KR20130004124A - Method for producing perovskite complex oxide and producing apparatus thereof - Google Patents

Abstract

PURPOSE: A manufacturing method of perovskite-type complex oxides, and a manufacturing device thereof are provided to reduce contents of a hydroxyl group inside perovskite-type complex oxide particles. CONSTITUTION: A manufacturing method of perovskite-type complex oxides comprises the following steps: heating a raw material solution including titanium dioxide powder inside a sealing container; and reacting hydroxide of elements composed of an A-site component with the heated material solution. In the second step, the temperature of the raw material solution is 100 deg. Celsius or higher. The reaction product of the second step is heat-treated at 800-1,000 deg. Celsius. A manufacturing device(10) of the perovskite-type complex oxides comprises an encapsulation container(12), a heating tool, and a feeding tool. [Reference numerals] (AA) Air inlet; (BB) Powderized hydroxides; (CC) Raw material solution

Description

TECHNICAL FOR PRODUCING PEROVSKITE COMPLEX OXIDE AND PRODUCING APPARATUS THEREOF

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for producing a perovskite-type composite oxide and a method for producing the same, and more particularly to a method for producing barium titanate, which is a perovskite-type composite oxide, and an apparatus for producing the same.

In recent years, as miniaturization of multilayer capacitors and the like has progressed, thinning of dielectric elements has progressed. In order to manufacture this kind of thin-layer multilayer capacitors, crystal grains of dielectric ceramics must be made small to suppress grain growth. For this purpose, composite oxides, which are raw materials for ceramics, are required to be fine and excellent in crystallinity.

As a method for producing perovskite-type composite oxides such as barium titanate, which are fine and excellent in crystallinity, for example, methods for producing perovskite-type composite oxides as shown in Patent Documents 1 and 2 have been proposed. have.

Perovskite-type production method of the composite oxide described in Patent Document 1, the elements constituting the, A site ingredient A method for producing a perovskite-type composite oxide represented by the general formula ABO _3, including crystal water (結晶水) Hydroxide; A titanium oxide powder having a specific surface area of 250 m ² / g or more; and a mixing treatment step of mixing the heat treatment to produce a solution in which the A-site component is dissolved only in the water of the crystal water. Melting solution generating step; And a reaction step for reacting the titanium oxide powder with the dissolving solution to produce a reaction compound.

In addition, Patent Document 1 discloses calcination of the composite oxide powder obtained by the above-described manufacturing method.

Moreover, the manufacturing method of the perovskite type | mold composite oxide of patent document 2 is made into titanium hydroxide colloid so that the injection composition (Ba / Ti) of titanium and barium may be set to 1.00-1.10 in presence of carboxylic acid and barium salt aqueous solution. Added to produce barium titanate nucleus particles, and then the reaction solution containing the barium titanate nucleus particles was hydrothermally treated in a temperature range of 100 ° C. to 350 ° C. to obtain cubic spherical barium titanate particles. It is the manufacturing method of the spherical barium titanate particle powder characterized by calcining the said spherical barium titanate particle | grains at the temperature range of 800 degreeC-1200 degreeC, and being tetragonal.

The composite oxide obtained by the manufacturing method of patent document 1 and patent document 2 is a cubic complex oxide which is ultrafine and excellent in crystallinity. And it is said that the tetragonal composite oxide excellent in crystallinity can be manufactured by calcining the obtained composite oxide.

Japanese Patent No. 4200427 Japanese Patent No. 4240190

However, in the cubic composite oxide obtained by the production methods described in Patent Documents 1 and 2, there is a concern that the crystallinity may not be sufficient because hydroxyl groups remain 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 possibility that a hydroxyl group may remain. Moreover, in patent document 2, since the temperature at the time of producing | generating a barium titanate nucleus particle is performed by less than 100 degreeC (70 degreeC in an Example), there exists a possibility that a hydroxyl group may remain in a nucleus part again.

Therefore, since the crystallinity of the cubic complex oxide is not sufficient, there is a problem that the crystallinity is not sufficient even when calcined and displaced into a tetragonal crystal.

Therefore, a main object of the present invention is to provide a method for producing a perovskite-type composite oxide and an apparatus for producing the perovskite-type composite oxide particles having high crystallinity.

The method for producing a perovskite-type composite oxide according to the present invention is a perovskite-type composite represented by general formula ABO ₃ (A includes at least one of Ba, Ca, and Sr, and B includes at least Ti). A method for producing an oxide, comprising: 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; It is a manufacturing method of a perovskite complex oxide.

Moreover, in the manufacturing method of the perovskite type complex oxide which concerns on this invention, it is preferable that the temperature of a raw material liquid becomes 100 degreeC or more by adding and reacting the hydroxide of the element which comprises A site component to the heated raw material liquid.

