JP2003073887A - Ferromagnetic zinc oxide film and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To develop a zinc oxide film, which contains an iron compound therein and shows ferromagnetism in a room temperature. SOLUTION: The manufacturing method comprises forming the zinc oxide film on the surface of a substrate, and treating it by a treatment liquid including a water-soluble iron salt and a reducing agent, to make the above zinc oxide film contain the iron compound; or treating the substrate with an electroless zinc oxide plating solution or an electrolytic zinc oxide plating solution containing the water-soluble iron salt, to form the zinc oxide film containing the iron compound on the surface of the substrate; and includes, after thus having formed the ferromagnetic zinc oxide film, a step of heat treating it under a vacuum, a reducing atmosphere, or non-oxidizing atmosphere.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a zinc oxide film which exhibits ferromagnetism at room temperature (25 ° C.) and a method for producing the same.

[0002]

2. Description of the Related Art Zinc oxide is an n-type semiconductor with a band gap of 3.3 eV, and is used as a transparent electrode for liquid crystal displays and solar cells, humidity and gas sensors, and high-frequency filters for portable devices. Surface acoustic wave device, ultraviolet laser oscillator device, etc.
In addition, it has become indispensable in the chemical industry as a photocatalytic material for antibacterial and environmental purification.

These properties are based on the phenomenon of charge transfer and charge separation due to electrons, but if the spin of electrons can be controlled further, they will be applied to giant magnetoresistive elements and spin field effect transistors. Is possible.

Such a material is called a magnetic semiconductor. In particular, if a zinc oxide-based material is successfully made into a magnetic semiconductor, it becomes possible to develop a new element capable of controlling light, charge and spin. Currently, manganese,
Fabrication by adding a transition element such as nickel or cobalt has been attempted, but the manifestation of ferromagnetism is limited to an extremely low temperature of 10 K or less, and only exhibits superparamagnetic behavior at room temperature. For industrial applications,
The expression of ferromagnetism at room temperature is essential, but it has not been realized at this time.

The present invention has been made in response to such a demand, and an object thereof is to provide a zinc oxide film exhibiting ferromagnetism at room temperature and a method for producing the same.

[0006]

Means for Solving the Problems and Modes for Carrying Out the Invention As a result of intensive studies in view of the above problems, the present inventors have treated the substrate with an electroless zinc oxide plating solution or an electrogalvanic zinc plating solution. To form a zinc oxide film on the surface of the substrate, and then the zinc oxide film is treated with a treatment solution containing a water-soluble iron salt and a reducing agent, or the substrate is electroless zinc oxide containing a water-soluble iron salt. It was found that a zinc oxide film exhibiting ferromagnetism at room temperature can be obtained by forming a zinc oxide film containing an iron compound on the surface of a substrate by treating with a plating solution or an electrogalvanic plating solution.

Therefore, the present invention makes it possible for the first time in the world to commercialize a zinc oxide magnetic semiconductor exhibiting ferromagnetism at room temperature. The present zinc oxide magnetic semiconductor contains iron as a transition element, exhibits magnetic hysteresis at room temperature, and exhibits, for example, a saturation magnetization of 28 emu / cc and a coercive force of about 34 Oe. That is, as compared with the conventional reports of a zinc oxide film containing NiO, etc., it succeeded in developing ferromagnetism at a temperature higher than 260 K and obtained a saturation magnetization about 7 times larger.

Although it has been theoretically predicted that zinc oxide exhibits ferromagnetism by the addition of iron, in the dry method such as the molecular beam epitaxy method which has been conventionally used for forming a zinc oxide film. Since it is difficult to add iron, the formation of an iron-added zinc oxide film has not been successful.
On the other hand, the inventors of the present invention succeeded in introducing a large amount of iron into the zinc oxide film by a method using an electrochemical reaction in an aqueous solution, which led to the present invention.

Further, since the method of the present invention does not necessarily require heating during film formation and after film formation, it can be formed on various materials such as metals, ceramics and polymers. In addition, it does not require large-scale equipment such as a vacuum exhaust device or heating furnace, and can use industrially used electroplating equipment, and even on a product with a large area and a complicated shape, a film of uniform thickness and composition can be obtained. And has the advantage that the film thickness and composition can be easily controlled by the production conditions.

