JPS62154232A - Production of magnetic iron nitride material - Google Patents

Abstract

PURPOSE:To prevent the damage of a plastic substrate and to obtain a medium consisting of iron nitride as a magnetic material at a high speed by bringing a gaseous compd. contg. iron atoms and gaseous compd. contg. nitrogen atoms into reaction at a low temp. near an ordinary temp. by making use of the light energy of a UV region. CONSTITUTION:An ion pentacarbonyl 1 is entrained in carrier gaseous Ar2 and is fed to a reactor 8. The flow rate of the Ar2 is regulated by a control valve 4 and is measured by a mass flow meter 3. Gaseous ammonia 5 is regulated by a control valve 7 and is measured by a mass flow meter 6; thereafter, said gas is supplied to the reactor 8. The pressure in the reactor is reduced by a vacuum pump 13. An ArF laser 12 having a rectangular section is oscillated by pulses from an ArF laser oscillator 11 and is irradiated through a window 13 onto a plastic film 10 placed on a pedestal 9. Active nitrogen atoms and iron atoms are formed by the irradiation of the ArF laser in the reactor 8 and the iron nitride is formed on the film 10.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing a iron nitride magnetic material with excellent corrosion resistance and magnetic properties, and is particularly suitable for producing a magnetic recording medium at a low temperature of 100°C or less. It is.

[Conventional technology]

Demand for high-density magnetic recording media is increasing with the aim of making magnetic recording and reproducing equipment smaller and lighter and improving the performance of magnetic recording and reproducing. For this reason, instead of the conventional coated magnetic recording medium using acicular r-FezOs as a magnetic material, methods are being considered in which fine metal particles are deposited directly on a substrate by vacuum evaporation or sputtering without using a binder. Although this method allows for higher density magnetic recording, the gold IRm particles are easily oxidized and have a problem in corrosion resistance.

On the other hand, iron nitride is stable in the atmosphere and F84
FeN iron nitride has a saturation magnetization 0.9 times that of pure iron, and FeN iron nitride has a saturation magnetization 1.3 times that of pure iron, and has a large coercive force, making it an excellent magnetic material for high-density magnetic recording media.

As a known technique for producing iron nitride-based magnetic materials, JP-A-59
There is No.-45911. This is a method of sputtering pure iron with Ar ions in a nitrogen atmosphere to synthesize a nitrogen-iron-containing iron magnetic film on a substrate. FeaN has the advantage of being able to synthesize iron magnetic films containing around 10% iron nitride.

[Problem that the invention seeks to solve]

The above-mentioned conventional techniques do not give much consideration to the fabrication of plastic-based magnetic recording media. In other words, when a plastic sheet is used for the substrate in this method, damage to the substrate by Ar ions is unavoidable, and To synthesize an iron nitride-containing iron magnetic film with excellent characteristics and subtle influence of partial pressure, 2X10 Ichiban-7XIO Ichiban To
It is necessary to maintain the film growth rate at 1 to 2 μm/
h, which is not a practical method for synthesizing a magnetic recording medium with a magnetic layer thickness of 0.5 to 1.0 μm.

An object of the present invention is to provide a method for manufacturing a magnetic recording medium using iron nitride as a magnetic material at a faster rate than before while preventing damage to a plastic substrate.

[Means for solving problems]

The above object is achieved by causing a gaseous compound containing an iron atom and a gaseous compound containing a nitrogen atom to react at a low temperature near room temperature using light energy in the ultraviolet region.

[Effect]

Iron pentacarbonyl absorbs ultraviolet light of 150 nm to 250 nm, decomposes without heating, and actively produces iron atoms.

On the other hand, ammonia absorbs ultraviolet light of 170 nm to 240 nm and decomposes without heating to generate active nitrogen atoms.

These active atoms react to form iron nitride. Furthermore, since ultraviolet light does not have enough energy to ionize atoms, the active atoms are radicals. As mentioned above.

By using ultraviolet light, it is possible to prevent damage to the plastic substrate due to ions and heat, and a high quality iron nitride magnetic film can be produced on the plastic substrate.

〔Example〕

The present invention will be explained in more detail below using specific examples. FIG. 1 shows a configuration diagram of the present invention.

Iron pentacarbonyl 1 is sent to reactor 8 along with carrier gas Ar2. The flow rate of 8r2 is adjusted by control valve 4:! and is measured by the mass flow meter 3. Further, ammonia gas 5 is regulated by a control valve 7, metered by a mass flow meter 6, and then supplied to the reactor 8.
The pressure is reduced to r. On the other hand, an ArF laser 12 having a rectangular cross section is oscillated with pulses from an ArF laser oscillator 11.
Plastic film 1 placed on pedestal 9 through window 13
0 is irradiated. At this time, in order to prevent iron nitride from being deposited on the surface of the window 13, Ar gas 17 is ejected from the ring-shaped nozzle 16 onto the window surface. Inside the reactor 8, Ar
By the FL laser irradiation, useful nitrogen atoms and iron atoms are generated, and iron nitride is generated on the plastic film 1o.

