JPH0530284B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to magnetic semiconductor spherical fine particles and a method for producing the same.

[Prior art and its problems] Conventionally, ferrite exists as magnetic fine particles. However, the grain shape of ferrite is not spherical,
It is rod-shaped, or flake-shaped like barium ferrite, and has anisotropy as a magnetic material. For this reason, when attaching ferrite to a base material such as a tape or disk to form a magnetic recording medium, it is difficult to arrange the ferrite on the base material while taking anisotropy into consideration. There was a problem that the magnetic anisotropy of the deposited ferrite was in different directions, making it impossible to obtain good magnetic properties.

In addition, conventional CVD (Chemical Vapor
A single component gas source is used for epitaxially growing materials such as
Even when forming a compound semiconductor, a gas source must be prepared for each growth component, which poses the problem of complicating the equipment and manufacturing process.

Therefore, the present invention aims to provide a magnetic recording medium that has no magnetic anisotropy and can be deposited on a base material and has good magnetic properties, as well as a magnetic recording medium that can generate a compound component gas of ferrite components and ceramic components as a CVD raw material. The purpose of the present invention is to provide semiconductor spherical fine particles and a method for manufacturing the same.

[Means for Solving the Problems] The present invention produces ferrite/ceramic composite particles in particle units in which ferrite crystals are adhered to the surface of fine ceramic particles, which are heated and melted and then heated at high speed with water, a cooling plate, etc. By thermal spraying onto a coolant, magnetic semiconductor spherical fine particles are obtained as a solid solution that is homogeneous on a particle-by-particle basis.

[Function] By heating and melting the ferrite/ceramic composite particles, a homogeneous solid solution of ferrite and ceramic components can be obtained, and by spraying this at high speed onto water or a cooling plate, amorphous magnetic semiconductor spherical fine particles can be obtained. is obtained, and is used as a magnetic material for perpendicular recording, as well as a ferrite ceramic compound.
A new material useful as a raw material for CVD can be obtained.

[Example] Ferrite-ceramic composite particles were previously invented and filed by the inventor of the present application, and the manufacturing method thereof is as follows.

First, in order to form a magnetic field, one or more magnets with strong magnetic force are placed in a container containing an aqueous ferric chloride solution (concentration 5 to 35%), and a large number of iron pieces (in the case of granular (particle size: 0.1 to 4 mm).
After fluid stirring, the aqueous solution is filtered to obtain a complex salt aqueous solution.

In this case, the ferric chloride aqueous solution is brought into contact with a magnetic iron piece in the container.
A multi-cell reaction by electrolytic ion exchange generates a large number of cathodes and anodes, hydrogen ions H ⁺ are released as hydrogen gas H ₂ at the cathode, and anions and cations form a stable complex salt aqueous solution.

Next, the particle size distribution is determined in advance as ceramic fine particles.
The complex salt aqueous solution is added to a ferric chloride aqueous solution (concentration 5 to 35%) mixed with zircon fine particles with a particle size distribution of 0.05 μ to several 100 μ, preferably 0.05 μ to 20 μ.
% to 50% and stir thoroughly to form a composite aqueous solution. This complex aqueous solution is acidic and Cl ^-
It is something that has.

By mixing a caustic soda aqueous solution (concentration 30%) into a composite aqueous solution containing a plurality of ceramic fine particles, the Cl ^- binds to Na ⁺ and becomes salt (NaCl), and in the aggregation process, ferrite (Fe ₃ O ₄ ) becomes black. It is brown in color and crystallizes and adheres almost uniformly to the surface of the ceramic fine particles, forming ferrite-ceramic composite particles. Also, salt (NaCl)
becomes dissolved in water.

In this state, the ferrite/ceramic composite particles are precipitated and the top layer is discarded, or the water is separated by centrifugation and water is added to make salt (NaCl).
After that, the water remaining in the ferrite-ceramic composite particles is separated and dried to obtain ceramic bodies, ie, ferrite-ceramic composite particles, evenly coated with highly pure ferrite.

The ferrite/ceramic composite particles produced in this way have ferrite (Fe ₃ O ₄ ) evenly coated on each fine ceramic particle.
When the particle size of the ceramic fine particles is 0.05μ to 20μ, the particle size (distribution) is approximately 0.1μ to 25μ.

In these ferrite/ceramic composite particles, the ferrite is strongly bonded and adhered to the surface of the ceramic fine particles, and is difficult to separate even by mechanical friction, impact, etc.

In the above case, ferric chloride was used as the ferrite component, but the invention is not limited to this.
Metal or metalloid chlorides such as nickel, cobalt chloride, barium chloride, titanium chloride, etc. may be added in combination.

For example, ferrite on the surface of ceramic fine particles.
If you want to coat nickel, use the dichloride mentioned above.
A composite aqueous solution of ferric chloride and nickel chloride may be used instead of the iron aqueous solution.

In addition, although zircon (ZrSiO ₄ ) is used as _the ceramic fine particles, the ceramic particles _are not limited to this _.
O ₃ ), non-metals such as metal or metalloid oxide particles such as cobalt oxide, titanium oxide, barium oxide, boron oxide, nitride particles such as silicon nitride, or carbide particles such as carbon or silicon carbide Compounds with and various composite fine particles thereof may also be used.

