention is a perovskite complex oxide represented by the general formula ABO ₃ (A includes at least one of Ba, Ca and Sr, and B includes at least Ti). A method for producing a product, comprising heating a raw material liquid containing at least titanium oxide powder inside a sealed container, and adding a hydroxide of an element constituting an A-site component to the heated raw material liquid to cause a reaction. Is a method for producing a perovskite complex oxide.
In the method for producing a perovskite complex oxide according to the present invention, the temperature of the raw material liquid becomes 100 ° C. or higher by adding and reacting the hydroxide of the element constituting the A site component to the heated raw material liquid. It is preferable.
Furthermore, the method for producing a perovskite complex oxide according to the present invention preferably includes a heat treatment step of heat treating the reaction product obtained in the reaction step at 800 ° C. to 1000 ° C.
The apparatus for producing a perovskite complex oxide according to the present invention is a perovskite complex oxide represented by the general formula ABO ₃ (A includes at least one of Ba, Ca and Sr, and B includes at least Ti). An apparatus for producing a perovskite complex oxide for producing a product, comprising: a sealed container for sealing a raw material liquid containing at least titanium oxide powder; and a heating of the raw material liquid sealed inside the sealed container An apparatus for producing a perovskite complex oxide, comprising heating means and charging means for charging a hydroxide of an element constituting an A-site component into a raw material liquid.

According to the method for producing a perovskite complex oxide according to the present invention, since the hydroxide of the element constituting the A-site component is introduced into the heated raw material liquid, the hydroxyl group in the perovskite complex oxide particles Perovskite-type composite oxide particles having a low content and high crystallinity can be obtained by a simple method.
In the method for producing a perovskite complex oxide according to the present invention, a hydroxide of an element constituting the A-site component is added to the heated raw material liquid, and the reaction is further performed at a high temperature of 100 ° C. When started, residual hydroxyl groups in the crystal lattice of the perovskite complex oxide can be reduced. Therefore, perovskite complex oxide particles with higher crystallinity can be obtained.
Furthermore, in the method for producing a perovskite type complex oxide according to the present invention, a perovskite type having a high tetragonal crystallinity is obtained by including a heat treatment step of heat treating the reaction product obtained in the reaction step at 800 ° C. to 1000 ° C. Composite oxide particles can be obtained.
According to the apparatus for manufacturing a perovskite complex oxide according to the present invention, according to the apparatus for manufacturing a perovskite complex oxide according to the present invention, the input means for supplying the hydroxide of the element constituting the A site component Therefore, the hydroxide of the element constituting the A-site component can be charged into the raw material liquid from the charging means while maintaining the high temperature and high pressure in the state of the sealed container.

  The above-described object, other objects, features, and advantages of the present invention will become more apparent from the following description of embodiments for carrying out the invention with reference to the drawings.

It is the schematic which shows one Embodiment of the manufacturing apparatus of the perovskite type complex oxide concerning this invention. It is explanatory drawing which showed the mechanism of the crystallinity improvement in the manufacturing method of the perovskite type complex oxide concerning this invention by contrast with the hydrothermal synthesis method. The time-series change of the temperature of the slurry in the reaction process in Example 1 thru | or Example 3, and the pressure in the inside of a sealed container is shown. It is the figure which showed the relationship between the specific surface area in Example 1 thru | or Example 3, and Comparative Example 1 and Comparative Example 2, and a lattice constant.

  An embodiment of a perovskite complex oxide production apparatus according to the present invention will be described. FIG. 1 is a conceptual diagram of an embodiment of a perovskite complex oxide production apparatus according to the present invention.

This apparatus for producing a perovskite complex oxide makes it possible to obtain perovskite complex oxide particles having a low hydroxyl content and high crystallinity in the crystal lattice of the perovskite complex oxide by a simple method. It is a manufacturing apparatus of perovskite type complex oxide. This perovskite complex oxide is represented by the general formula ABO ₃ . Hereinafter, an embodiment of a production apparatus for a perovskite complex oxide according to the present invention will be described in detail.

  The perovskite complex oxide production apparatus 10 shown in FIG. 1 includes a sealed container 12, a heating apparatus 14, a thermometer 16, a raw material charging apparatus 18, and a stirring blade 20.

  The sealed container 12 is provided for sealing a slurry-like raw material liquid containing at least titanium oxide powder among ceramic raw materials. The sealed container 12 is a container that can withstand the high temperature and high pressure necessary for the production of the perovskite complex oxide.