That is, the present invention provides the following ferromagnetic zinc oxide film and its manufacturing method. Claim 1: A ferromagnetic zinc oxide film exhibiting ferromagnetism at room temperature, characterized in that the zinc oxide film contains an iron compound. Claim 2: The total iron content of the iron compound is 20 in the film.
The ferromagnetic zinc oxide film according to claim 1, which is about 50% by weight. Claim 3: The ferromagnetic zinc oxide film according to claim 1 or 2, wherein a divalent iron compound and a trivalent iron compound coexist as the iron compound. Claim 4: After forming a zinc oxide film on the surface of a substrate, the zinc oxide film is treated with a treatment liquid containing a water-soluble iron salt and a reducing agent to contain an iron compound in the zinc oxide film. The method for producing a ferromagnetic zinc oxide film according to claim 1, which is characterized in that. [5] The method according to [4], wherein the zinc oxide film is formed by an electrogalvanizing zinc oxide method or an electroless zinc oxide plating method. [6] The method according to [4] or [5], wherein after the formation of the ferromagnetic zinc oxide film, heat treatment is performed in a vacuum, a reducing atmosphere or a non-oxidizing atmosphere. Claim 7: A substrate is treated with an electroless zinc oxide plating solution containing a water-soluble iron salt or an electrogalvanic zinc plating solution to form a zinc oxide film containing an iron compound on the surface of the substrate. 1. The method for producing a ferromagnetic zinc oxide film according to 1. Claim 8: The manufacturing method according to claim 7, wherein after the formation of the ferromagnetic zinc oxide film, heat treatment is performed in a vacuum, a reducing atmosphere or a non-oxidizing atmosphere.

The present invention will be described in more detail below.

In the present invention, the substrate on which the ferromagnetic zinc oxide film is formed is not particularly limited and may be any of metal, ceramics, polymer and the like. The shape may be plate-like, powder-like, fiber-like or the like.

The method for forming the zinc oxide film on the surface of the substrate is preferably a wet method, particularly an electroless zinc oxide plating method or an electrozinc oxide plating method, but a sputtering method, a molecular beam epitaxy method or a spray pyrolysis method. It may be produced by a dry method such as a lysis method or a wet method such as a sol-gel method. In this case, as the pretreatment method for the substrate, a known pretreatment method according to the type can be adopted,
Particularly when the substrate is non-conductive or semi-conductive, the plating is performed after the catalyst application treatment.

Specifically, in the case of forming an electroless zinc oxide film, it includes cleaning, surface conditioning, and catalyst application treatments.
The following steps can be performed. (1) Washing: A known degreasing agent or an organic solvent can be used, and known processing conditions can be used. (2) Surface conditioning: A known surface conditioning agent is used to impart an electric charge to the substrate surface. (3) Catalyst application: A catalyst is applied to the surface of the substrate (the catalyst application step). (4) Preparation of electroless zinc oxide film: A zinc oxide film is deposited on a substrate.

In this case, as the surface conditioner, an aqueous solution containing 1 to 50 g / L of a cationic surfactant or a cationic polymer compound as a main component can be used, and 1 to 10 at 10 to 60 ° C. It can be soaked for a minute.

The above-mentioned catalyst application treatment forms catalytic metal nuclei such as metallic palladium nuclei, metallic silver nuclei, etc. which enable electroless plating on the surface of the substrate, and Sn-P is formed on the surface of the substrate.
d, Sn-Ag, Sn-Ag-Pd can be formed.

