JP2000159786A - Organotitanium peroxide compound, its production and formation of complex oxide containing titanium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a new compound having high solubility in water, hardly causing hydrolysis or the like and stable in an aqueous solution or air, and expected to be used as a titanium source for production of barium titanate or the like extremely useful as a ferroelectric substance. SOLUTION: This new compound is a compound of the formula TiXAY(O2)Z (X, Y and Z are each 1-4; a ligand A is a carboxylic acid, acetylacetone, amines, or a peroxo ion), e.g. ammonium citratoperoxytitanate. The compound is obtained by allowing hydrogen peroxide to act on metal titanium to dissolve the titanium and to provide a titanium peroxide solution, dissolving one or more kinds selected from a carboxylic acid, acetylacetone, amines and a peroxo ion in an amount of >=1 molar time as much as the amount of the titanium in the titanium peroxide solution, and heating and drying the obtained solution. Citric acid, malic acid, glycolic acid and ethylenediamine tetraacetate are preferable as the ligand.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention can be used as a titanium source for producing powders, sintered bodies, thin films, fibers, and single crystals of oxides of titanium and composite oxides with other metals. , Organic titanium peroxy compounds that are stably soluble in water,
The present invention relates to a method for producing the same and a method for producing a titanium-containing composite oxide.

[0002]

2. Description of the Related Art As shown in Table 1, a titanium compound (organic titanate) which has high solubility in water and is stable in an aqueous solution and in air is not known at present.

[Table 1]

[0003] As shown in Table 1, a titanium compound has two or more valences.
Many are tetravalent. Titanium dioxide and the like are stable as used in pigments and the like, but do not dissolve in water at all. Titanium trichloride and the like dissolve in water, but are susceptible to air oxidation. Many titanium alkoxides are known, but all of them are very susceptible to hydrolysis, and thus require operation and storage in an inert gas atmosphere. Further, titanium alkoxide and trisacetylacetonato titanium salt have a very low flash point of about 15 to 74 ° C., and are extremely restricted in industrial operation and storage.

[0004]

SUMMARY OF THE INVENTION In view of such circumstances, the present inventors have high solubility in water and are stable in aqueous solutions and air without causing hydrolysis. The purpose is to propose a new titanium compound.

[0005] A titanium compound having such properties is expected to be used as a titanium source when producing barium titanate or the like which is extremely useful as a ferroelectric substance. Hereinafter, conventional techniques and problems in the production of barium titanate and the like will be described.

[0006] Ceramics having a perovskite structure have extremely excellent dielectric properties (ferroelectricity) and are important as raw materials for various electronic parts such as audio equipment and capacitors. For example, barium titanate, which is known as a perovskite-type ceramic, has conventionally been produced by any of a high-temperature solid-state reaction method, a coprecipitation method, and a sol-gel method. In the high-temperature solid-state reaction method, powders of titanium oxide and barium carbonate are used as raw materials, mixed, and fired at a high temperature to produce a target product. In the precipitation method, potassium potassium oxalate dihydrate (K ₂ TiO (C ₂ O ₄ ) ₂ .2H ₂ O) is dissolved in water, and a coprecipitate obtained by adding an aqueous barium nitrate solution thereto is filtered off. After drying, it is fired to produce the desired product. Sol-
In the gel method, an alkoxide of titanium and barium is dissolved in alcohol, water is added thereto, and the resulting gel is dried and fired to produce a target product.

In the high-temperature solid-state reaction method, powders, sintered bodies, and single crystals can be produced. However, firing at a high temperature of 1000 ° C. or more is necessary to complete the reaction. Deviation of composition occurs due to evaporation of component metals,
Also, heat treatment at a high temperature promotes abnormal grain growth, and there is a problem that reproducible electrical characteristics cannot be obtained.

Although the above-mentioned coprecipitation method can produce powders, sintered bodies, and single crystals, it is possible to lower the heat treatment temperature, but it involves precipitation, so that the high-temperature solid-state reaction method can be used. Similarly, there is a problem that thin films and fibers cannot be produced.

In the sol-gel method, powder, sintered body,
Although it is possible to produce thin films and fibers in addition to single crystals, it is more practical and can solve the above-mentioned problems, but the titanium alkoxide used as a titanium raw material is extremely incompatible with water. Due to its stability, there are problems such as that all operations and storage of raw materials must be performed in an inert gas atmosphere such as argon without moisture, and that a non-aqueous solvent must be used as a solvent.

