KR101477404B1 - Manufacturing method of highly crystalline silicon dioxide coated barium titanate and highly crystalline silicon dioxide coated barium titanate powder manufactured by the same - Google Patents

Abstract

According to the present invention, a method for preparing highly crystalline silicon dioxide (SiO_2)-coated barium titanate comprises: adding a material including silicon (Si) and heating the resultant to prepare a barium hydroxide raw material in which barium (Ba) is ionized; preparing a titanium (Ti) raw material dispersed in an acid or a base; mixing and reacting the barium hydroxide and the titanium raw material to obtain a barium titanate seed; mixing the barium titanate seed with pure water and a grain growing inhibiting agent for grain growth; and coating a surface of the grain grown barium titanate seed with silicon dioxide (SiO_2).

Description

[0001] The present invention relates to a method for producing high crystalline silicon dioxide-coated barium titanate and a high crystalline silicon dioxide-coated barium titanate powder prepared by the method, and more particularly, to a barium titanate-

Highly crystalline silicon dioxide (SiO ₂₎ coated with a highly crystalline silicon dioxide manufactured by the method and a method of barium titanate (SiO ₂₎ relates to a coating of barium titanate powder.

Today, with the tendency of thinning, high capacity and high reliability of the electronic parts industry, barium titanate particles used as a ferroelectric material of a multilayer ceramic capacitor (MLCC) are required to have a small size and good dielectric constant and reliability.

Examples of methods for producing such barium titanate powder include a solid phase method and a wet method, and the wet method includes an oxalate precipitation method and a hydrothermal synthesis method. In the solid phase method, the minimum particle size of the particles is usually as large as about 1 micron, and it is difficult to control the size of the particles, and there is a problem of aggregation of the particles and contamination which occurs during firing, so that it is difficult to prepare barium titanate as fine particles .

As the dielectric particle size becomes smaller, tetragonality is lowered, which is a phenomenon commonly seen in various methods. It is very difficult to secure the crystal axis ratio (c / a) when the particle size is smaller than 100 nm. Also, as the powder size becomes smaller, dispersion becomes more difficult. Thus, the higher the dispersibility of the powder is, the higher the dispersibility is required.

Since the conventional solid phase method or coprecipitation method forms a crystal phase by high-temperature calcination, a high-temperature calcination step and a pulverization step are required, resulting in poor shape of barium titanate synthesized and a wide particle size distribution. Which is difficult to disperse and has a problem of particle formation after grinding.

When barium titanate is synthesized in a hydrothermal solution without heat treatment, the dispersion problem can be solved, and hydrothermal synthesis can easily control the shape and synthesize barium titanate having a small size and narrow particle size distribution. However, since the perovskite crystal structure is synthesized in the aqueous system, the -OH group is substituted for oxygen in the oxygen moiety, which causes many defects such as pores, and it is difficult to increase the crystallinity of the synthesized particles.

Japanese Patent Application Laid-Open No. 2004-067504

To a process for producing high crystalline barium titanate and a highly crystalline barium titanate powder produced by the process.

One embodiment of the present invention is a method of manufacturing a barium hydroxide material, comprising: preparing a barium hydroxide raw material by adding a material containing silicon (Si) and then heating to ionize barium Ba; Providing a titanium (Ti) raw material dispersed in an acid or a base; Mixing and reacting the barium hydroxide and the titanium raw material to obtain a barium titanate seed; Mixing the barium titanate titanate with pure water and a grain growth inhibitor to form a grain; And coating the surface of the grain-grown barium titanate seed with silicon dioxide (SiO ₂ ). The present invention also provides a method for producing barium titanate of high crystalline silicon dioxide (SiO ₂ ).

The barium raw material may be barium hydroxide octahydrate.

The step of preparing the barium hydroxide raw material is characterized in that a substance containing silicon (Si) is added to barium hydroxide, stirred in a nitrogen atmosphere and heated to 70 ° C or higher to dissolve the barium hydroxide raw material.

The titanium (Ti) raw material may be titanium hydrate or titanium dioxide.