Moreover, in the manufacturing method of the perovskite type complex oxide which concerns on this invention, it is preferable to include the heat processing process of heat-processing the reaction product obtained at the reaction process at 800 degreeC-1000 degreeC.

An apparatus for producing a perovskite-type composite oxide according to the present invention is a perovskite-type composite represented by 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 an oxide, comprising: a sealing container for sealing a raw material liquid containing at least titanium oxide powder, heating means for heating a raw material liquid sealed in the sealed container, and a raw material An apparatus for producing a perovskite-type composite oxide, characterized by comprising an introduction means for introducing a hydroxide of an element constituting the A-site component into a liquid.

According to the method for producing a perovskite-type composite 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 content of hydroxyl groups in the perovskite-type composite oxide particles is small, and crystals are used. High perovskite composite oxide particles can be obtained by a simple method.

Further, in the method for producing a perovskite-type composite oxide according to the present invention, when a hydroxide of an element constituting the A-site component is added to a heated raw material solution and the reaction is started at a high temperature of 100 ° C or higher, Residual hydroxyl groups in the crystal lattice of the lobe-type complex oxide can be reduced. Thus, perovskite-type composite oxide particles having higher crystallinity can be obtained.

In addition, in the method for producing a perovskite-type composite oxide according to the present invention, when the reaction product obtained in the reaction step is subjected to a heat treatment process at 800 ° C to 1000 ° C, a tetragonal perovskite-type composite oxide has high crystallinity. Particles can be obtained.

According to the apparatus for producing a perovskite-type composite oxide according to the present invention, the apparatus for producing a perovskite-type composite oxide according to the present invention has a charging means for introducing a hydroxide of an element constituting the A-site component. Therefore, the hydroxide of the element which comprises A-site component can be thrown in into a raw material liquid from the injecting means, maintaining high temperature and high pressure with respect to the internal state of a sealed container.

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

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows one Embodiment of the manufacturing apparatus of the perovskite type complex oxide which concerns on this invention.
FIG. 2 is an explanatory diagram showing a mechanism of improving crystallinity in the method for producing a perovskite-type composite oxide according to the present invention in comparison with a hydrothermal synthesis method.
3 shows time series changes of the temperature of the slurry in the reaction step in Examples 1 to 3 and the pressure inside the sealed container.
4 is a diagram showing the relationship between the specific surface area and the lattice constant in Examples 1 to 3, Comparative Examples 1 and 2;

EMBODIMENT OF THE INVENTION One Embodiment of the manufacturing apparatus of the perovskite type complex oxide which concerns on this invention is described. 1 is a conceptual diagram of an embodiment of a manufacturing apparatus of a perovskite complex oxide according to the present invention.

The apparatus for producing a perovskite-type composite oxide is characterized in that it is possible to obtain perovskite-type composite oxide particles having a low crystallinity in the crystal lattice of the perovskite-type composite oxide and high crystallinity by a simple method. It is a manufacturing apparatus of a perovskite complex oxide.

This perovskite complex oxide is represented by general formula ABO ₃ . EMBODIMENT OF THE INVENTION Hereinafter, one Embodiment of the manufacturing apparatus of the perovskite type complex oxide which concerns on this invention is described in detail.

The manufacturing apparatus 10 of the perovskite type composite oxide of FIG. 1 is equipped with the sealing container 12, the heating apparatus 14, the thermometer 16, the raw material input device 18, and the stirring blade 20. As shown in FIG.

The sealing container 12 is provided in order to seal the raw material liquid of the slurry state containing at least titanium oxide powder among ceramic raw materials. The sealed container 12 is a container which can withstand the high temperature and high pressure required for manufacture of a perovskite complex oxide.

The first pipe 22 is connected to the sealed container 12. Openings are formed at both ends of the first pipe 22. One end of the first pipe 22 communicates with the sealed container 12 at the upper portion of the sealed container 12. The pressure gauge 22b and the 1st valve 22a are arrange | positioned at the intermediate part of the 1st piping 22. The pressure gauge 22b and the first valve 22a are disposed 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 22a is provided to open and close the passage of the first pipe 22. The 1st pressure gauge 22b is provided in order to monitor the pressure in the inside of the sealing container 12, and the inside of the 1st piping 22. As shown in FIG.

In addition, the second pipe 24 is connected to the sealed container 12. Openings are formed at both ends of the second pipe 24. One end of the second pipe 24 penetrates 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. Moreover, air is supplied from the other end of the 2nd piping 24 as needed. The second valve 24a, the second pressure gauge 24b, and the pressure control valve 24c are disposed in the middle portion of the second pipe 24. The 2nd valve 24a, the 2nd pressure gauge 24b, and the pressure control valve 24c are the 2nd pressure gauge 24b and the 2nd valve 24a toward the other end from one end of the 2nd piping 24. As shown in FIG. , The pressure control valve 24c is arranged in this order. In addition, the second valve 24a, the second pressure gauge 24b, and the pressure control valve 24c are provided outside the sealed container 12. The second valve 24a is provided to open and close the passage of the second pipe 24. The second pressure gauge 24b is provided to monitor the pressure inside the raw material input device 18 and inside the second pipe 24. The pressure control valve 24c is provided in order to adjust the pressure in the inside of the raw material input device 18, and the inside of the 2nd piping 24. As shown in FIG.

