JP2611845B2 - Method for producing garnet fine particle powder - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing garnet fine particle powder which is excellent in magneto-optical properties and is suitable for applications such as optical isolators, optical circulators, optical switches, optical waveguides, and optical memories. .

(Prior Art and Problems Thereof) Conventionally, as a material excellent in magneto-optical effect, a material made of an amorphous alloy of a rare earth metal and a transition metal has been known.

However, such an amorphous alloy material has a drawback that it is susceptible to oxidative corrosion and the magneto-optical characteristics are deteriorated. In addition, amorphous alloys have a low light transmittance, and therefore utilize the magneto-optical effect (Kerr effect) due to reflection on the surface. However, amorphous alloys generally have a small Kerr rotation angle and thus have a problem of low sensitivity. there were.

On the other hand, JP-B-56-15125 proposes a magneto-optical material using a garnet polycrystalline oxide thin film. A magnetic body using this oxide has excellent corrosion resistance, and has an advantage of high sensitivity because it utilizes a magneto-optical effect (Faraday effect) due to light transmitted through the magnetic film. However, since it is polycrystalline, there is a disadvantage that noise is increased due to light scattering, birefringence, and domain wall motion at crystal grain boundaries.

Further, when the above-described magnetic thin film is formed on a substrate, there is a problem that only a substrate having heat resistance can be used because the manufacturing temperature is as high as 500 ° C. or higher.

On the other hand, JP-A-62-119758 discloses a coating type magneto-optical recording material using yttrium iron garnet particles. In such a coating type medium, there is no adverse effect of the crystal grain boundary as in the polycrystalline oxide thin film, but the garnet particles described in the publication have a large particle size of 1.5 μm, and In the case where is used, since light scattering occurs, it is not suitable for applications utilizing light of a submicron wavelength.

(Objects of the Invention) The present invention solves the above-mentioned problems, is excellent in corrosion resistance, has a large magneto-optical effect, is excellent in light transmittance, and is used in optical isolators, optical circulators, optical switches, optical waveguides, optical memories, and the like. It is an object of the present invention to provide a method for producing garnet fine particle powder which is suitable for garnet.

(Means for Solving the Problems) The present invention provides a compound represented by the general formula: R _a Bi _b F _c M _d O _e (where R represents one or more rare earth elements selected from the group consisting of Y and lanthanum series elements, M is Al, Ga, Cr, M
n, Sc, In, Ru, Rh, Co, Fe (II), Cu, Ni, Zu, Li, Si, Ge, Zr, Ti,
One or more elements selected from the group consisting of Hf, Sn, Pb, Mo, V and Nb, a + b + c + d = 7.5-8.0, a + b = 2.
0-3.5, c + d = 4.5-6.0, a = 0.5-3.5, b = 0-2.
5, c = 3.0 to 6.0, d = 0 to 2.0, and e is the number of oxygen atoms satisfying the valence of another element. A) an alkoxide solution of each element selected in a ratio constituting the rare earth iron garnet represented by the formula (1) and a precipitate forming agent to form a precipitate, and baking the precipitate at 600 to 900 ° C. ,
The present invention relates to a method for producing garnet fine particle powder, characterized by obtaining rare earth iron garnet fine particles represented by the above general formula and having an average particle diameter of 30 to 1000 °.

The rare earth iron garnet fine particles in the present invention are R ₃ Fe ₅ O
Garnet represented by ₁₂ or a garnet in which a part of rare earth elements of the garnet is substituted by Bi, and / or a part of Fe is M
Is replaced by

R in the general formula is Y, La, Ce, Pr, Nd, Pm, Sm, Eu, G
One or more rare earth elements selected from the group consisting of d, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

M is an element that can be substituted for iron, and Al, Ga, Cr, Mn,
Sc, In, Ru, Rh, Co, Fe (II), Cu, Ni, Zu, Li, Si, Ge, Zr, Ti, H
One or more elements selected from the group consisting of f, Sn, Pb, Mo, V and Nb. Of the M elements, the trivalent elements Al, Ga, Cr, Mn, S
c, In, Ru, Rh, and Co alone, divalent element Co, Fe, Cu, Ni, and Zu, or monovalent element Li is tetravalent element, Si, Ge, Zr, Ti, H
It is preferred that f, Sn, Pb and Mo, or a combination of pentavalent elements V and Nb be substituted as an element equivalent to trivalent.