  A first pipe 22 is connected to the sealed container 12. Openings are provided at both ends of the first pipe 22. One end of the first pipe 22 communicates with the sealed container 12 at the upper part of the sealed container 12. A pressure gauge 22b and a first valve 22a are disposed in the middle portion of the first pipe 22. The pressure gauge 22b and the first valve 22a are arranged in order of the pressure gauge 22b and the first valve 22a from one end of the first pipe 22 toward the other end. The first valve 22 a is provided to open and close the passage of the first pipe 22. The first pressure gauge 22 b is provided to monitor the pressure inside the sealed container 12 and the inside of the first pipe 22.

  A second pipe 24 is connected to the sealed container 12. Openings are provided at both ends of the second pipe 24. One end portion of the second pipe 24 passes through the upper portion of the sealed container 12 and communicates with the raw material input device 18 at the upper portion of the raw material input device 18. Air is supplied from the other end of the second pipe 24 as necessary. A second valve 24a, a second pressure gauge 24b, and a pressure control valve 24c are disposed in the middle part of the second pipe 24. The second valve 24a, the second pressure gauge 24b, and the pressure control valve 24c are configured so that the second pressure gauge 24b, the second valve 24a, and the pressure are from the one end of the second pipe 24 toward the other end. The control valves 24c are arranged in this order. Further, the second valve 24 a, the second pressure gauge 24 b and the pressure control valve 24 c are provided outside the sealed container 12. The second valve 24 a is provided to open and close the passage of the second pipe 24. The second pressure gauge 24 b is provided to monitor the pressure inside the raw material charging device 18 and the inside of the second pipe 24. The pressure control valve 24 c is provided to adjust the pressure inside the raw material charging device 18 and inside the second pipe 24.

  The heating device 14 is provided to heat and keep the raw material liquid sealed inside the sealed container 12. The heating apparatus 14 is arrange | positioned at the outer periphery of the sealed container 12, for example.

  The thermometer 16 is provided for measuring the temperature of the raw material liquid sealed inside the sealed container 12. The thermometer 16 is arrange | positioned so that the upper part of the sealed container 12 may be penetrated and a raw material liquid may be reached, for example.

  The raw material charging device 18 holds a hydroxide of an element constituting the powdery A site component of the ceramic raw material (hereinafter simply referred to as a powdery hydroxide), and the powdery hydroxide is It is provided for charging the raw material liquid sealed in the sealed container 12. The raw material charging device 18 is arranged on the upper side inside the sealed container 12. The raw material charging device 18 includes a charging container 18a, a lid 18b, and a linkage member 18c. Since the raw material charging device 18 is disposed inside the sealed container 12, the powdered hydroxide can be charged toward the raw material liquid while the sealed container 12 is pressurized. Further, since the raw material charging device 18 is disposed inside the sealed container 12, the raw material charging device 18 itself is not required to have a pressure resistance capability that the sealed container 12 has.

  The charging container 18a is provided to hold the powdered hydroxide. The charging container 18a is formed in a conical shape convex in a side view. An opening for dropping the held powdered hydroxide toward the raw material liquid is formed on the lower end side of the charging container 18a. By making the shape of the charging container 18a conical, for example, it is more powdery than the cylindrical container having the same bottom area as the bottom area of the opening formed in the charging container 18a. A lot of things can be held. Further, by making the shape of the charging container 18a conical, the powdered hydroxide held in the charging container 18a can be smoothly dropped toward the raw material liquid after the lid 18b is opened. it can. In this way, since the raw material liquid and the powdered hydroxide are reacted, a good result having a uniform particle can be obtained.

  A lid 18b is disposed in close contact with the opening of the charging container 18a. The diameter of the lower end of the lid 18b is formed larger than the diameter of the opening of the charging container 18a. The lid portion 18b is connected to the charging container 18a via the linkage member 18c. Therefore, even when the lid portion 18b is opened, the lid portion 18b is connected to the charging container 18a and the linking member 18c, so that the lid portion 18b can be prevented from falling toward the raw material liquid.

  Here, as a method of charging the powdery hydroxide into the raw material liquid from the raw material charging device 18, opening and closing of the lid portion 18 b in the raw material charging device 18 is operated from the outside of the sealed container 12. In the present embodiment, for example, powdery hydroxide is charged from the raw material charging device 18 to the raw material liquid by the method described below.