The heating device 14 is provided to heat and heat the raw material liquid sealed in the sealed container 12. The heating device 14 is disposed at the outer circumference of the sealed container 12, for example.

The thermometer 16 is installed in order to measure the temperature of the raw material liquid sealed inside the sealing container 12. The thermometer 16 is arranged to reach the raw material liquid, for example, through the upper portion of the sealed container 12.

The raw material input device 18 stores a hydroxide (hereinafter simply referred to as a powdered hydroxide) of the elements constituting the powdered A-site component in the ceramic raw material, and stores the powdered hydroxide in the sealed container 12. It is installed to put in the sealed raw material liquid. The raw material input device 18 is disposed on the upper side inside the sealed container 12. The raw material input apparatus 18 is equipped with the container 18a for input, the lid part 18b, and the linkage member 18c. Since the raw material input device 18 is arrange | positioned inside the sealing container 12, in the state which the sealing container 12 was pressurized, powder-shaped hydroxide can be thrown in toward a raw material liquid. Moreover, since the raw material input device 18 is arrange | positioned inside the sealing container 12, the pressure-resistant ability to the extent that the sealing container 12 is equipped in the raw material input device 18 itself is not required.

An injection container 18a is provided for accommodating a powdered hydroxide. The dosing container 18a is formed in a convex shape convex downward from the side. At the lower end side of the container 18a for injection, an opening for dropping the stored powdered hydroxide toward the raw material liquid is formed. By making the shape of the container 18a for injection into a conical shape, for example, more powder-type hydroxide is contained than the cylinder of the cylindrical shape which has the same bottom area as the bottom area of the opening formed in the container for injection 18a. I can receive it. Moreover, by making the shape of the container 18a for injection into a conical shape, after opening the lid part 18b, the powder-shaped hydroxide contained in the container 18a for injection can be smoothly dropped toward a raw material liquid. Thus, since the raw material liquid and the powdered hydroxide are reacted, a good result in which the particles are arranged can be obtained.

The lid part 18b is arrange | positioned in close contact with the opening part of the container 18a for dispensing. The diameter of the lower end of the lid part 18b is formed larger than the diameter of the opening part of the container 18a for injection | throwing-in. The lid portion 18b is connected via the feeding container 18a and the linkage member 18c. Therefore, even when the lid part 18b is opened, since the lid part 18b is connected by the container 18a for injection | throwing-in and the linkage member 18c, it is said that the lid part 18b falls to the raw material liquid. You can prevent it.

Here, as a method of injecting powder hydroxide into the raw material liquid from the raw material input device 18, the opening and closing of the lid portion 18b in the raw material input device 18 is operated from the outside of the sealed container 12. In this embodiment, powder-shaped hydroxide is thrown in from the raw material input device 18 with respect to a raw material liquid by the method described below, for example.

That is, in the raw material input device 18, when the powder hydroxide is stored, the pressure inside the sealed container 12 is controlled by the first valve 22a and the second valve 24a. It adjusts so that it may become higher than the pressure in the inside of 18. Thereby, the state in which the lid part 18b of the raw material input device 18 is closed without being opened is maintained, and the powder-shaped hydroxide can be accommodated in the raw material input device 18. In addition, since the diameter of the lower end of the lid 18b is larger than the diameter of the opening of the container 18a, the lid 18b can be prevented from sinking in the container 18a during pressurization. By setting the pressure difference as described above, the powdered hydroxide can be stored.

On the other hand, when opening the lid part 18b of the raw material input device 18, air is supplied toward the raw material input device 18 from the other end of the second pipe 24. And the pressure control valve 24c adjusts the pressure in the inside of the 2nd piping 24, and opens the 2nd valve 24a, and the pressure in the inside of the raw material input device 18 is sealed container 12 Beyond the pressure inside the), the lid portion 18b is opened.

The stirring blade 20 is provided in order to stir the raw material liquid sealed to the sealing container 12. As shown in FIG. In addition, the stirring blade 20 is installed in order to stir so that a powdery hydroxide may be thrown into a raw material liquid, to make it react smoothly, and to obtain the slurry raw material liquid containing a reaction product. The stirring blade 20 is provided with the wing | blade part 20a and the shaft part 20b. The wing part 20a is arrange | positioned at the lower side inside the sealing container 12. As shown in FIG. One end of the shaft portion 20b is connected to the center of the wing portion 20a. In addition, the other end of the shaft portion 20b penetrates the upper portion of the sealed container 12 and extends outward from the sealed container 12, for example, a prime mover (not shown) is connected. The wing 20a is rotated by the prime mover through the shaft 20b, whereby the raw material liquid is stirred.