The step of mixing and reacting the barium hydroxide and the titanium raw material may be carried out at 80 ° C or higher.

The step of mixing and reacting the barium hydroxide and the titanium raw material can be carried out using any one of rapid stirring, microwave and ultrasonic.

In the step of mixing and reacting the barium hydroxide and the titanium raw material, the mixing molar ratio (barium / titanium) of barium and titanium may be 1 or more and 3 or less.

Also, in the step of mixing and reacting the barium hydroxide and the titanium raw material, the mixing molar ratio (barium / titanium) of barium and titanium may be 1.2 or more and 2 or less.

The grain growth inhibitor may be a substance that lowers the polarity of the solvent, lowers the pH, and inhibits re-precipitation.

The grain growth inhibitor may be at least one selected from the group consisting of ethyl silicate, silicic acid, vinytriethoxysilane, and tetrahydroxy silane.

The concentration of the barium titanate seed to be mixed in the grain growth step may be 0.01 to 0.7 M.

The grain growth step is characterized in that the barium titanate seed and the pure water and the grain growth inhibitor are mixed and sealed and reacted in an autoclave at a temperature of 150 to 380 ° C for 1 to 72 hours with stirring.

In another embodiment of the present invention, a silicon dioxide (SiO ₂ ) coating layer is formed on the surface, and the average thickness of the silicon dioxide (SiO ₂ ) coating layer is 0.01 nm to 20 nm, and the maximum thickness the ratio of (tmax) (tmax / tmin) is highly crystalline silicon dioxide satisfying the _{tmax / tmin ≤ 2.0 (SiO 2} ) provides a coating of barium titanate powder.

The barium titanate powder has an average particle diameter of 5 to 200 nm and a crystal axis ratio (c / a) of 1.003 to 1.010.

The crystal axis ratio (c / a) is 1.001 to 1.005 when the particle size of the barium titanate powder is 5 to 20 nm, 1.003 to 1.0055 when the particle size of the barium titanate powder is 20 to 40 nm, 1.0062, 1.0062 to 1.009 in the case of 60 to 80 nm, and 1.0080 to 1.01 in the case of 80 to 200 nm.

The barium titanate powder produced by the process for producing barium titanate of high crystallinity silicon dioxide (SiO ₂ ) coated according to the present invention is prepared by mixing barium hydroxide and titanium raw material to form a rapid seed and slowly ingrowing under high temperature and high pressure, (C / a), has excellent particle size distribution, has almost no pores in its interior, has no large particles, has no necking, has excellent dispersibility, has a high surface density There is no aggregation phenomenon during firing and there is an effect of stable sintering in a wide range.

In addition, when barium titanate powder coated with silicon dioxide (SiO ₂ ) of the present invention is applied to a multilayer ceramic electronic component as a dielectric, necking between particles is suppressed at the beginning of firing, and the additive can be spread well along grain boundaries, By lowering the temperature, reliability and electrical characteristics of the parts can be improved.

Specifically, when barium titanate powder coated with silicon dioxide (SiO ₂ ) is used as a raw material, the final firing temperature at which densification is completed is delayed while inter-particle necking is delayed, thereby improving the connectivity of the internal electrode So that the capacitance can be increased.

1 is a flow chart showing steps in the method for producing highly crystalline silicon dioxide (SiO ₂₎ coated barium titanate according to an embodiment of the invention;
2 is an SEM (Scanning Electron Microscope) photograph of barium titanate powder according to Example 1 of the present invention.
3 is a TEM (Transmission Electron Microscope) photograph of barium titanate powder according to Example 1 of the present invention.
Figs. 4 and 5 are enlarged photographs of part of the photograph of Fig.
6 is an SEM (Scanning Electron Microscope) photograph of barium titanate powder according to Example 2 of the present invention.
7 is a TEM (Transmission Electron Microscope) photograph of barium titanate powder according to Example 3 of the present invention.
Figs. 8 and 9 are enlarged photographs of part of the photograph of Fig.
10 is a graph showing the results of STEM EDS (Scanning Transmission Electron Microscope Energy Dispersive Spectrometry) analysis of barium titanate powder according to Example 3 of the present invention.
11 is a graph showing the results of TMA (Thermo Mechanical Analyzer) measurement of barium titanate powder according to Examples and Comparative Examples of the present invention.
12 is a cross-sectional photograph of a multilayer ceramic capacitor manufactured using barium titanate powder according to an embodiment of the present invention.
13 is a cross-sectional photograph of a multilayer ceramic capacitor manufactured using barium titanate powder according to a comparative example of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention may be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. Furthermore, embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art. Accordingly, the shapes and sizes of the elements in the drawings may be exaggerated for clarity of description, and the elements denoted by the same reference numerals in the drawings are the same elements.

