JPH0546083B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an amorphous oxide magnetic material characterized by having ferromagnetism and a method for producing the same.

Conventionally, many reports have been made regarding amorphous oxide magnetic materials and methods for producing the same.
However, all of these amorphous oxide magnetic materials have paramagnetic or antiferromagnetic properties,
Nothing was known that exhibited industrially useful ferromagnetism. If a ferromagnetic amorphous oxide magnetic material is obtained, a magnetic material useful for various uses as a magnetic core, a high magnetostrictive material, a transformer material, a magneto-optical element material, and other magnetic materials can be obtained.

By the way, the present inventors previously discovered that ferrite (a ferromagnetic oxide having a spinel crystal structure, a hexagonal crystal structure, or a garnet crystal structure) and phosphorus pentoxide. _{( P2O5} )
He was the first in the industry to invent a method for producing an amorphous oxide magnetic material with ferromagnetic properties by melting an oxide mixture at 1300°C to 1600°C and then ultra-quenching it from a temperature of at least 1200°C. (Special Application No. 163491, 1982). In addition, in this case, a part of the composition range of phosphorus pentoxide is replaced by boron oxide (B ₂ O ₃ ), germanium oxide (GeO ₂ ), bismuth oxide (Bi ₂ O ₃ ), tantalum oxide (Ta ₂ O ₅ ), and gallium oxide. It was also revealed that it can be replaced with a single oxide or two or more oxides selected from (Ga ₂ O ₃ ), selenium oxide (SeO ₂ ), and tellurium oxide (TeO ₂ ).

In the above invention, it is well known that the ionic radius of phosphorus ions in phosphorus pentoxide (P ₂ O ₅ ) is relatively small, and this small ionic radius is one of the reasons why amorphous oxide magnetic materials are easily produced. The inventors had speculated that this might be the cause. However, as research continued, it became clear that amorphous oxide magnetic materials were not limited to those with small ionic radii as mentioned above, but also those with large ionic radii, such as bismuth ions in bismuth oxide (Bi ₂ O ₃ ). It has become clear that it plays an extremely effective role in manufacturing. That is, after heating and melting a sample in which the composition range of ferrite is 70 to 92.5 mol % and the remaining bismuth oxide (Bi ₂ O ₃ ) composition range is 30 to 7.5 mol % at a temperature of 1300 ° C to 1600 ° C. It has been found that useful amorphous oxide magnetic materials with ferromagnetic properties can be produced by ultra-rapid cooling from a temperature of at least 1200°C or higher. This material has properties that are extremely useful as magneto-optical element materials and cores.

Figure 1 shows the above-mentioned mixed oxide of manganese ferrite (MnFe ₂ O ₄ ) and phosphorus pentoxide (P ₂ O ₅ ) placed in a platinum crucible, heated and melted at 1350°C for about 10 minutes, and then cooled with water. It shows the magnetic saturation value (emu/g) when it is rapidly cooled by passing it between twin rolls and made into an amorphous ribbon (thickness about 30 to 50 microns). As is clear from FIG. 1, when the composition of the sample is 92.5MnFe ₂ O ₄ .7.5P ₂ O ₅ , this is the composition boundary between the amorphous oxide region and the polycrystalline oxide region. Furthermore, when the content of manganese ferrite is 70 mol% or less, the magnetic saturation value becomes significantly small. The case of ferrite-bismuth oxide also exhibits substantially the same behavior as the graph in FIG. 1 (therefore, the graph is omitted). Moreover, similar behavior is shown not only in manganese ferrite but also in barium ferrite and cobalt ferrite. This fact is the reason why the content of ferrite is limited to 70 to 92.5 mol% in the present invention.

In the present invention, a part of the bismuth oxide (Bi ₂ O ₃ ) composition is replaced by boron oxide (B ₂ O ₃ ), germanium oxide (GeO ₂ ), antimony oxide (Sb ₂ O ₃ ), and vanadium pentoxide (V ₂ O 3 ). It was also confirmed that one or more oxides selected from tantalum pentoxide (TaO), and lead oxide (PbO) can be substituted in the range of 0 to ₁₀ mol%. Addition of these oxides has the effect of promoting melting of the sample and increasing the magnetic saturation value.

When preparing the ferromagnetic amorphous oxide magnetic material of the present invention, if the temperature at which the sample is melted is 1300°C or lower, an amorphous oxide cannot be obtained no matter how rapidly it is cooled after melting. Nakatsuta. Furthermore, it is important to ultra-quickly cool a sample melted at a temperature of 1300°C to 1600°C from a temperature of 1200°C or higher; no matter how slowly or rapidly the sample is cooled from a temperature below 1200°C, amorphous amorphous It has been confirmed through many experiments that this cannot be achieved. When solidifying a molten sample by ultra-quenching, it is desirable that the quenching rate is fast. That is, the faster the cooling rate, the more uniform the amorphous structure can be obtained. Therefore, there is also a method of ultra-quenching the molten material by pouring it onto a metal plate partially immersed in liquid nitrogen. As a result of experiments, it has been found that it is desirable to perform ultra-quench cooling at a rate of at least 5° C. per second.

Figure 2 shows an example of the composition of the present invention.
A sample with the composition 92MnFe ₂ O ₄ 8Bi ₂ O ₃ was heated at 1400℃.
After heating and melting for 10 minutes, this was immediately poured onto the surface of a body plate immersed in liquid nitrogen, and the X-ray diffraction line of the ultra-quenched sample is shown. Figure 2 clearly shows that this sample is in an amorphous state.

