JP2000273694A - Composition for electrolytically forming rare earth oxide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily improve an adhesion property and to uniformize the thickness or composition a composition by effecting an electrolysis with a base material as cathode in a composition obtained by incorporating nitric acid ions or nitrous acid ions into an aqueous solution prepared by dissolving a rare earth compound and forming a film consisting of a rare earth oxide. SOLUTION: The composition for forming the rare earth oxide is obtained by dissolving a nitric acid ion source or nitrous acid ion source into the aqueous solution of about 0.0001 to 0.5 mol/l in concentration prepared by dissolving the nitrate of the water-soluble rare earth compound, more preferably rare earth element at anion concentration of 0.0001 to 1.0 mol/l. The rare earth element is preferably Ce, Tb, Y, Eu, etc. The electrolysis is effected with the base material for forming the rare earth oxide as cathode in this composition. At this time, the liquid temperature of the bath is preferably about 20 to 90 deg.C, the pH about 1 to 5, the cathode potential about -0.2 to -2.0 V in Ag/AgC standard and the current density about 0.001 to 200 mA/cm2. The rare earth oxide film formed in the manner described above is subjected to a heat treatment at 100 to 800 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a composition for electrolytically forming a rare earth oxide film, a method for forming a rare earth oxide film, and a rare earth oxide film.

[0002]

2. Description of the Related Art Conventionally, a rare earth oxide film is formed on a substrate by a dry method such as a CVD method, a vapor deposition method or a sputtering method, a spray pyrolysis method, a sol-gel method, or a wet method such as a liquid phase growth method. A method of forming a film on a substrate has been attempted. Among them, the sputtering method can form a film at a low temperature and can form a uniform film. Therefore, at present, most rare earth oxide films are produced by this method. However, in a dry method such as a sputtering method, a CVD method, a vapor deposition method, or the like, processing such as decompression of a film formation chamber, mixing of gas, and heating of a substrate is required during film formation. A large-scale manufacturing device including a heating device, a high-frequency power supply, and the like is required. Moreover, in these methods, the film formation rate is low, the composition and the film thickness are difficult to control, the area of the substrate that can be used is limited, and it is difficult to form a uniform film on a substrate having a complicated shape. There are disadvantages.

Further, in the spray pyrolysis method or the sol-gel method, it is necessary to heat the substrate at 300 to 900 ° C. after forming the film on the substrate, so that a heating furnace is required and the usable substrate material is limited.

[0004] In order to make the rare earth oxide film usable in a wide range, large-scale equipment such as a vacuum evacuation device and a heating furnace is not required, and the film can be formed on a substrate having a large area and a complicated shape. It is desired to develop a method of forming a rare earth oxide film which has a high film forming rate, a uniform film thickness and a uniform composition, and which can be easily controlled.

[0005]

SUMMARY OF THE INVENTION The main object of the present invention is to:
An object of the present invention is to provide a method capable of forming a rare earth oxide film having a uniform thickness and composition by a simple operation.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of the above problems, and as a result, have dissolved a rare earth compound and at least one kind of anion selected from nitrate ion and nitrite ion. The substrate is immersed in an aqueous solution in which is present, and electrolysis is performed using the substrate as a cathode. It has also been found that a rare earth oxide film having a uniform thickness and composition can be formed. Then, it has been found that by heating the formed rare earth oxide film, the crystallinity is improved and the adhesion to the base material and the like are further improved, and the present invention has been completed.

