JPH1171103A - Precursor of composite metal oxide and production of composite metal oxide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a precursor of a uniform chemical composition without impurities remaining by removing water from an aqueous solution containing a plurality of metal compounds of different metal elements decomposing lower than a specific temperature to vaporize the other components than the metal elements. SOLUTION: A metal compound that decomposes at <=450 deg.C, preferably at <=250 deg.C and vaporizes the components other than the metals, for example, a complex or a metal salt of an organic acid that satisfies these conditions are preferably used as a water-soluble metal compound. The complexing substance is, for example, acetic, formic, acrylic, maleic, citric or benzoic acid, even when it is an ammonium salt of the complex, no NOx occurs. These organic acid is used in the form of an organic acid salt but the combination thereof with a complex is preferred. In a preferred embodiment, transition metal elements are used as a metal, Ti, Zr, Ta, Bi and the like can be used in the field of ferroelectric substance and rare earth elements as Eu, Ce, Sm and the like can be used in the field of fluorescence. A plurality of aqueous solutions of water-soluble metal compounds are subjected to spray drying to remove the water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite metal oxide precursor and a method for producing a composite metal oxide, and more particularly, to a composite metal oxide precursor and a composite metal oxide having a uniform chemical composition. It relates to a manufacturing method.

[0002]

2. Description of the Related Art Composite metal oxides, particularly composite metal oxides containing transition metals, are used for magnetic materials, dielectrics, phosphors, photocatalysts and the like. Such a composite metal oxide is required to be highly single-phased or ultrafine-particled, have a uniform chemical composition, and be manufactured by a simple operation as much as possible.

Conventionally, a composite metal oxide is produced by a solid-state reaction method in which powdery oxides of two or more metals are mixed and heated at a high temperature, or a composite metal oxide is prepared from a solution in which raw materials are dissolved. A liquid phase method in which a precursor of an oxide is separated and the obtained precursor is subjected to an oxidation treatment is used.

[0004] The above-mentioned solid-phase reaction method is simple in process, but unreacted raw material oxides and the like remain in a product, so that a composite metal oxide having a uniform chemical composition cannot be obtained.
There are drawbacks such as a high temperature required for the reaction.

[0005] In the liquid phase method, (a) a metal salt of an organic acid is dissolved in an organic solvent, and then a part of the organic solvent is evaporated by heating to obtain a gel-like precursor. Citric acid method for thermal decomposition of the body
Vol. 10, No. pp. 943-949), (b) a coprecipitation method in which a precipitating agent such as an alkali or oxalic acid is added to an aqueous solution of a metal salt to precipitate a hydroxide or an oxalate of the metal, and the obtained precipitate is oxidized; (C) an alkoxide method for thermally decomposing a metal alkoxide obtained by reacting a metal compound with an alcohol, (d) a group of metal ions capable of forming a composite metal oxide and a complexable organic substance capable of decomposing under the action of heat A method of forming a stable solution, and rapidly concentrating the solution to thermally decompose the obtained product (for example, JP-B-49-6040)
And (e) a complex polymerization method in which a metal salt or alkoxide and an oxycarboxylic acid or a polyamino chelating agent are polymerized with a polyol in a solvent (JP-A-6-11).
No. 5934).

The citric acid method (a) and the alkoxide method (c) require a step of removing the organic solvent from the raw materials, and the operation is complicated. Furthermore, at the time of solvent removal, a uniform composite metal oxide cannot always be obtained due to the difference in solubility of each raw material compound. In particular, in the alkoxide method, it is extremely difficult to uniformly disperse the individual components in the raw materials due to the difference in the hydrolysis rate of each metal element. The coprecipitation method (b) is applied only to a specific metal element. When there are many kinds of metal elements, a composite metal oxide having a target metal ratio cannot be obtained.

The method (d) described in Japanese Patent Publication No. 49-6040 discloses a method of preparing a solution of a starting material, which comprises "an ion containing each (metal) element combined in a chemical compound to be produced". And "an extremely complex organic substance that can be decomposed by the action of heat". The above-mentioned "ion containing a (metal) element" is obtained from metal nitrates, sulfates, phosphates, chlorides, and the like. In many examples, metal nitrates are used. However, in the above-mentioned method, the produced composite metal oxide contains residual impurities, and a uniform composite metal oxide is not always obtained. In the method (e) described in JP-A-6-115934, a phosphor having a uniform chemical composition can be obtained by being highly monophasic or ultrafine, but a large amount of organic substances must be used. It has the disadvantage that it must be done.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a composite metal having a simple chemical process, containing no residual impurities, and having a uniform chemical composition. An object of the present invention is to provide a method for producing an oxide precursor and a composite metal oxide.

