JP2018177546A - Oxide film-forming material and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film-forming material capable of uniformly forming a film with superior properties and being obtained inexpensively.SOLUTION: An aqueous acidic solution is prepared which is obtained by dissolving zinc acetate as a Znion source and which contains Znions as a main component and contains Alions. To the aqueous acidic solution, an aqueous alkali solution in an amount less than its neutralization equivalent is dropwise added to cause a precipitate of zinc aluminum acetate hydrate, and this precipitate is collected. A solution of a film-forming material thus obtained is allowed to adhere on a substrate surface and is calcined, so that an oxide with high quality and high performance can be obtained which has a favorable electrical conductivity and an oriented polycrystal structure.SELECTED DRAWING: Figure 3

Description

  The present invention includes, for example, a transparent conductive material of a solar cell panel, a seed layer for forming a ZnO-based transparent conductive material sputtered film (a base layer of a sputtered film), a dye-sensitized solar cell electrode material, a gas sensor chip (detector) , A material for forming a thin film or thick film constituting a catalyst or the like, and a method of manufacturing the same.

  A solar cell panel such as polycrystalline silicon has a transparent conductive film that functions as a conductor (electrode) that extracts electric energy from sunlight. Conventionally, many of such transparent conductive films are made of ITO (indium-tin oxide), ATO (antimony-tin oxide), GZO (gallium-zinc oxide), AZO (aluminum-zinc oxide), etc. The material is usually formed by sputtering or the like (for example, Patent Document 1, Patent Document 2, Non-Patent Document 1, etc.).

JP-A-7-84274 Japanese Patent Laid-Open No. 2000-40429

Hisao Makino, 5 others, "Structural and electrical properties of Ga-doped ZnO thin films deposited on inorganic nanosheets," Proceedings of the 58th Joint Conference on Applied Physics, Proceedings of the Institute of Applied Physics, 2011, P. . 21-010

  However, the ITO-based transparent conductive film is expensive as a raw material of indium, which increases the manufacturing cost. In addition, although ATO materials, AZO materials and the like are expected as substitutes for ITO materials, ATO materials have problems such as occurrence of coloring and increase in electrical resistance. In addition, GZO-based materials and AZO-based materials are difficult to ensure the uniformity of the film in film formation by sputtering, and it is difficult to obtain a high-quality ultra thin film, and sufficient electricity is required unless the film thickness is increased. Conductivity can not be obtained. Therefore, conventionally, it is common to use an ITO-based material as the transparent conductive material.

  On the other hand, a wet film forming method such as a printing method using zinc oxide powder or the like as a paste or ink is known, and in particular, a film forming technique by the printing method is a seed layer (sputtered film for forming a ZnO based transparent conductive material sputtered film) Underlying layer), a dye-sensitized solar cell electrode material, a gas sensor chip, a catalyst and the like, it can be said that the technique is suitable for forming a thin film or a thick film. However, the wet film forming method such as the conventional printing method does not require a vacuum apparatus such as a sputtering method, and has the advantage of being able to form a film inexpensively, but in order to improve the conductivity of zinc oxide, There are problems such as firing in a reducing atmosphere or requiring high temperature for firing.

  Accordingly, the object of the present invention is to solve the problems of the prior art as described above, and inexpensively produce high quality oxide film which can be used as a transparent conductive film or gas sensor chip etc., particularly oxide film having good conductivity. It is an object of the present invention to provide a material for forming an oxide film which can be formed into a film and a method for producing the same.

The inventors of the present invention have found that a specific hydroxide (zinc aluminum acetate hydrate) obtained as a precipitate by a specific method is suitable as a film forming material by a wet film forming method, and includes this film forming material By depositing a solution or paste on a substrate surface and baking it, a high quality oxide film having a highly conductive oriented polycrystalline structure (a polycrystalline structure in which the directions of crystal planes are aligned) is formed at low cost. I found out what I could do.
The present invention has been made based on such findings, and the gist of the present invention is as follows.

[1] An acidic aqueous solution in which zinc acetate is dissolved as a Zn ²⁺ ion source, which is mainly composed of Zn ²⁺ ions and further contains an alkaline aqueous solution smaller than the neutralization equivalent dropwise to an acidic aqueous solution containing Al ³⁺ ions A method for producing a material for forming an oxide film, comprising forming a precipitate of aluminum acetate hydrate and recovering the precipitate.
[2] In the production method of the above-mentioned [1], the amount of Zn ²⁺ ions in the acidic aqueous solution is m (mole), the amount of Al ³⁺ ions is n (mole), and the amount of OH ⁻ ions in the alkaline aqueous solution dropped into the acidic aqueous solution Ratio of Al ³⁺ ion amount n (mol) to [Zn ²⁺ ion amount m (mol) + Al ^{3 +} ion amount n (mol)] in the acidic aqueous solution is 0.001 to 10%. And an alkaline aqueous solution is dropped to the acidic aqueous solution so as to satisfy the following equation (1):
0.2X ≦ x <0.8X (1)
Where X = 2m + 3n

[3] above in the manufacturing method of [2], the ratio of the 0.01% of the aqueous acid solution ^{[Zn 2+} ion amount m (mol) + ^{Al 3+} ion amount n (mol)] for ^{Al 3+} ion amount n (mol) An alkaline aqueous solution is dropped to an acidic aqueous solution so as to satisfy the following equation (2) by setting the amount to less than 2%, and a method of producing a material for forming an oxide film.
0.4 x ≦ x ≦ 0.6 x (2)
Where X = 2m + 3n
[4] The method for producing an oxide film-forming material according to any one of the above [1] to [3], wherein the recovered precipitate is dried to form a powder.

[5] An oxide film-forming material comprising zinc aluminum acetate hydrate which is a strip-like layered hydroxide.
[6] In the oxide film-forming material of the above-mentioned [5], zinc aluminum acetate hydrate is characterized in that the X-ray diffraction peak to be measured is a hydrate identified by c value = 39.1568 ± 0.5206 Å. A material for forming an oxide film.
[7] In the oxide film-forming material according to the above [5] or [6], zinc aluminum acetate hydrate is a hydrate obtained as a precipitate in a precipitation method, and an oxide film is formed. Material.
[8] In the oxide film forming material according to any one of the above [5] to [7], a gel material or a powder obtained by drying the gel material is described. Material.

