KR100437482B1 - Method for producing multi-metal oxide powder - Google Patents

Abstract

The present invention relates to a method for producing a composite metal oxide powder, by improving the conventional solid-state method, a portion of the required amount of one or more metal oxides of weak reactivity among the metal oxide constituting the composite metal oxide metal salt or metal alkoxide The present invention relates to a method of eliminating the calcination process for forming a phase or significantly lowering the temperature by adding a solid solution to facilitate a solid solution reaction in a heat treatment process. Or it provides a simple process that does not require the grinding step for the fine powder and the filtration and washing step in the liquid phase method.

Description

Composite metal oxide powder manufacturing method {METHOD FOR PRODUCING MULTI-METAL OXIDE POWDER}

The present invention relates to a method for producing a composite metal oxide powder. More specifically, the present invention relates to a simple method for producing a composite metal oxide that can improve the conventional solid-state method to omit or lower the high temperature or repetitive heat treatment.

As a general method for producing metal oxide powder, solid phase method and liquid phase method are well known.

Commonly used solid-state method is iii) by mixing a metal oxide or metal carbonate in water or an organic solvent, ii) drying the mixed slurry, and iii) solid solution reaction between the mixed powder by high temperature heat treatment. It consists of the process of synthesize | combining the compound which has a new phase. In producing single-phase dielectric powders by this method, high temperature calcination, repeated calcination or grinding is often required. The synthesis of the metal oxide powder by this method is greatly influenced by the degree of mixing as well as the contact area where the solid solution reaction of the mixed powder occurs. Thus, solidarity has its own limitations.

On the other hand, the liquid phase method is a liquid phase mixing method in which a reaction may occur between molecules of a component by an efficient method of mixing reactants. Liquid phase methods include precipitation, coprecipitation, sol-gel processes and the like. The liquid phase method consists of i) dissolving a metal compound in water or an organic solvent and then precipitating to form a precursor such as a metal hydroxide compound or a composite metal compound, and ii) calcining the precursor powder to produce a composite metal oxide powder. The liquid phase method has the advantage of synthesizing a single phase dielectric at a lower temperature than the solid phase method, but the disadvantage is that the process is complicated and the starting material is expensive.

Agglomeration of the composite metal oxide precursor generally occurs during drying and heat treatment, and particularly, in the solid phase method, the heat treatment temperature is high and the size of the particles is increased. Therefore, the pulverization process is performed after the heat treatment. In this case, since it is easy to be contaminated during the grinding process, it is desirable to minimize the grinding process.

Hydrothermal synthesis is known as another method for producing a composite metal oxide powder. This process does not require calcination or pulverization, but high temperature and high pressure are required for the synthesis of the composite metal oxide powder, and the continuous process is difficult.

Several recent patents on the preparation of composite metal oxide powders disclose new processes for synthesizing composite metal oxide powders and processes which improve upon the known methods. U.S. Patent No. 5,783,165 discloses a method for producing barium titanate powder using barium carbonate in place of barium chloride or barium nitrate used in producing barium titanate by the oxalic acid method. U.S. Patent No. 5,846,505 discloses a method of producing a powder of ABO3 type which is a perovskite single phase and has excellent crystallinity by heat-treating a mixed powder of barium carbonate and titanium dioxide in an NH ₄ I or I ₂ atmosphere. . U.S. Patent No. 5,908,802 discloses a method for preparing lead-based perovskite powder by adding oxalic acid to an alcohol solution in which lead acetate and metal alkoxide are dissolved to precipitate a precursor of an oxalic acid composite metal compound. U. S. Patent No. 5,900, 223 discloses a method for producing perovskite powder into fine spherical particles of uniform size without heat treatment. Here, a method is introduced in which an acidic metal compound aqueous solution and a strong basic aqueous solution are simultaneously added to a high temperature basic aqueous solution to cause an immediate reaction and crystallization. In addition, U.S. Patent No. 6,007,870 discloses a structure having a core-shell by treating crystalline ceramic powder with hot water so that the surface of the ceramic powder is slowly dissolved in water, and then fine ceramic powder is accumulated on the surface during cooling. A method for producing a ceramic powder having improved sinterability is disclosed.

The present invention is a method of improving the solid-phase method to improve the reactivity of the solid solution reaction between the components, the manufacturing method according to the present invention is required amount of one or more metal oxides of weak reactivity among the metal oxide constituting the composite metal oxide By adding a portion of the metal salt or metal alkoxide to facilitate the solid solution reaction in the heat treatment process, there is an advantage that can omit the calcination step for forming the phase or lower the temperature significantly.