[0009]

The present inventors have conducted intensive studies on the method described in Japanese Patent Publication No. 49-6040 in order to achieve the above object, and as a result, have found that the method including "(metal) element If, for the preparation of "ions", certain compounds are used instead of metal inorganic salts, such as metal nitrates, sulfates, phosphates, chlorides, surprisingly, they do not contain residual impurities, In addition, they have found that a precursor of a composite metal oxide having a uniform chemical composition can be obtained.

The present invention has been completed based on the above findings, and a first gist thereof is to prepare a metal compound aqueous solution by mixing a plurality of water-soluble metal compounds containing different metal elements with water, A method for producing a precursor of a composite metal oxide for removing water from the aqueous metal compound solution, wherein the plurality of water-soluble metal compounds decompose at 450 ° C. or lower to vaporize components other than metal. And a method for producing a precursor of a composite metal oxide.

[0011] A second aspect of the present invention is to provide a composite metal solution in which a plurality of water-soluble metal compounds containing different metal elements are mixed with water to prepare a metal compound aqueous solution, and water is removed from the metal compound aqueous solution. A method for producing a precursor of an oxide, wherein a complex or a metal salt of an organic acid is used as the plurality of water-soluble metal compounds.

A third aspect of the present invention resides in a method for producing a composite metal oxide, which comprises oxidizing the precursor.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
First, a method for producing a precursor of a composite metal oxide according to the present invention will be described. In the present invention, (1) 450 ° C. or lower, preferably 25
It is important to use a metal compound which decomposes below 0 ° C. to vaporize components other than metal, (2) a complex or a metal salt of an organic acid. Most of the compound (1) is satisfied by the compound (2). Therefore, the following description is based on the compound of the above (2). In the present invention, the reasons for using the specific compounds as described above are as follows.

(1) When a complex or a metal salt of an organic acid is used, it is not necessary to remove a large amount of an organic solvent which needs to be recovered as in the citric acid method or the alkoxide method. The precursor manufacturing process is simplified.

(2) The ligands of the complex include nitrates, sulfates,
Unlike ions such as phosphates, silicates, and chlorides, they are sufficiently decomposed and disappear even at a low temperature of, for example, about 250 ° C., so that halogen, sulfur, nitrogen,
There is an advantage that there is no residual element such as silicon and phosphorus, and there is no concern about increasing the particle size. This is exactly the same in the case of metal salts of organic acids.

(3) Since the metal salt of an organic acid is composed of only a metal element, a carbon element, a hydrogen element, and an oxygen element, NOx,
There is no generation of harmful gases such as SOx and halogen gas. Such advantages are also obtained in the case of a complex that decomposes at a temperature much lower than the high temperature required for the generation of NOx and SOx, and can be achieved by selecting a ligand as necessary.

The complexing substance used in the complex is not particularly restricted but includes, for example, saturated monocarboxylic acids such as acetic acid, formic acid, propionic acid and butyric acid, and unsaturated carboxylic acids such as acrylic acid, methacrylic acid and maleic acid. Oxycarboxylic acids such as citric acid, lactic acid, tartaric acid, malic acid, hydroacrylic acid, lactic acid, and glycolic acid, and aromatic carboxylic acids such as benzoic acid, salicylic acid, itaconic acid, cinnamic acid, and fumaric acid are used. In the present invention, a complex in the form of an ammonium salt can be used for stabilization. Even when the complex in the form of an ammonium salt is used, there is no concern about generation of NOx as described above.
On the other hand, as the organic acid used for the metal salt of the organic acid, the same organic acid as described above is used.

In the present invention, from the viewpoint of solubility, it is particularly preferable to use a complex, and the use of a metal salt of an organic acid is preferably used in combination with the complex. Further, among the complexes, a complex using a carboxylic acid or an oxycarboxylic acid as a complexing substance is preferable, and a complex using lactic acid, acetic acid, acrylic acid, or salicylic acid is particularly preferable. These complexes have high solubility in water, stabilize the dissolved state of the metal in the aqueous solution, and have excellent stability such as the valency of each metal element added with good productivity during dehydration. For example, specific examples of complexes using lactic acid and acetic acid include hydroxy complexes and oxo complexes represented by the following structural formulas (I) to (VI). Among these,
Particularly preferred are hydroxy complexes of oxycarboxylic acids and metals represented by formulas (I) to (III).