In this case, Sn, A on the non-conductive substrate
g and Pd are applied by an aqueous solution such as a sensitizing-activating method, an alkali catalyst method, a catalyst-accelerator method, a method of applying thermal decomposition after applying an organometallic complex, A dry method such as a sputtering method can be used.
In particular, sensitizing with an aqueous solution-silver activity-
The application method using palladium activity can be easily applied by controlling the process, aqueous solution, and treatment conditions. For example, as the sensitizing solution, SnCl ₂ , Sn
A divalent tin salt such as SO ₄ is dissolved in an acid solution such as hydrochloric acid or sulfuric acid to contain 1 to 50 g / L of divalent tin ions, and a pH of 0.
Use a strongly acidic solution of about 1 to 1.5,
Immersion treatment is carried out at 0 ° C. for 10 seconds to 5 minutes, and then silver ion-containing activator containing 0.0001 to
What is 0.5 mol / L is used, pH may be set to 5-11, a liquid temperature may be set to 15-60 degreeC, and immersion processing may be performed for 10 seconds-5 minutes. As the activator containing palladium, a divalent palladium salt such as PdCl ₂ , PdSO ₄ or the like is dissolved in an acid solution such as hydrochloric acid or sulfuric acid, and divalent Pd ion is adjusted to 0.
It is preferable to use a solution containing 0 to 1 g / L and having a pH of 1 to 3 and subjecting it to immersion treatment at 10 to 60 ° C. for 1 second to 5 minutes. If it is soaked for too long, Pd nuclei may be aggregated and agglomerated.

In this case, each of the steps of applying Sn, Ag, and Pd may be performed once, or may be repeated a plurality of times.

To make Sn, Ag and Pd within the above range
From 1500 nuclei / μm²Or more, preferably
Is 2000 nuclei / μm²Above, more preferably 2500 nuclei
/ Μm ²Above, especially 3000 nuclei / μm²With the above nuclear density
can do. In this case, the high density Pd nuclear dispersion layer is
The average surface roughness is 0.5 nm or less, particularly 0.3 nm or less.
And the catalyst core particle size is 2 nm or less,
It is preferably 1.5 nm or less, more preferably 1 nm or less.
And can form dense and dense layers. Na
This high-density Pd nuclear dispersion layer is used as a catalyst layer for electroless plating.
When used as a catalyst, the particle size of the catalyst nucleus is 0.
The thickness is preferably 03 nm or more. Above nuclear density, average
Roughness and average particle size are for AFM (atomic force microscope) observation
More measurable.

The weight ratio of Sn, Ag and Pd is I
It can be analyzed by CP (inductively coupled plasma emission spectroscopic analyzer).

The electroless zinc oxide film depositing solution in the above step (4) is not particularly limited as long as it is a liquid for depositing zinc oxide, but zinc salt such as zinc nitrate is 0.0
1 to 0.5 mol / L, preferably 0.05 to 0.2 m
ol / L, amine borane-based reducing agents such as dimethylamine borane, and other reducing agents in an amount of 0.001 to 0.5 mol / l.
L, preferably 0.0005 to 0.3 mol / L, particularly 0.0001 to 0.2 mol / L, and a treatment liquid having a pH of about 4 to 9, particularly about 6.5, can be suitably used, and a treatment liquid of 10 to 80 can be suitably used. A method of dipping at 10 ° C. for 10 to 200 minutes can be adopted.

In this case, the thickness of the zinc oxide film can be 0.005 μm or more, preferably 0.005 to 2 μm, but is not limited to this.

Further, the electroless zinc oxide film may be formed on the electroless zinc oxide film from the above composition liquid by using the electroless zinc oxide film as a cathode.

In this case, the electrolytic zinc oxide film depositing solution is not particularly limited as long as it is a liquid that deposits zinc oxide, but zinc salt such as zinc nitrate 0.01 to 0.5 mo
A treatment liquid containing 1 / L, preferably 0.05 to 0.2 mol / L and having a pH of about 4 to 9, particularly pH 6 can be preferably used, and a conductive substrate using zinc, carbon, platinum or the like as an anode. 1cm ² per 0.1 to 20 Coulomb,
Preferably, a zinc oxide film can be obtained by energizing for 1 to 10 coulombs. The bath temperature is used in the range of 10 to 80 ° C. If the substrate has a material that can be electroplated, electroless zinc oxide plating may be omitted and only electrogalvanic zinc plating may be performed.

Here, the film characteristics of the zinc oxide containing the divalent and trivalent iron compounds may be appropriately selected according to the application.

For example, when utilizing transparency, the surface roughness is preferably 200 nm or less, preferably 100 nm or less, and particularly preferably 10 nm or less. When forming a zinc oxide film having such transparency characteristics,
In the electroless zinc oxide plating method, sensitizing-silver activation-palladium activation treatment can be used as the catalyst application treatment. The zinc oxide film that has been subjected to this catalyst application step can have a visible light transmittance of 55% or more, particularly 75% or more, even when the method of incorporating an iron compound described below is used.

