JPS59213602A - Composite metallic solution - Google Patents

Abstract

PURPOSE:To obtain a composite metallic soln. which is used for manufacturing high-purity, ultrafine grain of ceramics by adding a chelating agent to a mixed system of >=2 kinds of metallic alkoxides. CONSTITUTION:A chelating agent having >=2 carbonyl groups is added to a mixed system of >=2 kinds of metallic alkoxides contg. Ba, Ti etc., and dissolved in the presence of aldehyde to obtain the composite metallic soln. The soln. is hydrolyzable and stable in preservation. By heating this soln., ultrafine grain or thin films of a composite material of composite oxides for manufacturing ceramics contg. operational metals can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composite metal solution prepared by adding a chelating agent to two or more metal alkoxides, and a method for producing a composite material using the solution.

Composite materials, especially thin films and ultrafine particles with a uniform composition in which two or more metals exist in the form of oxides or nitrides (usually particles with a particle size of about 1 μm or less and which cannot be crushed mechanically) , have excellent electromagnetic, optical, and mechanical functions, and are useful as materials for functional ceramics that can be fully used as active elements, and research and development is progressing on these functional ceramics. It is no exaggeration to say that most of the properties of the desired product are controlled by the materials used. Conventional methods for producing functional ceramics include methods that utilize in-phase reactions between inorganic compounds. However, with this method, it is not possible to obtain materials that exhibit sufficient functionality, and it is also difficult to obtain materials with high purity, small particle size, and high stoichiometry.In addition, after dissolving metal inorganic salts in an aqueous solution, There are methods to obtain particles by co-precipitation with , alkali or polycarboxylic acid, or by thermally decomposing these.

However, most of the starting materials used in this method are inorganic carbonates, chlorides, sulfates, nitrates, etc. that become ionically active in aqueous solutions, so even when heat treated, ions become internal impurities. There are disadvantages such as the remaining grains, the grain size becoming too large due to grain growth, and the need for high-temperature firing treatment to obtain the desired product.

Therefore, as a method to solve these drawbacks, a method of producing highly pure and ultrafine ceramic raw materials at a lower heat treatment temperature than conventional methods has been investigated by hydrolyzing or directly thermally decomposing metal alkoxides, which are organometallic compounds. ing.

It is known that metal alkoxides can be purified to high purity using chemical methods, and that by direct thermal decomposition or hydrolysis followed by firing, they can be converted into highly pure, ultrafine particles that are ideal as raw materials for functional ceramics. It is being

However, in order to maximize its functionality, functional ceramic materials are rarely used as a single compound, and are often used with trace amounts of other components added or as a composite compound. many. Therefore, no matter how small the particle size is with a single composition, in order to achieve the desired composition, it is necessary to perform further heat treatment and stir a solid phase reaction, which may cause grain growth or chemical stoichiometry. may become unstable.

In order to obtain such a composite oxide containing two or more metals,
Attempts are being made to directly obtain the desired composite oxide by preparing a mixed metal alkoxide system or by synthesizing composite metal alkoxides and decomposing them, but these methods have the following drawbacks. be.

In other words, the hydrolyzability of metal alkoxides differs significantly depending on the element and the type of alkoxy group, and therefore a mixed system of two or more metal alkoxides is unstable and may not have a uniform composition. . Furthermore, in the case of complex metal alkoxides, isolation of the target product is difficult, components that become impurities are included, yields are low, and they are not practical. In particular, when the metal is a transition metal such as nickel, copper, cobalt, or zinc, many of their alkoxides are insoluble in organic solvents, so they cannot be hydrolyzed in a common solvent system, and a uniform powder cannot be formed. do not have. In this way, in the method using only metal alkoxides and composite metal alkoxides, there are limits to the combinations that can be used to form composite oxides, and the degree of freedom is limited.

In addition, methods are being considered to adjust the hydrolyzability of each metal alkoxide, such as increasing the number of carbon atoms in the alkoxy group to slow down the rate of hydrolysis. However, there is almost no improvement in stability.