[0019]

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[0020]

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As the metal, a metal whose valence is easily changed by another element coexisting with the metal is preferable, and a transition metal element is particularly preferable. Among them, Ti, V, Cr,
Mn, Co, Ni, Cu, Fe, Zr, Nb, Mo, H
f, Ta, W, Ir, Os, etc., 3B group (Ga, In),
Group 4B (Sn, Pb), group 5B (Sb, Bi), and group 6B (Po) have good stability in a metal compound solution, and their composition over time during production of a composite metal oxide. Little change.

In the above, PZT (Pb, Zr, Ti
Titanium (Ti), zirconium (Zr), tantalum (Ta), niobium (Nb), bismuth (Bi), etc., which are usually used for ferroelectric applications such as SBT (Sr, Bi, Ta). It is preferable to apply it in improving the polarization characteristics. In addition, europium (Eu), terbium (Tb), praseodymium (Pr), cerium (Ce), samarium (Sm), which are rare earth elements whose valences are easily changed, which are usually used in a light emitting center for phosphor use, Application to dysprosium (Dy) is also preferable because the valence of the element during drying and oxidation can be easily controlled.

That is, when the present invention is applied to the production of a phosphor, the metal elements constituting the matrix and the activator are uniformly mixed, and have excellent crystallinity and high purity. In addition, a fine particle phosphor having a particle size of 1 μm or less can be obtained. As the phosphor, for example, blue light-emitting phosphor Ba
MgAl ₁₄ O ₂₃ : Eu and others, Y ₃ Al ₅ O as a green light-emitting phosphor
₁₂ : Ce, Y ₃ Al ₅ O ₁₂ : Tb, etc., and a red-emitting phosphor Y
₂ O ₃ : Eu, (Y, Gd) BO ₃ : Eu, Sr (Ti,
Al) O ₃ : Pr and others.

In addition to the above-mentioned applications, the present invention also relates to a filter pigment for display, such as Al ₂ O ₃ .CoO
System, Fe ₂ O ₃ system, and other transparent conductors such as ITO (In, S
n-based), ATO (Sb, Sn-based), (Co, Fe) -based colored conductor as a display anti-reflection film, and LiCoO ₂ , LiNiO ₂ , and LiMn as positive electrode active agents for secondary batteries
₂ O ₄ can also be applied to other manufacturing.

The content of the metal in the aqueous solution of the metal compound is usually in the range of 5 to 80% by weight, preferably 40 to 70% by weight, based on the aqueous solution of the metal compound. The aqueous solution of the metal compound is prepared by weighing the amount of the water-soluble metal compound corresponding to the amount of each metal in the composite metal oxide and mixing it with water to form an aqueous solution.

In preparing the above-mentioned aqueous solution of the metal compound, the pH of the aqueous solution of the metal compound is usually in the range of 4 to 7, preferably 5 to 6. When lowering the pH of the aqueous metal compound solution, a carboxylic acid or an oxycarboxylic acid is usually added. When increasing the pH, add a small amount of a cationic compound such as ammonia, alcoholamine, alkyl alcoholamine, or a basic amino acid, which does not evaporate easily and does not remain, or does not easily generate harmful gas upon oxidation heating. Done by

The reason for adjusting the pH is that the pH, which precipitates as a hydroxide, is greater than 7, Y, Eu, Al, Mg, Z
n, Co, etc., and S whose precipitated pH is less than 4
By taking into account c, Hf, Ce, Ti, Zr, V, In, etc., and finely adjusting the pH to a range of 4 to 7 according to the pH at which the contained metal precipitates, the uniformity of each metal in the precursor is improved. This is because the mixing property can be further enhanced.

In order to stabilize various metals in the aqueous solution of the metal compound, the aqueous solution of the metal compound contains a polysaccharide such as polyvinyl alcohol and alginic acid, a natural sugar such as sucrose and glucose, and a surfactant such as polyoxyethylene alkyl ether. An agent or a derivative thereof can be added.

The method for removing water from the aqueous metal compound solution includes a heat drying method, a spray drying method, a reduced pressure drying method and a freeze drying method. Furthermore, there is a method of applying a mixed metal compound aqueous solution on a stationary or rotating substrate (for example, a Si wafer) and drying.