  That is, when the raw material charging device 18 holds the powdered hydroxide, the pressure inside the sealed container 12 is changed to the pressure inside the raw material charging device 18 by the first valve 22a and the second valve 24a. Adjusted to be higher. Thereby, the closed state is maintained without opening the cover 18b of the raw material charging device 18, and the raw material charging device 18 can hold the powdered hydroxide. Moreover, since the diameter of the lower end of the cover part 18b is formed larger than the diameter of the opening part of the charging container 18a, it is possible to prevent the cover part 18b from sinking into the charging container 18a during pressurization. It is possible to hold the powdered hydroxide by setting the pressure difference as described above.

  On the other hand, when opening the lid 18 b of the raw material charging device 18, air is supplied from the other end of the second pipe 24 toward the raw material charging device 18. Then, the pressure inside the second pipe 24 is adjusted by the pressure control valve 24c, the second valve 24a is opened, and the pressure inside the raw material charging device 18 exceeds the pressure inside the sealed container 12, The lid 18b is opened.

  The stirring blade 20 is provided for stirring the raw material liquid sealed in the sealed container 12. Further, the stirring blade 20 is provided to stir the powdered hydroxide into the raw material liquid and then cause a smooth reaction to obtain a slurry-like raw material liquid containing a reaction product. The diffusion blade 20 includes a blade portion 20a and a shaft portion 20b. The wing part 20 a is disposed on the lower side inside the sealed container 12. One end of the shaft portion 20b is connected to the center of the wing portion 20a. The other end of the shaft portion 20b extends through the upper portion of the sealed container 12 and extends to the outside from the sealed container 12, and is connected to, for example, a prime mover (not shown). The wing part 20a is rotated by the prime mover via the shaft part 20b, whereby the raw material liquid is agitated.

According to the apparatus for producing a perovskite complex oxide according to the present invention, the raw material charging device 18 is disposed inside the sealed container 12, and the lid 18 b of the raw material charging device 18 is opened and closed by an external operation from the sealed container 12. Therefore, it is possible to feed the powdery hydroxide into the raw material liquid from the raw material charging device 18 while maintaining the high temperature and high pressure for the state inside the sealed container 12.
Moreover, according to the manufacturing apparatus of the perovskite type complex oxide according to the present invention, since the heating device 14 is provided, the raw material liquid is made to be desired by the heating device 14 before the raw material liquid and the powdered hydroxide are reacted. It can be heated to temperature.

  Next, an embodiment of a method for producing a perovskite complex oxide according to the present invention using the perovskite complex oxide production apparatus 10 will be described. FIG. 2 is an explanatory diagram showing the crystallinity improvement mechanism in the method for producing a perovskite complex oxide according to the present invention in comparison with the hydrothermal synthesis method.

  As shown in FIG. 2, the manufacturing method of the perovskite type complex oxide by the hydrothermal synthesis method is such that the temperature during the reaction of reacting the raw material liquid containing titanium oxide powder with the powdered hydroxide is less than 100 ° C. Therefore, there is a concern that a hydroxyl group remains in the lattice of the composite oxide. Therefore, the crystallinity of the reaction product obtained by the method for producing the perovskite complex oxide is low.

  On the other hand, the method for producing a perovskite complex oxide according to the present invention differs from the hydrothermal synthesis method in that a raw material liquid containing at least titanium oxide powder is heated inside a sealed container 12 as shown in FIG. Then, a reaction step in which a hydroxide of an element constituting the powdery A-site component (hereinafter simply referred to as a powdered hydroxide) is added to the heated raw material liquid to react with the raw material liquid. I have.

The method for producing a perovskite complex oxide according to the present invention is a method for producing a perovskite complex oxide represented by the general formula ABO ₃ .

First, a ceramic raw material is prepared to produce a perovskite complex oxide represented by the general formula ABO ₃ . For example, powdered Ba (OH) ₂ is prepared as a hydroxide of Ba which is an element constituting the A site component. The prepared powdered Ba (OH) ₂ is put into the raw material charging device 18.

Moreover, the element which comprises a B site component contains Ti at least. For example, TiO ₂ powder is prepared as the oxide powder of Ti constituting the B site component. Then, put a TiO ₂ powder and pure water in a sealed container 12, by mild agitation, a slurry-like raw material solution containing TiO ₂ powder is prepared.

Next, the first valve 22a and the second valve 24a connected to the sealed container 12 are closed to bring the sealed container 12 into a sealed state, and then the raw material liquid containing TiO ₂ powder is heated using the heating device 14. Heated. The heating temperature of the raw material liquid is set so that the temperature during the reaction step is 100 ° C. or higher, for example, 58 ° C., 80 ° C., and 100 ° C. are appropriately set.