[9] A solution or paste containing the material for forming an oxide film according to any one of the above [5] to [8] is attached to a substrate surface and fired to form zinc having an oriented polycrystalline structure on the substrate surface. A method of forming an oxide film comprising forming an aluminum-based oxide film.
[10] A solution or paste containing the material for forming an oxide film obtained by the manufacturing method according to any one of the above [1] to [4] is attached to a substrate surface and then fired to orient the substrate surface. Method of forming an oxide film characterized in that a zinc aluminum-based oxide film having a crystalline polycrystalline structure is formed.
[11] In the method of forming the above [9] or [10], the oxide film-forming material is a gel-like substance or a powder obtained by drying the gel-like substance, and a solution or paste to which the material is added The formation method of the oxide film characterized by using.

The oxide film forming material of the present invention is a high quality, high performance oxide film having an oriented polycrystalline structure with good conductivity by attaching a solution or paste containing the same to a substrate surface and baking it. Since the film forming method is a wet method, the target oxide film can be obtained inexpensively.
Moreover, according to the manufacturing method of this invention, the above materials for oxide film formation can be manufactured stably, efficiently, and at low cost.

According to the precipitation method, Al relative to 1 L ([amount of Zn ²⁺ ions (mol) + amount of Al ^{3 +} ions (mol)] of an acidic aqueous solution having a Zn ²⁺ ion concentration of 0.098 mol / L and an Al ³⁺ ion concentration of 0.002 mol / L) A precipitate obtained by dropping 1 L of an aqueous solution of NaOH having an OH ⁻ ion concentration of 0.1 mol / L to 1 L of a 0.1 mol / L acidic aqueous solution in which the ratio of ³⁺ ion amount (mol) is 2% Chart of zinc aluminum acetate hydrate, which is a zinc oxide, and XRD of zinc aluminum acetate hydrate (Zn ₂ Al (OH) ₆ (C ₂ H ₃ O ₂ .2.6H ₂ O)) in the XRD library data. Chart and XRD chart of basic zinc acetate (Zn (OH) _1.58 (CH ₃ COO) _0.42 · 0.31H ₂ O) in the XRD library data Enlarged view around the main peak of the XRD chart in Figure 1 An SEM photograph of zinc aluminum acetate hydrate, the XRD chart of which is shown in FIG. An SEM photograph of an oxide film obtained by coating an aqueous solution containing zinc aluminum acetate hydrate shown in FIG. 1 and FIG. 3 on a glass substrate by a bar coating method and firing it. After an aqueous solution containing zinc aluminum acetate hydrate shown in FIG. 1 and FIG. 3 is coated on a glass substrate by a bar coating method, an XRD chart of an oxide film obtained by firing is provided. According to the precipitation method, 1 L of an acidic aqueous solution of 0.1 mol / L in which the ratio of the Al ³⁺ ion amount (mol) to [Zn ²⁺ ion amount (mol) + Al ³⁺ ion amount (mol)] is 10% OH ⁻ ion SEM photograph of the precipitate obtained by dropping 1 L of an aqueous solution of NaOH having a concentration of 0.04 to 0.23 mol / L A precipitate obtained by dropping 1 L of an aqueous solution of NaOH having an OH ⁻ ion concentration of 0.02 to 0.22 mol / L into 1 L of a 0.1 mol / L acidic aqueous solution containing only Zn ²⁺ ions by a precipitation method SEM picture of According to the precipitation method, 1 L of an acidic aqueous solution of 0.1 mol / L in which the ratio of the Al ³⁺ ion amount (mol) to the [Zn ²⁺ ion amount (mol) + Al ³⁺ ion amount (mol)] is 20% OH ⁻ ion SEM photograph of the precipitate obtained by dropping 1 L of an aqueous solution of NaOH having a concentration of 0.1 to 0.24 mol / L The proportion of Al ³⁺ ion amount (mol) to [Zn ²⁺ ion amount (mol) + Al ³⁺ ion amount (mol)] by precipitation method 1 L of 0.1 mol / L acidic aqueous solution in which the ratio is 0 to 25% OH ^- graph showing the relationship between ion concentration and Zn yield ^- in the case of ion concentration to obtain a precipitate was added dropwise a different aqueous NaOH 1L, OH of the dropped aqueous NaOH According to the precipitation method, 1 L of an acidic aqueous solution of 0.1 mol / L in which the ratio of the amount of Al ³⁺ ions (mol) to the amount of Zn ²⁺ ions (mol) + Al ³⁺ ions (mol) is 2 to 25% OH ^- graph showing the relationship between ion concentration and Al yields ^- in the case of ion concentration to obtain a precipitate was added dropwise a different aqueous NaOH 1L, OH of the dropped aqueous NaOH According to the precipitation method, 1 L of an acidic aqueous solution of 0.1 mol / L in which the ratio of Al ³⁺ ion amount (mol) to [Zn ²⁺ ion amount (mol) + Al ³⁺ ion amount (mol)] is 2% OH ^- ion For the precipitate (zinc aluminum acetate hydrate) obtained by dropping 1 L of an aqueous solution of NaOH at a concentration of 0.04 to 0.16 mol / L, respectively, the c value of the lattice constant is determined by peak analysis of the XRD chart Graph showing the relationship between the c value and the OH ^- ion concentration of NaOH aqueous solution The proportion of Al ³⁺ ion amount (mol) to [Zn ²⁺ ion amount (mol) + Al ³⁺ ion amount (mol)] by precipitation method is 0 to 33% to 1 L of 0.1 M / L acidic aqueous solution The c value of the lattice constant is determined by peak analysis of the XRD chart for the precipitate obtained by dropping 1 L of an aqueous NaOH solution having an OH ⁻ ion concentration of 0.1 mol / L, and the c value and [Zn ^{2+ of the} acidic aqueous solution Graph showing the relationship between the ratio of the amount of Al ³⁺ ion (mole) to the amount of ion (mole) + Al ^{3 +} ion amount n (mole) (Al ^{3 +} ion addition amount) The proportion of Al ³⁺ ion amount (mol) to [Zn ²⁺ ion amount (mol) + Al ³⁺ ion amount (mol)] by precipitation method 1 L of 0.1 mol / L acidic aqueous solution in which the ratio is 0 to 25% An oxide film formed using a powder of a precipitate (material for forming an oxide film) obtained by dropping 1 L of an aqueous solution of NaOH having an OH ⁻ ion concentration of 0.1 mol / L and 0.22 mol / L. for a graph showing the relationship between the volume resistivity and the acidic aqueous solution ^{[Zn 2+} ion content (mol) + ^{Al 3+} ion content (mol)] ^{Al 3+} ion amount with respect to the ratio of (moles) ^{(Al 3+} ions added amount)

  The present inventor examined in order to find a material (material for film formation) suitable for a transparent conductive film for solar cell panels and the like. With regard to the production of this material, in order to realize high uniformity and control of the crystal shape with a molecular size that is difficult to realize by dry methods such as gas phase method, the wet method was studied. Films consisting of oriented polycrystals are generally expected to exhibit characteristics similar to single crystals in bulk oxide polycrystals (including thick film materials), but control of crystal shape by wet method Thus, the synthesis of zinc aluminum acetate hydrate, which is a precursor of such oriented polycrystals, can be expected.