Of the above, the spray drying method is preferred from the viewpoint of productivity and operability. The spray drying method is a method of drying droplets generated by mechanically spraying using a spraying device, and the spraying method is usually an ultrasonic spraying method of generating droplets using ultrasonic waves. Or a two-fluid nozzle, but an electrostatic spraying method is also applicable. Further, in order to improve the wettability between the aqueous metal compound solution and the substrate, an organic solvent having a hydroxyl group such as alcohol and polyol was added to the aqueous metal compound solution subjected to the above treatment to prepare a uniform mixed solution. After applying the mixed solution, it can be dried.

In the case of the heating and drying method, drying is preferably performed at a temperature of less than 250 ° C. The reason is 250 ℃
If heat drying at temperatures above complexes or metal salts of organic acids is thermally decomposed, CHx, H ₂ O, to produce a variety of fragments, such as COx, occur localized redox reactions, mixed metal oxide This is because the dispersibility, uniform mixing property, or stability of valence of the metal in the precursor of the product is easily impaired.
The drying atmosphere does not necessarily need to be an oxidizing air atmosphere, and may be a neutral atmosphere such as a nitrogen atmosphere or a reducing atmosphere as necessary.

In any of the drying methods, when water in the aqueous metal compound solution is removed, the metal compounds uniformly mixed and dissolved in the aqueous solution do not separate and precipitate due to differences in their solubility and hydrolysis. Such considerations are necessary.

Next, a method for producing the composite metal oxide of the present invention will be described. The composite metal oxide is obtained by oxidizing a precursor of the composite metal oxide. In this case, the precursor of the composite metal oxide may be formed on the substrate. The oxidation treatment is generally performed by heating and baking means, and in this case, for example, an electric furnace, a gas furnace, a steam furnace, or the like can be appropriately used.

The oxidation treatment is usually performed after heating and evaporating components other than metals in the air. The heating and firing temperature in the oxidation treatment is usually 250 to 800 ° C., preferably 400 to 800 ° C.
~ 700 ° C. When the oxidation treatment temperature is lower than 250 ° C., there is a tendency that the components other than the metal of the precursor are not thermally decomposed and vaporized. When the oxidation treatment temperature is higher than 800 ° C., a part of the precursor tends to sinter and not be converted into a single phase or ultrafine particles, or the composition tends not to be stabilized by evaporation of the metal.

In the present invention, the oxidation treatment is performed in addition to the above.
Irradiation with vacuum ultraviolet rays or short-wavelength ultraviolet rays in the air, in a vacuum, or in an inert atmosphere can also be performed. In any case, according to the present invention, it is possible to obtain a composite metal oxide in which the precursor is crystallized by the oxidation treatment, the single phase is formed, the fine particles are formed, and the composition is stabilized.

In short, according to the present invention, by selecting a water-soluble metal compound containing a desired metal element, for example, PZT (Pb-Zr-Ti-based composite oxide), SBT
(Sr-Bi-Ta based composite oxide) and other ferroelectrics, Y
₂ O ₃ : Eu, (Y, Gd) BO ₃ : Eu, Sr (Ti,
Al) O ₃ : Pr, BaMgAl ₁₄ O ₂₃ : Eu, Y ₃ Al
₅ O ₁₂ : oxide phosphor such as Tb, Al ₂ O ₃
Oxide oxides such as CoO-based and Fe ₂ O ₃ -based (Co, F
e) colored conductor, LiCoO ₂ , LiNiO ₂ , LiM
A composite oxide such as a secondary battery positive electrode active material such as n ₂ O ₄ can be produced.

In particular, according to the present invention, it is possible to produce a desired composite metal oxide while eliminating the drawbacks of the conventional method which harms the environment by producing colored waste gas in duplicate during the production of the oxide. In addition, applications in which a film made of a desired composite metal oxide is formed on a substrate and used, for example, a film made of a ferroelectric substance is formed on a base such as a silicon wafer to manufacture various storage elements. In such cases, a metal salt compound is directly applied on a substrate to form a precursor, and then oxidized to form a composite metal oxide film, thereby providing a dense, pinhole-free and dielectric-free film. A ferroelectric film can be manufactured efficiently. In addition, for example, when a phosphor is formed on a substrate such as glass to produce a phosphor film such as a display or a fluorescent lamp, the phosphor contains a metal element constituting each of a host crystal and an activator. Oxidation treatment can be performed after applying a water-soluble compound of metal onto a substrate to form a precursor, so that a fine and dense phosphor in which the activator metal element is uniformly dispersed in the base (metal oxide crystal) can be efficiently used. It can be formed well on a substrate.

[0038]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention. The evaluation method used in the present invention is as follows.