  When the heated raw material liquid reaches a desired temperature, the powdered hydroxide held in the raw material input device 18 is input to the raw material liquid and reacts with the raw material liquid. As described above, when the powdered hydroxide is charged into the heated raw material liquid, immediately after the charging, as shown in FIG. 2, the temperature of the raw material liquid rapidly rises to 100 ° C. or higher due to the reaction.

  In addition, when the heating temperature of the raw material liquid before the reaction is set to 58 ° C., the temperature of the raw material liquid immediately after adding the powdered hydroxide to the raw material liquid does not exceed 100 ° C., but in the subsequent reaction step, Over 100 ° C. Further, when the heating temperature of the raw material liquid before the reaction is set to 80 ° C., the temperature of the raw material liquid immediately after the powdered hydroxide is added to the raw material liquid exceeds 100 ° C.

  Then, the raw material liquid is stirred using the stirring blade 20 while keeping the temperature of the raw material liquid sealed inside the sealed container 12 using the heating device 14. Thereafter, when the first valve 22a and the second valve 24a are opened, the pressure inside the sealed container 12 is returned to atmospheric pressure, and the raw material liquid is cooled, slurry-like barium titanate is obtained. And the obtained slurry-like barium titanate is taken out from the sealed container 12 and put into a drier to evaporate water, whereby barium titanate powder is obtained as a reaction product.

  Subsequently, the reaction product obtained in the reaction step described above is heat-treated at 800 ° C to 1000 ° C. By this heat treatment step, the crystal system of the reaction product is changed from cubic to tetragonal, and barium titanate, which is a perovskite complex oxide particle having high desired crystallinity, is obtained.

  According to the method for producing a perovskite complex oxide according to the present invention, since the hydroxide of the element constituting the A site component is introduced into the heated raw material liquid, it reacts at a high temperature of 100 ° C. or higher. Therefore, the reaction can be performed in a short time, and the content of the hydroxyl group in the crystal lattice of the perovskite complex oxide can be reduced. Therefore, perovskite complex oxide particles having high crystallinity can be obtained.

In the above embodiment, the method for producing barium titanate has been described in detail. However, the method for producing the perovskite complex oxide according to this embodiment is a perovskite complex oxide similar to barium titanate. For example, it can be applied to the production of strontium titanate and barium calcium titanate. Therefore, in the present embodiment, in the perovskite complex oxide represented by the general formula ABO ₃ , the element constituting the A site component includes at least one of Ba, Ca, and Sr.

  Next, experimental examples of the method for producing a perovskite complex oxide according to the present invention will be described below.

1. Production of Barium Titanate Powder A method for producing barium titanate powder using the perovskite complex oxide production apparatus 10 will be described with reference to FIG. 3 and Table 1. FIG. 3 shows time-series changes in the temperature of the slurry (raw material liquid) during the reaction steps in Examples 1 to 3 and the pressure inside the sealed container 12 of the perovskite complex oxide production apparatus 10. Table 1 shows the charging temperature of Ba (OH) ₂ in Examples 1 to 3 and Comparative Example 1, the peak temperature immediately after charging Ba (OH) ₂ , and the maximum temperature in the reaction process.

Example 1
Ba (OH) ₂ and TiO ₂ (specific surface area 300 cm ² / g) were prepared as ceramic raw materials. First, 35.96 g of TiO ₂ powder was weighed, placed in a sealed container 12 together with 0.1 L of pure water, and stirred gently to prepare a slurry (raw material solution) containing TiO ₂ powder. Next, 77.10 g of Ba (OH) ₂ powder was weighed so that the molar ratio with the Ti element was 1: 1, and this was put into the raw material charging device 18 installed inside the sealed container 12. .

Next, after the first valve 22 a and the second valve 24 a connected to the sealed container 12 were closed to bring the sealed container 12 into a sealed state, the slurry was heated using the heating device 14. The first pressure gauge 22b and the thermometer 16 continued to heat the slurry while monitoring the pressure inside the sealed container 12 and the temperature of the slurry, respectively. Then, when the temperature of the slurry reached 58 ° C., the pressure control valve 24c was adjusted and the second valve 24a was opened in order to put the Ba (OH) ₂ powder into the slurry. A few seconds after opening the second valve 24a, if the value of the second pressure gauge 24b rises to coincide with the first pressure gauge 22b and a rapid increase in the temperature of the slurry is observed, immediately The sealed valve 12 was sealed by tightening the second valve 24a.