The ratio of each element in the above general formula is a + b
+ C + d = 7.5-8.0, a + b = 2.0-3.5, c + d = 4.5
~ 6.0, a = 0.5 ~ 3.5, b = 0 ~ 2.5, c = 3.0 ~ 6.0, d
= 0 to 2.0, and e is the number of oxygen atoms satisfying the valence of another element.

In the present invention, the Faraday rotation angle can be increased by substituting a part of the rare earth element of garnet with Bi of preferably 0.25 to 2.5. Further, by partially replacing iron with M of preferably 0.3 to 2.0, the Curie temperature can be lowered and the saturation magnetization can be reduced.

Further, in the present invention, a part of R of the rare earth iron garnet fine particles may be further substituted by a divalent element such as Pb, Ca, and Mg. You may compensate.

The average particle size of the rare earth iron garnet fine particles in the present invention is 30 to 1000 °, preferably 100 to 600 °. If the average particle size is smaller than 30 °, it becomes superparamagnetic due to thermal disturbance. On the other hand, when the angle is larger than 1000 °, light is scattered and noise is generated, which is not preferable. The particle shape is preferably optically symmetric and preferably spherical, but may be polyhedral or plate-like.

In the present invention, an alkoxide solution of each element selected in a ratio constituting the rare earth iron garnet represented by the above general formula, and a precipitate forming agent are mixed to form a precipitate,
By firing the precipitate at 600 to 900 ° C., rare earth iron garnet fine particles can be obtained.

In the present invention, first, a precipitate is formed by mixing an alkoxide solution of each element selected in a ratio constituting the rare earth iron garnet represented by the above general formula and a precipitate forming agent.

The alkoxide solution of each element is obtained by dissolving an alkoxide of each element, for example, methoxide, ethoxide, propoxide, butoxide and the like in a solvent.

As the solvent, usually, alcohols, ethers and a mixed solvent thereof are used.

The alkoxide solution of each of the above elements is desirably prepared so that the total ion concentration in the slurry after the precipitation is from 0.01 to 2.0 mol /. Total ion concentration of 0.01
If it is less than mmol / mol, the amount of garnet produced is small, and if it is more than 2.0 mol /, particles become large or a heterogeneous phase is produced, which is not preferable.

Further, the ratio of each element is determined by the ratio of each element constituting the rare earth iron garnet represented by the above general formula, but R and Bi may be used in excess of the required amount by about 10 mol%. Good.

As the precipitate forming agent, sodium hydroxide, potassium hydroxide, aqueous ammonia, ammonium carbonate, amines, oxalic acid, water and the like are used.

Examples of a method of mixing the alkoxide solution of each element with the precipitate forming agent include a method of adding an alkoxide solution of each element to the precipitate forming agent and a method of continuously mixing both. The precipitation may be performed at once or in multiple stages.

Next, the obtained precipitate is filtered, washed, dried and calcined to obtain rare earth iron garnet fine particles. The firing temperature varies depending on the composition of the rare earth iron garnet, but is 600 to 900 ° C. If the temperature is too low, crystallization is not sufficient, and if the temperature is too high, the particles become large or sintering occurs, which is not preferable. Firing time is 10 minutes ~
About 30 hours is appropriate. The firing atmosphere is not particularly limited, but an air atmosphere is generally convenient.

The garnet fine particle powder obtained by the present invention is used for applications such as optical isolators, optical circulators, optical switches, optical waveguides, and optical memories.

For example, a magneto-optical recording medium can be obtained by providing a magnetic layer composed of garnet fine particle powder and a binder on a substrate.

As the binder, an amorphous binder of an inorganic oxide or an organic binder is used. In particular, in order to reduce noise due to light scattering, it is desirable that the refractive index of the binder is matched with the refractive index of the rare earth iron garnet fine particles, and the deviation from the refractive index of the rare earth iron garnet fine particles is ± 20% or less, especially ± 20%. It is preferably 10% or less.