(1) Evaluation of the uniformity of the chemical composition of the composite metal oxide: Observation of the X-ray diffraction diagram of the composite metal oxide with an X-ray diffractometer was caused by the composite metal oxide crystal and other by-products. Judgment was made based on the presence or absence of the obtained diffraction line, and the following two rankings were made. When the diffraction pattern of the metal oxide in the raw material component was not recognized and only the diffraction pattern of the synthesized composite metal oxide was recognized, the diffraction was indicated by ○, and the diffraction of the by-product alone such as the metal oxide in the raw material component was performed. The case where a pattern was recognized was indicated by x.

(2) Evaluation of change in chemical composition of composite metal oxide: After dissolving the obtained composite metal oxide, quantitative analysis of each added metal was performed by inductively coupled high-frequency plasma (ICP) analysis. The exact chemical composition was analyzed and ranked in the following two ways. The case where the amount of each additive metal in the starting material was unchanged and 100% consumed even after the synthesis was indicated by ○, and the case where the amount of each additive metal in the starting material changed after the synthesis was indicated by x.

(3) Impurity residual contamination evaluation of the composite metal oxide: After dissolving the obtained composite metal oxide, a chemical analysis was performed by ICP analysis to confirm the presence or absence of the element in the metal compound raw material. And ranked in two ways.場合 indicates that no element other than the metal in the metal compound raw material remained after the synthesis, and x indicates that the element other than the metal in the raw material remained after the synthesis.

(4) Evaluation of decomposition waste gas generated during production of composite metal oxide: Analysis of waste gas generated by decomposition during production of composite metal oxide, and the possibility of generation when nitrate is used When a certain yellow gas was not recognized, it was indicated by ○, and when it was recognized, it was indicated by ×.

Example 1 Lead acetate trihydrate (Pb (CH ₃ CO ₃₎ was added to 90 g of deionized water.
O) ₂ · 3H ₂ O) 228 g (0.6 mol) and 50 wt% dihydroxybislactato titanium having a pH of 7 (formula (I)
332 g (0.6 mol) of an aqueous solution of an ammonium salt of a compound represented by the following formula (manufactured by Nippon Soda) was added. After stirring the aqueous solution for 10 minutes, the pH was adjusted to 4.5. Next, water was removed from the above aqueous solution using a spray dryer (Okawara Kakoki Co., Ltd., model L8, two-fluid nozzle) at an air pressure of 3 kg / cm ² and a body temperature of 150 ° C. to obtain a composite metal oxide. Was obtained.

Next, the above-mentioned precursor was baked at 600 ° C. for 1 hour in the air and oxidized to obtain a composite metal oxide. In this oxidation treatment, no yellow gas generated in the case of nitrate as shown in Comparative Example 4 described later was found in the decomposed waste gas. FIG. 1 is an X-ray diffraction diagram of the composite metal oxide thus obtained. As is apparent from FIG. 1, no diffraction lines other than the diffraction line caused by the PbTiO ₃ crystal were detected. The evaluation results of the obtained composite metal oxide are shown in Tables 1 and 2 below.

Example 2 Lead acetate trihydrate (Pb (CH ₃ COO) ₂ ) was added to 9 g of deionized water.
3H ₂ O) 22.8 g (0.06 mol) and pH 7
33.2 g (0.06 mol) of an aqueous ammonium salt solution of 0 wt% dihydroxybislactato titanium (compound represented by the formula (I), manufactured by Nippon Soda) was added. The pH of the resulting aqueous solution after stirring was adjusted to 6.5. Next, the above aqueous solution was applied to the surface of the aluminum plate at a thickness of about 1 mm, and heated at an actual temperature of 100 ° C. in the air to remove water, thereby obtaining a precursor of the composite metal oxide.

Next, the above-mentioned precursor was baked at 600 ° C. for 1 hour in the air and oxidized to obtain a composite metal oxide. During this oxidation treatment, no yellow gas generated in the case of nitrate of Comparative Example 3 described later was recognized in the decomposed waste gas. The evaluation results of the obtained composite metal oxide are shown in Tables 1 and 2 below.

Example 3 In 9 g of deionized water, lead acetate trihydrate (Pb (CH ₃ CO _{3)
O) 2 · 3H 2 O)} 22.8g (0.06 mol), pH7
Ammonium salt of a 50 wt% aqueous solution of dihydroxybislactato titanium (compound represented by formula (I),
16.6 g (0.03 mol) of a 20 wt% aqueous solution of zirconyl acetate (compound represented by formula (IV), manufactured by Nippon Metal Chemical Co., Ltd.) 3 previously adjusted to pH 3 with acetic acid
3.78 g (0.03 mol) were added in this order. Then, after the pH of the obtained aqueous solution after stirring was adjusted to 6 with ammonia, 1 wt% of polyvinyl alcohol was added to the aqueous solution. Then, after applying the above aqueous solution to the surface of the heating rotary drum at a thickness of about 100 μm,
By heating at 00 ° C. to remove water, a precursor of the composite metal oxide was obtained.