  Subsequently, while keeping the slurry sealed inside the sealed container 12 using the heating device 14, the slurry was reacted for 1 hour while stirring the slurry using the stirring blade 20. Thereafter, the heating was stopped, the first valve 22a and the second valve 24a were opened, and the slurry was left in a state where the pressure inside the sealed container 12 was returned to atmospheric pressure. Then, after the slurry was cooled, the slurry was taken out from the sealed container 12 and put in a drier to evaporate the water, whereby the barium titanate powder in Example 1 was obtained.

FIG. 3A shows time-series changes in the temperature of the slurry and the pressure inside the sealed container 12 during the reaction step in Example 1. FIG. First, Ba (OH) ₂ was charged when the temperature indicated by I in FIG. 3A, that is, the temperature of the slurry reached 58 ° C. When turning on the Ba (OH) _2, immediately after, as shown in II of FIG. 3 (a), Ba (OH ) 2 heat of solution, and the reaction heat, the peak temperature of the slurry rapidly to 92 ° C. Rose. Thereafter, when the reaction was performed for 1 hour, the temperature of the slurry gradually increased, and as shown by III in FIG. 3A, the temperature of the slurry increased to 114 ° C. which was the maximum temperature. In Example 1, the temperature of the slurry immediately after the introduction of Ba (OH) ₂ did not exceed 100 ° C., but the temperature of the slurry exceeded 100 ° C. during the subsequent reaction step.

(Example 2)
In Example 2, a slurry containing TiO ₂ powder was prepared in a sealed container 12 in order to prepare the same ceramic raw material as in Example 1. Then, Ba (OH) ₂ powder was put in the raw material charging device 18.

Next, after the first valve 22 a and the second valve 24 a connected to the sealed container 12 were closed to bring the sealed container 12 into a sealed state, the slurry was heated using the heating device 14. The first pressure gauge 22b and the thermometer 16 continued to heat the slurry while monitoring the pressure inside the sealed container 12 and the temperature of the slurry, respectively. Then, when the temperature of the slurry reached 80 ° C., the pressure control valve 24c was adjusted and the second valve 24a was opened in order to put the Ba (OH) ₂ powder into the slurry. A few seconds after opening the second valve 24a, if the value of the second pressure gauge 24b rises to coincide with the first pressure gauge 22b and a rapid increase in the temperature of the slurry is observed, immediately The sealed valve 12 was sealed by tightening the second valve 24a.

  Subsequently, as in Example 1, the slurry sealed inside the sealed container 12 using the heating device 14 was kept warm, while the slurry was stirred using the stirring blade 20 for 1 hour. Thereafter, the heating was stopped, the first valve 22a and the second valve 24a were opened, and the slurry was left in a state where the pressure inside the sealed container 12 was returned to atmospheric pressure. Then, after the slurry was cooled, the slurry was taken out from the sealed container 12 and put in a drier to evaporate the water, whereby the barium titanate powder in Example 2 was obtained.

FIG. 3B shows time-series changes in the temperature of the slurry and the pressure inside the sealed container 12 during the reaction step in Example 2. First, Ba (OH) ₂ was added when the temperature indicated by I in FIG. 3B, that is, the temperature of the slurry reached 80 ° C. When turning on the Ba (OH) _2, immediately after, as shown in II in FIG. 3 (b), Ba (OH ) 2 heat of solution, and the reaction heat, the peak temperature of the slurry rapidly to 113 ° C. Rose. Thereafter, when the reaction was performed for 1 hour, the temperature of the slurry gradually increased, and the temperature of the slurry increased to 133 ° C., which was the maximum temperature, as indicated by III in FIG. In Example 2, the temperature of the slurry immediately after Ba (OH) ₂ was charged exceeded 100 ° C., and then the temperature of the slurry exceeded 100 ° C. until the reaction was completed.

(Example 3)
In Example 3, a slurry containing TiO ₂ powder was prepared inside the sealed container 12 in order to prepare the same ceramic raw material as in Example 1. Then, Ba (OH) ₂ powder was put in the raw material charging device 18.

Next, after the first valve 22 a and the second valve 24 a connected to the sealed container 12 were closed to bring the sealed container 12 into a sealed state, the slurry was heated using the heating device 14. The first pressure gauge 22b and the thermometer 16 continued to heat the slurry while monitoring the pressure inside the sealed container 12 and the temperature of the slurry, respectively. Then, when the temperature of the slurry reached 100 ° C., the pressure control valve 24c was adjusted and the second valve 24a was opened in order to put the Ba (OH) ₂ powder into the slurry. A few seconds after opening the second valve 24a, if the value of the second pressure gauge 24b rises to coincide with the first pressure gauge 22b and a rapid increase in the temperature of the slurry is observed, immediately The sealed valve 12 was sealed by tightening the second valve 24a.