According to the apparatus for producing perovskite-type composite oxide according to the present invention, the raw material input device 18 is disposed inside the sealed container 12, and the raw material input device ( Since the opening and closing of the lid portion 18b of 18) is controlled, powdered hydroxide can be introduced into the raw material liquid from the raw material input device 18 while maintaining the high temperature and high pressure with respect to the internal state of the sealed container 12. .

In addition, according to the apparatus for producing perovskite complex oxide according to the present invention, since the heating device 14 is provided, the raw material liquid is desired by the heating device 14 before the raw material liquid and the powdered hydroxide react. It can be heated to one temperature.

Next, one Embodiment of the manufacturing method of the perovskite type | mold composite oxide which concerns on this invention using the manufacturing apparatus 10 of the perovskite type composite oxide is demonstrated. FIG. 2 is an explanatory diagram showing a mechanism of improving crystallinity in the method for producing a perovskite-type composite oxide according to the present invention in comparison with a hydrothermal synthesis method.

As shown in Fig. 2, in the method for producing a perovskite-type composite oxide according to the hydrothermal synthesis method, the temperature at the time of the reaction of reacting a raw material liquid containing titanium oxide powder with a powdered hydroxide is less than 100 ° C, so that the complex oxide There may be a hydroxyl group remaining in the lattice of. Therefore, the crystallinity of the reaction product obtained by this method for producing a perovskite complex oxide is low.

On the other hand, unlike the hydrothermal synthesis method, the method for producing a perovskite complex oxide according to the present invention, as shown in Figure 2, after heating the raw material liquid containing at least titanium oxide powder in the sealed container 12, A hydroxide (hereinafter referred to simply as a powdered hydroxide) of an element constituting the powdered A-site component is added to the heated raw material liquid, and a reaction step of reacting with the raw material liquid is provided.

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

First, in order to manufacture the perovskite complex oxide represented by general formula ABO ₃ , a ceramic raw material is prepared. As the hydroxide of Ba which is an element constituting the A-site component, for example, a powdery Ba (OH) ₂ is prepared. The prepared Ba (OH) ₂ is introduced into the raw material input device 18.

In addition, the element which comprises the B site component contains at least Ti. As the oxide powder of Ti constituting the B-site component, for example, TiO ₂ powder is prepared. Then, the TiO ₂ powder and the pure water are put in the sealed container 12 and stirred lightly to prepare a slurry-like raw material solution containing the TiO ₂ powder.

Next, the first valve (22a) and a second tightening the valve (24a), and then the sealed container 12 in a sealed state, the heater TiO ₂ powder by using a 14 connected to the sealed container 12, The raw material liquid containing the is heated. The heating temperature of a raw material liquid is set so that the temperature at the time of a reaction process may be 100 degreeC or more, for example, 58 degreeC, 80 degreeC, and 100 degreeC are suitably set.

When the heated raw material liquid reaches the desired temperature, the powdered hydroxide contained in the raw material input device 18 is introduced into the raw material liquid to react with the raw material liquid. In this way, when a powdered hydroxide is added to the heated raw material liquid, immediately after the addition, as shown in FIG. 2, the temperature of the raw material liquid is rapidly raised to 100 ° C. or higher by reaction.

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 the powdered hydroxide is added to the raw material liquid does not exceed 100 ° C., but exceeds 100 ° C. in the subsequent reaction step. In addition, when the heating temperature of the raw material liquid before reaction is set to 80 degreeC, the temperature of the raw material liquid immediately after inject | pouring powder-shaped hydroxide to a raw material liquid exceeds 100 degreeC.

And the raw material liquid is stirred using the stirring blade 20, keeping the raw material liquid sealed in the inside of the sealing container 12 using the heating apparatus 14. As shown in FIG. Then, when the 1st valve 22a and the 2nd valve 24a are opened, the pressure in the inside of the sealing container 12 is returned to atmospheric pressure, and a raw material liquid is cooled, a slurry barium titanate will be obtained. And the obtained slurry barium titanate is taken out from the sealing container 12, it puts in a drier, and evaporates moisture, and barium titanate powder is obtained as a reaction product.

Subsequently, the reaction product obtained in the reaction process mentioned above is heat-processed at 800 degreeC-1000 degreeC. By this heat treatment step, the crystal system of the reaction product becomes tetragonal from cubic crystal, whereby barium titanate, which is a perovskite-type composite oxide particle having desired crystallinity, is obtained.

According to the method for producing a perovskite-type composite oxide according to the present invention, since the hydroxide of the element constituting the A-site component is added to the heated raw liquid, the reaction is performed at a high temperature of 100 ° C. or higher, so that it can be reacted in a short time. In addition, the content of hydroxyl groups in the crystal lattice of the perovskite complex oxide can be reduced. Thus, perovskite-type composite oxide particles having high crystallinity can be obtained.