Next, the above-mentioned precursor was baked at 600 ° C. for 1 hour in the air and oxidized to obtain a composite metal oxide. During this oxidation treatment, no yellow gas generated in the case of nitrate of Comparative Example 3 described later was recognized in the decomposed waste gas. The evaluation results of the obtained composite metal oxide are shown in Tables 1 and 2 below.

Example 4 Strontium lactate (Sr (CH ₃ CH (O
H) COO) ₂ ) 5 wt% in 96 g (0.018 mol)
213 g of bismuth citrate (C ₆ H ₅ BiO ₇ ) (0.02
4 mol), 5 wt% tantalum oxalate (TaO (CO
O) ₃ ) 314 g (0.017 mol), 27 g of 5 wt% niobium ammonium oxalate (NH ₃ NbO (COO) ₃ )
(0.004 mol) were added in this order. Then, the pH of the obtained aqueous solution after stirring was adjusted to 6 with ammonia, and then isopropyl alcohol (IPA) was added so as to be 50 wt% with respect to the aqueous solution. Then
Silicon wafer (4 inch dummy wafer, Shin-Etsu Astec, platinum electrode 0.2mμ)
The above aqueous solution was applied on the surface of (adhesion) with a thickness of about 2 μm, and then heated at an actual temperature of 150 ° C. to remove water, thereby obtaining a precursor of the composite metal oxide.

Next, the above precursor was baked in the air at 700 ° C. for 1 hour and oxidized to form a thin SBT ferroelectric film of about 0.3 μm on the wafer surface. In these series of composite oxide thin film formation process,
No colored gas such as yellow gas was generated in the waste gas generated during the oxidation treatment of the precursor.

Further, as a result of providing a platinum electrode on both surfaces of the SBT ferroelectric thin film and conducting the current, no phenomenon of dielectric breakdown was observed, and the insulating property was good. Then, as a result of performing a polarization process by applying a high electric field, the residual polarization amount is 5 μC
/ Cm ² or more, showing satisfactory characteristics as a ferroelectric. The evaluation results of the composite metal oxide obtained at this time are shown in Tables 1 and 2 below.

Comparative Example 1 223.2 g of PbO particles having a purity of 99.9 wt% or more (1
Mol) and 79.9 g (1 mol) of TiO ₂ particles were wet-mixed in a ball mill for 24 hours, dried, placed in a heat-resistant sintering vessel and heat-treated at 600 ° C. for 1 hour to obtain a composite metal oxide. No yellow gas due to nitrate was found in the waste gas. FIG. 2 shows the X of the composite metal oxide thus obtained.
A line diffraction diagram was shown. As is clear from FIG. 2, in addition to the diffraction line caused by the target PbTiO ₃ crystal, a diffraction line caused by a metal oxide in the by-produced raw material is also observed.
It has been found that the chemical composition of the obtained product is not always a uniform composite metal oxide. The evaluation results of the obtained composite metal oxide are shown in Tables 1 and 2 below.

Comparative Example 2 A composite metal oxide was obtained in the same manner as in Comparative Example 1, except that the firing temperature was changed to 800 ° C. FIG.
Shows an X-ray diffraction diagram of the composite metal oxide thus obtained. As is apparent from FIG. 3, the target PbTiO
_{In addition} to the diffraction line caused by the crystal of ₃ , a diffraction line caused by a metal oxide in the by-product raw material was also observed, and the chemical composition of the obtained product was not necessarily a uniform composite metal oxide. I knew it wasn't. The evaluation results of the obtained composite metal oxide are shown in Tables 1 and 2 below.

Comparative Example 3 In Example 2, lead acetate trihydrate (Pb (CH ₃ CO ₃
Example 2 except that 19.9 g (0.06 mol) of lead nitrate (Pb (NO ₃ ) ₂ ) was used instead of 2.8 g (0.06 mol) of O) ₂ .3H ₂ O). An aqueous solution of a metal salt was prepared in the same manner. The pH of this aqueous solution after stirring was about 1. Next, the above aqueous solution is applied to the surface of the aluminum plate to a thickness of about 1 mm,
By heating at 0 ° C. to remove water, a precursor of the composite metal oxide was obtained.