As described above, the sol-gel method has the advantage of being excellent in reproducibility and being capable of producing a product in a desired form, but has no water-stable compound, and therefore has limitations in production. There was a problem that there were many. That is, the novel titanium compound aimed at by the present invention can be operated stably and under mild conditions without being subjected to various restrictions in the above-mentioned production of barium titanate and storage of the raw materials. Therefore, the novel titanium compound aimed at by the present invention is stably dissolved in water without using a non-aqueous solvent as in the above-mentioned sol-gel method, and accompanied by precipitation as in the case of a coprecipitation method. No powder, sintered body, single crystal,
It is expected that barium titanate having a desired form, such as a thin film or a fiber, can be produced, and that production that does not require firing at an extremely high temperature of 1000 ° C. or more as in a high-temperature solid-state reaction method can be performed.

[0011]

Means for Solving the Problems In order to achieve the above-mentioned object, the present inventor has set forth a formula Ti _X A _Y (O ₂ ) _Z (where 1 ≦ X
≦ 4, 1 ≦ Y ≦ 4, 1 ≦ Z ≦ 4), and the ligand A is one or more organic titanium peroxy compounds selected from the group consisting of carboxylic acids, acetylacetones, amines, and peroxo ions. And found that the powder and the aqueous solution are stable for a long period of time, and that the organic titanium peroxy compound is used as a starting material for titanium and water is used as a solvent. Regardless, it has been found that various titanium-containing composite oxides can be produced without generating precipitates on the way, and the present invention has been completed.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The ligand A in the organic titanium peroxy compound Ti _X A _Y (O ₂ ) _Z of the present invention is at least one selected from the group consisting of carboxylic acids, acetylacetones, amines and peroxo ions as described above. It is. As the carboxylic acid, α-hydroxycarboxylic acid (citric acid, malic acid, tartaric acid, citramalic acid, lactic acid, glycolic acid),
Tricarballylic acid, succinic acid, oxalic acid, maleic acid,
It is preferable to use malonic acid, acrylic acid, acetic acid. As the amines, it is preferable to use ethylenediamine and ethylenediaminetetraacetic acid (EDTA).
Further, among these ligands A, it is particularly preferable to use citric acid, malic acid, glycolic acid, and EDTA.

The organic titanium peroxy compound Ti _{X of the} present invention
When the number of Ti moles X in A _Y (O ₂ ) _Z exceeds 4, a polymer of titanium metal is formed and becomes insoluble in water. On the other hand, when the number of moles of the ligand A exceeds 4, the molecule is excessively ionized negatively and is easily decomposed. If the molar number Z of peroxo ions also exceeds 4, the molecules are excessively negatively ionized and are easily decomposed.

Such an organic titanium peroxy compound Ti
_X A _Y (O ₂ ) _Z is prepared by dissolving 1 part of titanium in a titanium peroxide solution obtained by dissolving hydrogen peroxide in titanium metal powder.
One or more times the molar amount of the above-mentioned carboxylic acid, acetylacetone, amines, and peroxo ion are added and dissolved, and the mixture is dissolved and heated and dried.

The obtained organic titanium peroxy compound Ti _X
A _Y (O _{2) Z} is a novel compound has a high solubility in water, the powder state _{(Ti X A Y (O 2} ) Z M W, M = (NH 4
⁺ ), K, Na, Cs, Rb) and in the state of an aqueous solution are stable for a long period of time. The flash point is also high.

The present invention also relates to an industrial application of the organotitanium peroxy compound as a metal salt of an organotitanium peroxy compound, an alkali metal, an alkaline earth metal, a transition metal element of the fourth to sixth period, a rare earth element, and an actinoid element. One or more compounds selected from the group consisting of and mixed and dissolved in water, the resulting solution is concentrated and gelled, and then the gel is coated on a thin film as it is or on an appropriate substrate, or Also proposed is a method for producing a titanium-containing composite oxide in which is stretched into a fibrous form and heat-treated at a predetermined temperature.

[0017]

EXAMPLES [Synthesis of Titanium Peroxycitrate Compound] First, about 0.25 g of titanium metal powder (350 mesh) was prepared.
20 ml of 30% aqueous hydrogen peroxide and 5 ml of 30% aqueous ammonia were mixed in a beaker and dissolved while cooling in a water bath to obtain a yellow transparent titanium peroxy solution. Next, citric acid was added to the obtained solution in an amount of 1 mol or more with respect to titanium. After the added citric acid was completely dissolved, it was dried by heating at 80 ° C. on a hot plate to obtain a yellow powder of the target titanium peroxycitrate compound. The powder was analyzed by X-ray diffraction, Raman spectroscopy, and carbon-13 NMR spectroscopy to obtain a titanium peroxycitrate compound (NH ₄ ) ₄ [T
i ₂ (C ₆ H ₄ O ₇ ) ₂ (O ₂ ) ₂ ] .4H ₂ O.