In the above embodiment, the method for producing barium titanate has been described above, but the method for producing a perovskite complex oxide according to the present embodiment is a perovskite complex oxide similar to barium titanate, for example, titanic acid. The present invention can also be applied to the production of strontium or barium calcium titanate. Therefore, in this embodiment, in the perovskite complex oxide represented by the general formula ABO ₃ , the element constituting the A-site component contains at least one of Ba, Ca, and Sr.

Next, the experimental example of the manufacturing method of the perovskite type complex oxide which concerns on this invention is demonstrated below.

1. Fabrication of Barium Titanate Powder

The manufacturing method of the barium titanate powder using the manufacturing apparatus 10 of a perovskite type complex oxide is demonstrated with reference to FIG. 3 and Table 1. FIG. 3 shows the temperature of the slurry (raw material liquid) in the reaction process in Examples 1 to 3 and the pressure in the sealed container 12 of the production apparatus 10 for the perovskite complex oxide. Represents a time series change. In addition, Table 1 shows the addition temperature of Ba (OH) ₂ in Example 1 thru | or Example 3, and Comparative Example 1, the peak temperature immediately after addition of Ba (OH) ₂ , and the maximum temperature in a reaction process.

Ba (OH) ₂ input temperature (℃) Peak temperature (℃) Temperature (℃) Example 1 58 92 114 Example 2 80 113 133 Example 3 100 127 142 Comparative Example 1 58 95 95

 (Example 1)

Ba (OH) ₂ and TiO ₂ (specific surface area 300cm 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 gently stirred to prepare a slurry (raw material liquid) containing the TiO ₂ powder. Next, 77.10 g of Ba (OH) ₂ powder was weighed so that the molar ratio with Ti element was 1: 1, and this was put into the raw material input device 18 installed in the sealed container 12.

Next, after tightening the 1st valve 22a and the 2nd valve 24a connected to the sealing container 12 to make the sealing container 12 sealed, the slurry is heated using the heating apparatus 14 next. did. The heating of the slurry was continued while monitoring the pressure inside the sealed container 12 and the temperature of the slurry with the first pressure gauge 22b and the thermometer 16, respectively. Then, at the stage where the temperature of the slurry became 58 ° C., in order to introduce Ba (OH) ₂ powder into the slurry, the pressure control valve 24c was adjusted to open the second valve 24a. After opening the second valve 24a, a few seconds later, when the value of the second pressure gauge 24b rises, coincides with the first pressure gauge 22b, and a sudden increase in the temperature of the slurry is observed, the second The valve 24a was tightened to seal the sealing container 12.

Subsequently, it was made to react for 1 hour, stirring the slurry using the stirring blade 20, keeping the slurry sealed in the inside of the sealing container 12 using the heating apparatus 14. As shown in FIG. Then, heating was stopped, the 1st valve 22a and the 2nd valve 24a were opened, and the slurry was left to stand in the state which returned the pressure in the inside of the sealing container 12 to atmospheric pressure. After the slurry was cooled, the slurry was taken out from the sealed container 12, placed in a drier, and evaporated to obtain barium titanate powder in Example 1.

In FIG.3 (a), the time-series change of the temperature of the slurry in the reaction process in Example 1, and the pressure in the inside of the sealing container 12 is shown. First, Ba (OH) ₂ was added when the temperature indicated by I in FIG. 3 (a), that is, the temperature of the slurry became 58 ° C. When Ba (OH) ₂ was added, immediately after that, as shown by II in FIG. 3 (a), the peak temperature of the slurry rapidly rose to 92 ° C. due to the heat of dissolution of Ba (OH) ₂ and the heat of reaction. . Then, when it reacted for 1 hour, the temperature of a slurry rose gradually and as shown to III of FIG. 3 (a), the temperature of the slurry rose to 114 degreeC which is the maximum temperature. In Example 1, the temperature of the slurry immediately after addition 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)

Example 2 prepared a slurry containing TiO ₂ powder in a sealed container 12 in order to prepare a ceramic raw material similar to Example 1. And Ba (OH) ₂ powder was put into the raw material input device 18.

Next, after tightening the 1st valve 22a and the 2nd valve 24a connected to the sealing container 12 to make the sealing container 12 sealed, the slurry was heated using the heating apparatus 14. . The heating of the slurry was continued while monitoring the pressure inside the sealed container 12 and the temperature of the slurry with the first pressure gauge 22b and the thermometer 16, respectively. Then, at the stage where the temperature of the slurry became 80 ° C, the pressure control valve 24c was adjusted to open the second valve 24a in order to introduce Ba (OH) ₂ powder into the slurry. After opening the second valve 24a, a few seconds later, when the value of the second pressure gauge 24b rises, coincides with the first pressure gauge 22b, and a sudden increase in the temperature of the slurry is observed, the second The valve 24a was tightened to seal the sealing container 12.