[Example 1] Using the practical apparatus schematically shown in Fig. 1, iron pentacarbonyl was used as the iron atom-containing compound, ammonia was used as the nitrogen atom-containing compound, and Ar with a wavelength L of 93 nm was used as the light energy. An experiment was conducted to synthesize iron nitride using an F laser.

The experimental conditions were a pressure of 10 Torr and a substrate temperature of 25 to 100 Torr.
°C, laser output 10 mJ/pulse, 10 pulse/
The reaction was carried out for 30 minutes with win. In addition, the substrate was water-cooled as necessary.

After the experiment, the magnetic properties of the precipitates, the single-element composition, X-ray diffraction,
Corrosion resistance etc. were measured.

Figure 2 shows the measurement results of magnetic properties.The saturation magnetization is 160.
amu/g and coercive force of about 10,000 e, indicating that it is an excellent magnetic material with both saturation magnetization and coercive force larger than that of ferrite.

The elemental composition is Fea, aN, and is composed of iron and nitrogen. Further, the X-ray diffraction results showed an amorphous structure, and the film thickness was 3 μm when examined using an electron microscope.

Figure 3 shows the change in saturation magnetization when the sample was left in a 60°C saturated humidity atmosphere for 80 hours. It can be seen that there is almost no change in saturation magnetization even after being left for 8 days, indicating that it has very excellent corrosion resistance.

[Example 2] Using the same equipment as in Example 1, the light source was a KrF laser with a wavelength of 248 nm and an output of 20 mJ/pulse, and a wavelength L of 57 nm.
The reaction was carried out for 1 hour under the same conditions as in Example 1 using an F laser with an output of 4 m J/' pulse.

Although the precipitation rate was reduced to 1/2 to 115 times that of the ArF laser, iron nitride having magnetic properties and corrosion resistance comparable to those of Example 1 and l1i1 was obtained. The precipitation rate was reduced by K.
This is thought to be due to a decrease in the light absorption rate of iron pentacarbonyl and ammonia 2 in the rF and F ray→〆 wavelength ranges.

[Example 3] Using the same apparatus as in Example 1 and using an inexpensive 80 W mercury lamp as a light source, a reaction was carried out for 1 hour under the same conditions as in Example 1. The deposition rate was almost the same as in Example 2, and the magnetic properties were similar to those in Example 1.

From the above, it is clear that ArF, KrF, F lasers and mercury lamps can be used as light sources.

[Example 4] Ferric chloride was used as the iron atom-containing compound, methylamine was used as the nitrogen-containing compound, and Ar was used as the light source.
F was used to react for 1 hour. Although the precipitation rate was considerably reduced, the saturation magnetization and coercive force of the precipitates were approximately the same as in Example 1.

From the above experiments, the iron source is iron pentacarbonyl, and the nitrogen source is not limited to ammonia, but is a compound containing iron or nitrogen that absorbs ultraviolet light and is decomposed by these ultraviolet lights. I know that anything is good. For example, iron sources include iron halides, and nitrogen sources include amines.

FIG. 4 shows another embodiment of the invention.

The feature of this device configuration is that a gas 21 such as ammonia containing nitrogen atoms and a gas 22 such as iron pentacarbonyl containing iron atoms are separated, and the gas 21 that does not precipitate particles even when decomposed is always used with ultraviolet light 23. The reason is that the window 24 through which the air passes through is always cleaned. According to this method,
This prevents photochemical reactants from depositing on the surfaces of windows and lenses, blocking light from passing through.

〔Effect of the invention〕

According to the present invention, it is possible to synthesize an iron nitride magnetic material with excellent magnetic properties and corrosion resistance without damaging substrates such as plastics, and the recording material can be used for producing high-density magnetic tapes.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing one embodiment of the present invention, Fig. 2 is a graph showing actual measurement results of magnetic properties of precipitates, Fig. 3 is a graph showing results of corrosion resistance test of precipitates, and Fig. 4 is a graph showing results of a corrosion resistance test of precipitates. FIG. 3 is a diagram showing another embodiment. 1... Iron pentacarbonyl, 2... Ar gas, 5...
... Ammonia gas, 8... Reactor, 10... Substrate, 11... ArF laser oscillator, 12... ArF laser, 14... Vacuum pump.

Claims (1)

[Claims] 1. Gaseous molecules containing iron atoms and gaseous molecules containing nitrogen atoms are introduced into a reactor, and light energy such as laser light or ultraviolet light is applied to the gases. A method of manufacturing iron nitride magnetic material on a substrate such as plastic at a low temperature of 100°C or less by causing a chemical reaction. 2. The method for producing an iron nitride magnetic material according to claim 1, wherein the gaseous molecule containing iron atoms is an iron carbonyl compound. 3. The method for producing a iron nitride magnetic material according to claim 1, wherein the gaseous molecule containing nitrogen atoms is ammonia. 4. The method for producing an iron nitride magnetic material according to claim 1, wherein the optical energy is ArF, KrF or F_2 laser.