1 is a flow chart showing steps in the method for producing highly crystalline silicon dioxide (SiO ₂₎ coated barium titanate according to an embodiment of the invention;

Referring to FIG. 1, the process for producing highly crystalline barium titanate according to the present embodiment includes: (S1) preparing a barium hydroxide raw material by adding a substance containing silicon (Si) and then heating it to ionize barium Ba; Providing a titanium (Ti) raw material dispersed in an acid or a base (S2); Mixing and reacting the barium hydroxide and the titanium raw material to obtain a barium titanate seed (S3); (S4, S5) mixing the barium titanate titanate with pure water and a grain growth inhibitor and grain growth under high pressure; And a step (S6) for coating of silicon dioxide (SiO ₂₎ on the surface of the mouth of growth of barium titanate oxide; includes.

Barium hydroxide is used as the raw material of Ba.

(Si) -based salt or a silicon (Si) -based alkoxide and barium hydroxide octahydrate (Ba (OH) ₂ 8H ₂ O) as a substance containing silicon (Si) so that barium carbonate can not be formed by carbon dioxide in the atmosphere The mixture is stirred in a nitrogen atmosphere and heated to 70 DEG C or higher to completely dissolve the barium hydroxide to prepare barium hydroxide raw material in which barium (Ba) is ionized (S1).

In the present invention, it is important to completely ionize barium (Ba) raw materials under heating, since nucleation must be rapidly performed when mixed and reacted with a raw material of titanium (Ti) to be described later.

As the titanium (Ti) raw material, a functional titanium (TiO _{x / 2} (OH) _4-X ) or titanium oxide (TiO ₂ ) sol may be used. If titanium is used, a small amount of basic substance such as ammonia is added and milled and dispersed. The titanium oxide (TiO ₂ ) sol is preferably dispersed in acid or base rather than dispersing the carbon chain using a long dispersing agent. The smaller the particle size of the titanium raw material, the better (S2).

The dispersed titanium sol is rapidly mixed with the dissolved barium hydroxide octahydrate to obtain a barium titanate seed (S3). It is important that the barium (Ba) ion and the titanium (Ti) raw material react quickly at the moment of mixing.

In this reaction, the molar ratio of barium to titanium (Ba / Ti ratio) of the reactants is 1 or more and 3 or less, but may be 1.2 or more and 2 or less.

It is preferable to maintain the temperature at 50 캜 to 200 캜 or below and the temperature at 100 캜 to 150 캜 to maintain seed formation of barium titanate. After the completion of the seed generation, the temperature is lowered to 100 ° C or lower, and then the gaseous gas formed while purging with nitrogen is removed, which is effective for removing impurities such as a cracking agent.

In order to accelerate the reaction, the mixing temperature should be 80 ° C or higher. Then, the reaction is continued until the seed generation is terminated.

There are three methods to accelerate the seed production of barium titanate by mixing titanium raw material with barium raw material, namely ① rapid stirring, ② using microwave, and ③ using ultrasonic wave.

First, when using the rapid stirring method, a small hole is made in the closed reactor to connect the valve. Connect the tank for raw material input. Open the valve of the main reactor and purge it with nitrogen and lock it. After each tank is heated to 70 ° C to 200 ° C, the valve of the main reactor is opened to remove the gas pressure, and the valve of the tank containing the raw material is simultaneously opened and pressurized to rapidly feed the raw material. The impeller is rotated at the time of input so that the number of revolutions per minute is not less than 250 and not more than 50000. When the raw material input is completed, all the valves are closed and stirred, and the temperature is maintained until the seed generation is completed.