That is, the present invention provides the following composition for forming a rare earth oxide film by electrolysis, a method for forming a rare earth oxide film, and a rare earth oxide film. 1. A rare earth oxide film electrolytic formation composition comprising an aqueous solution in which a rare earth compound is dissolved, wherein the aqueous solution contains at least one anion selected from nitrate ions and nitrite ions. 2. Item 1. The rare earth oxide according to item 1, comprising an aqueous solution in which (i) a water-soluble rare earth compound and (ii) at least one compound selected from a compound serving as a nitrate ion source and a compound serving as a nitrite ion source are dissolved. A composition for forming a membrane electrolysis. 3. Item 2. The composition for electrolytically forming a rare earth oxide film according to Item 1, which comprises an aqueous solution in which a nitrate of a rare earth element is dissolved. 4. Item 4. The composition for electrolytically forming a rare earth oxide film according to any one of Items 1 to 3, wherein the rare earth compound is a compound containing at least one rare earth element selected from cerium, terbium, yttrium, and europium. 5. Item 5. A method for forming a rare earth oxide film, comprising performing electrolysis using the rare earth oxide forming substrate as a cathode or an anode in the composition for forming an rare earth oxide film according to any one of the above items 1 to 4. . 6. Item 100 is the rare earth oxide film formed by the method of Item 5.
A method for forming a rare-earth oxide film, comprising performing a heat treatment at -800 ° C. 7. Item 7. A rare earth oxide film formed on a substrate by the method according to item 5 or 6.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The composition for electrolytically forming a rare earth oxide film of the present invention is an aqueous solution in which a rare earth compound is dissolved,
This is an aqueous solution containing at least one anion selected from nitrate ions and nitrite ions.

As the rare earth compound, a water-soluble compound containing a rare earth element such as cerium, terbium, yttrium and europium can be used. Types of water-soluble compounds include nitrates, sulfates, oxalates, acetates,
Various rare earth compounds such as carbonates and chlorides can be mentioned. These rare earth compounds can be used alone or in combination of two or more.

The concentration of the rare earth compound in the composition is not particularly limited, but may be 0.0001 mol / l to 0.5 mol.
about 1 / l is preferable, and 0.001 to 0.1 mol / l
The degree is more preferred. If the concentration of the rare earth compound is too low, it is difficult to form a rare earth oxide film even if the electrolysis conditions are adjusted. On the other hand, if the concentration is too high, a hydroxide is easily formed, which is not preferable.

The composition of the present invention must contain at least one anion selected from nitrate ions and nitrite ions. When these anions are not present in the composition of the present invention, a rare earth oxide film cannot be formed even by performing an electrolytic operation. The amount of at least one anion selected from nitrate ions and nitrite ions is not particularly limited, but is usually 0.0001 mol / l to 1.0 mol / l as anion concentration.
Preferably in the range of about 0.001 mol
More preferably, it is in the range of about 0.1 mol / l to about 0.1 mol / l.

In the composition of the present invention, in order for at least one anion selected from nitrate ions and nitrite ions to be present in an aqueous solution, a compound serving as a nitrate ion source and a compound serving as a nitrite ion source are usually used. At least one compound selected from the above may be dissolved in water as a solvent.

As a compound serving as a nitrate ion source, nitric acid, water-soluble nitrate and the like can be used. Specific examples of the nitrate include ammonium nitrate, sodium nitrate, potassium nitrate, lithium nitrate, urea nitrate and the like.

As a compound serving as a nitrite ion source, a water-soluble nitrite can be used, and specific examples thereof include potassium nitrite and sodium nitrite.

The compound serving as a nitrate ion source and the compound serving as a nitrite ion source can be used alone or in combination of two or more.

When a rare earth element nitrate is used as the rare earth compound, the nitrate itself serves as a nitrate ion source. In addition, a compound serving as a nitrate ion source or a compound serving as a nitrite ion source is added. You don't have to. In this case, there is no unnecessary component in the bath,
A highly pure rare earth oxide can be formed in a wide concentration range.

In order to form a rare earth oxide film using the composition of the present invention, a substrate for forming a rare earth oxide film may be immersed in the composition, and electrolysis may be performed using the substrate as a cathode. As an electrolysis method, a normal electrolysis method may be employed, and electrolysis may be performed without stirring or under stirring.

The cathode potential at the time of electrolysis is Ag / AgC
Using the 1 electrode as a reference electrode, the voltage is preferably about -0.2 V to -2.0 V, and more preferably about -0.5 V to -1.6 V. The current density at the time of electrolysis varies depending on the type of the base material to be used, but when electrolysis is performed in the above potential range, it is usually 0.001 mA / cm ^{2 to} 200 m.
The current density becomes about A / cm ² .