  Specifically, a precursor for obtaining an oxide having an oriented polycrystalline structure (in particular, a thin film having a film thickness of several tens of nm to a thick film of several tens of μm or more) by a precipitation method which is one of wet methods The objective is to obtain zinc aluminum acetate acetic acid which is a body, to form a film (by applying and baking to form an oxide film) on a substrate using this precursor, and to obtain an oxide film having desired performance. The following tests and examinations were conducted.

First, the synthesis of zinc aluminum hydrate (the formation of a precipitate) by a precipitation method was performed under the following test conditions.
In the preparation of an acidic aqueous solution containing Zn ²⁺ ions and Al ³⁺ ions (hereinafter sometimes referred to as “metal solution” for convenience), anhydrous zinc acetate (Zn (CH ₃ COO) ₂ ), Al ³⁺ ions as a Zn ²⁺ ion source Basic aluminum acetate dihydrate (Al ₂ O (CH ₃ COO) ₄ · 2H ₂ O) was used as a source. Moreover, NaOH aqueous solution was used as alkaline aqueous solution (mineralization material).

In the metal solution, the total of Zn ²⁺ ion and Al ³⁺ ion is 0.1 mol / L, and the ratio (below) of Al ³⁺ ion amount (mol) to [Zn ²⁺ ion amount (mol) + Al ³⁺ ion amount (mol)] For convenience of explanation, it is prepared so that it is referred to as "the amount of addition of Al ³⁺ ions" is 0 to 25%. The amount of added Al ³⁺ ions (blended level) at this time is shown in Table 1.
The liquid was fed by dropping an aqueous solution of NaOH into the metal solution, and the liquid feeding speed was 1 L / 1 hour. The OH ^- ion concentration of the aqueous NaOH solution is changed by about 0.2 mol / L (0.04 to 0.22 mol / L) considered to be a neutralization equivalent, and 1 L of the aqueous NaOH solution is added dropwise to 1 L of the metal solution. I got a precipitate. The level of the OH ⁻ ion concentration of the NaOH aqueous solution dropped is shown in Table 2.

The solution containing the white precipitate after the precipitation reaction was stirred and aged for 6 to 24 hours, and then the precipitate was collected by suction filtration. This precipitate (gel-like substance) could be obtained by adding distilled water and washing (3 times) by centrifugation, and then performing vacuum drying at 30 ° C. to obtain a dry powder. In addition, dried powder was able to be obtained also by drying at 40 ° C. × 12 hr.
Identification of the mineral phase by XRD (BRUKER; D8 ADVANCE) and shape observation by SEM (HITACHI; S-4300) were performed for the precipitate (solid content) obtained as described above.

Table 3 shows the mineral phase of the precipitate identified by XRD. Table 3 shows the precipitates obtained in each test combining the levels 1 to 8 (Table 1) of the added amount of Al ³⁺ ions of the metal solution and the levels a to h (Table 2) of the OH ⁻ ion concentration of the aqueous NaOH solution. It is a compilation of mineral phases. In Table 3, the order of symbols and the size of characters indicate the magnitude of diffraction intensity when a mineral phase is identified.
In the identification of the mineral phase by XRD, when the Al ³⁺ ion addition amount of the metal solution is 0%, that is, when the metal solution contains only Zn ²⁺ ion, the OH ⁻ ion concentration is 0.04 to 0.22 mol / The mineral phase of the precipitate obtained by the dropwise addition of an aqueous solution of L NaOH is, in order from the lower OH ⁻ ion concentration, i) zinc acetate hydrate (denoted as “ZaH” in Table 3), ii) zinc hydroxide (Shown as "ZH" in Table 3) and iii) Zinc oxide (shown as "ZnO" in Table 3), i) mixed phase of ii) and ii) mixed phase of ii) and iii) respectively Observed in

On the other hand, when the OH ^- ion concentration of the dropped NaOH aqueous solution is relatively low (0.16 mol / L or less), the mineral phase of the precipitate obtained when Al ^{3 +} ion is added to the acidic aqueous solution is When the added amount of Al ³⁺ ions in the acidic aqueous solution is 0.001 to 10%, it is identified as zinc aluminum acetate hydrate (denoted as “ZaH-Al” in Table 3), and the added amount of Al ³⁺ ions in the acidic aqueous solution is When it exceeded 10%, it was identified as zinc aluminum acetate hydrate (denoted as "ZAH" in Table 3) having a relatively high Al concentration (higher than the above "ZaH-Al"). Here, “ZAH” is zinc aluminum acetate water corresponding to zinc aluminum acetate hydrate (Zn ₂ Al (OH) ₆ (C ₂ H ₃ O ₂ .2.6H ₂ O)) in the XRD library data. In contrast to being a hydrate, "ZaH-Al" is composed of a layered structure having a strip-like outer shape, and is considered to be a novel zinc aluminum acetate hydrate which has not been known so far.

That is, among the precipitates shown in Table 3, the OH ^- ion concentration is 0.04 to 0.16 mol in 1 L of a 0.1 mol / L metal solution in which the amount of Al ^{3 +} ions added is 0.001 to 10%. The precipitate obtained by dropwise addition of 1 L of NaOH aqueous solution / L is zinc aluminum acetate hydrate which is a material of the present invention (material for forming an oxide film), and this zinc aluminum acetate hydrate is strip-shaped It has a layered structure (layered hydroxide) having an outer shape.

In FIG. 1, 1 L of a metal solution having a Zn ²⁺ ion concentration of 0.098 mol / L and an Al ³⁺ ion concentration of 0.002 mol / L according to the precipitation method (0.1 mol in which the addition amount of Al ³⁺ ions is 2%) and XRD chart of the zinc aluminum acetate hydrate (invention material) is a precipitate ion concentration is obtained by dropping NaOH aqueous solution 1L of 0.1 mol / L, ^- / L of metal solution 1L) in OH XRD chart of zinc aluminum acetate hydrate (Zn ₂ Al (OH) ₆ (C ₂ H ₃ O ₂ .2.6H ₂ O) in the XRD library data and basic zinc acetate in the XRD library data It shows the XRD chart _{(Zn (OH) 1.58 (CH} 3 COO) 0.42 · 0.31H 2 O). FIG. 2 is an enlarged view around the main peak of the XRD chart of FIG.