Next, when a microwave is used, a microwave induction terminal is inserted into the reactor, and a tank for injecting raw materials is connected to the reactor and sealed as in the case of the rapid stirring method. After purging the reactor with nitrogen, each raw material tank is warmed up. The valve of the main reactor is opened to remove the gas pressure, and the valve of the tank containing the raw material is simultaneously opened and pressurized to rapidly feed the raw material. When injecting, heat the microwave while turning the impeller. When the input of raw materials is completed, all valves are closed and stirred, and maintained at a temperature of microwave to react until the seed generation is completed.

Finally, in the case of using ultrasonic waves, it is preferable to use a tubular ultrasonic device as an ultrasonic device. The ultrasonic vibrating part is designed to be about 30% to 95% of the length of the reactor. The ultrasonic vibration part is put into the reactor and sealed. The titanium material is placed in the main reactor and the tank for barium raw material is connected and sealed. After purging the reactor with nitrogen, the main reactor and each raw material tank are also warmed. The valve of the main reactor is opened to remove the gas pressure, the ultrasonic wave is operated, and the valve of the tank containing the barium raw material is simultaneously opened and pressurized to rapidly feed the raw material. Rotate the impeller at the time of injection. Operate the ultrasonic wave and maintain the temperature until the seed generation is completed.

After the seed formation is completed, the formed seed is recovered. When exposed to the atmosphere, barium carbonate (BaCO ₃ ) may be formed.

According to an embodiment of the present invention, silicon (Si) may exist in a dissolved state in the recovered barium titanate seed.

As described later, the barium titanate surface may be coated with the silicon (Si) during the step of cooling the barium titanate seed.

It is recommended that the grain growth grow slowly at high temperatures. Slowly ingrowing with high energy, the atoms are arranged in the most stable state, and defects are removed. The grain growth is fast when the concentration is high or the pH is high. Therefore, after seed formation is completed, pure water is further added to lower the concentration and pH. At this time, the barium titanate titanate formed after the seed formation is precipitated, and the pH can be further lowered by partially discarding the filtrate.

The concentration of barium titanate in the grain growth is from 0.01M to 0.7M.

In order to slow the growth of the mouth, a mouth growth inhibitor may be added. Examples of the mouth growth inhibitor include Butylene Glycol, Dimethoxyethane, Hexanediol, Hexyleneglycol, Methoxyethanol Methoxyethanol), substances lowering the polarity of the solvent, substances lowering the pH such as acids including acetic acid and nitric acid, or substances such as sodium alkylsulfate, alkyl A substance which inhibits re-precipitation such as surfactants including alkylbenzene sulfonate, N-acrylamino acid salt, acrlyamide, diethanol amine, amine oxide and the like Can be used.

Specifically, though not limited thereto, the grain growth inhibitor may be at least one selected from the group consisting of ethyl silicate, silicic acid, vinytriethoxysilane, and tetrahydroxy silane. .

This step is carried out using an autoclave. The autoclave is filled with the precipitate prepared by the rapid seed formation method described above, pure water and an inhibitor of grain growth, and the autoclave is heated from 150 to 380 ° C for 1 to 72 hours The reaction is carried out with stirring for a period of time.

After lowering the temperature, the formed product is taken out, washed and filtered to remove excess barium and dried at 200 ° C or lower to obtain barium titanate powder coated with silicon dioxide (SiO ₂ ).

The silicon dioxide (SiO ₂ ) coating layer may be a layer type, and the average thickness of the coating layer may be 0.01 nm to 20 nm, but is not limited thereto.

In addition, the silicon dioxide (SiO ₂₎ coating layer is non-(tmax / tmin) that tmax / tmin ≤ 2.0 of the minimum thickness (tmin) compared to the maximum thickness (tmax) of which surrounds a uniform entirety of the barium titanate powder, the coating layer Can be satisfied.