Therefore, the present invention can produce a single-phase composite metal oxide powder without requiring a high-temperature heat treatment, a repeated heat treatment and a pulverization process to obtain fine powder in the solid phase method and a filtration and washing process in a liquid phase method. It provides a simple and easy process.

The present invention relates to a more simplified method for producing a composite metal oxide powder.

The present invention is a method of improving the solid-phase method to improve the reactivity of the solid solution reaction between the components, the manufacturing method according to the present invention is stoichiometric of one or more metal oxides of weak reactivity among the metal oxide constituting the composite metal oxide Adding a portion of the required amount to the metal salt or metal alkoxide to facilitate the solid solution reaction in the heat treatment process.

More specifically, the process according to the present invention,

a) preparing a slurry by mixing a metal oxide constituting the composite metal oxide with a solvent by using one or more metal oxide powders having low reactivity, using less than stoichiometric amount required

b) mixing the slurry by adding an insufficient amount of a constituent metal oxide with a metal salt or a metal alkoxide,

c) hydrolyzing the added metal salt or metal alkoxide, and

d) removing the solvent of the mixture, drying, and heat treating the dried mixture to produce a composite metal oxide powder.

In the step a), the organic solvent is used as the solvent, the metal oxide powder is used less than the stoichiometric amount is required 90-95% or 90-99 mol% of the stoichiometric amount of the metal oxide, Preferably it means 90 to 97 mol%. Therefore, the amount of metal salt or metal alkoxide added is 5 to 10% by weight or 1 to 10 mol% of the stoichiometric requirement. If the amount of the added metal salt or metal alkoxide is less than the above range, it hardly affects it, and thus, the excellent effect cannot be expected. At this time, it is particularly preferable that the amount of the added metal salt or metal alkoxide is 3 to 10 mol%.

In the step b), as the metal salt to be added, it is preferable to use a metal nitrate as the metal alkoxide, such as propoxide, isopropoxide, isobutoxide or n-butoxide.

In the step c), the water used to hydrolyze the metal salt or metal alkoxide is used in excess of the stoichiometric necessary amount, it is particularly preferred to use 1.2 to 3 times the excess of water.

In step d), the solvent may be removed or dried by spray drying or rotary drying.

The composite metal oxide powder prepared by the method of the present invention includes, for example, Pb (Zr (1-w), Tiw) O ₃ (0 <w <0.6), (Zr (1-x), Snx) TiO ₃ (0 <x <0.8), PbTiO ₃ , BaTiO ₃ , (1-y) Pb (Mg _1/3 Nb _2/3 ) O ₃ -yPTiO ₃ (0 <y <0.5), and the like.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the scope of the present invention is not limited thereto.

<Example>

Example 1

Preparation of Pb [Zr (1-w), Tiw] O ₃ Powder

Lead oxide (0.10 mole), zirconium dioxide (0.0477 mole) and titanium dioxide (0.0423 mole) were placed together with isopropanol in a polypropylene vessel and mixed by ball milling for 24 hours using zirconia balls. Transfer the mixed slurry to a beaker, add zirconium n-propoxide (0.0053 mol) and titanium isopropoxide (0.0047 mol), hydrolyze by adding excess water, and then at room temperature for 4 hours. Stirred. Solvent was removed by rotary evaporator. The dried powder was calcined and sintered at various temperatures, and the characteristics at each temperature are shown in Table 1.

Sintered Density and Dielectric Properties Calcination Temperature (℃) Sintering Temperature (℃) Density (g / cm ³ ) Dielectric constant Dielectric loss (%) Resistivity (Ω.cm) 100 10001100 7.597.73 11601270 2.61.0 6.8E112.1E12 700 10001100 7.727.71 12601350 1.60.5 4.6E114.6E11 800 10001100 7.647.37 11601370 1.00.6 4.4E116.2E11

Comparative Example 1

Lead oxide (0.1 mol), zirconium dioxide (0.053 mol) and titanium dioxide (0.047 mol) were placed together with isopropanol in a polypropylene vessel and mixed by ball milling for 24 hours using zirconia balls. The mixed slurry was dried using a rotary evaporator to obtain a powder. The powder thus dried was calcined at 800 ° C. for 2 hours to obtain a perovskite single phase. As can be seen in Table 1, the production method according to Example 1 produced a powder having excellent physical properties even at a lower calcination temperature than the method according to Comparative Example 1.