Table 2 shows the properties of the obtained titanium peroxycitrate compound.

[Table 2] In addition, the evaluation symbol in the column of solubility and stability in the table,
The following contents are shown. The same applies to Table 3 described later. Solubility: ＝= 50 g or more dissolved in 100 g of water. ＝= 10 to 50 g dissolved in 100 g of water. Δ = 1 to 10 g dissolved in 100 g of water. × = insoluble in water or 1 g or less in 100 g of water. Stability: ＝= stable for a long time without hydrolysis. ＝= Hydrolyses very slowly but maintains water solubility. Δ = gradual hydrolysis and insolubilization. × = Very fast hydrolysis and insolubilization.

[Synthesis of Titanium Peroxymalate Compound]
First, metal titanium powder (350 mesh) of about 0.25
g, 30% hydrogen peroxide solution 20 ml, 30% ammonia solution 5
ml was mixed in a beaker and dissolved while cooling in a water bath to obtain a yellow transparent titanium peroxy solution.
Next, malic acid was added to the obtained solution in an amount of at least 1 mol of titanium. After the added malic acid was completely dissolved, it was heated and dried at 80 ° C. on a hot plate to obtain a yellow powder of the target titanium peroxymalate compound. The powder was analyzed by X-ray diffraction, Raman spectroscopy, and carbon-13 NMR spectroscopy to obtain a titanium peroxymalate compound (NH ₄ ) ₂ [T
_{i 2 (C 4 H 3 O} 5) 2 (O 2) 2] · 4H was confirmed to be ₂ O. Table 2 also shows the properties of the obtained titanium peroxymalate compound.

[Synthesis of Titanium Peroxyglycolic Acid Compound] First, a titanium metal powder (350 mesh) of about 0.2
5 g, 20 ml of 30% aqueous hydrogen peroxide and 5 ml of 30% aqueous ammonia were mixed in a beaker and dissolved while cooling in a water bath to obtain a yellow transparent titanium peroxy solution. Next, glycolic acid was added to the obtained solution in an amount of at least 1 mole of titanium. After the added glycolic acid was completely dissolved, it was heated and dried at 80 ° C. on a hot plate to obtain a yellow powder of the target titanium peroxyglycolic acid compound. The powder was analyzed by X-ray diffraction, Raman spectroscopy, and carbon-13 NMR spectroscopy to obtain a titanium peroxyglycolic acid compound (NH ₄ ) ₄ [Ti ₂ (C ₂ H ₂ O ₃ ) ₄ (O ₂ ) ₂ ] .4H ₂ O was confirmed. The properties of the obtained titanium peroxyglycolic acid compound are also shown in Table 2.

[Synthesis of Titanium Peroxy EDTA Compound]
First, metal titanium powder (350 mesh) of about 0.25
g, 30% hydrogen peroxide solution 20 ml, 30% ammonia solution 5
ml was mixed in a beaker and dissolved while cooling in a water bath to obtain a yellow transparent titanium peroxy solution.
Next, EDTA was added to the resulting solution in an amount of 1 mol or more with respect to titanium. After the added EDTA was completely dissolved, it was heated and dried at 80 ° C. on a hot plate to obtain a yellow powder of the target titanium peroxy EDTA compound. This powder was subjected to X-ray diffraction, Raman spectroscopy, and carbon-13 NMR spectroscopy to obtain a titanium peroxy EDTA compound (NH ₄ ) ₄ [T
i ₂ (EDTA) ₂ (O ₂ ) ₂ ] .4H ₂ O. Table 2 also shows the properties of the obtained titanium peroxy EDTA compound.

Table 3 shows the properties of typical titanium alkoxides (three kinds) and trisacetylacetonato titanium salts (one kind) as comparative examples.

