JPH01313329A - Production of thin film of compound metal oxide - Google Patents

Abstract

PURPOSE:To obtain easily a thin film of a compound metal oxide from a mixture consisting of each specified compd. of Bi, Sr, Ca and Cu without causing generation of powder and without performing heat-treatment by dissolving said mixture in an org. solvent, coating the soln. on a substrate, and irradiating the coated substrate with ultraviolet rays and infrared rays. CONSTITUTION:A Bi alkoxide expressed by Bi(OR1)(OR2)(OR3), (wherein each R1 to R3 is 1-6C alkyl), is mixed with alkoxides of Sr and Ca expressed by A(OR1) (OR2), (wherein A is Sr and Ca), an org. acid salt of Cu(e.g., formate), a Cu alkoxide expressed by Cu(OR)l(X)m, (wherein R is R1; each l and m is zero or 1-2; l+m is 2; X is a group expressed by the formula I or II), and a beta-di-ketone complex or beta-ketoester complex in a proportion so as to contain same proportions of metals as those in an aimed compound metal oxide, and the mixture is dissolved in an org. solvent(e.g., ethanol). The soln. is then coated on a substrate(e.g., ZrO2) on a solid, and irradiated with ultraviolet rays and infrared rays, to cause decomposition and oxidation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a composite metal oxide thin film. More specifically, the present invention relates to a method for producing a composite metal oxide thin film having a specific composition useful as a superconducting material and a magnetic sensor. In particular, a composite metal oxide of bismuth, strontium, calcium, and copper with a specific composition is expected to exhibit superconductivity at an angle of 77 degrees or more.

[Conventional technology and problems]

The general method for manufacturing composite metal oxides is as follows: (1) After physically grinding and mixing each metal component in the powder state of each oxide, carbonate, etc., a solid phase reaction is performed by firing. (2) Each metal component is made into a homogeneous solution in the form of water-soluble salts such as nitrates, hydrochlorides, and sulfates, and carbonate ions, hydroxide ions, oxalate ions, etc. are added to this solution to form insoluble A method of co-precipitating each component in the form of hydroxide, carbonate, oxalate, etc., separating the precipitate, and calcining it, (3)
A method in which a mixture of alkoxides, β-diketone complexes, β-ketoester complexes, organic acid salts, etc. of each metal component is dissolved in an organic solvent to form a homogeneous solution, hydrolyzed, and the precipitate separated, followed by firing. .

etc. to obtain the desired composite metal oxide powder, and further,
There is a method in which a target is prepared by a method such as hot pressing, and a thin film is formed on a substrate by a method generally called sputtering.

However, in these methods, composite metal oxide powder must first be synthesized, and in each of the powder farming methods, in method (1), the contact areas of the powder particles are mixed and then fired in the powder state. Since the reaction proceeds from the start, unreacted portions tend to remain, which may cause a deviation from the target composition.

In method (2), since the precipitation conditions for each element in the solution are different, it does not necessarily result in co-precipitation of the same proportion of the same metal as the proportion of the metal in the solution, so deviation from the target composition still occurs. It's inevitable. Furthermore, inorganic anions (NO, -1C do, so4''-, etc.), which are the starting materials,
Even after heat treatment, impurities remain inside and deteriorate the properties of the powder.

In method (3), a precipitate having the desired composition can be obtained, but heat treatment is required to remove residual organic substances or hydroxyl groups.

There are other problems.

Furthermore, in order to manufacture thin films by sputtering, expensive sputtering equipment and hot press equipment must be used.

Alternatively, as a method of using alkoxides, etc., the alkoxides of each metal component, β-diketone complexes, β-ketoester complexes, or mixtures of organic acid salts, etc. are dissolved in an organic solvent to form a homogeneous solution. After that, there is a method of applying this solution to a substrate, hydrolyzing it with moisture in the air, and heat-treating it to obtain a composite metal oxide thin film. heat treatment is required, and depending on the atmosphere, carbon, etc. may remain.

There are other problems.

Means for Solving Problem c] These problems are solved by using bismuth alkoxide, strontium alkoxide, calcium alkoxide, and organic acid salts of copper, alkoxides, β-diketone complexes, or β-ketoester complexes as starting materials. This is achieved by dissolving a mixture of these in an organic solvent, applying this solution to a substrate, and then irradiating it with ultraviolet and infrared rays to cause decomposition and oxidation reactions.

[Structure of the invention]

The present invention combines bismuth alkoxide, strontium alkoxide, calcium alkoxide, and copper organic acid salts, alkoxides, β-diketone complexes, or β-
The mixture is mixed so that the metal is contained in the same proportion as the metal in the composite oxide intended to form the ketoester complex, dissolved in an organic solvent, and while this solution is applied to a solid substrate, it is irradiated with ultraviolet and infrared rays. Provided is a method for producing a composite metal oxide thin film, which comprises performing decomposition and oxidation.

In the present invention, what is bismuth alkoxide?

-Tsuriyo Bi (OR”) (OR”) (OR'
), and R'', R'', and R' are the same or different 01-C6 alkyl groups.

In the present invention, the alkoxides of strontium and calcium are defined as -A (OR') (OR')
), A is Sr or Ca, R1, R2
are the same or different C1-C, alkyl groups.

In the present invention, specific examples of copper organic acid salts include formate, propionate, acetate, citrate, gluconate, tartrate, oxalate, naphthenate, 2-ethylhexanoate, etc. be.

Copper alkoxides, β-diketone complexes and β-ketoester complexes are represented by Cu(OR)n(X), where R is a 00-C6 hydrocarbon group, Q is Oll or 2, 1, and m is Oll or 2, α+m=2, or is represented by the general formula, and R'' and R'' are 01 to C6 hydrocarbon groups.