  Subsequently, as in Example 1, the slurry sealed inside the sealed container 12 using the heating device 14 was kept warm, and the slurry was reacted for 1 hour while stirring the slurry using the stirring blade 20. Thereafter, the heating was stopped, the first valve 22a and the second valve 24a were opened, and the slurry was left in a state where the pressure inside the sealed container 12 was returned to atmospheric pressure. Then, after the slurry was cooled, the slurry was taken out from the sealed container 12 and put in a drier to evaporate the water, whereby the barium titanate powder in Example 3 was obtained.

FIG. 3C shows time-series changes in the temperature of the slurry and the pressure inside the sealed container 12 during the reaction step in Example 3. First, Ba (OH) ₂ was charged when the temperature indicated by I in FIG. 3C, that is, the temperature of the slurry reached 100 ° C. When turning on the Ba (OH) _2, immediately after, as shown in II of FIG. 3 (c), Ba (OH ) 2 heat of solution, and the reaction heat, the slurry temperature was rapidly raised to 127 ° C. . Thereafter, when the reaction was performed for 1 hour, the temperature of the slurry gradually increased, and as shown by III in FIG. 3C, the temperature of the slurry increased to 142 ° C. which was the maximum temperature. In Example 3, the temperature of the slurry immediately after the addition of Ba (OH) ₂ exceeded 100 ° C., and thereafter, the temperature of the slurry exceeded 100 ° C. until the reaction was completed.

(Comparative Example 1)
First, in order to prepare the same ceramic raw material as in Example 1, a slurry containing TiO ₂ powder was prepared inside the sealed container 12. Then, Ba (OH) ₂ powder was put in the raw material charging device 18.

Next, after the first valve 22a connected to the sealed container 12 was opened and the second valve 24a was closed, the slurry was heated using the heating device 14. The first pressure gauge 22b and the thermometer 16 continued to heat the slurry while monitoring the pressure inside the sealed container 12 and the temperature of the slurry, respectively. Then, when the temperature of the slurry reached 58 ° C., the pressure control valve 24c was adjusted and the second valve 24a was opened in order to put the Ba (OH) ₂ powder into the slurry. A few seconds after opening the second valve 24a, if a rapid increase in the temperature of the slurry is observed, the second valve 24a is immediately closed and the sealed container 12 is in a state before the second valve 24a is opened. I made it.

  Subsequently, as in Example 1, the slurry sealed inside the sealed container 12 using the heating device 14 was kept warm, while the slurry was stirred using the stirring blade 20 for 1 hour. Then, the heating with respect to the sealed container 12 was stopped and left to stand. Then, after the slurry was cooled, the slurry was taken out from the sealed container 12 and put in a dryer to evaporate the water, whereby the barium titanate powder in Comparative Example 1 was obtained.

In Comparative Example 1, since the first valve 22a was opened in the reaction step, the peak temperature of the slurry immediately after the introduction of Ba (OH) ₂ was 95 ° C. unlike the above Examples 1 to 3. The temperature of the slurry in the reaction process did not exceed 100 ° C., and the maximum temperature of the slurry in the reaction process was 95 ° C.

(Comparative Example 2)
In Comparative Example 2, the barium titanate powder was produced by a so-called hydrothermal synthesis method.

First, TiO ₂ powder and Ba (OH) ₂ powder were weighed, and pure water was added so that the slurry concentration was 1.0 mol / L in terms of BaTiO ₃ to prepare a slurry.

  And the produced slurry was put into the sealed container 12, the temperature of the slurry was raised to 200 ° C. while stirring, and the hydrothermal reaction was carried out by holding at 200 ° C. for 1 hour. Thereafter, the pressure inside the sealed container 12 was returned to atmospheric pressure, heating to the sealed container 12 was stopped, and the slurry was allowed to stand. Then, after the slurry was cooled, the slurry was taken out from the sealed container 12 and put in a dryer to evaporate the water, whereby the barium titanate powder in Comparative Example 2 was obtained.

2. Evaluation of barium titanate powder X-ray diffraction (using CuKα as a radiation source) was performed on the barium titanate powders according to Examples 1 to 3 and Comparative Examples 1 and 2 obtained by the method described above. The crystal structure and lattice constant were determined by the Rietveld method. The specific surface areas of the barium titanate powders according to Examples 1 to 3 and Comparative Examples 1 and 2 were determined by the BET method.