[Table 3]

[Strontium titanate (SrTi
Synthesis of O ₃ )] The titanium peroxycitric acid compound obtained as described above and strontium nitrate are used in a molar ratio T of metal.
i: Sr was weighed so as to be 1: 1 and dissolved in water. The obtained solution was stirred while being heated to 80 ° C., and water was gradually evaporated to produce a gel. The obtained gel is 35
The precursor was heated and decomposed in a heating mantle set at 0 ° C. to obtain a precursor. The obtained precursor was heated at 250 ° C.
Heat treatment was performed at 0 ° C., 400 ° C., 450 ° C., and 500 ° C. for 12 hours each, and at 550 ° C., 600 ° C., and 650 ° C. for 2 hours. As can be seen from the X-ray diffraction pattern in FIG.
The precursor and the powder obtained by the heat treatment at 250 to 400 ° C. were amorphous. On the other hand, crystallization of strontium titanate started at 450 ° C., and at 500 ° C. or higher, single-phase strontium titanate was obtained.

[Barium tetratitanate (BaTi
Synthesis of ₄ O ₉ )] The titanium peroxycitric acid compound obtained as described above and barium nitrate are used in a molar ratio of metal Ti: B.
The sample was weighed so that a became 4: 1 and dissolved in water. The precursor obtained through the same steps as in the synthesis of the strontium titanate was heated at 700 ° C. and 800 ° C. in air at 2 ° C., respectively.
Heat treated for hours. As can be seen from the X-ray diffraction pattern in FIG. 2, single-phase barium tetratitanate was obtained by the heat treatment at 800 ° C.

Although several embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be implemented in any manner unless the configuration described in the claims is changed. it can. For example, titanium peroxy compounds are not limited to ammonium salt forms, but may be K, N
Confirmation experiments were also performed on the respective salt forms of a, Cs, and Rb. In addition, confirmation experiments were performed on other ligands, and it was confirmed that a similar three-dimensional structure was obtained. Further, the titanium-containing composite oxide is not limited to the examples described above, and may include an alkali metal, an alkaline earth metal, a fourth to sixth period transition metal element,
It has been confirmed that various composite oxides can be similarly produced using metal salts of rare earth elements and actinoid elements. Furthermore, it was confirmed that not only powder but also a thin film and a fiber could be processed and heat-treated to produce the same.

[0026]

As described above, the organotitanium peroxy compound of the present invention is a novel compound,
Unlike the titanium alkoxide used in the gel method, it is not affected by moisture or moisture, is stable in a powder state or an aqueous solution state over a long period of time, and has high solubility in water. In addition, it has a high flash point, an excellent property not found in conventional organic titanates. Therefore, the organotitanium peroxy compound of the present invention can be easily used in a general-purpose facility without requiring an inert gas or the like for handling operation and storage, and is extremely useful as a titanium source for various titanium-containing composite oxides. Useful.

The method for producing an organotitanium peroxy compound of the present invention can be produced under mild conditions using water in the air without using special equipment, equipment, expensive reagents and the like. Extremely practical.

Further, the method for producing a titanium-containing composite oxide of the present invention uses an organic titanium peroxy compound which is stably soluble in water as a starting material and does not involve the formation of precipitates as in the conventional coprecipitation method. Not only a sintered body and a single crystal, but also a thin film and a fiber can be produced, and they can be produced without requiring firing at an extremely high temperature of 1000 ° C. or more as in a high-temperature solid-state reaction method.

[Brief description of the drawings]

FIG. 1 shows the X of strontium titanate obtained in Examples.
4 is a chart showing a line diffraction pattern.

FIG. 2 shows the X of barium tetratitanate obtained in an example.
4 is a chart showing a line diffraction pattern.

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Claims (3)

[Claims] 1. The compound represented by the general formula: Ti _X A _Y (O ₂ ) _Z (where 1 ≦ X ≦ 4, 1 ≦ Y ≦ 4, 1 ≦ Z ≦ 4), and the ligand A is a carboxylic acid. , Acetylacetone,
An organic titanium peroxy compound, which is at least one selected from the group consisting of amines and peroxo ions. 2. A titanium peroxy solution, which is prepared by dissolving a metal titanium powder by the action of a hydrogen peroxide solution, adding and dissolving at least one selected from the group consisting of carboxylic acid, acetylacetone, amines and peroxo ions to titanium. Is dried by heating. 3. The organic titanium peroxy compound according to claim 1, and at least one selected from the group consisting of alkali metal, alkaline earth metal, fourth to sixth period transition metal elements, rare earth elements, and metal salts of actinoid elements. After mixing and dissolving the compound in water and concentrating and gelling the obtained solution,
A method for producing a titanium-containing composite oxide, comprising heat-treating at a predetermined temperature.