Next, the above-mentioned precursor was baked in the air at 600 ° C. for 1 hour and oxidized to obtain a composite metal oxide. During this oxidation treatment, yellow gas was observed in the decomposed waste gas. The evaluation results of the obtained composite metal oxide are shown in Tables 1 and 2 below.

Example 5 Magnesium acetate tetrahydrate (Mg) was added to 180 g of deionized water.
21.4 g (0.1 mol) of (CH ₃ COO) ₂ .4H ₂ O) and 32.2 g (0.2 mol) of AlOH (CH ₃ COO) ₂ (compound represented by the formula (VI)) were added. . After stirring the aqueous solution for 10 minutes, the pH was adjusted to 5.5. Then, using a spray dryer (Okawara Kakoki Co., Ltd., “model L8, disk nozzle; 16000 rpm”), the substance temperature was 1
Water was removed from the above aqueous solution at 50 ° C. to obtain a precursor of a composite metal oxide.

Next, the above-mentioned precursor was baked at 600 ° C. for 1 hour in the air and oxidized to obtain a composite metal oxide. At the time of this oxidation treatment, no yellow gas was recognized in the decomposed waste gas. Table 2 below shows the evaluation results of the obtained composite metal oxide.

Example 6 180 g of deionized water was mixed with zinc salicylate trihydrate (Zn (C _{6
H 5 (OH) COO) 2} · 3H 2 O) 39.4g (0.1
Mol) and aluminum lactate (C ₉ H ₁₅ AlO ₉ )
8 g (0.2 mol) were added. After stirring the aqueous solution for 10 minutes, the pH was adjusted to 4.5. Next, the above aqueous solution was applied to the surface of the titanium plate at a thickness of about 1 mm, and then heated at an actual temperature of 100 ° C. in the air to remove water, thereby obtaining a precursor of the composite metal oxide.

Next, the above precursor was baked at 600 ° C. for 1 hour in the air and oxidized to obtain a composite metal oxide. During this oxidation treatment, no yellow gas was found in the decomposed waste gas. Table 2 below shows the evaluation results of the obtained composite metal oxide.

Example 7 In 90 g of deionized water, yttrium acetate tetrahydrate (Y (CH ₃ C)
_{OO) 3 · 4H 2 O)} 8.2g (0.024 mole) and europium acetate tetrahydrate _{(Eu (CH 3 COO) 3} · 4H 2
O) 0.4 g (0.001 mol) was added. After stirring the aqueous solution for 10 minutes, the pH was adjusted to 5.5. Then, a vacuum dryer (manufactured by Okawara Seisakusho, "Batch type vacuum dryer B"
V-1 "), water was removed from the aqueous solution under the conditions of a degree of reduced pressure of 1 to 80 Kpa and an actual temperature of 120 ° C. to obtain a composite metal oxide precursor.

Next, the above-mentioned precursor was baked in the air at 600 ° C. for 1 hour and oxidized to obtain a composite metal oxide. During this oxidation treatment, no yellow gas was found in the decomposed waste gas. The resulting composite oxide is
From X-ray diffraction diagram, chemical analysis and measurement of emission spectrum, it was found to be an ultrafine phosphor having a composition of Y ₂ O ₃ : Eu and a particle diameter of 1 μm or less. And this phosphor has 2
As a result of irradiation with 54 nm ultraviolet light, red light with high luminance was emitted. Table 2 below shows the evaluation results of the obtained composite metal oxide.

Example 8 Yttrium acetate tetrahydrate (Y (CH) was added to 90 g of deionized water.
8.2 g (0.024 mol) of ₃ COO) ₃ .4H ₂ O) and europium acetate tetrahydrate (Eu (CH ₃ COO) ₃ .4)
H ₂ O) was added 0.4 g (0.0001 mol). At this time, the pH of the aqueous solution was adjusted to 5.5. Next, the above aqueous solution was applied to the surface of the aluminum plate at a thickness of about 1 mm, and heated at an actual temperature of 100 ° C. in the air to remove water, thereby obtaining a precursor of the composite metal oxide.

Next, the above precursor was baked at 600 ° C. for 1 hour in the air and oxidized to obtain a composite metal oxide. During this oxidation treatment, no yellow gas was found in the decomposed waste gas. From the results of the X-ray diffraction diagram, the chemical analysis, and the emission spectrum, the composite oxide film formed on the aluminum plate was found to have a composition of Y ₂ O ₃ : Eu and an ultrafine fluorescent particle having a particle size of 1 μm or less. It was a very dense and pinhole-free film composed of a body. 2 on this membrane
As a result of irradiation with 54 nm ultraviolet light, red light with high luminance was emitted. The evaluation results of the obtained composite metal oxide are shown in Tables 1 and 2 below.