As described above, the silicon dioxide (SiO ₂ ) coating layer uniformly surrounds the entire barium titanate powder particle, and the ratio of the maximum thickness tmax to the minimum thickness tmin of the coating layer is tmax / tmin < 2.0, the intergranular necking is suppressed at the initial stage of firing, and the initial firing is delayed, but when firing starts, rapid and stable firing can be achieved.

Accordingly, when the barium titanate powder coated with silicon dioxide (SiO ₂ ) is used as a raw material, the final firing temperature at which the densification is completed while delaying the inter-particle necking is reduced compared to the prior art, So that the capacitance can be increased.

When the ratio (tmax / tmin) of the maximum thickness tmax to the minimum thickness tmin of the coating layer exceeds 2.0, silicon dioxide (SiO ₂ ) is not uniformly coated on the surface of the barium titanate powder, the effect of delaying the necking and the effect of reducing the final firing temperature.

A 60 nm thick barium titanate powder coated with silicon dioxide (SiO ₂ ) and obtained by rapid seed formation and grain growth control as described above was subjected to rapid seed formation and grain growth control without seed formation and grain growth, A 60-nm thick barium titanate powder was mixed with a sintering additive, a plasticizer and a binder, respectively, and then a multilayer ceramic capacitor was prepared and heat-treated.

In the case of the powder synthesized by the method proposed by the present invention, even if the powder is uniformly formed after the completion of the densification and the powder is uniformly formed, but the powder having a low crystallinity is not synthesized due to rapid seed formation and grain growth control as in the present invention , And after the densification was completed, the grain growth was abrupt.

In the case of the powder of the present invention, not only the dielectric constant and the reliability are high but also the firing window is wide.

(SiO ₂ ) coated barium titanate powder according to another embodiment of the present invention has a silicon dioxide (SiO ₂ ) coating layer formed on its surface, and the average thickness of the silicon dioxide (SiO ₂ ) coating layer is 0.01 nm to 20 nm, and the ratio (tmax / tmin) of the maximum thickness tmax to the minimum thickness tmin of the coating layer can satisfy tmax / tmin? 2.0.

The high crystalline silicon dioxide (SiO ₂ ) coated barium titanate powder produced by the above-mentioned method for producing high crystalline silicon dioxide (SiO ₂ ) coated barium titanate has an average particle diameter of 5 to 200 nm and a crystal axis ratio (c / a) Is in the range of 1.003 to 1.010.

The crystal axis ratio (c / a) is 1.001 to 1.005 when the particle size of the barium titanate powder is 5 to 20 nm, 1.003 to 1.0055 when the particle size of the barium titanate powder is 20 to 40 nm, 1.0062, 1.0062 to 1.009 in the case of 60 to 80 nm, and 1.0080 to 1.01 in the case of 80 to 200 nm.

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments, but the present invention is not limited thereto.

Example 1)

(Barium hydroxide octahydrate (Ba (OH) ₂ 8H ₂ O) and 1 mol% of tetrahydroxy silane relative to barium hydroxide are poured into the reactor and dissolved by stirring at 100 ° C or higher. The titanium oxide (TiO ₂ ) sol is also prepared by heating to 60 ° C or higher. The barium (Ba) solution and the titanium oxide (TiO ₂ ) sol are rapidly added and mixed. And reacted at 110 ° C with stirring. Stirred at a high speed of 300 rpm or more, allowed to react for 10 minutes, and transferred to barium titanate to complete the seed formation.

Pure water is added to lower the concentration and pH of the mixture. At this time, the pH should be 11.5. The temperature was raised to 250 DEG C and barium titanate was grown for 20 hours.

The BET specific surface area of the powder obtained by washing with pure water after filtration and drying was 16.2 m ² / g, the particle size measured by SEM (scanning electron microscope) was 64 nm, D 99 / D 50 was 1.5, (C / a) value was 1.008.

2 is a SEM photograph of the powder obtained in Example 1. Fig.

FIG. 3 is a TEM (Transmission Electron Microscope) photograph of barium titanate powder according to Example 1 of the present invention, and FIGS. 4 and 5 are enlarged photographs of part of the photograph of FIG.