A compound in which R3 is a hydrogen atom or a C1 to C5 hydrocarbon group.

Almost any organic solvent can be used in the method of the invention as long as it dissolves and is inert towards the alkoxide and copper complex. Specific examples include ester necks such as ethyl acetate and ethyl propionate, methyl alcohol,
Alcohols such as ethyl alcohol, rho- and 1so-propyl alcohol, n-, 1so-1sec- and tert-butyl alcohol, n-pentyl alcohol, 1so-amyl alcohol, hexyl alcohol, octyl alcohol, pentane, hexane, cyclohexane, Aliphatic saturated hydrocarbons such as methylcyclohexane, aromatic hydrocarbons such as benzene, toluene and xylene, cyclic ethers such as tetrahydrofuran and dioxane, cellosolves such as methyl cellosolve, ethyl cellosolve and butyl cellosolve, dimethyl formamide , formamides such as diethylformamide.

Sulfoxides such as dimethyl sulfoxide and diethyl sulfoxide, and the like. These solvents can be used alone or in combination of two or more.

The solvent is preferably one that is sufficiently dry and does not contain carbon dioxide gas, and there is no limit to the amount of the organic solvent used. It is used in an amount that allows the three components to react easily.

The organic solvent composition may be heated to reflux to ensure sufficient uniformity before application to the substrate.

In the present invention, the atmosphere when irradiating ultraviolet rays and infrared rays may be vacuum, inert gas, oxygen, air,
Nitrous oxide etc. are used.

〔Effect of the invention〕

Bismuth alkoxide, strontium alkoxide, calcium alkoxide, copper organic acid salt, β-
A diketone complex or a β-ketoester complex can be purified to a high degree by distillation or recrystallization, and a complex oxide having a metal element ratio in its composition can be obtained. According to the method of the present invention, a composite metal oxide thin film with high purity and a composition that closely matches the target composition can be obtained without producing powder or using expensive equipment.

[Specific disclosure of the invention]

The invention will now be illustrated by examples.

Example 1 Bismuth triisopropoxide 81 (OCH(CL)
) 23319.3g, Strontium diisopropoxide boxoxide Sr[0CH(CH3)z)z 1
0.28g, calcium diisopropoxide Ca(O
CH (CH, ), ) 27.9 g and copper acetylacetonate Cu (CH3CQCHCOC) 131.26.1
After dissolving 5 g of isopropanol in 1 oood of isopropanol and refluxing for 3 hours at the boiling point of isopropanol, the solution was diluted to a thickness of 1 ooOd.
Apply to a magnesium oxide plate measuring 3 cm in length and width.

After drying in the air, apply it to a depth of 5 cm with the coated side facing up.
Place it in a ventilated quartz chamber measuring 20 cm in length and width.
A low-pressure mercury lamp and an infrared lamp as ultraviolet light sources were simultaneously irradiated from above for 30 minutes. When the surface of this plate was quantitatively analyzed using an xg microanalyzer, it was found that B
i: Sr: Ca: Cu: ○=1=1:1
:2:5.5. Furthermore, the superconducting transition temperature (hereinafter referred to as Tc) of this thin film was measured and found to be 756.

Example 2 Bismuth triethoxide Bi (QC, R5), 17
．． 2g, strontium jetoxide 5r (OCJ,
) 8.88g, Calcium Jetoxide Ca (OC
2Hs)z 6.5g and 2-ethylhexanoate steel c
ucc4H,CHCC,H,)COO).

Dissolve 34.99 g in ethanol 10100O, heat under reflux for 3 hours at the boiling point of ethanol, then apply this solution to a zirconium oxide plate with a thickness of 1 mm and 3 cm in length and width. After drying in the air, turn the coated side upward. The sample was placed in a ventilated quartz chamber with a depth of 5 cm and a length and width of 20 cm, and was irradiated from above with a low-pressure mercury lamp as an ultraviolet g source and an infrared lamp at the same time for 1 hour. When the surface of this plate was quantitatively analyzed using an X-ray microanalyzer, it was found that Bi
: Sr : Ca : Cu :○=1=1 :
l:,2:5.5. Furthermore, the T of this thin film
When c was measured, it was 78''.

Example 3 Bismuth triisopropoxide Bx (OCH(CH
3)2).

19.3g, strontium jetoxide Sr (O
Cz Hs )z 8.88 g, calcium jetoxide Ca (OCH3)z 5.1 g and copper acetylacetonate)' Cu (CH3COCHCOCH,).

After dissolving 26.15 g in 1000 d of benzene and heating under reflux for 2 hours at the boiling point of benzene, the solution was heated to a thickness of 0.5 g.
Coat it on a silicon wafer measuring 3 cm in length and width, and dry it in the air.
The sample was placed in a ventilated quartz chamber of 200 m in diameter, oxygen was supplied, and a low-pressure mercury lamp as an ultraviolet source and an infrared lamp were simultaneously irradiated from above for 2 hours. When the surface of this plate was quantitatively analyzed using an X-ray microanalyzer, we found that
Bi: Sr: Ca: Cu: 0=1:1
:1:2:5,5. Furthermore, when the Tc of this thin film was measured, it was 76°.

Claims (1)

[Claims] 1. Bismuth alkoxide, strontium alkoxide, calcium alkoxide, and organic acid salts of copper,
The alkoxide, β-diketone complex, or β-ketoester complex is mixed so that the metal is contained in the same proportion as the metal in the target composite metal oxide, dissolved in an organic solvent, and this solution is applied to a solid substrate. 1. A method for producing a composite metal oxide thin film, which comprises irradiating the composite metal oxide thin film with ultraviolet rays and infrared rays to cause decomposition and oxidation.