  According to the XRD chart of FIG. 1, the zinc aluminum acetate hydrate of the present invention has a lattice constant d of 13.30062 Å of the main peak (001) by X-ray diffraction, and basic zinc acetate (main peak (001 Zinc aluminum acetate hydrate (main peak (001)) which is in the higher angle side with respect to the main peak of the lattice constant d of 14.6) and in the XRD library data which is also relatively consistent For the main peak of the lattice constant d of 11.50000 Å), the main peak is seen at a lower angle side than that. From this, the zinc aluminum acetate hydrate of the present invention belongs to the basic zinc acetate hydrate, but is a layered compound different from the structure of the known (XRD library) similar hydroxide. I know that there is.

The crystal structure of the zinc aluminum acetate hydrate is present inventive material is inherently high pH conditions where the ion enters, pH is low condition ^{- -} OH If (high OH ion concentration) (low OH ^- ion concentration) Therefore, it is considered that CH ₃ COO ⁻ ions enter in a manner to compensate for the shortfall. The crystal structure is considered to be that of a basic salt having a structure in which anions other than OH ⁻ enter not the interlayer but the basic layer, unlike LDH (layered double hydroxide). As a conceivable composition (however, a composition excluding aluminum) is x: y: z = 2: 1: 3 in Zn _x (CH ₃ COO) _y (OH) _z , and zinc aluminum which is the material of the present invention In acetic acid hydrate, it is estimated that it is 2: 1 + alpha: 3- alpha from the low OH < ^- > ion concentration. The basic zinc acetate (Zn (OH) _1.58 (CH ₃ COO) _0.42 · 0.31 H ₂ O) of which the XRD chart is shown in FIG. 1 has a composition ratio of x: y from the XRD library data. z = 2: 0.86: 3.16, and it is presumed that it can be obtained under conditions where the OH ^- ion concentration is higher than that of the zinc aluminum acetate hydrate of the present invention.

FIG. 3 shows an SEM photograph of zinc aluminum acetate hydrate (powder obtained by vacuum-drying a precipitate) which is an inventive material of which the XRD chart is shown in FIG. Zn (OH) _1.58 (CH ₃ COO) _0.42 · 0.31 H ₂ O or hydrotalcite ((Mg _0.667 Al _0.333 ) (OH) ₂ (CO ₃ ) indicated in the XRD library Layered hydroxides (layered double hydroxides) such as _0.167 (H ₂ O) _0.5 ; magnesium aluminum hydroxide carbonate hydrate) are often observed as scaly particles, but in the present invention material It can be seen that certain zinc aluminum acetate hydrates have a layered structure with a characteristic strip-like outer shape.

  An aqueous solution of zinc aluminum acetate hydrate (an aqueous solution with a solid content ratio of 30% by mass) as the material of the present invention shown in FIGS. 1 and 3 was applied to a glass substrate surface by a bar coating method and dried at 100 ° C. Thereafter, firing was performed at 900 ° C. for 4 hours in the atmosphere to obtain an oxide film. The glass substrate (Corning # 1737) used for film formation was used after the surface was cleaned with acetone. Further, as a bar coater for applying an aqueous solution, “YBA-1 type” manufactured by Yoshimitsu Seiki Co., Ltd. was used.

  The glass substrate on which the oxide film was formed was cut and processed, and with respect to the oxide film, observation of the surface by SEM and identification of a mineral phase by XRD (investigation of crystallinity) were performed. The SEM photograph of the oxide film is shown in FIG. According to this, it can be seen that the oxide film has a trace of strip shape of zinc aluminum acetate hydrate which is a raw material (precursor), and the surface has a large unevenness and a porous structure.

  The result (XRD chart) which identified the mineral phase of the said oxide film by XRD is shown in FIG. According to this, although peaks corresponding to three main peaks (100), (002) and (101) of hexagonal ZnO are observed, it can be seen that the peak intensity of (002) is extremely large. Since the film formed by the bar coating method has a relatively large film thickness and large surface irregularities, the information in the thickness direction of the film is also collected, and the information of (100) and (101) planes is also mixed it is conceivable that.

  The strip-like zinc aluminum acetate hydrate was coated on a glass substrate and fired, as can be seen from the SEM photograph of FIG. 4, had a strip shape after firing, and from the information of XRD, It can be seen that the (002) plane, that is, the c-plane is emphasized. It is considered that the c-planes are aligned, that is, the c-axis is upright on the glass substrate. From the above, it was found that an oxide film having an oriented polycrystalline structure can be obtained on a glass substrate or the like by the strip-shaped zinc aluminum acetate hydrate (precursor) which is the material of the present invention.

According to the XRD chart of FIG. 1, the X-ray diffraction peak of zinc aluminum acetate hydrate which is the present invention material is basic zinc acetate which is a layered hydroxide (Zinc Acetate Hydrate; lattice constant is a value = 3.14700, For c value = 4.76 900), not only the main peak is seen on the high angle side, but a value = 3. 1016 ± 0.0306 Å, c value = 39.1568 ± 0.5 206 Å, and a value is close. , C value is greatly different. The zinc aluminum acetate hydrate of the present invention comprises zinc aluminum acetate hydrate (Zn ₂ Al (OH) ₆ (C ₂ H ₃ ), which is based on known basic zinc acetate and XRD library data. It can be seen that this is a layered compound different from the structure of O ₂ .2.6H ₂ O), hexagonal system, a value = 3.07850, c value = 38.1677).

Next, the method for producing the material for forming an oxide film (zinc aluminum acetate hydrate) of the present invention will be described in detail.
The material for forming an oxide film is an acidic aqueous solution in which zinc acetate is dissolved as a Zn ²⁺ ion source, and the alkaline aqueous solution containing Zn ²⁺ ion as a main component and further containing Al ³⁺ ion is less than the neutralization equivalent. The aqueous solution is added dropwise, and the aqueous solution is maintained at a pH lower than the neutralization equivalent (usually, about pH 6.0 to 7.8) to form a precipitate of zinc aluminum acetate hydrate, and this precipitate is recovered It can be obtained by
Aluminum acetate, aluminum nitrate, aluminum chloride or the like can be used as the Al ³⁺ ion source of the acidic aqueous solution, and one or more of these are dissolved in the aqueous solution. Moreover, as alkaline aqueous solution, 1 or more types, such as sodium hydroxide aqueous solution and ammonia aqueous solution, can be used.