Further, when utilizing excellent conductivity, the film thickness of the zinc oxide film produced by the electroless zinc oxide plating method or the electrozinc oxide plating method is 0.05 to 0.5 μm, particularly 0.1 to 0. The thickness can be set to 0.3 μm, and when such a zinc oxide film is used, the specific resistance value is 5.0 × 10 ¹⁰ to 1.
It can be set to 0 × 10 ⁻³ Ω · cm.

Further, in order to control the specific resistance value as described above, the bath conditions such as the concentration of the water-soluble zinc salt and the concentration of the amine borane-based reducing agent in the electroless zinc oxide plating method or the electrozinc oxide plating method, the treatment time, etc. The specific resistance value of the zinc oxide film can be controlled to 2.5 × 10 ^{10 to} 1.0 × 10 ⁻³ Ω · cm by controlling the treatment conditions of 1) or by controlling the dopant in the film. . In the control method using a dopant, in order to increase the specific resistance value, it is sufficient to dope a monovalent metal (for example, Na, Li, K, Cu ⁺ , Ag, etc.) into the film, and conversely decrease the specific resistance value. For this, a trivalent metal may be doped into the film. As a method of doping these metals, a method of immersing the zinc oxide film in an aqueous solution containing the metal to be doped can be adopted.

In the present invention, the zinc oxide film thus formed contains an iron compound. The means for incorporating the iron compound is to treat the zinc oxide film with an iron-containing solution. Examples of the method include a method of adding a water-soluble iron salt to the electroless or electrogalvanic zinc plating solution, and plating with the plating solution.

Here, as the iron-containing solution (treatment liquid), a water-soluble iron salt such as iron nitrate is added to iron ions (iron ions having a valence of 3
0.001 to 0.05 mol / L,
In particular, 0.005-0.03 mol / L, amine borane-based reducing agents such as dimethylamine borane, phosphorus-based reducing agents such as sodium hypophosphite, hydrazine, formaldehyde,
A reducing agent capable of reducing iron such as L-ascorbic acid and phenanthroline is contained in an amount of 0.005 to 0.1 mol / L, particularly 0.01 to 0.05 mol / L, and a pH of 2 to
It is possible to use an aqueous solution adjusted to 6, especially 2.5 to 5.

In this case, it is considered that trivalent iron ions are preferentially substituted or dispersed in the zinc oxide film by the treatment with the iron-containing solution. Further, it is important that the iron-containing solution contains an iron reducing agent. The reducing agent reduces trivalent iron ions in the iron-containing solution to divalent iron ions to increase the amount of divalent iron ions, whereby divalent iron is replaced or dispersed in the zinc oxide film. It will be easier to do. The divalent iron ion: trivalent iron ion ratio in the solution is preferably 1: 5 to 5: 1, and particularly preferably 1: 3 to 3: 1 in terms of molar ratio. This can be confirmed by measurement by ESCA. This ratio can be realized by controlling the DMAB concentration and pH of the iron-containing solution. The higher the DMAB concentration, the higher the proportion of divalent iron ions in the solution. Moreover, if the pH is raised, the ratio of divalent iron ions can be increased.

The above zinc oxide (plating) film is treated at 20 to 80 ° C., particularly 30 to 60 ° C.
Immersion treatment may be performed for 10 to 90 minutes, particularly 20 to 60 minutes.
If the treatment time is shorter than 10 minutes, the ferromagnetism may not be exhibited. It is considered that this is because divalent iron was not sufficiently contained in the zinc oxide film. Also, the processing time is 60
If the length is longer than this, the wurtzite structure of zinc oxide may be destroyed, the n-type semiconductor characteristics that are characteristics of the zinc oxide film may be lost, and the light transmittance may be reduced.

When a water-soluble iron salt is added to the plating solution for plating, the water-soluble iron salt such as iron nitrate is converted into iron ions (the iron ion may be divalent or trivalent) in an amount of 0.001.
.About.0.05 g / L, particularly 0.005 to 0.03 g / L is added to the electroless zinc oxide plating solution or the electrogalvanic zinc plating solution, and plating may be performed under the above conditions.