Subsequently, in the same manner as in Example 1, the slurry was sealed using the heating device 14 while the slurry was stirred using the stirring blade 20 for 1 hour while keeping the slurry sealed. Then, heating was stopped, the 1st valve 22a and the 2nd valve 24a were opened, and the slurry was left to stand in the state which returned the pressure in the inside of the sealing container 12 to atmospheric pressure. After the slurry was cooled, the slurry was taken out from the sealed container 12, put in a dryer, and evaporated to obtain a barium titanate powder in Example 2.

In FIG.3 (b), the time-series change of the temperature of the slurry in the reaction process in Example 2, and the pressure in the inside of the sealing container 12 is shown. First, Ba (OH) ₂ was added when the temperature indicated by I in FIG. 3 (b), that is, the temperature of the slurry became 80 ° C. When Ba (OH) ₂ was added, immediately after that, as shown by II in FIG. 3 (b), the peak temperature of the slurry rapidly rose to 113 ° C. due to the heat of dissolution of Ba (OH) ₂ and the heat of reaction. . Then, when it reacted for 1 hour, the temperature of a slurry rose gradually and as shown to III of FIG. 3 (b), the temperature of the slurry rose to 133 degreeC which is the maximum temperature. In Example 2, the temperature of the slurry immediately after addition of Ba (OH) ₂ exceeded 100 ° C., and then the temperature of the slurry exceeded 100 ° C. until the reaction was completed.

 (Example 3)

Example 3 also prepared a slurry containing TiO ₂ powder in the sealed container 12 in order to prepare a ceramic raw material similar to Example 1. FIG. And Ba (OH) ₂ powder was put into the raw material input device 18.

Next, after tightening the 1st valve 22a and the 2nd valve 24a connected to the sealing container 12 to make the sealing container 12 sealed, the slurry is heated using the heating apparatus 14 next. did. The heating of the slurry was continued while monitoring the pressure inside the sealed container 12 and the temperature of the slurry with the first pressure gauge 22b and the thermometer 16, respectively. Then, at the stage where the temperature of the slurry became 100 ° C, in order to introduce Ba (OH) ₂ powder into the slurry, the pressure control valve 24c was adjusted to open the second valve 24a. A few seconds after opening the second valve 24a, the value of the second pressure gauge 24b rises and coincides with the first pressure gauge 22b. 2 valve 24a was tightened and the sealing container 12 was made into the sealed state.

Subsequently, in the same manner as in Example 1, the slurry was sealed using the heating device 14 while the slurry was stirred using the stirring blade 20 for 1 hour while keeping the slurry sealed. Then, heating was stopped, the 1st valve 22a and the 2nd valve 24a were opened, and the slurry was left to stand in the state which returned the pressure in the inside of the sealing container 12 to atmospheric pressure. Then, after the slurry was cooled, the slurry was taken out from the sealed container 12, put in a drier, and evaporated water to obtain a barium titanate powder in Example 3.

In FIG.3 (c), the time-series change of the temperature of the slurry in the reaction process in Example 3, and the pressure in the inside of the sealing container 12 is shown. First, Ba (OH) ₂ was added when the temperature indicated by I in FIG. 3 (c), that is, the temperature of the slurry became 100 ° C. When Ba (OH) ₂ was added, immediately after that, as shown by II in FIG. 3 (c), the slurry temperature rose rapidly to 127 ° C. due to the heat of dissolution of Ba (OH) ₂ and the heat of reaction. Then, when it reacted for 1 hour, the temperature of a slurry rose gradually and as shown to III of FIG. 3 (c), the temperature of the slurry rose to 142 degreeC which is the maximum temperature. In Example 3, the temperature of the slurry immediately after addition of Ba (OH) ₂ exceeded 100 ° C, and even after that, the temperature of the slurry exceeded 100 ° C until the reaction was completed.

 (Comparative Example 1)

First, in order to prepare a ceramic raw material similar to Example 1, a slurry containing TiO ₂ powder was produced inside the sealed container 12. And Ba (OH) ₂ powder was put into the raw material input device 18.

Next, after making the 1st valve 22a connected to the sealing container 12 into the open state, and making the 2nd valve 24a into the tightened state, the slurry was heated using the heating apparatus 14. The heating of the slurry was continued while monitoring the pressure inside the sealed container 12 and the temperature of the slurry with the first pressure gauge 22b and the thermometer 16, respectively. And when the temperature of the slurry became 58 degreeC, in order to introduce Ba (OH) ₂ powder into a slurry, the pressure control valve 24c was adjusted and the 2nd valve 24a was opened. After a few seconds after opening the second valve 24a, if a sudden rise in the temperature of the slurry is observed, the second valve 24a is immediately tightened to close the sealed container 12 before opening the second valve 24a. I was in a state.