In addition to being used to produce ultrafine powders, metal alkoxides are being used to form thin films of metal oxides. This method utilizes the hydrolyzability of metal alkoxides, and by applying metal alkoxides to the roots, hydrolyzing them with moisture in the air, and then heat-treating them, #mechanical oxide thin knees can be easily formed. available.

Application examples of thin film formation using this metal alkoxide include insulating films, alkali penetration prevention films, and antireflection films using tetraethyl silicate; heat ray reflective films using tetraisopropyl titanate, optical filters, and substrates for promoting adhesion with organic substances. However, for the above-mentioned reasons, methods using metal alkoxides have not yet been put to practical use.

Thin film technology is an important technology that forms the basis of the current electronic industry, and various thin films are produced mainly using air-through technology.

Composite oxide thin films are also expected to have a wide range of applications, including optical-related devices, memory materials, piezoelectric materials, and sensors, and some have even been put into practical use. However, thin film forming methods using hollow technology have high equipment costs, high utility costs, difficulty in forming large areas, high melting point oxides require multiple film formations, crystallinity and stoichiometry. A strong membrane that is difficult to change,
Currently, there are limitations to the fields of application due to disadvantages such as low productivity.

On the other hand, the manufacturing method of oxide thin film using metal alkoxide is simple and requires only inexpensive equipment, can be easily made into a large area, has high productivity and low cost, and has a uniform and stoichiometric property. This method has an advantage over the SiW film formation method that uses nasal air technology, such as good film change. If this method makes it possible to manufacture various thin composite oxide films, it will improve It is clear that one new application function will be found.

The present inventors focused on the fact that metal alkoxides easily react with chelating agents to produce metal chelates or partially chelated partial alkoxides, and as a result of extensive studies, they developed a mixed system of two or more metal alkoxides. When a chelating agent is added, metal alkoxides with poor stability and metal alkoxides with high angular rate of hydrolysis can preferentially rebound with the chelating agent and be stabilized, and transition metal alkoxides that are insoluble in organic solvents can also be stabilized with complex metal solutions. We have arrived at the present invention by discovering that the desired composite metal component can be stably converted by hydrolysis, and that an ultrafine particle thin film can be converted by handling in the same manner as a single metal alkoxide.

Although the detailed explanation of this reaction has not yet been elucidated, the addition of a chelating agent averages out the stability and hydrolyzability of two or more metal alkoxides, and there is also some coordination between the metals or a complex metal chelate component. It is thought that it is creating.

The metal alkoxide used in the present invention is not particularly limited in that it has a hydrolyzable alkoxy group,
For example, the general formula M1(OR1,)u, Ml(X)a(O
R1)b, Ml(01'1a(OR3)ゎ
, Ml[N(OR1)m]n, a single composition metal alkoxide, a partial metal alkoxide, a composite metal alkoxide, or a multimer of these metal alkoxides.

In the above general formula, M and N are the same or different metal atoms, such as lithium, sodium, potassium, mubidium, cesium, beryllium, magnesium, calcium, strontium, barium,
Titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, iron, nickel, cobalt, copper, zinc, cadmium, mercury, boron, aluminum, gallium, indium, thallium, silicon, germanium, tin, Lead, metal,
Examples include antimony, bismuth, selenium, tellurium, and lanthanoid metals.

R1, R2s and R3 are the same or different organic functional groups, preferably alkyl groups, aryl groups, alkenyl groups having 1 to 20 carbon atoms, particularly preferably 1 to 8 carbon atoms,
It is an aralkyl group or a hydroxyl-substituted product or a halogen-substituted product thereof.

n is the valence of metal eAy', and m is 1 for the valence of metal N.
Or a positive integer that is the sum of 2.

X is a halogen atom, an oxygen atom, a nitrogen atom, or various organic functional groups.