Example 2

Preparation of PbTiO ₃

Lead oxide (0.10 mole) and titanium dioxide (0.090 mole) were placed together with isopropanol in a polypropylene container and mixed by ball milling for 24 hours using zirconia balls. The mixed slurry was transferred to a beaker, hydrolyzed by the addition of 0.01 mol titanium isopropoxide and the addition of excess water, stirred at room temperature for 4 hours, and then the solvent of the slurry was removed by rotary evaporator. The dried powder was calcined at 600 ° C. for 2 hours. X-ray diffraction analysis showed that PbTiO ₃ was produced in a single phase.

Example 3

Preparation of (Zr (1-x), Snx) TiO ₃ (Zirconium stannic titanate: ZST)

Tin dioxide (0.02 mol), zirconium dioxide (0.072 mol) and titanium dioxide (0.09 mol) were placed in a vessel with polypropylene isopropanol and mixed by ball milling for 24 hours using zirconia balls. The mixed slurry was transferred to a beaker, and hydrolyzed by adding 0.008 mol zirconium n-propoxide and 0.01 mol titanium isopropoxide and adding excess water while stirring. Solvent was removed on a rotary evaporator. The dried powder was calcined at 1250 ° C. for 2 hours. X-ray diffraction analysis confirmed that a ZST single phase was obtained.

Comparative Example 2

Powder obtained by mixing tin dioxide (0.02 mol), zirconium dioxide (0.08 mol) and titanium dioxide (0.10 mol) together with isopropanol in a polypropylene container with a ball mill for 24 hours using zirconia balls and drying the powder After calcining at for 4 hours to obtain a ZST single phase, in this case, it can be seen that a higher calcination temperature than in the preparation according to Example 3.

Example 4

Preparation of 0.9 [Pb (Mg _1/3 Nb _2/3 ) O ₃ ] -0.1PbTiO ₃ (0.9PMN-0.1PT) Powder

Lead oxide (0.10 mole), niobium oxide (0.03 mole), and titanium dioxide (0.005 mole) were placed together with isopropanol in a polypropylene barrel and ball milled for 24 hours using zirconia balls (5 °). Then, 0.005 mol titanium isopropoxide was added and hydrolyzed by the addition of excess water, followed by addition of 0.03 mol magnesium nitrate solution. Each addition was ball milled for 2 hours after each addition. Solvent was removed by rotary evaporator. The dried precursor powder was calcined at 900 ° C. for 2 hours. As a result, it was confirmed that PMN-PT of perovskite single phase was obtained by X-ray diffraction analysis. The dried powder was calcined and sintered at various temperatures. The characteristics obtained at this time are shown in Table 2.

Sintered Density and Dielectric Properties Calcination Temperature (℃) Sintering Temperature (℃) Density (g / cm ³ ) Dielectric constant Dielectric loss (%) 100 100010501100 7.737.767.70 142011341811519 0.500.390.23 500 100010501100 7.547.557.60 156811523415170 0.620.390.37

Comparative Example 3

Lead oxide (0.10 mole), niobium oxide (0.03 mole), magnesium oxide (0.03 mole), and titanium dioxide (0.01 mole) are combined with isopropanol in a polypropylene barrel and ball milled for 24 hours using zirconia balls (5 °). After that, the mixture was dried and then calcined at 1200 ° C. for 4 hours to obtain a perovskite phase (˜95%). As can be seen in Table 2, the production method according to Example 4 produced a powder having excellent physical properties even at a lower calcination temperature than the method according to Comparative Example 3.

Comparative Example 4

Niobium oxide (0.03 mol) and magnesium oxide (0.03 mol) were mixed together with isopropanol and zirconia balls (5 °) in a polypropylene barrel and ball milled for 24 hours, the mixture was dried, and the dried powder was dried at 4O &lt; 0 &gt; C. The calcined powder was calcined at 800 ° C. for 2 hours by ball milling the column bite compound obtained by calcination for 24 hours using zirconia ball in isopropanol such as lead oxide (0.10 mol) and titanium dioxide (0.01 mol). To obtain a perovskite single phase powder. As can be seen in Table 2, the production method according to Example 4 produced a powder having excellent physical properties even at a lower calcination temperature than the method according to Comparative Example 3.