As the anode, an insoluble material such as carbon, platinum, and platinum-plated titanium can be used. When an insoluble material is used as the anode, a continuous operation can be performed by replenishing the rare earth compound and the nitrate and adjusting the pH of the electrolytic solution.

The temperature of the solution during the electrolysis may be usually about 20 to 90 ° C., preferably about 40 to 70 ° C.

If the pH of the solution during the electrolysis is too high, it is difficult to obtain a rare earth oxide film due to the formation of a precipitate.
It is preferable to set it to about 2.5 to 4.

Since the film thickness of the formed rare earth oxide film increases in accordance with the electrolysis time, a rare earth oxide film having a desired film thickness can be obtained by appropriately setting the electrolysis time.

In the present invention, the type of the substrate on which the rare earth oxide film is formed is not particularly limited, and any material that is a target of ordinary electroplating can be used as the substrate. Specific examples include metal materials such as copper and iron, NESA glass,
Glass materials such as ITO glass, ceramic materials, and plastics materials are exemplified. A non-conductive material such as a ceramic material or a plastics material may be subjected to a conductive treatment by a wet treatment such as an electroless plating method or a dry treatment such as a PVD method according to a conventional method. In the base material,
Before performing the electrolysis, a pretreatment may be performed in accordance with a conventional method. In addition, after the electrolysis, operations that are usually performed such as washing with water and drying may be performed.

In the present invention, by the above-described electrolysis method,
After the formation of the rare earth oxide film, by further performing a heat treatment, the crystallinity of the rare earth oxide film is improved, and the adhesion to the base material is improved. Heat treatment temperature is 100-800 ° C
Degree is preferable, and about 200 to 600 ° C. is more preferable. The time of the heat treatment is not particularly limited, and may be a time at which the improvement of the characteristics is recognized, but may be generally about 30 minutes to 3 hours.

[0025]

According to the composition for electrolytically forming a rare earth oxide film of the present invention, a rare earth oxide film can be formed by a very simple method of electrolysis from an aqueous solution. According to the electrolysis method from such an aqueous solution, a simple apparatus such as an electroplating apparatus widely used industrially is used without requiring a large-scale apparatus such as an evacuation apparatus and a heating furnace. hand,
There is an advantage that a rare earth oxide film having a uniform film thickness and composition can be formed on a substrate having a large area or a substrate having a complicated shape, and the film thickness and composition can be easily controlled by electrolysis conditions.

The formed rare earth oxide film can be widely used for various uses such as a magnetic material, a ferroelectric material, a battery material, and a catalyst.

[0027]

EXAMPLES The present invention will be further described below with reference to Examples and Comparative Examples. Examples 1 to 6 and Comparative Examples 1 to 6 A composition for electrolytic formation of a cerium oxide film comprising an aqueous solution containing the components shown in Tables 1 and 2 below was prepared. The amounts of the cerium compound and the nitrate in these compositions are shown in mol / l.

[0028]

[Table 1]

[0029]

[Table 2]

In each of these compositions, NESA glass was used as a cathode, and a Pt plate was used as an anode to perform electrolysis to obtain NESA.
An electrodeposited film was deposited on the glass. Tables 1 and 2 show the electrolysis conditions. The potential (V) is shown based on the Ag / AgCl electrode.

The results of examination of the type of the obtained electrodeposited film by X-ray diffraction are shown in Table 3 below. When the compositions of Comparative Examples 1 to 6 were used, a film could not be formed.

[0032]

[Table 3]

From the above results, it is understood that the cerium oxide film can be formed by using the composition of the present invention by a simple method of electrolysis in an aqueous solution. Examples 7 to 12 and Comparative Examples 7 to 12 A terbium oxide film electrolytic formation composition comprising an aqueous solution containing the components shown in Tables 4 and 5 below was prepared.
The amounts of the terbium compound and nitrate in these compositions are shown in mol / l.

[0034]

[Table 4]

[0035]

[Table 5]

In each of these compositions, NESA glass was used as a cathode, and a Pt plate was used as an anode to perform electrolysis to obtain NESA.
An electrodeposited film was deposited on the glass. Tables 4 and 5 list the electrolysis conditions. The potential (V) is shown based on the Ag / AgCl electrode.