Among the metals M1, metals whose alkoxides can be easily produced and are inexpensive include, for example, aluminum, gallium,
Examples include yttrium, indium, silicon, titanium, germanium, zirconium, tin, vanadium, niobium, antimony, tantalum, bismuth, chromium, molybdenum, tungsten, manganese, iron, and especially iron, titanium, zirconium, silicon, and aluminum.

The compound that forms an alkoxide with the metal M may be any monohydric or polyhydric alcohol having an alcoholic hydroxyl group represented by the general formula HOR (R is the same as R1, R2 or R3 above). Preferred specific examples include: For example, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, pentyl alcohol, hexyl alcohol, 2-ethylhexyl alcohol, octyl alcohol, t-butyl alcohol, lauryl alcohol, 1,4-methane Examples include diol, glycerin, ethylene glycol, octyl alcohol, and monoalkyl ether of ethylene glycol.

Specific examples of metal alkoxides used in the present invention include those listed above, as well as those manufactured by DC Bradley (D, O, B
radley) et al., metal curvature alkoxycise (Meta
1 Alkoxides, 1978, Academic Press, Inc., may also be used.

Further, the metal alkoxide used in the present invention preferably has appropriate hydrolyzability and stability. Usually, their properties are determined by the frequency of the metal and alcohol being reacted; in general, the higher the number of carbon atoms in the alcohol used, the slower the rate of hydrolysis of metal alkoxides; Decomposition speed increases. Therefore, it is important to appropriately determine the metal and alcohol to be used depending on the desired hydrolysis rate and stability.

The chelating agent used in the present invention is not particularly limited, as long as it is soluble in the metal alkoxide mixed system among oxygen-containing compounds, nitrogen-containing compounds, sulfur-containing compounds, etc. that are conventionally known as chelating agents. Specific examples include EDTA (ethylenediaminetetraacetic acid), NTA (,
:) IJD triacetic acid), UDA (uramyl diacetic acid), dimethylglyoxime, dithizone, oxine, β-diketone, glycine, methylacetoacetate, ethyl acetoacetate, mercaptans, and monohydric carbones such as lylunic acid, oleic acid, octylic acid, etc. Examples include 1N or two or more types of polycarboxylic acids such as oxalic acid, citraconic acid, maleic acid, phthalic acid, and naphthenic acid. Particularly useful are β-diketones, methyl acetoacetate, ethyl acetoacetate, monocarboxylic acids and polycarboxylic acids.

Examples of the β-diketone include acetylacetone, diisobutyrylmethane, dipivaloylmethane, 3-methylpentane-2,4-dione, 2,2-dimethylpentane-3,5-dione, or fluorinated products thereof. Among them, acetylacetone is particularly preferred.

The solution of the present invention does not particularly require a solvent as long as the two or more metal alkoxides used are all liquid.
A common solvent is required when they are incompatible or in phase.

Common examples include monohydric or polyhydric alcohols;
Carboxylic acid esters; ketones; aromatic solvents such as benzene, toluene, and xylene; ethers such as dioxane and tetrahydrofuran; and nitrogen-containing organic solvents such as N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, and pyridine; A mixed solvent of two or more types may be mentioned. Among them, monohydric or polyhydric lower alcohols; lower carboxylic acid esters; ethers such as dioxane and tetrahydrofuran; and nitrogen-containing organic solvents such as N-methyl-2-pyrrolidone, dimethylformamide, and dimethylacetamide can be widely used in the present invention. However, the specific solvent may be appropriately selected depending on the combination of metal alkoxide and chelating agent used.

Note that when a chelating agent is added in the coexistence of two or more metal alkoxides, if a large amount of the chelating agent is used or if the chelating agent has a strong chelating ability, precipitation may occur and the two may not be compatible.

At that time, by adding an aldehyde and performing a heat treatment if necessary, a uniform solution can be obtained. The heat treatment is usually preferably carried out at a temperature below the reflux temperature of the solvent. This effect is particularly noticeable when the chelating agent is a β-diketone.

The addition of aldehyde has the effect of not only the above-mentioned solubilizing effect but also the effect of further suppressing the sublimation of the chelated metal complex.