The thickness of the magnetic layer is 0.05 to 2.0 μm, especially 0.2 to 1.0 μm
Is preferable from the viewpoint of the stability of the recording bit.

The magnetic layer is formed by dispersing or dissolving rare earth iron garnet fine particles and a binder in water or an organic solvent, applying the dispersion on a substrate, and then curing the binder by heat treatment or the like. At this time, the hardening of the rare earth iron garnet fine particles is applied in a direction perpendicular to the substrate by applying a stress due to the hardening of the binder. Alternatively, the orientation treatment may be performed by applying a magnetic field in a direction perpendicular to the substrate.

The substrate is not particularly limited, and is a single crystal substrate, a polycrystalline substrate, an amorphous substrate such as glass, an inorganic material substrate such as a composite substrate, or an acrylic resin, a polycarbonate resin, a polyester resin, a polyamide resin, a polyimide resin, or the like. Organic material substrate can be used.

Further, a light reflection layer can be provided between the substrate and the magnetic layer or on the magnetic layer. Cu, Cr, Al, Ag,
Au, TiN, etc. are used. This light reflection layer is formed on a substrate or a magnetic layer by a plating method, a vapor deposition method, or the like after coating.

(Examples) Examples and comparative examples are shown below, and the present invention will be described in more detail.

Example 1 1.18 mol of sodium hydroxide (NaOH) was dissolved in 80 ml of water, and separately yttrium ethoxide [Y (OC ₂ H ₅ ) ₃ ]
0.122 mol and iron ethoxide [Fe (OC ₂ H ₅ ) ₃ ] 0.203 mol
Was dissolved in 80 ml of ethanol. Then, while stirring the sodium hydroxide solution, the ethanol solution was gradually added dropwise to neutralize the solution, thereby producing a precipitate.

The obtained precipitate was washed with water, filtered and dried, and then calcined at 800 ° C. to obtain garnet fine particles.

The resulting garnet fine particles, the average particle diameter of 350 Å, X-ray powder diffraction spectra and the composition analysis result, a Y _3.0 Fe _5.0 O _12, was garnet single phase.

Example 2 2.67 mol of sodium hydroxide was dissolved in 80 ml of water.
0.033 mol of bismuth ethoxide [Bi (OC ₂ H ₅ ) ₃ ], 0.033 mol of yttrium ethoxide and 0.109 mol of iron ethoxide
Was dissolved in 220 ml of ethanol. Then, while stirring the sodium hydroxide solution, the ethanol solution was gradually added dropwise to neutralize the solution, thereby producing a precipitate.

The obtained precipitate was washed with water, filtered and dried, and then calcined at 700 ° C. to obtain garnet fine particles.

The obtained garnet fine particles had an average particle diameter of 380 °, and as a result of X-ray powder diffraction spectrum and composition analysis, were Y _1.5 Bi _1.5 Fe _5.0 O ₁₂ , and were in a garnet single phase.

Example 3 1.93 mol of sodium hydroxide was dissolved in 80 ml of water, and 0.030 mol of bismuth propoxide [Bi (OC ₃ H ₇ ) ₃ ], 0.030 mol of gadolinium propoxide [Gd (OC ₃ H ₇ ) ₃ ], iron propoxy were separately dissolved. 0.085 mol of iron [Fe (OC ₃ H ₇ ) ₃ ] and 0.016 mol of aluminum propoxide [Al (OC ₃ H ₇ ) ₃ ] were dissolved in 220 ml of ethanol. Then, while stirring the sodium hydroxide solution, the ethanol solution was gradually added dropwise to neutralize the solution, thereby producing a precipitate.

The obtained precipitate was washed with water, filtered and dried, and then calcined at 700 ° C. to obtain garnet fine particles.

The obtained garnet fine particles had an average particle diameter of 410 °, and as a result of X-ray powder diffraction spectrum and composition analysis, were Gd _1.5 Bi _1.5 Fe _4.2 Al _0.8 O ₁₂ , and were in a garnet single phase.