  Table 2 shows the measurement results. FIG. 4 shows the relationship between the specific surface area and the lattice constant.

  As shown in Table 2, the barium titanate crystal systems according to Examples 1 to 3 and Comparative Examples 1 and 2 were all cubic.

Further, paying attention to the lattice constant in Table 2, it was confirmed that the lattice constant was decreased as the charging temperature of Ba (OH) ₂ was increased. This is presumably because the hydroxyl groups remaining in the lattice were reduced by increasing the temperature at which the barium titanate particles were generated. Moreover, according to FIG. 4, it has confirmed that crystallinity was high compared with the comparative example 1 whose temperature of the slurry in the whole reaction process is less than 100 degreeC.

Furthermore, the comparative example 2 in Table 2 shows the evaluation result of the barium titanate powder obtained by the general hydrothermal synthesis method. When the lattice constant of Comparative Example 2 is compared with the lattice constant of Example 2 having a specific surface area equivalent to that of Comparative Example 2, it is confirmed that the crystallinity is not sufficient because the lattice constant according to Comparative Example 2 is larger. did it. This is because TiO ₂ and Ba (OH) ₂ are mixed at room temperature and then placed in a sealed container 12 to gradually raise the temperature of the slurry to 200 ° C. This is probably because the hydroxyl groups remained.

  Moreover, the obtained barium titanate powder was calcined at a temperature of 800 ° C to 1000 ° C. By calcination, grains were grown and the crystal system was dislocated to obtain tetragonal barium titanate. Further, when Examples and Comparative Examples having the same specific surface area were compared, tetragonal barium titanate powder having a large axial ratio c / a could be obtained in Examples with high crystallinity.

3. Production of Strontium Titanate Powder A method for producing strontium titanate powder using the perovskite complex oxide production apparatus 10 will be described with reference to Table 3. Table 3 shows the charging temperature of Sr (OH) ₂ in Example 4 and Comparative Example 3, the peak temperature immediately after the charging of Sr (OH) ₂ , and the maximum temperature in the reaction process.

Example 4
Sr (OH) ₂ and TiO ₂ (specific surface area 300 cm ² / g) were prepared as ceramic raw materials. First, 30.00 g of TiO ₂ powder was weighed, put into a sealed container 12 together with 0.1 L of pure water, and stirred gently to prepare a slurry (raw material solution) containing TiO ₂ powder. Next, 45.70 g of Sr (OH) ₂ powder was weighed so that the molar ratio with the Ti element was 1: 1, and this was put into the raw material charging device 18 installed inside the sealed container 12. .

Next, after the first valve 22 a and the second valve 24 a connected to the sealed container 12 were closed to bring the sealed container 12 into a sealed state, the slurry was heated using the heating device 14. While the pressure inside the sealed container 12 and the temperature of the slurry were monitored with the first pressure gauge 22b and the thermometer 16, the heating of the slurry was continued. Then, when the temperature of the slurry reached 100 ° C., the pressure control valve 24c was adjusted and the second valve 24a was opened in order to put the Sr (OH) ₂ powder into the slurry. A few seconds after opening the second valve 24a, if the value of the second pressure gauge 24b rises to coincide with the first pressure gauge 22b and a rapid increase in the temperature of the slurry is observed, immediately The sealed valve 12 was sealed by tightening the second valve 24a.

  Subsequently, while keeping the slurry sealed inside the sealed container 12 using the heating device 14, the slurry was reacted for 1 hour while stirring the slurry using the stirring blade 20. Thereafter, the heating was stopped, the first valve 22a and the second valve 24a were opened, and the slurry was left in a state where the pressure inside the sealed container 12 was returned to atmospheric pressure. Then, after the slurry was cooled, the slurry was taken out from the sealed container 12 and put in a dryer to evaporate the water, thereby obtaining the strontium titanate powder in Example 4.

(Comparative Example 3)
First, in order to prepare the same ceramic raw material as in Example 4, a slurry containing TiO ₂ powder was prepared inside the sealed container 12. Then, Sr (OH) ₂ powder was put into the raw material charging device 18.