Preferred aldehydes include aldehydes having 1 to 8 carbon atoms, particularly formaldehyde, paraformaldehyde, acetaldehyde, penzaldehyde, and the like.

The solubilizing effect of adding aldehyde is particularly excellent when the metal alkoxide used is a metal alkoxide of Group 1 or Group II of the periodic table, and a chelating agent is added to form a precipitate. 3-5
Excellent when a chelating agent is added to a valent transition metal alkoxide.

The amount of aldehyde used is 0.001 mol or more, usually 0.001 mol or more, per 1 mol of the chelating agent added. The above effect is exhibited at imol or more.

The amount of the chelating agent added must be such that the number of functional groups in the chelating agent is less than the total number of alkoxy groups in the metal alkoxide, and preferably the number of functional groups in the chelating agent is less than the total number of alkoxy groups in the metal alkoxide. 50 of the total number of bases
Adjust so that it is below %.

In the present invention, in addition to the common solvent, an organic acid or an antioxidant may be added in order to promote thermal decomposition or increase storage stability, and the film thickness may be controlled during thin film production. Therefore, thickeners such as cellulose polymers, polyhinyl acetate, glycerin, and polyethylene glycol, which have a viscosity adjusting effect, may be added, and other organic metals such as metal organic acids may be added to further replenish the metal components. Compounds may also be added. However, it is important that these additives are soluble in the common solvent and do not adversely affect the formation of ultrafine particles and thin films during thermal decomposition.

The solution used in the present invention is hydrolyzable like metal alkoxide alone and has excellent storage stability, and can easily form ultrafine particles or thin films of complex oxide composite materials containing any metal by heating. can be manufactured.

When using the composite metal solution of the present invention, a composite material with a desired composition can be obtained by selecting and combining various metal alkoxides. If you are aiming for a composite material containing alkali metals, alkaline earth metals, or metals that cannot form metal alkoxides, which have poor stability, or if you are aiming for a composite material in which trace components are uniformly mixed, it is extremely Useful.

Furthermore, by selecting various atmospheres during heating, the composition of the resulting composite material can be changed. For example, when heated in the air, composite oxides are converted, and when heat treated in a reducing atmosphere containing hydrogen, carbon monoxide, etc., composite metals (including alloys) are converted. Also NH3 and N2
Composite materials containing nitrides can be changed by heat treatment in a nitrogen atmosphere containing nitrides.

Methods for producing composite materials in the form of ultrafine particles include, for example, heating the composite metal solution as it is to pyrolyze it, adding a small amount of water or ammonia water to hydrolyze it, and then heating it to pyrolyze it. There are two methods: a method of thermally decomposing the solution by heating it in the form of a liquid or mist, and a method of gasifying the solution and then decomposing it with plasma or laser light. Ultrafine particles obtained by thermal decomposition in the form of dregs or plasma decomposition have particularly excellent dispersibility. Generally, the faster the thermal decomposition rate is, the smaller the particle size of the ultrafine particles and the better the stoichiometry.

The composite metal oxide thin film can be produced by applying the composite metal solution of the present invention onto a substrate by spraying, dipping, spin coating, etc. and then heating it to thermally decompose it. Methods such as spraying a solution and thermally decomposing it on the substrate, gasifying the solution and then heating it to thermally decompose it, or depositing the decomposed product on the substrate while decomposing it with plasma or laser light, or printing method, etc. In the case of using a metal alkoxide alone, the same method can be adopted.In particular, the coating method and the method of producing a thin film by spray pyrolysis are highly productive and practical with inexpensive equipment.

When manufacturing a thin film by a coating method, the metal component content in the solution is 0.01 to 20% (weight%, the same applies hereinafter), preferably 0.1 to 10%, and the heating temperature is 200 ° C or higher. Generally, a good quality thin film is replaced. If the metal component content is less than 0.01%, the coating components may burst on the substrate and cause coating unevenness, and if it is more than 20%, the film thickness after one coating will become thicker, so heat treatment is necessary. Cracks may occur due to thermal distortion and decomposition gas during the process, or the material may thermally decompose without adhering to the substrate and turn into particles, resulting in turbidity.