Example 4 1.93 mol of sodium hydroxide was dissolved in 80 ml of water, and 0.030 mol of bismuth ethoxide, 0.030 mol of cisprosium ethoxide [Dy (OC ₂ H ₅ ) ₃ ], 0.085 mol of iron ethoxide and 0.016 mol of aluminum ethoxide were separately dissolved. 220 ml of ethanol
Was dissolved. Then, while stirring the sodium hydroxide solution, the ethanol solution was gradually added dropwise to neutralize the solution, thereby producing a precipitate.

The obtained precipitate was washed with water, filtered and dried, and then calcined at 700 ° C. to obtain garnet fine particles.

The obtained garnet fine particles had an average particle diameter of 410 °, and as a result of X-ray powder diffraction spectrum and composition analysis, were Dy _1.5 bi _1.5 Fe _4.2 Al _0.8 O ₁₂ and were in a garnet single phase.

 The refractive index of the fine particles was 2.6.

This fine particle powder is added to an aqueous solution containing bismuth nitrate, yttrium nitrate, and ferric nitrate in a molar ratio of Bi: Y: Fe = 28: 10: 62, and after sufficiently dispersing, the diameter is 3 inches.
It was applied on a glass substrate having a thickness of 1 mm. Next, by heating and decomposing at 250 ° C., an amorphous BiYFe oxide film containing rare earth iron garnet fine particles was formed. The refractive index of this binder was 2.6.

 The thickness of the obtained coating film was 0.5 μm.

A reflective film of aluminum was formed on this coating film by an evaporation method to obtain a magneto-optical recording medium.

633n against a magnetic field in the direction perpendicular to the film surface of the obtained medium
When the Faraday rotation angle of the m light was measured by the polarization plane modulation method, it was 1.0 deg.

In addition, when the S / N was evaluated for this medium,
It turned out to be very high and low noise.

Comparative Example 1 0.030 mol of bismuth oxide [Bi ₂ O ₃ ], 0.030 mol of dysprosium oxide [Dy ₂ O ₃ ], 0.085 mol of iron oxide [Fe ₂ O ₃ ], and 0.016 mol of aluminum oxide [Al ₂ O ₃ ] mixed with NaCl Then 1200
By baking at ℃, garnet fine particles were obtained.

The obtained garnet fine particles had an average particle size of 3 μm, and as a result of X-ray powder diffraction spectrum and composition analysis, were Dy _1.5 Bi _1.5 Fe _4.2 Al _0.8 O ₁₂ and were in a garnet single phase.

Using these particles, a magneto-optical recording medium was manufactured in the same manner as in Example 4.

633n against a magnetic field in the direction perpendicular to the film surface of the obtained medium
When the Faraday rotation angle of the m light was measured by the polarization plane modulation method, it was 0.9 deg.

When the S / N was evaluated for this medium,
Was low.

(Effect of the Invention) The garnet fine particle powder obtained by the present invention is excellent in corrosion resistance, large in magneto-optical effect, and excellent in light transmittance, and is used for optical isolators, optical circulators, optical switches, optical waveguides, optical memories, etc. It is suitable for use.
Also, productivity is good.

Claims (1)

(57) [Claims] 1. A general formula _{R a Bi b Fe c M d} O e ( wherein, R represents one or more rare earth elements selected from the group consisting of Y and lanthanides, M is Al, Ga, Cr, M
n, Sc, In, Ru, Rh, Co, Fe (II), Cu, Ni, Zu, Li, Si, Ge, Zr, Ti,
One or more elements selected from the group consisting of Hf, Sn, Pb, Mo, V and Nb, a + b + c + d = 7.5-8.0, a + b = 2.
0-3.5, c + d = 4.5-6.0, a = 0.5-3.5, b = 0-2.
5, c = 3.0 to 6.0, d = 0 to 2.0, and e is the number of oxygen atoms satisfying the valence of another element. A) forming a precipitate by mixing an alkoxide solution of each element selected in a ratio constituting the rare earth iron garnet represented by the formula (1) with a precipitate forming agent, and calcining the precipitate at 600 to 900 ° C. ,
A method for producing garnet fine particle powder, characterized by obtaining rare earth iron garnet fine particles represented by the above general formula and having an average particle size of 30 to 1000 °.