Subsequently, in the same manner as in Example 1, the slurry was sealed using the heating device 14 while the slurry was stirred using the stirring blade 20 for 1 hour while keeping the slurry sealed. Thereafter, heating 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, placed in a drier, and evaporated to obtain a barium titanate powder in Comparative Example 1.

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

 (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 prepared slurry was put into the sealing container 12, the temperature of the slurry was raised to 200 degreeC, stirring, and it maintained at 200 degreeC for 1 hour, and performed hydrothermal reaction. Then, the pressure in the inside of the sealed container 12 was returned to atmospheric pressure, heating to the sealed container 12 was stopped, and the slurry was left to stand. Then, after the slurry was cooled, the slurry was taken out from the sealed container 12, placed in a dryer, and evaporated to obtain a barium titanate powder in Comparative Example 2.

2. Evaluation of barium titanate powder

X-ray diffraction was performed on the barium titanate powders according to Examples 1 to 3 obtained by the above-described method, and Comparative Examples 1 and 2 (where CuKα is the source) and Rietveld The crystal structure and lattice constant were calculated by the method. In addition, 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. 4 shows the relationship between the specific surface area and the lattice constant.

Sample number Crystal structure Lattice constant (nm) Specific surface area (m ² / g) Example 1 Cubic 0.4032 66.6 Example 2 Cubic 0.4018 41.5 Example 3 Cubic 0.4017 34.6 Comparative Example 1 Cubic 0.4040 61.1 Comparative Example 2 Cubic 0.4033 42.7

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

In addition, when paying attention to the lattice constants in Table 2, it was confirmed that the lattice constants became smaller as the input temperature of Ba (OH) ₂ was increased. This is considered to be because the hydroxyl groups remaining in the lattice are reduced by increasing the temperature at which the barium titanate particles are produced. Moreover, according to FIG. 4, it was confirmed that crystallinity is high compared with the comparative example 1 whose temperature of the slurry in the whole reaction process is less than 100 degreeC.

In addition, the comparative example 2 in Table 2 shows the evaluation result of the barium titanate powder obtained by the general hydrothermal synthesis method. Comparing the lattice constant of Comparative Example 2 with the lattice constant of Example 2 having a specific surface area equivalent to that of Comparative Example 2, it was confirmed that the crystallinity was not sufficient because the lattice constant according to Comparative Example 2 was large. This is because TiO ₂ and Ba (OH) ₂ are mixed at room temperature and then placed in a sealed container 12 and the temperature of the slurry is gradually raised to 200 ° C., since the temperature at which the reaction is started is low, the hydroxyl group remains. I think it was because.

Furthermore, the obtained barium titanate powder was calcined at a temperature of 800 ° C to 1000 ° C. By calcination, the particles were grown, the crystal system was displaced, and a tetragonal barium titanate was obtained. In addition, when comparing Examples and Comparative Examples with the same specific surface area, in Examples with high crystallinity, tetragonal barium titanate powder having a large axial ratio c / a was obtained.

3. Fabrication of Strontium Titanate Powder

With reference to Table 3, the manufacturing method of the strontium titanate powder using the manufacturing apparatus 10 of a perovskite type | mold composite oxide is demonstrated. Table 3 shows the addition temperature of Sr (OH) ₂ in Example 4 and the comparative example 3, the peak temperature immediately after addition of Sr (OH) ₂ , and the maximum temperature in a reaction process.

Sr (OH) ₂ Input Temperature (℃) Peak temperature (℃) Temperature (℃) Example 4 100 129 132 Comparative Example 3 65 95 97

 (Example 4)

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

Next, after tightening the 1st valve 22a and the 2nd valve 24a connected to the sealing container 12 to make the sealing container 12 sealed, the slurry was heated using the heating apparatus 14. . The heating of the slurry was continued while monitoring the pressure inside the sealed container 12 and the temperature of the slurry with the first pressure gauge 22b and the thermometer 16. Then, at the stage where the temperature of the slurry became 100 ° C, the pressure control valve 24c was adjusted to open the second valve 24a in order to introduce Sr (OH) ₂ powder into the slurry. After opening the second valve 24a, a few seconds later, when the value of the second pressure gauge 24b rises, coincides with the first pressure gauge 22b, and a sudden increase in the temperature of the slurry is observed, the second The valve 24a was tightened to seal the sealing container 12.

Subsequently, it was made to react for 1 hour, stirring the slurry using the stirring blade 20, keeping the slurry sealed in the inside of the sealing container 12 using the heating apparatus 14. As shown in FIG. Then, heating was stopped, the 1st valve 22a and the 2nd valve 24a were opened, and the slurry was left to stand in the state which returned the pressure in the inside of the sealing container 12 to atmospheric pressure. Then, after the slurry was cooled, the slurry was taken out from the sealed container 12, put in a drier, and evaporated water to obtain strontium titanate powder in Example 4.