However, these conditions depend on the combination of the metal alkoxide and chelating agent used, the type of common solvent, the application method, and the application method.
X, f Vt: 1 The above conditions may be greatly reduced depending on the qi, so it is important to determine the optimal conditions according to each combination.

In addition, when using the dipping method, the pulling speed is 0.5
A thin film with excellent homogeneity can be obtained at a rate of ~100 cm2/min, preferably 2-200 l/min.

If a thin film is manufactured by the pyrolysis method, the substrate is heated in advance to a temperature of 200°C or higher, preferably 400°C or higher, and the metal component content in the solution is reduced to 0.0°C.
It is obtained by blowing air or an inert gas such as nitrogen, argon, or helium, or a gas containing water vapor as a carrier gas onto the substrate at a concentration of 1 to 20%, preferably 0.05 to 5%. . When a stable metal ketone complex is used, especially by including water vapor in the carrier gas, decomposition is improved and a thin film with excellent film quality and stoichiometry can be obtained. In order to improve the film quality, it is important to make the particles of the sprayed mist uniform and fine, and it is preferable to spray particles of 20 μm or less. For this purpose, it is preferable to vibrate the nozzle and the space in which the mist is scattered using high frequency or ultrasonic waves to make the mist uniformly fine, or to apply an electric field between the nozzle and the substrate to quickly deposit the mist on the substrate. Note that the throughput of the solution and the flow rate of the carrier gas vary greatly depending on the apparatus, and need to be adjusted appropriately.

The thickness of the thin film to be formed can be adjusted by adjusting the metal component content, viscosity, coating strength, etc. of the composite metal solution used, but in the dipping method, the film thickness is usually 100 to 30 mm thick with one coating.
000X, preferably 100 to 1500X, and in the spray pyrolysis method, 300
If it exceeds 3000X, it is preferable to perform a heat treatment and then reapply to remove the carbide. A laminate of thin films of the same or different compositions may be obtained by repeatedly applying solutions of the same or different compositions.

Note that by changing the heat treatment conditions of the composite metal solution, composite materials with different crystal states can be manufactured. Normally, at the beginning of heating, the material becomes an amorphous phase with no crystalline phase, and as it is further heated, crystallization gradually progresses. Therefore, by appropriately selecting the heating conditions, it is possible to change the thin film of the composite material to any desired crystalline state. This thin film formation method is unprecedented, and the resulting membranes with different crystal states can be expected to have new functions.

The amorphous phase is usually obtained at around 600 to 500°C, when the decomposition of the contained organic substances is completed, and at 400°C or higher, the formation of 71.11 products progresses. However, such temperature changes depending on the composition of the target composite material, so it is necessary to understand the tendency and adjust it each time.

Any material can be used as the substrate material as long as it can withstand the heat applied during thin film formation, such as glass, ceramic plates such as alumina and silica, metal plates such as stainless steel, metal foil, polyimide, etc. Examples include heat-resistant resin films, but those with excellent surface smoothness are particularly preferred.

The composite metal oxide fine particles and thin films obtained by the present invention are extremely promising as new functional materials, such as various sensor materials, conductive film materials, optical-related device materials, magnetic recording materials, piezoelectric collector materials, It has excellent performance as a dielectric material.

Next, the present invention will be explained based on Examples and Comparative Examples, but the present invention is not limited only to these Examples.

Example 1 Barium triimpropoxide 5', 177 and titanium tetraisopropoxide 5.69. was dissolved in 100 g of absolute ethyl alcohol, and an equimolar ratio of 2. When this was added, scuttling occurred. Furthermore, when 0.3y (0.5 molar ratio) of paraformaldehyde was added and refluxed for 10 minutes, a reddish-brown transparent homogeneous solution was obtained, and when the solvent was converted to tetrahydrofuran, it was stable for more than 1 month. Ta. This solution is hydrolyzable and can be applied to quartz glass (dip coating at a rate of 10 am/min to form a transparent thin film without clouding).
By firing this for 800°01 hour, transparent E
A TiO3 thin film was obtained.