Note that in the present specification, ceramic means all inorganic substances excluding metal bodies used in general academic terminology. Most of them are oxides, nitrides, carbides, borides, etc. In addition, the ferrite crystals deposited on the surface of the ceramic fine particles are mainly produced by alkali reduction of a complex salt aqueous solution.
Magnetic oxide polycrystals (composite suboxides, _e.g. Fe/Ni/Co _/
etc/Ox, etc.).

Next, the thus obtained powder of ferrite-ceramic composite particles (average particle size 0.6 μm) is reduced and melted at high temperature using a plasma spraying device. At this time,
Ferrite and ceramic melt simultaneously at the same temperature, resulting in a state in which the ferrite component and ceramic component are homogeneously mixed and bonded. This is done at high speed (approximately 30m/
sec), by colliding with water or a cooling plate for rapid cooling, to obtain amorphous magnetic semiconductor spherical fine particles in which a ferrite component and a ceramic component are combined.

The magnetic semiconductor spherical fine particles obtained in this way have a good solid solution of a ferrite component (Fe ₃ O ₄ ) and a ceramic component (ZrO ₂ or ZrSiO ₄ ), so they are heat resistant, highly accurate, and strong. It is magnetic. Moreover, these magnetic semiconductor spherical fine particles have a homogeneous solid solution of ferrite components and ceramic components,
These are semiconductor particles in an amorphous state. Therefore, it exhibits excellent magnetic properties as a recording magnetic material, and since it is a spherical fine particle when mixed with an organic binder, etc., the mixing ratio can be increased. This means that the manufacturing process in manufacturing the magnetic recording medium is facilitated, and a homogeneous product with good characteristics can be obtained.

In addition, when manufacturing ceramic/ferrite semiconductor devices, etc., it becomes possible to simultaneously deposit multiple components as raw materials for CVD. i.e. current CVD
However, if the magnetic semiconductor fine particles according to the present invention are used as a raw material for CVD, it becomes possible to generate gases for ceramic and ferrite components, which are multi-components. Single crystal epitaxial growth of ferrite can now be formed with a desired component ratio.

(Example 1) According to the method for producing ferrite-ceramic composite particles described above, magnetite (Fe ₃ O ₄ ) was 60% by weight as a ferrite component, and zirconia (ZrO ₂ ) was 40% by weight as a ceramic component. Zirconia/magnetite composite oxide fine particles were manufactured by coating zirconia fine particles with magnetite oxide crystals. Then, as mentioned above,
This zirconia-magnetite composite fine particle powder is reduced and melted at high temperature using a high-frequency thermal plasma spraying device. In other words, the thermal spraying condition is high frequency output: 4M
Hz/75Kw, gas used: argon gas, gas flow rate: 60l/min during high frequency thermal plasma.
The zirconia-magnetite composite fine particles are fed using 15 l/min of argon gas as a carrier gas, and are injected into a cooling water tank in a 1/2 atm vacuum chamber at a plasma flame speed of about 30 m/sec to rapidly cool the particles. Magnetic semiconductor spherical fine particles of 0.5 to 5μ were obtained.

When we measured the magnetic properties of this powder of magnetic semiconductor spherical fine particles that was melted and solidified, we found that
Magnetism (MFB(T)) was 0.18 emu/g, and residual magnetic flux density (MPH (A/m)) was 5HK.

Furthermore, in the above thermal spraying step, molten zirconia,
Instead of injecting magnetite composite fine particles into a cooling water tank to obtain magnetic semiconductor spherical fine particles, a solid solution film identical to the magnetic semiconductor spherical fine particles of the present invention is created by thermal spraying onto an alumina (Al ₂ O ₃ ) substrate, and the temperature When the electrical resistance value was measured, the temperature/electrical resistance characteristics were negative resistance characteristics (semiconductor characteristics) of 10KΩ/30°C to 10Ω/500°C.

[Effects of the Invention] As described above, according to the present invention, magnetic semiconductor fine particles can be obtained that exhibit unprecedented functions and characteristics, especially as magnetic materials for recording and materials for forming semiconductors.

Claims (1)

[Claims] 1. A ferric chloride aqueous solution is brought into contact with a large number of iron pieces in a magnetic field to form a complex salt aqueous solution, and a large number of ceramic fine particles are mixed with the complex salt aqueous solution to form a ferric chloride aqueous solution.
Mix it into an iron aqueous solution and stir it to form a composite aqueous solution.
By mixing and stirring the composite aqueous solution with an aqueous solution of caustic soda, ferrite is almost evenly deposited on the entire surface of the single fine particles of the ceramic body in a crystalline state, and then washed with water and dried to form ferrite/ceramic. After manufacturing the composite particles,
A method for producing magnetic semiconductor spherical fine particles, which comprises melting the powder of the ferrite-ceramic composite particles in a plasma spraying device, and rapidly cooling the powder by spraying it onto a coolant at high speed to form solid solution spherical fine particles.