Referring to FIG. 3 to FIG. 5, it can be seen that a uniform silicon dioxide (SiO ₂ ) coating layer is formed on the surface of the powder obtained in Example 1.

Example 2)

The barium hydroxide octahydrate (Ba (OH) ₂ 8H ₂ O) and tetrahydroxy silane in an amount of 0.5 mol% based on the barium hydroxide are poured into the reactor and dissolved by stirring at 100 ° C. or higher. The titanium oxide (TiO ₂ ) sol is also prepared by heating to 60 ° C or higher. The barium (Ba) solution and the titanium oxide (TiO ₂ ) sol are rapidly added and mixed. And reacted at 110 ° C with stirring. Stirred at a high speed of 300 rpm or more, allowed to react for 10 minutes, and transferred to barium titanate to complete the seed formation.

Pure water is added to lower the concentration and pH of the mixture. At this time, the pH should be 11.5. TEOS (Tetraethoxysilane) is further added. The temperature was raised to 250 DEG C and barium titanate was grown for 1 hour.

The BET specific surface area of the powder obtained by washing with pure water after filtration and drying was 38 m ² / g, the particle size measured by SEM (scanning electron microscope) was 25 nm, D 99 / D 50 was 1.5, (C / a) value was 1.008. 6 is an SEM photograph of the powder obtained in Example 2. Fig.

Example 3)

(Barium hydroxide octahydrate) (Ba (OH) ₂ 8H ₂ O) and 5 mol% of vinytriethoxysilane relative to barium hydroxide are poured into the reactor and dissolved by stirring at 100 ° C or higher. Titanium oxide (TiO ₂₎ is prepared by heating to upset at least 60 ℃. Barium (Ba) solution and the titanium oxide (TiO ₂₎ sol is mixed with a rapidly added. And reacted at 110 ° C with stirring. Stirred at a high speed of 300 rpm or more, allowed to react for 10 minutes, and transferred to barium titanate to complete the seed formation.

Pure water is added to lower the concentration and pH of the mixture. At this time, the pH should be 11.5. The temperature was raised to 250 DEG C and barium titanate was grown for 20 hours.

The BET specific surface area of the powder obtained by washing with pure water after filtration and drying was 20 m ² / g, the particle size measured by SEM was 62 nm, the D99 / D50 was 1.5, the shape was spherical, The value of c / a was 1.0082.

FIG. 7 is a TEM (Transmission Electron Microscope) photograph of barium titanate powder according to Example 3 of the present invention, and FIGS. 8 and 9 are enlarged photographs of part of the photograph of FIG.

Referring to FIGS. 7 to 9, it can be seen that a uniform silicon dioxide (SiO ₂ ) coating layer is formed on the surface of the powder obtained in Example 3.

FIG. 10 is a graph showing the results of analysis of Scanning Transmission Electron Microscope Energy Dispersive Spectrometry of barium titanate powder according to Example 3 of the present invention. FIG.

Referring to FIG. 10, it can be seen that a uniform silicon dioxide (SiO ₂ ) coating layer is formed on the surface of barium titanate powder according to Example 3 of the present invention.

Comparative Example

All the other conditions were the same as those of Example 1, except that rapid seeding and rapid seeding were not performed, and stirring was performed at low speed. In addition, pure water and an inhibitor of grain growth were not added during the grain growth. The synthesized powders were very large and uneven.

11 is a graph showing the results of TMA (Thermo Mechanical Analyzer) measurement of barium titanate powder according to Examples and Comparative Examples of the present invention.

11, in the case of silicon dioxide (SiO ₂ ) -coated barium titanate powder according to an embodiment of the present invention, the inter-particle necking is delayed as compared with the comparative example, the shrinkage starting temperature becomes higher and shrinks rapidly at a high temperature .

When the silicon dioxide (SiO ₂ ) coated barium titanate powder according to the embodiment of the present invention is used as a raw material, the connectivity of the internal electrode can be greatly improved.

12 is a cross-sectional photograph of a multilayer ceramic capacitor manufactured using barium titanate powder according to an embodiment of the present invention.