Next, after the first valve 22a connected to the sealed container 12 was opened and the second valve 24a was closed, the slurry was heated using the heating device 14. The first pressure gauge 22b and the thermometer 16 continued to heat the slurry while monitoring the pressure inside the sealed container 12 and the temperature of the slurry, respectively. Then, when the temperature of the slurry reached 65 ° C., the pressure control valve 24c was adjusted and the second valve 24a was opened in order to put the Sr (OH) ₂ powder into the slurry. A few seconds after opening the second valve 24a, if the value of the second pressure gauge 24b rises to coincide with the first pressure gauge 22b and a rapid increase in the temperature of the slurry is observed, immediately The second valve 24a was tightened to bring the sealed container 12 into a state before the second valve 24a was opened. Here, after the Sr (OH) ₂ powder was put into the slurry, it took 12 minutes to reach 95 ° C. which is the peak temperature shown in Table 3.

  Subsequently, in the same manner as in Example 4, while the slurry to be sealed was kept warm inside the sealed container 12 using the heating device 14, the slurry was reacted for 1 hour while stirring the slurry using the stirring blade 20. Thereafter, the heating of the sealed container 12 was stopped and the slurry was allowed to stand. Then, after the slurry was cooled, the slurry was taken out from the sealed container 12 and put in a drier to evaporate the water, whereby the strontium titanate powder in Comparative Example 3 was obtained.

4). Evaluation of Strontium Titanate Powder With respect to the strontium titanate powder according to Example 4 and Comparative Example 3 obtained by the above-described method, the lattice constant was determined by the Rietveld method.

  As a result of the measurement of the lattice constant, the lattice constant of the strontium titanate powder according to Example 4 was 0.3914 nm, and the lattice constant of the strontium titanate powder according to Comparative Example 3 was 0.3922 nm.

  Thus, in the sealed manufacturing method, the temperature rise considered to accompany the reaction was completed in a short time, and the lattice constant tended to decrease. Therefore, it is considered that a uniform and highly crystalline strontium titanate powder is obtained by this production method.

  In the above-described embodiment, as a method of charging powdery hydroxide into the raw material liquid from the raw material charging device, the lid of the raw material charging device is opened and closed by the second valve and pressure provided outside the sealed container. Although it is performed by operating the control valve, it is not limited to this, and other means that can feed powdered hydroxide into the raw material liquid from the raw material charging device by operation from the outside of the sealed container are used. Also good. That is, in order to open and close the lid portion by an operation from the outside of the sealed container, for example, the lid portion may be opened and closed by rotating the lid portion. Then, the lid may be opened by applying water pressure from the inside to the outside of the raw material charging apparatus.

  In the above-described embodiment, the raw material charging device is disposed inside the sealed container. However, the raw material charging device is not limited to this, and powdered hydroxide may be charged into the raw material liquid from the raw material charging device. For example, the raw material charging device may be arranged on the upper side of the sealed container.

  The method for manufacturing a perovskite complex oxide and the apparatus for manufacturing the same according to the present invention are particularly suitably used for electronic parts such as multilayer ceramic capacitors used in connection with downsizing of various electronic devices.

DESCRIPTION OF SYMBOLS 10 Perovskite type complex oxide production apparatus 12 Sealed container 14 Heating apparatus 16 Thermometer 18 Raw material charging apparatus 18a Loading container 18b Lid 18c Linking member 20 Stirring blade 20a Wing 20b Shaft 22 First piping 22a First pipe 22a Valve 22b First pressure gauge 24 Second piping 24a Second valve 24b Second pressure gauge 24c Pressure control valve

Claims (4)

A method for producing a perovskite complex oxide represented by a general formula ABO ₃ (A includes at least one of Ba, Ca and Sr, and B includes at least Ti),
It comprises a reaction step of heating a raw material liquid containing at least titanium oxide powder inside a sealed container, and adding and reacting a hydroxide of an element constituting the A site component to the heated raw material liquid. The manufacturing method of a perovskite type complex oxide.   2. The perovskite type composite according to claim 1, wherein a temperature of the raw material liquid becomes 100 ° C. or more by adding and reacting a hydroxide of an element constituting the A site component to the heated raw material liquid. Production method of oxide.   The method for producing a perovskite complex oxide according to claim 1 or 2, further comprising a heat treatment step of heat-treating the reaction product obtained in the reaction step at 800 ° C to 1000 ° C. Perovskite complex oxide production apparatus for producing a perovskite complex oxide represented by the general formula ABO ₃ (A includes at least one of Ba, Ca and Sr, and B includes at least Ti) Because
A sealed container for sealing a raw material liquid containing at least titanium oxide powder;
Heating means for heating the raw material liquid sealed inside the sealed container;
Charging means for charging a hydroxide of an element constituting the A-site component to the raw material liquid;
An apparatus for producing a perovskite complex oxide, comprising:

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