As described above, after the zinc oxide (plating) film is formed, the iron is subjected to an immersion treatment using an iron-containing solution or a plating treatment using an electroless or electrolytic zinc oxide plating solution containing a water-soluble iron salt. A zinc oxide film containing the compound is obtained.

This iron-containing zinc oxide film has ferromagnetism at room temperature (25 ° C.) in the as-treated state,
It does not require heat treatment or the like to develop ferromagnetism.

As described above, the zinc oxide film of the present invention contains an iron compound, and as the iron compound, iron oxide (Fe ₂ O ₃ , Fe ₃ O _4, etc.) and other A compound containing divalent iron ion and trivalent iron ion of
In particular, it is preferable that the divalent iron compound and the trivalent iron compound coexist. Further, the zinc oxide film of the present invention may contain metallic iron in addition to the iron compound.

In this case, the iron content in the zinc oxide film is preferably 20 to 50% by weight, particularly 30 to 45% by weight, and the saturation magnetization at room temperature (25 ° C.) is 15 to 40 emu / cc. , Especially 20-30 emu / c
c, the coercive force is preferably 20 to 100 Oe, and particularly preferably 50 to 80 Oe. The divalent iron: trivalent iron (weight ratio) in the film is 1:25 to 25: 1, and particularly 1:10.
It is preferably 10: 1. This ratio is
It can be confirmed by measurement by the ESCA method.

As described above, the iron compound-containing zinc oxide film has ferromagnetism even if it is not heat-treated, but in a non-oxidizing atmosphere (vacuum, reducing atmosphere, argon, helium, The magnetic properties are improved by performing the heat treatment under a non-oxidizing atmosphere such as nitrogen. The vacuum atmosphere may be under a vacuum of 1 × 10 ⁻² to 1 × 10 ⁻⁷ torr. As the reducing atmosphere, a hydrogen atmosphere or a nitrogen atmosphere containing 1 to 5% by weight of hydrogen can be adopted.

The heat treatment time may be 5 to 120 minutes, especially 10 to 60 minutes. The heating temperature may be 150 to 800 ° C., preferably
It is 300-600 degreeC. By heating, the content of divalent iron in the zinc oxide film increases, exhibits magnetic hysteresis at room temperature, and has a saturation magnetization of 20 to 60 emu / cc, especially 30.
˜50 emu / cc, coercive force of 150 to 500 Oe, especially 250 to 350 Oe, which can be confirmed by VSM measurement.

The ferromagnetic zinc oxide film of the present invention can be used as it is deposited on the substrate, and the ferromagnetic zinc oxide film can be immersed in water from the substrate and irradiated with ultrasonic waves. May be used for peeling, or the peeled ferromagnetic zinc oxide film may be pulverized into particles and then kneaded into a resin paste as a magnetic material for use.

[0041]

EXAMPLES The present invention will be specifically described below by showing Examples and Comparative Examples, but the present invention is not limited to the following Examples.

Example 1 Soda lime glass was used as a non-conductive substrate, and a catalyst was applied in the following steps. Catalyst application i. The degreasing substrate was immersed in the following degreasing agent solution at 50 ° C. for 3 minutes. ii. Rinse with water at 25 ° C. for 15 seconds iii. Surface Conditioning The solution was immersed in the following surface conditioner solution at 30 ° C. for 5 minutes. iv. Washing with water 25 ° C, 15 seconds v. Sensitizing It was immersed in the following sensitizing solution at 20 ° C. for 1 minute. vi. Rinse with water at 25 ° C for 15 seconds vii. Catalysis Addition The above silver activating solution was dipped at 20 ° C. for 1 minute. viii. Rinse with water at 25 ° C for 15 seconds ix. Catalytic Immersion It was immersed in the following palladium activating solution at 20 ° C. for 1 minute. x. Washing with water 25 ℃ for 15 seconds

Next, the following electroless ZnO plating solution was used for immersion treatment at pH 6.3 and 68 ° C. for 1 hour.