13 is a cross-sectional photograph of a multilayer ceramic capacitor manufactured using barium titanate powder according to a comparative example of the present invention.

12 and 13, when a high crystalline silicon dioxide (SiO ₂ ) -coated barium titanate powder is used, the grain boundary of the dielectric grain does not occur even at a high temperature, whereas when uncoated barium titanate powder is used, It can be seen that the intestines grow a lot.

The present invention is not limited by the above-described embodiments and the accompanying drawings, but is intended to be limited only by the appended claims. It will be apparent to those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. something to do.

Claims (19)

Providing a barium hydroxide raw material ionized with barium (Ba) by adding a substance containing silicon (Si) and then heating;
Providing a titanium (Ti) raw material dispersed in an acid or a base;
Mixing and reacting the barium hydroxide and the titanium raw material to obtain a barium titanate seed;
Mixing the barium titanate titanate with pure water and a grain growth inhibitor to form a grain; And
A step of coating a silicon dioxide (SiO ₂₎ on the surface of the mouth of growth of barium titanate oxide;
Highly crystalline silicon dioxide containing (SiO ₂₎ coating method for producing a barium titanate.
The method according to claim 1,
The barium raw materials The method for manufacturing a highly-crystallized silicon dioxide (SiO ₂₎ coated with barium titanate, barium hydroxide octahydrate cargo.
The method according to claim 1,
The method comprising providing the barium hydroxide raw materials by stirring in a nitrogen atmosphere after the addition of material containing silicon (Si) on a barium hydroxide, a highly crystalline silicon dioxide, comprising a step of heating to melt above 70 ℃ (SiO ₂₎ coating Process for the preparation of barium titanate.
The method according to claim 1,
The titanium (Ti) raw material is amorphous silicon dioxide anti-caking as a function of titanium or titanium dioxide (SiO ₂₎ coating method for producing a barium titanate.
The method according to claim 1,
Steps of mixing, reaction of the barium hydroxide and titanium raw materials The method for producing a highly crystalline silicon dioxide (SiO ₂₎ coated barium titanate is performed in more than 80 ℃.
The method according to claim 1,
The method of the mixing barium hydroxide and titanium raw material, reacting-bonding is carried out by using any one of a rapidly stirred, microwave and ultrasonic-crystalline silicon dioxide (SiO ₂₎ coated barium titanate.
The method according to claim 1,
The mixing barium hydroxide and titanium raw materials, the mixing mole ratio of the barium and titanium in the step of reaction (barium / titanium) is 3 or less highly crystalline silicon dioxide over 1 (SiO ₂₎ coating method for producing a barium titanate.
8. The method of claim 7,
The mixing barium hydroxide and titanium raw materials, the mixing mole ratio of the barium and titanium in the step of reaction (barium / titanium) is 1.2 or less than or equal to two highly crystalline silicon dioxide (SiO ₂₎ coating method for producing a barium titanate.
The method according to claim 1,
Wherein the grain growth inhibitor is a material that lowers the polarity of the solvent, lowers the pH, and inhibits re-precipitation of the high-crystalline silicon dioxide (SiO ₂ ) coated barium titanate.
10. The method of claim 9,
The grain growth inhibitors are silicic acid ethyl (ethyl silicate), silicic acid (silicic acid), vinyl tri-ethoxy silane (vinytriethoxysilane) and tetra-hydroxy-silane is at least one highly crystalline silicon dioxide is selected from the group consisting of (tetrahydroxy silane) (SiO ₂₎ Coated barium titanate.
The method according to claim 1,
The concentration of the barium oxide is mixed in the grain growth step is 0.01 ~ 0.7 M of highly crystalline silicon dioxide (SiO ₂₎ coating method for producing a barium titanate.
The method according to claim 1,
Wherein the step of grain growth comprises mixing the barium titanate seed with the pure water and the grain growth inhibitor, sealing the mixture, and reacting the mixture in an autoclave at a temperature of 150 to 380 DEG C for 1 to 72 hours with stirring. (SiO ₂₎ coating method for producing a barium titanate.
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