The results of examination of the type of the obtained electrodeposited film by X-ray diffraction are shown in Table 6 below. When the compositions of Comparative Examples 7 to 12 were used, a film could not be formed.

[0038]

[Table 6]

From the above results, it can be seen that a terbium oxide film can be formed by using the composition of the present invention by a simple method of electrolysis in an aqueous solution. Examples 13 to 18 and Comparative Examples 13 to 18 Yttrium oxide film electrolytic formation compositions comprising aqueous solutions containing the components shown in Tables 7 and 8 below were prepared. The amounts of the yttrium compound and the nitrate in these compositions are shown in mol / l.

[0040]

[Table 7]

[0041]

[Table 8]

In each of these compositions, NESA glass was used as a cathode, and a Pt plate was used as an anode to perform electrolysis to obtain NESA glass.
An electrodeposited film was deposited on the glass. Tables 7 and 8 show the respective electrolysis conditions. The potential (V) is shown based on the Ag / AgCl electrode. In Examples 13 to 18, after the electrodeposited film was formed, heat treatment was performed under the conditions shown in Table 7.

The type of the obtained electrodeposited film was examined by an X-ray diffraction method, and the result is shown in the following table. When the compositions of Comparative Examples 13 to 18 were used, a film could not be formed.

[0044]

[Table 9]

From the above results, it can be seen that the use of the composition of the present invention enables the formation of an yttrium oxide film by a simple method of electrolysis in an aqueous solution. Examples 19 to 24 and Comparative Examples 19 to 24 Europium oxide film electrolytic formation compositions comprising aqueous solutions containing the components shown in Tables 10 and 11 below were prepared. The amounts of the europium compound and nitrate in these compositions are shown in mol / l.

[0046]

[Table 10]

[0047]

[Table 11]

In each of these compositions, the NESA glass was used as a cathode and the Pt plate was used as an anode to perform electrolysis to obtain NESA.
An electrodeposited film was deposited on the glass. In Table 10 and Table 11,
Each electrolysis condition is described. The potential (V) is Ag / AgCl
Shown on an electrode basis. In Examples 19 to 24, after forming the electrodeposited film, heat treatment was performed under the conditions shown in Table 10.

The type of the obtained electrodeposited film was examined by the X-ray diffraction method, and the result is shown in the following table. When the compositions of Comparative Examples 19 to 24 were used, a film could not be formed.

[0050]

[Table 12]

From the above results, it is understood that the europium oxide film can be formed by using the composition of the present invention by a simple method of electrolysis in an aqueous solution.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Junichi Katayama 47-13 Kamishinjo, Seika-cho, Soraku-cho, Soraku-gun, Kyoto F-term (reference) 4G076 AA02 AB07 AC02 BC08 BD02 BG02 CA10 DA01 DA03 DA07 DA30

Claims (7)

[Claims] An aqueous solution in which a rare earth compound is dissolved,
A composition for electrolytically forming a rare earth oxide film, comprising an aqueous solution containing at least one anion selected from nitrate ions and nitrite ions. (I) a water-soluble rare earth compound, and (ii)
The composition for electrolytic formation of a rare earth oxide film according to claim 1, comprising an aqueous solution in which at least one compound selected from a compound serving as a nitrate ion source and a compound serving as a nitrite ion source is dissolved. 3. The composition for electrolytically forming a rare earth oxide film according to claim 1, comprising an aqueous solution in which a nitrate of a rare earth element is dissolved. 4. The method according to claim 1, wherein the rare earth compound is cerium, terbium,
The composition for electrolytically forming a rare earth oxide film according to any one of claims 1 to 3, which is a compound containing at least one rare earth element selected from yttrium and europium. 5. The rare earth oxide film according to any one of claims 1 to 4, wherein the electrolysis is performed using the rare earth oxide forming substrate as a cathode. Formation method. 6. A method for forming a rare earth oxide film, comprising heating the rare earth oxide film formed by the method of claim 5 at 100 to 800 ° C. 7. A rare earth oxide film formed on a substrate by the method according to claim 5.