As more specific conditions of the production method of the present invention, the amount of Zn ²⁺ ions in the acidic aqueous solution to be used is m (moles), the amount of Al ^{3 +} ions is n (moles), and the alkaline aqueous solution to be dropped into this acidic aqueous solution OH ^- when the amount of ions was x (mol), ^{Al 3+} ions loading in the acidic aqueous solution (i.e. ^{[Zn 2+} ion amount m (mol) + ^{Al 3+} ion amount n (mol)] ^{Al 3+} ion amount n (mol for The aqueous alkaline solution is preferably added dropwise to the acidic aqueous solution so as to satisfy the following formula (1) by setting the ratio of 0.001) to 0.001%.
0.2X ≦ x <0.8X (1)
Where X = 2m + 3n

Further, it is more preferable to add an alkaline aqueous solution dropwise to the acidic aqueous solution so that the addition amount of Al ³⁺ ions in the acidic aqueous solution is 0.01% or more and less than 2%, and the following formula (2) is satisfied.
0.4 x ≦ x ≦ 0.6 x (2)
Where X = 2m + 3n
Here, the acidic aqueous solution used in the method of the present invention is an aqueous solution containing Zn ²⁺ ion as a main component and containing Al ³⁺ ion and having a pH of about 6.0 to 7.5, and an alkaline aqueous solution having a pH of 12.0 to 14.0. It is an aqueous solution of some degree.

The amount of OH ⁻ ions x (mole) in the aqueous alkaline solution is defined by the amount of Zn ²⁺ ions m (mole) and the amount of Al ³⁺ ions n (mole) of the acidic aqueous solution as described above. On the other hand, the total concentration (m + n mol / L) of Zn ²⁺ ion and Al ³⁺ ion in the acidic aqueous solution is not particularly limited, but preferably about 0.05 to 0.5 mol / L. If the total concentration of Zn ²⁺ ion and Al ³⁺ ion is less than 0.05 mol / L, productivity is low, while if it exceeds 0.5 mol / L, precipitates become high concentration and high viscosity, so stirring and aging There is a concern that problems may occur and that the uniformity of the precipitate (such as the size of the precipitate agglomerates) may also be reduced. However, the total concentration (m + n mol / L) exceeding 0.5 mol / L can also be obtained if sufficient consideration and consideration are given to the stirring power of stirring curing and the shape and size of the reaction vessel.
The pH of the aqueous solution is not particularly limited when the alkaline aqueous solution is dropped in the acidic aqueous solution so as to satisfy the above-mentioned formula (1) (preferably the above-mentioned formula (2)). The aqueous solution is maintained at about pH 6.0 to 7.8.

The feature of the production method of the present invention is an acidic aqueous solution in which zinc acetate is dissolved as a Zn ²⁺ ion source, which is mainly composed of Zn ²⁺ ion and further containing less than the neutralization equivalent to an acidic aqueous solution containing Al ³⁺ ion. of adding an alkaline aqueous solution, i.e., necessary for the neutralization of the acidic aqueous solution OH ^- less than ion quantity of OH ^- by ion adding alkaline aqueous solution to be supplied, strip-shaped hydroxide (zinc aluminum It is at the point of producing a precipitate of acetic acid hydrate). As mentioned previously, the crystal structure of the hydroxide is inherently high pH conditions where the ion enters, pH is low condition ^{- -} OH if (high OH ion concentration) (low OH ^- ion concentration) Therefore, it is considered that it can be obtained by the introduction of CH ₃ COO ⁻ ions in a form that compensates for the shortfall.

As described above, Table 3 shows an acidic aqueous solution in which zinc acetate is dissolved as a Zn ²⁺ ion source, and the alkaline aqueous solution is dropped into an acidic aqueous solution containing Zn ²⁺ ion as a main component and further containing Al ³⁺ ion. Showing the mineral phase of the precipitate obtained by changing the Al ³⁺ ion addition amount of the acidic aqueous solution and the OH ⁻ ion concentration in the alkaline aqueous solution to be dropped according to the level of Table 1 and Table 2 There is.
In FIGS. 6 to 8, like the precipitates shown in Table 3, precipitates obtained by dropping 1 L of an aqueous solution of NaOH having different OH ⁻ ion concentrations into 1 L of metal solutions having different amounts of added Al ^{3 +} ions by precipitation. Shows a SEM photograph of In addition, the numerical value displayed on each SEM photograph is OH < ^- > ion concentration (mol / L) of the used NaOH aqueous solution.

FIG. 6 shows a precipitate obtained by dropping 1 L of an aqueous solution of NaOH having different OH ⁻ ion concentration into 1 L of a 0.1 mol / L metal solution in which the addition amount of Al ³⁺ ions is 10%, among which OH ⁻ The precipitate obtained by dropwise addition of an aqueous solution of NaOH having an ion concentration of 0.04 to 0.16 mol / L (usually, the pH of the aqueous solution from which the precipitate is generated is about 6.0 to 7.8) is strip-shaped Zinc aluminum acetate hydrate. Among them, the higher the OH ⁻ ion concentration of the aqueous NaOH solution, the higher the Zn yield, and the precipitate obtained by dropping the aqueous NaOH solution with an OH ⁻ ion concentration of 0.06 to 0.16 mol / L ( In general, the pH of the aqueous solution in which the precipitate is generated is about 6.5 to 7.8), and particularly high Zn retention is obtained (approximately 60% or more). Compared to this, the precipitate obtained by dropping an aqueous solution of NaOH having an OH ^- ion concentration of 0.04 mol / L (usually, the pH of the aqueous solution from which the precipitate is generated is about 6.0) is a precipitate. And the Zn yield is reduced.

On the other hand, under highly alkaline synthesis conditions, that is, a precipitate obtained by dropwise addition of an aqueous NaOH solution having an OH ^- ion concentration of 0.18 mol / L (usually, the pH of the aqueous solution from which the precipitate is generated is about 11) is The main component is a zinc oxide having a hexagonal scaly zinc hydroxide and a regular octahedral structure in which hexagonal scaly crystals are accumulated, and this is mixed with particulate zinc oxide. Furthermore, the precipitate obtained by dropping an aqueous solution of NaOH having an OH ⁻ ion concentration of 0.20 mol / L or more (usually, the pH of the aqueous solution which precipitates is 12 or more) is mainly composed of granular zinc oxide, It becomes a mixed phase of this and zinc hydroxide having a regular octahedral structure in which zinc flakes having a hexagonal scale shape and crystals having a hexagonal scale shape are accumulated.