 (Comparative Example 3)

First, in order to prepare a ceramic raw material similar to Example 4, a slurry containing TiO ₂ powder was prepared inside the sealed container 12. And Sr (OH) ₂ powder was put into the raw material input device 18.

Next, after making the 1st valve 22a connected to the sealing container 12 into the open state, and making the 2nd valve 24a into the tightened state, the slurry was heated using the heating apparatus 14. The heating of the slurry was continued while monitoring the pressure inside the sealed container 12 and the temperature of the slurry with the first pressure gauge 22b and the thermometer 16, respectively. Then, at the stage where the temperature of the slurry became 65 ° C, the pressure control valve 24c was adjusted to open the second valve 24a in order to inject the Sr (OH) ₂ powder into the slurry. After opening the second valve 24a, a few seconds later, when the value of the second pressure gauge 24b rises, coincides with the first pressure gauge 22b, and a sudden increase in the temperature of the slurry is observed, the second The valve 24a was tightened and the sealed container 12 was made into the state before opening of the 2nd valve 24a. Here, after injecting Sr (OH) ₂ powder into the slurry, 12 minutes were required to reach 95 ° C. which is the peak temperature shown in Table 3.

Then, like Example 4, it stirred for 1 hour, stirring the slurry using the stirring blade 20, keeping the slurry sealed inside the sealing container 12 using the heating apparatus 14. As shown in FIG.

Then, heating to the sealed container 12 was stopped and the slurry was left to stand. After the slurry was cooled, the slurry was taken out from the sealed container 12, placed in a drier, and evaporated to obtain strontium titanate powder in Comparative Example 3.

4. Evaluation of Strontium Titanate Powder

About the strontium titanate powder which concerns on Example 4 and Comparative Example 3 obtained by the method mentioned above, the lattice constant was calculated | required by the Rietveld method.

As a result of measuring 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 closed manufacturing method, the temperature rise considered to be accompanied by reaction was completed in a short time, and the lattice constant tended to become small. Therefore, it is thought that the uniform and high crystallinity of strontium titanate powder is obtained by this manufacturing method.

In the above-mentioned embodiment, as a method of inject | pouring powder hydroxide into a raw material liquid from a raw material input device, opening and closing of the lid part in a raw material input device is carried out by operation of the 2nd valve and pressure control valve provided in the outer side of a sealed container. Although it is performed, it is not limited to this, The other means which can inject | pour powder-type hydroxide into a raw material liquid from a raw material input device by operation from the exterior of a sealed container may be used. That is, in order to open and close the lid part by operation from the outside of the sealed container, for example, the lid part may be opened and closed by rotating the lid part, and the raw material is introduced into the lid part by opening and closing by mechanical operation with respect to the lid part. The lid may be opened by adding water pressure from the inside to the outside of the apparatus.

In addition, in the above-mentioned embodiment, although the raw material input device is arrange | positioned inside the sealing container, it is not limited to this, The raw material input device is an example so that powder-shaped hydroxide can be injected into a raw material liquid from a raw material input device. For example, you may arrange | position it at the upper side of a sealed container.

The manufacturing method and the manufacturing apparatus of the perovskite-type composite oxide according to the present invention are particularly suitably used for electronic components such as multilayer ceramic capacitors used for miniaturization of various electronic devices.

10 Production apparatus of perovskite complex oxide
12 sealed containers
14 heating device
16 thermometer
18 raw material dosing device
18a container for dosing
18b lid
18c linkage member
20 stirring wings
20a wing
20b shaft
22 1st Piping
22a first valve
22b first pressure gauge
24 2nd Piping
24a second valve
24b second pressure gauge
24c pressure control valve

Claims (4)

A method for producing a perovskite-type composite oxide represented by general formula ABO ₃ (A includes at least one of Ba, Ca, and Sr, and B includes at least Ti),
And 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. Method for producing a composite oxide. The method of claim 1,
A method for producing a perovskite complex oxide, wherein the temperature of the raw material liquid is 100 ° C. or more by adding and reacting a hydroxide of the element constituting the A-site component with the heated raw material liquid. The method according to claim 1 or 2,
And a heat treatment step of heat-treating the reaction product obtained in the reaction step at 800 ° C to 1000 ° C. Apparatus for producing perovskite complex oxide for producing perovskite complex oxide represented by general formula ABO ₃ (A includes at least one of Ba, Ca, and Sr, and B includes at least Ti) as,
A sealing container for sealing the raw material liquid containing at least titanium oxide powder,
Heating means for heating the raw material liquid sealed in the sealed container;
An apparatus for producing a perovskite-type composite oxide, characterized by comprising a feeding means for injecting a hydroxide of an element constituting the A-site component into the raw material liquid.

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