Comparative Example 4 Yttrium nitrate hexahydrate (Y (NO
_Three)_Three・ 6 H_TwoO) 9.2 g (0.024 mol) and chloride
Europium hexahydrate (EuCl_Three・ 6H_TwoO) 0.36 g
(0.001 mol) was added. Stir the aqueous solution for 10 minutes
Later pH was about 1. Then, place it on the surface of the titanium plate.
After applying the above aqueous solution to a thickness of about 1 mm,
By heating at a temperature of 100 ° C to remove water, composite gold
A precursor of the group oxide was obtained.

Next, the above precursor was baked at 600 ° C. for 1 hour in the air and oxidized to obtain a composite metal oxide. During this oxidation treatment, yellow gas was observed in the decomposed waste gas. The resulting composite oxide film is represented by X
From the results of X-ray diffraction diagram, chemical analysis and emission spectrum measurement, it was found to be a phosphor in the form of ultrafine particles having a composition of Y ₂ O ₃ : Eu and a particle diameter of 1 μm or less. When this film was irradiated with ultraviolet light of 254 nm, it emitted red light with high luminance. Table 2 below shows the evaluation results of the obtained composite metal oxide.

[0066]

[Table 1]

[0067]

[Table 2]

[0068]

According to the present invention described above, a metal salt of a complex or an organic acid, that is, a metal compound which decomposes at 450 ° C. or lower, preferably 250 ° C. or lower to vaporize components other than metal is used. By doing so, a composite metal oxide precursor and a composite metal oxide having a uniform and stable composition in terms of chemical composition can be obtained. The precursor of the composite metal oxide and the composite metal oxide obtained by the production method of the present invention are suitably used as materials suitable for ferroelectrics, piezoelectrics, magnetics, phosphors, photocatalysts, and the like.

[Brief description of the drawings]

FIG. 1 is an X-ray diffraction pattern of the composite metal oxide obtained in Example 1.

FIG. 2 is an X-ray diffraction pattern of the composite metal oxide obtained in Comparative Example 1.

FIG. 3 is an X-ray diffraction pattern of the composite metal oxide obtained in Comparative Example 2.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI C01G 23/00 C01G 23/00 C 25/00 25/00 35/00 35/00 C C07F 7/00 C07F 7/00 A 7 / 24 7/24 7/28 7/28 F

Claims (10)

[Claims] An aqueous metal compound solution is prepared by mixing a plurality of water-soluble metal compounds containing different metal elements with water, and water is removed from the metal compound aqueous solution. A method for producing a precursor of a composite metal oxide, wherein a metal compound that decomposes at 450 ° C. or lower and vaporizes components other than metal is used as the plurality of water-soluble metal compounds. 2. A method for producing a precursor of a composite metal oxide, comprising preparing a metal compound aqueous solution by mixing a plurality of water-soluble metal compounds containing different metal elements with water and removing water from the metal compound aqueous solution. A method for producing a precursor of a composite metal oxide, wherein a complex or a metal salt of an organic acid is used as the plurality of water-soluble metal compounds. 3. The method according to claim 2, wherein the ligand of the complex is a carboxylate ion or an oxycarboxylate ion. 4. The method for producing a precursor of a composite metal oxide according to claim 1, wherein the metal element is a metal element whose valence can be changed by an element that coexists. 5. The method for producing a precursor of a composite metal oxide according to claim 1, wherein at least one of said metal elements is a transition metal element. 6. The method according to claim 1, wherein the metal element is at least one selected from the group consisting of titanium, zirconium, niobium, bismuth, europium, terbium, praseodymium, cerium, samarium and dysprosium. A method for producing a precursor of a composite metal oxide. 7. The method for producing a precursor of a composite metal oxide according to claim 1, wherein the pH of the aqueous metal compound solution is 4 to 7. 8. The composite metal according to claim 1, wherein an organic solvent having a hydroxyl group is added to the aqueous solution of the metal compound to form a uniform mixed solution, and then applied to a substrate to remove water. A method for producing an oxide precursor. 9. The method for producing a precursor of a composite metal oxide according to claim 1, wherein the water is removed by spray drying. 10. A method for producing a composite metal oxide, comprising oxidizing the precursor obtained by the method according to claim 1.