On the other hand, FIG. 7 shows the precipitation obtained by dropping 1 L of an aqueous solution of NaOH having different OH ⁻ ion concentration into 1 L of a 0.1 mol / L metal solution containing 0% of Al ^{3 +} ions, ie, only Zn ²⁺ ions. It is a thing. Among them, the precipitate obtained by dropping an aqueous solution of NaOH having an OH ⁻ ion concentration of 0.04 to 0.16 mol / L is zinc acetate hydrate, but the strip-shaped zinc aluminum acetate of FIG. Similar to the hydrate, it has a strip-like outer shape.
Further, FIG. 8 is a precipitate obtained by dropping 1 L of an aqueous solution of NaOH having different OH ⁻ ion concentration to 1 L of a 0.1 mol / L metal solution in which the additive amount of Al ³⁺ ions is 20%. Among them, the precipitate obtained by dropping an aqueous solution of NaOH having an OH ⁻ ion concentration of 0.1 to 0.175 mol / L is zinc aluminum acetate hydrate, but the zinc aluminum acetate hydrate of FIG. Not like a strip of paper.

Here, in FIG. 6, when the OH ⁻ ion concentration of the NaOH aqueous solution from which a strip-like zinc aluminum acetate hydrate is obtained is 0.04 to 0.16 mol / L, the Zn ²⁺ ion amount m in the acidic aqueous solution ( Mol), Al ³⁺ ion amount n (mol), and OH ^- ion amount x (mol) in the alkaline aqueous solution dropped to this acidic aqueous solution are the above formula (1), that is, 0.2 x ≦ x <0.8 x ( However, there is a relationship of X = 2m + 3n). Therefore, in the present invention, it is preferable to drop the alkaline aqueous solution into the acidic aqueous solution so as to satisfy the above-mentioned equation (1).

In addition, with regard to the addition amount of Al ³⁺ ions from which strip-like zinc aluminum acetate hydrate is obtained, (i) FIG. 6 shows that the addition amount of Al ³⁺ ions is 10%, and (ii) strip-like zinc of FIG. The aluminum acetate hydrate is 2% of Al ³⁺ ion addition, (iii) According to Table 3, zinc aluminum acetate hydrate is obtained at Al ³⁺ ion addition of 0.001 to 10% (Iv) Even in the case of FIG. 7 in which the addition amount of Al ³⁺ ions is 0%, a precipitate obtained by dropping an aqueous solution of NaOH having an OH ⁻ ion concentration of 0.04 to 0.16 mol / L (zinc (zinc Acetic acid hydrate is similar to the strip-like zinc aluminum acetate hydrate of FIG. 6 from the viewpoint of being strip-like, etc., and the preferable Al ³⁺ ion addition amount of the acidic aqueous solution is 0.001 to 1 This Al ³⁺ is considered to be 10%. It is preferable to set it as the range of on addition amount.

Further, in FIG. 6, in particular, the OH ^- ion concentration of the aqueous NaOH solution from which the strip-like zinc aluminum acetate hydrate containing no heterophase is stably obtained is 0.08 to 0.12 mol / L, In this case, the amount of Zn ²⁺ ions m (mol) in the acidic aqueous solution, the amount of Al ^{3 +} ions n (mol), and the amount of OH ⁻ ions x (mol) in the alkaline aqueous solution dropped into the acidic aqueous solution That is, the relationship of 0.4X ≦ x ≦ 0.6X (where X = 2m + 3n) is obtained. Therefore, in the present invention, it is more preferable to drop the alkaline aqueous solution into the acidic aqueous solution so as to satisfy the above-mentioned formula (2).
Moreover, there is no formation of spinel when forming an oxide film, and the electrical conductivity is particularly high (see FIG. 13 described later), because the addition amount of Al ³⁺ ions in the acidic aqueous solution is 0.01% or more and less than 2% In this case, the addition amount of Al ³⁺ ions in the acidic aqueous solution is more preferably 0.01% or more and less than 2%.

The precipitates shown in Table 4 (the precipitates obtained in each test combining the levels 1 to 8 of the added amount of Al ^{3 +} ions of metal solution and the levels a to h of the OH ⁻ ion concentration of the NaOH aqueous solution) The result of having identified the mineral phase by XRD is shown about the sintered body obtained by baking at 900 degreeC. According to Table 4, regardless of the OH ⁻ ion concentration of the NaOH aqueous solution, when the Al ^{3 +} ion addition amount of the metal solution is less than 2%, the fired body is a single phase of ZnO (in FIG. ). On the other hand, when the addition amount of Al ^{3 +} ions in the metal solution is 2% or more, the sintered body contains ZnAl ₂ O ₄ (denoted as “Sp” in Table 4) which is a spinel phase, and Al The proportion of the spinel phase increases as the addition amount of ³⁺ ions increases. Since the spinel phase is an insulator, it reduces the electrical conductivity of the oxide film, so that the amount of Al ³⁺ ions added to the metal solution is preferably less than 2% from the viewpoint of securing the electrical conductivity of the oxide film. In Table 4, the size of the letter "Sp" indicates the size of the diffraction intensity when the mineral phase is identified.

FIG. 9 shows that 1 L of NaOH aqueous solution having different OH ⁻ ion concentrations is added dropwise to 1 L of 0.1 mol / L acidic aqueous solution containing 0 to 25% of Al ³⁺ ions by precipitation method to obtain a precipitate In some cases, the relationship between the OH ⁻ ion concentration of the dropped NaOH aqueous solution and the Zn retention (the mass ratio at which Zn ²⁺ ions in the solution became a precipitate) was investigated. Further, FIG. 10 is a precipitation method in which 1 L of NaOH aqueous solution having different OH ⁻ ion concentrations is dropped to 1 L of 0.1 mol / L acidic aqueous solution containing 2 to 25% of Al ³⁺ ions, and the precipitate is precipitated. In this case, the relationship between the OH ⁻ ion concentration of the dropped NaOH aqueous solution and the Al yield (the mass ratio at which Al ^{3 +} ions in the solution have become a precipitate) is investigated.