Further, using the following iron-containing solution, the solution was heated at 50 ° C. for 3 hours.
Immersion treatment for 0 minutes was performed. Degreasing agent Asahi Cleaner C-4000 5 g / L Surface conditioner Sulcup CD-202 50 mL / L Sensitizing solution SnCl ₂ 15 g / L HCl (36%) 45 mL / L pH 0. 5 Silver activation solution AgSO ₄ 3 g / L pH 7.0 Palladium activation solution PdCl ₂ 1.5 g / L HCl (36%) 1.5 mL / L pH 2.8 Electroless ZnO plating solution Zn (NO ₃ ) ₂ 0.1 mol / L DMAB 0.005 mol / L pH 6.3 Iron-containing solution Iron nitrate 0.1 mol / L DMAB 0.03 mol / L pH 3.9

The iron compound-containing zinc oxide film obtained by the above method was measured by VSM at 25 ° C. and the results are shown in FIG. The iron compound-containing zinc oxide film exhibits magnetic hysteresis and is found to be ferromagnetic. Moreover, a peak of zinc oxide was shown by X-ray diffraction. Saturation magnetization is 28e
The mu / cc and coercive force were about 34 Oe.

The iron content in this iron compound-containing zinc oxide film was 40% by weight (ICP measurement), of which divalent iron was 4% by weight and trivalent iron was 36% by weight (ESC).
A measurement).

Example 2 The iron compound-containing zinc oxide film obtained in Example 1 was subjected to vacuum (10 ⁻⁵ torr) at 450 ° C.
And heat treated for 30 minutes. Fig. 1 shows the results of the VSM measurement of the iron compound-containing zinc oxide film after the heat treatment at 25 ° C.
Shown in. Magnetic hysteresis was observed and saturation magnetization was about 37
It was emu / cc and coercive force was about 280 Oe, and improvement in magnetic properties was confirmed. Further, a peak of zinc oxide was observed by X-ray diffraction.

Comparative Example 1 The iron compound-containing zinc oxide film obtained in Example 1 was heat-treated in the air at 450 ° C. for 30 minutes. 25 ° C of iron compound-containing zinc oxide film after heat treatment
FIG. 1 shows the result of the measurement by VSM at the same time. No magnetic hysteresis was observed.

[Examples 3 to 9 and Comparative Examples 2 to 4] An iron compound-containing zinc oxide film was prepared in the same manner as in Example 1 except that the treatment time of the iron-containing treatment solution and the reducing agent were changed as shown in Table 1. Was produced. Regarding the obtained iron oxide containing zinc oxide film, presence or absence of magnetic hysteresis (VSM measurement), weight ratio of divalent and trivalent iron in the film (ESCA measurement), specific resistance value, visible light transmittance, zinc oxide Table 1 shows the results of measuring the presence or absence of the peak (X-ray diffraction).

[0050]

[Table 1]

[Examples 10 to 12] An iron compound-containing zinc oxide film which was treated with an iron-containing solution in the same manner as in Example 1 using the zinc oxide film obtained by the treatment method shown in the following a) to c) was used. Presence of magnetic hysteresis (VSM measurement), weight ratio of divalent and trivalent iron in the film (ESCA measurement), presence of zinc oxide peak (X-ray diffraction), specific resistance value, visible light transmittance The measured results are shown in Table 2.

[0052]

[Table 2]

<Method for Producing Zinc Oxide Film> a) Production using a DC magnetron sputtering method on a glass substrate. B) A soda lime glass substrate was prepared by subjecting the surface of the soda lime to publicly known surface treatment and then performing the following electrogalvanizing plating. Zinc nitrate 0.1 mol / L DMAB 0.3 mol / L pH 6.5 Anode platinum cathode Current density 1 mA / cm ² Bath temperature 60 ° C. Treatment time 60 minutes c) Soda lime glass substrate was pretreated in the same manner as in Example 1. After applying the catalyst, the following electroless zinc oxide plating was performed, heated at 450 ° C. in a reducing atmosphere, and further subjected to the following electrozinc oxide plating. Electroless zinc oxide plating bath Zinc nitrate 0.1 mol / L boric acid 0.3 mol / L pH 6.5 Bath temperature 65 ° C. Treatment time 60 minutes Electrogalvanic plating bath zinc nitrate 0.1 mol / L Boric acid 0.3 mol / L pH 6.5 Bath temperature 65 ° C. Treatment time 60 minutes Cathode current density 1 mA / cm ²