Example 5

Preparation of 0.9 [Pb (Mg _1/3 Nb _2/3 ) O ₃ ] -0.1PbTiO ₃ (0.9PMN-0.1PT)

Lead oxide (0.1 mole), titanium dioxide (0.01 mole), and niobium oxide (0.03 mole) were added together with isopropanol and zirconia ball (5 °) in a polypropylene barrel, ball milled for 24 hours, and then mixed with 0.03 molar magnesium nitrate. An aqueous solution was added and ball milled for 2 hours. Solvent was removed on a rotary evaporator. The dried powder was calcined at 900 ° C. for 2 hours. X-ray diffraction analysis confirmed that PMN-PT of perovskite single phase was obtained. The dried powder was calcined at various temperatures and then sintered. The characteristics obtained at this time are shown in Table 3.

Sintered Density and Dielectric Properties Calcination Temperature (℃) Sintering Temperature (℃) Density (g / cm ³ ) Dielectric constant Dielectric loss (%) 100 100010501100 7.717.727.69 139711210711239 0.430.370.32 500 100010501100 7.717.647.39 156611509914082 0.420.310.32

Example 6

Preparation of Barium Titanium (BaTiO ₃ ) Powder

Barium carbonate (0.10 mole) and titanium dioxide (0.095 mole) were mixed with isopropanol and zirconia ball (5 °) in a polypropylene barrel and ball milled for 24 hours, mixed with 0.05 mole titanium butoxide solution and ball milled for 2 hours. And hydrolyzed by adding excess water. Solvent was removed on a rotary evaporator. Single phase barium carbonate powder was calcined at 1000 ° C. by X-ray diffraction analysis. The particle size distribution was affected by calcination temperature and time. The results are shown in Table 4.

Sintered Density and Dielectric Properties Calcination temperature / hour (℃ / hour) Sintering Temperature / Hour (℃ / Hour) Density (g / cm ³ ) Dielectric constant Resistivity (Ω.cm) 1100 / 6Ti (O-iPr) 4 1250/21300/2 5.715.64 26992137 1.96E122.05E12 1100/6 Ti (O-iBu) 4 1250/21300/2 5.735.87 37553712 3.41E128.00E10

Comparative Example 5

Barium carbonate (0.10 mole) and titanium dioxide (0.10 mole) were mixed together with isopropanol and zirconia ball (5 °) in a polypropylene barrel and ball milled for 24 hours, then the mixture was dried and the dried powder was dried at 1200 ° C. Calcination for hours gave a perovskite single phase. As can be seen in Table 4, the preparation method according to Example 6 produced a powder having excellent physical properties even at a lower calcination temperature than the method according to Comparative Example 5.

The present invention adds a portion of the required amount of one or more metal oxide powders having weak reactivity to metal salts or metal alkoxides, thereby facilitating solid solution reactions between the constituents during the heat treatment process, thereby preventing phase formation in the conventional solid phase method. It provides a process for producing a simple composite metal oxide powder that can omit the calcination process or significantly lower the calcination temperature, does not require grinding to obtain fine powder, and does not require filtration and washing in the liquid phase method. In addition, by reducing the amount of the metal oxide powder used, the effect of reducing the manufacturing cost can also be obtained.

Claims (8)

At least two metal oxides selected from the group consisting of lead oxide, tin oxide, titanium oxide, zirconium oxide, barium oxide precursor, magnesium oxide and niobium oxide are mixed in a solvent, and at least one metal oxide having low reactivity among them Is mixed in an amount of 90 to 99 mol% of the stoichiometric amount by using less than the stoichiometric amount to prepare a composite metal oxide slurry, To the slurry is mixed by adding metal nitrate or C ₁ to C ₆ metal alkoxide by a deficiency of the stoichiometric requirement, Excess water is used to hydrolyze the added metal nitrate or metal alkoxide, Removing and drying the solvent of the mixture, the method of producing a composite metal oxide powder comprising the step of heat-treating the dried mixture. The method of claim 1, wherein the amount of the metal oxide to be used is in the range of 90 to 97 mol% of the stoichiometric amount, and the amount of the metal nitrate or metal alkoxide is in the range of 3 to 10 mol% of the stoichiometric amount. Way. delete delete delete The method of claim 1 or 2, wherein the metal alkoxide is propoxide, isopropoxide, isobutoxide or n-butoxide of a metal. The composite metal oxide of claim 1 or 2, wherein the composite metal oxide is formed of Pb (Zr _(1-w) , Ti _w ) O ₃ (0 <w <0.6), (Zr _(1-x) , Sn _x ) TiO _3. (0 <x <0.8), PbTiO ₃ , BaTiO ₃ or (1-y) Pb (Mg _1/3 Nb _2/3 ) O ₃ -yPTiO ₃ (0 <y <0.5). The process according to claim 1, wherein 1.2 to 3 times the amount of water used for the hydrolysis is used.