As shown in FIG. 9, it can be seen that the OH ⁻ ion concentration of the aqueous NaOH solution should be about 0.08 mol / L or more (ie, x ≧ 0.4 ×) in order to make the Zn yield 60% or more. In addition, when the OH ^- ion concentration of the NaOH aqueous solution is about 0.18 mol / L or more (that is, x 0.9 0.9 X), the Zn yield is close to 100%, but as mentioned earlier, the precipitate has a hexagonal scale Or zinc hydroxide having a regular octahedral structure in which crystals of hexagonal scale are accumulated, or zinc hydroxide having a regular octahedron structure in which crystals of hexagonal scale and hexagonal scale are accumulated It becomes a mixed phase of zinc oxide and granular zinc oxide, or becomes granular zinc oxide, and the strip-like hydroxide (zinc aluminum acetate hydrate) which is the material of the present invention can not be obtained.
With regard to the Al yield, as shown in FIG. 10, if the OH ⁻ ion concentration of the NaOH aqueous solution is less than about 0.22 mol / L, a yield of 100% is obtained.

Further, as described above, the zinc aluminum acetate hydrate according to the present invention is largely different from the basic zinc acetate having a lattice constant of c value, and this c value and zinc aluminum acetate hydrate The relationship between the generation conditions and the strip shape was investigated.
According to the precipitation method, 1 L of NaOH aqueous solution with an OH ⁻ ion concentration of 0.04 to 0.16 mol / L is added dropwise to 1 L of 0.1 mol / L acidic aqueous solution in which the amount of Al ³⁺ ions added is 2%. For the obtained precipitate (zinc aluminum acetate hydrate), c value of the lattice constant was determined by peak analysis of the XRD chart. The relationship between the c value and the OH ^- ion concentration of the aqueous NaOH solution is shown in FIG.

In addition, 1 L of an aqueous solution of NaOH with an OH ⁻ ion concentration of 0.1 mol / L is added dropwise to 1 L of a 0.1 mol / L acidic aqueous solution containing 0 to 25% of Al ³⁺ ions by precipitation. With respect to the obtained precipitate (zinc acetic acid hydrate, zinc aluminum acetic acid hydrate), c value of the lattice constant was determined by peak analysis of the XRD chart. The relationship between the c value and the addition amount of Al ^{3 +} ions in the acidic aqueous solution is shown in FIG. In addition, three points of the right end in FIG. 12 are points of Al ³⁺ ion addition amount 20%, 25%, 33%, and the c value of the 33% point is a quoted value from the XRD database.

As shown in FIG. 11, when the addition amount of Al ³⁺ ions in the acidic aqueous solution is 2%, a precipitate obtained by dropping an aqueous NaOH solution having an OH ⁻ ion concentration of 0.04 to 0.16 mol / L ( Zinc aluminum acetate hydrate) has a lattice constant c value of c = 39.1568 ± 0.5206 Å. On the other hand, as shown in FIG. 12, when the Al ³⁺ ion addition amount is 10% or less, the c value of the lattice constant is in the range of c = 39.1568 ± 0.1229 Å even if the Al ³⁺ ion addition amount changes, and the OH ⁻ ion concentration It becomes smaller than the variation due to the change of. Therefore, Al in the zinc aluminum acetate hydrate of the present invention has Zn sites replaced, penetrates into the structure of zinc acetate hydrate, or precipitates and adheres as zinc acetate hydrate as amorphous. whether the thing for, although not necessarily clear, mineral phase of acetate hydrate consisting of zinc and aluminum, with Al ³⁺ ions added amount is 10% or less, the change in lattice constant depending on the Al ³⁺ ion amount It can be seen that the change is also small and depends only on the amount of alkali (OH ^- ion concentration) to be added.
Therefore, the strip-shaped precipitate characterizing the zinc aluminum acetate hydrate of the present invention is a hydrate whose measured X-ray diffraction peak is specified by the c value = 39.1568 ± 0.5206 Å (the lattice constant c It can be said that the value is a hydrate of c = 39.1568 ± 0.5206 Å).

In the production method of the present invention, an acidic aqueous solution in which zinc acetate is dissolved as a Zn ²⁺ ion source, which is mainly composed of Zn ²⁺ ions and further contains Al ³⁺ ions, is an alkaline aqueous solution less than the neutralization equivalent. The resultant is dropped to form a precipitate of zinc aluminum acetate hydrate, and this precipitate is recovered and used as a material (product) for forming an oxide film. In general, the form of the oxide film-forming material is a gel-like substance recovered from a precipitated state or a gel-like substance obtained by drying (for example, vacuum drying). Specifically, (i) a gel-like substance (precipitate) recovered from an aqueous solution is washed to form an oxide film-forming material in a wet state; (ii) a gel-like substance is washed There is an application form such as using the dried powder (dried powder) as a material for forming an oxide film, but is not limited thereto.

In the production method of the present invention, after dropping the alkaline aqueous solution to the acidic aqueous solution, the operation until recovering the precipitate from the aqueous solution and the method for recovering the precipitate are not particularly limited, and a general method may be used.
Moreover, in order to dry the precipitate (gel-like substance) recovered from the aqueous solution, a general drying means such as a blast dryer may be used, or a vacuum drying means may be used.

A film (oxide) can be formed on the substrate surface by the material for film formation of the present invention manufactured as described above. That is, after a solution or paste containing the material for forming a film is attached to the substrate surface, the film can be formed by baking. As described above, the hydroxide (zinc aluminum acetate hydrate) which is a material for forming a film is usually a gel-like substance recovered from a precipitated state or a powder obtained by drying the gel-like substance, Such gel-like substance or powder is dissolved or dispersed in a solvent such as water, and this solution (or paste with high solid content) is coated (or printed) on the substrate surface and then fired. As the coating method, any method such as screen printing method, dip coating method, bar code method can be adopted according to the thickness of the film to be formed. The firing temperature is generally about 250 ° C. to about 1100 ° C. As a result, a zinc aluminum double oxide film of oriented polycrystalline structure can be formed on the substrate surface.
Alternatively, after the solution is coated, it may be dried at a temperature of about 40 to 100 ° C., and may be fired thereafter. In the case of a paste, baking may be performed after the polymer material or the like formulated for paste formation is decomposed and removed at a temperature of about 200 to 400 ° C.