In addition, by removing the solvent from this solution and baking it at 600°O for 1 hour, BaTi with a particle size of 0.1 μm or less was produced.
O3 ultrafine particles have been changed. Even after hydrolysis and calcination, BaTiO3 ultrafine particles were changed in the same way.

Example 2 15 g of iron triethoxide and 1,35 g of strontium diisopropoxide were used so that the molar ratio of Fe:Sr was 12=1. Dissolve in 100g of absolute ethyl alcohol and add 0.5F of acetylacetone! When added, scuttling occurred. Add 0.2g of formalin to this and
When the mixture was heated at 0°0 for 10 minutes, the scuttling dissolved and became a homogeneous solution.

After dipping this solution into a quartz glass plate at a speed of 100 m/min, it was baked at 800°O for 1 hour.
A thin illumination of red transparent strontium ferrite (Sr0.6Fe 203 ) with a thickness of about 1 aoo× was obtained.

Further, when the solvent was removed from this solution, the solution was dried and then fired at 8000c for 1 hour, strontium ferrite particles with a -order particle size of 0.08μ were obtained.

Example 6 Iron triisopropoxide 11.647 and zinc jetoxide 3.8 were mixed so that the molar ratio of Fe:Zn was 2:1.
When Zinc Jetoxide was added to 100 g of diluted ethyl alcohol, the zinc jetoxide did not dissolve but precipitated.

When citraconic acid 2y was added to this system with stirring and refluxed, a homogeneous solution was obtained.

After removing the solvent from this solution, it was calcined at 600°0 for 1 hour, resulting in Z nF e 204 with a particle size of 0.2μ.
Spinel ferrite powder changed.

Example 4 16.3y of lead diisopropoxide, 7.12g of titanium tetraisopropoxide, and 9,60y of zirconium tetrabutoxide were added to 100g of anhydrous ethyl alcohol so that the molar ratio was Pb:Ti:Zr=2:iz. After adding 10F! of oleic acid, the mixture was heated under reflux for 60 minutes to obtain a homogeneous solution.

This solution is bistable for more than 1 month and after removal of the solvent
By calcining for 1 hour at °G, p
b (z r o , 5 T 1o , 5 )03 powder was obtained.

When this solution was dipped onto a quartz glass plate at a rate of 10 am/min and fired at 800°○ for 1 hour, a transparent Bb (Zr.
5"Ti, 5)03 thin film was changed.

Comparative Example 1 As in Example 1, 5.17 tons of barium triisopropoxide and 5.691 tons of titanium tetraisopropoxide were used for a total of 100 y so that the Ba:T-0 molar ratio was 1:1.
After mixing with absolute ethyl alcohol, 10 am /
When dipped onto a quartz glass plate at a speed of
The surface becomes particulate and becomes a whitish thin film with poor uniformity 1
I only gained 14%.

When this solution was stored in a sealed container for 2 days, a large amount of precipitate was formed and it was found that the solution was poor in stability.

Comparative Example 2 As in Example 2, anhydrous ethanol was prepared by adding iron triethoxide and strontium isopropoxide so that Fe:sr=12:1 (molar ratio).
When this solution was left sealed for 2 days, a large amount of precipitate formed and it was found that the solution was poor in stability.

Claims (1)

[Claims] A composite metal solution comprising a chelating agent added to 12 or more metal alkoxides. 2. The solution according to claim 1, which contains a common solvent. 6. The solution according to claim 1, wherein the chelating agent is a ketone having two or more carbonyl groups. 4. The solution according to claim 1 or 2, which is dissolved in the presence of an aldehyde. A method for producing a composite material, which comprises heating a composite metal solution prepared by adding a chelating agent to 52 or more types of metal alkoxides.