Examples 13 to 14 The presence or absence of magnetic hysteresis, saturation magnetization, and coercive force of the iron compound-containing zinc oxide film prepared under the same conditions as in Example 1 except that the following electroless zinc oxide plating bath was used. Table 3 shows the VSM measurement), the weight ratio of divalent and trivalent iron in the coating (ESCA measurement), the specific resistance value, the visible light transmittance, and the presence or absence of a zinc oxide peak (X-ray diffraction). Show. The obtained iron compound-containing zinc oxide film was heat-treated under vacuum (10 ⁻⁵ torr) at 450 ° C. for 30 minutes (Example 14). The results of measuring the film characteristics as in Example 13 are also shown in Table 3.

[0055]

[Table 3]

Electroless zinc oxide plating bath Zinc nitrate 0.1 mol / L Iron nitrate 0.01 mol / L DMAB 0.01 mol / L pH 5.9 Bath temperature 60 ℃ Processing time 60 minutes

[0057]

According to the present invention, a zinc oxide film exhibiting ferromagnetism at room temperature is provided.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between coercive force and saturation magnetization of films of Examples 1 and 2 and Comparative Example 1.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C25D 5/50 C25D 5/50 5/56 5/56 A 9/08 9/08 H01F 10/14 H01F 10 / 14 41/26 41/26 H01L 21/285 H01L 21/285 S 301 301Z 21/288 21/288 EZ (72) Inventor I ▲ Sakino Masanobu Nara Prefecture North ▲ Kumigaoka 1 chome 4 1 (72) Inventor Yoshiji Saijo 1-5-1 Exit Hirakata-shi, Osaka Prefecture Central Research Institute, Uemura Industrial Co., Ltd. (72) Katsuhisa Tanabe 1-5-1 Uemura, Exit 1 Hirakata, Osaka Kogyo Co., Ltd. Central Research Institute F-term (reference) 4K022 AA02 AA03 AA04 AA05 AA13 AA43 AA44 AA46 BA09 BA15 BA25 BA33 DA01 EA01 EA04 4K024 AA18 AB17 BA01 BA11 BB09 BB12 BB14 BB27 DB01 DB03 DB10 GA16 4M104 DD36 BB36 DD52 DD55 DD78 GG04 GG20 HH16 5E049 AB01 AB09 BA16 BA30 EB06 LC01

Claims (8)

[Claims] 1. A ferromagnetic zinc oxide film exhibiting ferromagnetism at room temperature, characterized by containing an iron compound in the zinc oxide film. 2. The ferromagnetic zinc oxide film according to claim 1, wherein the total iron content including the iron compound is 20 to 50% by weight in the film as iron. 3. The ferromagnetic zinc oxide film according to claim 1, wherein a divalent iron compound and a trivalent iron compound coexist as the iron compound. 4. After forming a zinc oxide film on the surface of the substrate,
2. The production of a ferromagnetic zinc oxide coating according to claim 1, wherein the zinc oxide coating is treated with a treatment liquid containing a water-soluble iron salt and a reducing agent so that the zinc oxide coating contains an iron compound. Method. 5. The method according to claim 4, wherein the zinc oxide film is produced by an electrogalvanizing zinc oxide method or an electroless zinc oxide plating method. 6. After formation of the ferromagnetic zinc oxide film, under vacuum,
The manufacturing method according to claim 4, wherein the heat treatment is performed in a reducing atmosphere or a non-oxidizing atmosphere. 7. A substrate is treated with an electroless zinc oxide plating solution containing a water-soluble iron salt or an electrolytic zinc oxide plating solution to form a zinc oxide film containing an iron compound on the surface of the substrate. Item 1. A method for producing a ferromagnetic zinc oxide film according to Item 1. 8. After formation of the ferromagnetic zinc oxide film, under vacuum,
The manufacturing method according to claim 7, wherein the heat treatment is performed in a reducing atmosphere or a non-oxidizing atmosphere.