Among the precipitates shown in Table 3, precipitation obtained by dropping 1 L of an aqueous solution of NaOH having an OH ⁻ ion concentration of 0.1 mol / L to 1 L of a 0.1 mol / L metal solution having different addition amounts of Al ³⁺ ions And the precipitate obtained by dropping 1 L of an aqueous solution of 0.22 mol / L of OH ⁻ ion into 1 L of a 0.1 mol / L metal solution containing different amounts of added Al ³⁺ ions, and drying this A solution (solid content ratio 30 mass%) in which the oxide film forming material is dispersed in water is applied to a glass substrate by a bar coating method, and the solution is formed at 100 ° C. After drying, it was fired at 900 ° C. for 4 hours to obtain an oxide film.
The volume resistivity of this oxide film was measured using a thin film resistance measuring device (manufactured by Mitsubishi Chemical Analytech Co., Ltd .; Loresta GP MCP-T610). FIG. 13 shows the results, and shows the relationship between the Al ³⁺ ion addition amount (log memory) of the metal solution and the volume resistivity (log memory) of the oxide film.

According to FIG. 13, at any OH ⁻ ion concentration, although the volume resistivity decreases in the range of Al ³⁺ ion addition amount of 0.01% or more and less than 0.2%, the OH ⁻ ion concentration is 0. Compared to the case of 22 mol / L, the OH ^- ion concentration of 0.1 mol / L has lower overall volume resistivity, and the range of Al ³⁺ ion addition amount of 0.01% or more and less than 0.2%. The decrease in volume resistivity is remarkable. Here, zinc aluminum, which is a material of the present invention, is a precipitate obtained with an OH ⁻ ion concentration of 0.1 mol / L and an Al ^{3 +} ion addition amount of 0.001 to 10% (preferably 0.01% or more and less than 2%). Although it is an acetic acid hydrate, according to FIG. 13, the zinc aluminium acetic acid hydrate which is the material of the present invention shows superiority in the electric conductivity. This is because the oxide film formed by the comparative material obtained under the conditions of high alkali synthesis (OH ^- ion concentration 0.22 mol / L) is in the form of random particles, whereas the zinc aluminum acetate water of the present invention material is In the oxide film formed by the hydrate, the c-plane of hexagonal ZnO excellent in conductivity is formed with a significant difference in parallel to the glass substrate by realizing the oriented polycrystalline structure as described above. It is thought that it depends on the matter.
Incidentally, any of OH ^- also in ion concentration, but ^{Al 3+} ions added amount up to about 0.02% decrease increases with the volume resistivity of the ^{Al 3+} ion ^{amount, Al 3+} ions added amount of 0.02% The volume resistivity tends to increase when the amount of Al ³⁺ ions is increased, which is considered to be due to the formation of spinels with high resistance at grain boundaries.

The film formed of the film forming material (precursor) of the present invention is a transparent conductive material of a solar cell panel, a seed layer for forming a ZnO based transparent conductive material sputtered film (a base layer of a sputtered film), a dye sensitizing type It is suitable as a solar cell electrode material, a gas sensor, a catalyst and the like.
ZnO is a hexagonal wurtzite crystal and has a crystal structure having a c-axis direction (perpendicular to the c-plane) excellent in light transmittance and a c-plane direction excellent in electric conductivity. By using a precursor hydroxide (zinc aluminum acetate hydrate) which is a material of the present invention, an oriented polycrystal in which the c-axis is orthogonal to the substrate and the c-plane is parallel to the substrate in the substrate to be formed into a film You can get
Further, in the present invention, since it is considered that control of electric conductivity and sintered particle size is also possible by appropriate addition of Al, it is considered to be suitable for a gas sensor chip utilizing a two-dimensional porous structure.

Claims (11)

An acidic aqueous solution in which zinc acetate is dissolved as a Zn ²⁺ ion source, which is mainly composed of Zn ²⁺ ion, and an alkaline aqueous solution containing less than the neutralization equivalent is added dropwise to an acidic aqueous solution containing Al ³⁺ ion A method of producing a material for forming an oxide film, which comprises forming a precipitate of a hydrate and recovering the precipitate. When the amount of Zn ²⁺ ions in the acidic aqueous solution is m (moles), the amount of Al ^{3 +} ions is n (moles), and the amount of OH ⁻ ions in the alkaline aqueous solution dropped into the acidic aqueous solution is x (moles) of the rate of ^{[Zn 2+} ion amount m (mol) + ^{Al 3+} ion amount n (mol)] for ^{Al 3+} ion amount n (mol) 0.001 to 10% and so as to satisfy the following formula (1) The method for producing an oxide film-forming material according to claim 1, wherein the alkaline aqueous solution is dropped into the acidic aqueous solution.
0.2X ≦ x <0.8X (1)
Where X = 2m + 3n The proportion of the aqueous acid solution ^{[Zn 2+} ion amount m (mol) + ^{Al 3+} ion amount n (mol)] for ^{Al 3+} ion amount n (mol) is less than 2% or more 0.01%, and the following equation (2) The method for producing an oxide film-forming material according to claim 2, wherein the alkaline aqueous solution is dropped to the acidic aqueous solution so as to satisfy the above.
0.4 x ≦ x ≦ 0.6 x (2)
Where X = 2m + 3n   The method for producing an oxide film-forming material according to any one of claims 1 to 3, wherein the recovered precipitate is dried to form a powder.   What is claimed is: 1. A material for forming an oxide film, comprising zinc aluminum acetate hydrate which is a strip-like layered hydroxide.   The material for forming an oxide film according to claim 5, wherein the zinc aluminum acetate hydrate is a hydrate whose measured X-ray diffraction peak is specified by c value = 39.1568 ± 0.5206 Å.   The oxide film-forming material according to claim 5 or 6, wherein zinc aluminum acetate hydrate is a hydrate obtained as a precipitate in a precipitation method.   The oxide film-forming material according to any one of claims 5 to 7, which is a gel-like substance or a powder obtained by drying the gel-like substance.   A solution or paste containing the material for forming an oxide film according to any one of claims 5 to 8 is attached to a substrate surface and then fired to form a zinc aluminum oxide having an oriented polycrystalline structure on the substrate surface. A method of forming an oxide film, comprising forming a film.   An oriented polycrystal structure on a substrate surface by adhering a solution or paste containing a material for forming an oxide film obtained by the manufacturing method according to any one of claims 1 to 4 on the substrate surface and baking it. And forming a zinc aluminum-based oxide film of   11. The oxide according to claim 9, wherein the oxide film-forming material is a gel-like substance or a powder obtained by drying the gel-like substance, and a solution or paste to which the material is added is used. How to form a film.