When melting a sample, Fe ³⁺ ions in ferrite are reduced to Fe ²⁺ ions, which tends to cause undesirable phenomena such as lowering magnetism and lowering electrical resistance. Therefore, when melting the sample of the present invention, it is desirable to melt the sample in an oxidizing atmosphere with an oxygen partial pressure of 0.2 to 10 atm. The higher the oxygen partial pressure in the atmosphere, the easier it is to produce a high-quality amorphous oxide magnetic material. But 10
It is difficult to mass-produce it industrially in an atmosphere with an oxygen partial pressure higher than atmospheric pressure.

Furthermore, according to the present invention, the magnetic properties of the amorphous oxide ferromagnetic material of the present invention can be further improved by subjecting it to ultra-quenched cooling and then reheating. Figure 3 shows how the magnetic saturation values of three types of MnFeO ₄ -Bi ₂ O ₃ systems increase with reheating temperature.

As shown in FIG. 3, when the amorphous oxide magnetic material of the present invention produced by the above-described ultra-quench cooling is reheated from room temperature while gradually increasing the temperature, the magnetic saturation value increases. and the crystallization temperature at which the amorphous state changes to the _{polycrystalline state} (approximately 650
℃), the magnetic saturation value showed a tendency to decrease. This is thought to be due to the precipitation of a nonmagnetic crystalline phase above the crystallization temperature. Therefore, it is important to improve the magnetism of the amorphous material by heating it for a long time at a temperature lower than the crystallization temperature.

The ferromagnetic amorphous oxide magnetic material of the present invention thus obtained allows light to pass through it well, and is therefore extremely useful industrially as a magneto-optical element material. It also has high electrical resistance, so it is important as a core in high frequency ranges.

Example 1 A mixed powder of 85 mol% cobalt ferrite, 12 mol% bismuth oxide, and 3 mol% boron oxide was placed in a platinum crucible, heated and melted at 1350°C in an electric furnace, and then cooled in water. It was rapidly cooled by passing it between rolls. The magnetic saturation value of the sample prepared in this way is
It was 17.4 emu/g. Electrical resistance value is 350Ω-cm
It was hot. It was confirmed by X-ray diffraction and microscopic composition observation that this sample was amorphous. When this sample was heated in air at 600°C for 10 hours, its magnetic saturation value increased to 20.2 emu/g.

Example 2 A sample consisting of 70 mol% barium ferrite, 20 mol% bismuth oxide, 5 mol% antimony oxide, and 3 mol% lead oxide was heated and melted at 1400°C for 20 minutes in an atmosphere with an oxygen partial pressure of 2 atmospheres. Thereafter, it was immediately cooled by passing between twin rolls to obtain an amorphous amorphous ribbon with a thickness of about 20 microns. The magnetic saturation value of this sample at room temperature is 13.2 emu/g, and the coercive force is 3200
It was Elsted. When this amorphous amorphous ribbon was reheated at 620°C for 5 hours in an atmosphere with an oxygen partial pressure of 2 atm, its magnetic saturation value was 23.5 emu/g.
It increased to .

[Brief explanation of the drawing]

Figure 1 shows manganese ferrite (MnFe ₂ O ₄ )
Figure 2 is a graph showing the relationship between the content of (the remainder is phosphorus pentoxide, P ₂ O ₅ ) and the magnetic saturation value.
Figure 3 shows the X-ray diffraction pattern showing that the sample with the composition 92MnFe ₂ O ₄ .8Bi ₂ O ₃ is amorphous, and Figure 3 shows the pattern of manganese ferrite (MnFe ₂ O ₄ ) and bismuth oxide (Bi ₂ 3 is a graph showing the relationship between temperature and magnetic saturation value when amorphous amorphous oxide magnetic materials having three types of compositions consisting of O ₃ ) are reheated in air.

Claims (1)

[Claims] 1. Manganese ferrite, barium ferrite,
and 70 to 92.5 mol% of ferrite selected from cobalt ferrite and bismuth oxide (Bi ₂ O ₃ ) 30
An oxide magnetic material having a composition consisting of ~7.5 mol% and having a ferromagnetic amorphous structure. 2 Manganese ferrite, barium ferrite,
and 70 to 92.5 mol% of ferrite selected from cobalt ferrite, and 30 to 7.5 mol% of oxides, and less than 10 mol% of the oxides are boron oxide (B ₂ O ₃ ), germanium oxide (GeO ₂ ), Antimony oxide (Sb ₂ O ₃ ), vanadium pentoxide (V ₂ O ₅ ),
Tantalum pentoxide (Ta ₂ O ₅ ) and lead oxide (PbO)
An oxide magnetic material comprising one or more selected from the above, having a composition in which the remainder of the oxide is bismuth oxide (Bi ₂ O ₃ ), and having a ferromagnetic amorphous structure. 3 Manganese ferrite, barium ferrite,
and 70 to 92.5 mol% of ferrite selected from cobalt ferrite and bismuth oxide (Bi ₂ O ₃ ) 30
After preparing a mixture having a composition consisting of ~7.5 mol % and heating and melting the mixture at a temperature of 1300 °C to 1600 °C in an oxidizing atmosphere with an oxygen partial pressure of 0.2 to 10 atm, at least 1200 °C 5℃ per second from temperature above ℃
1. A method for producing a ferromagnetic amorphous oxide magnetic material, which is characterized by rapidly cooling the material at a rate above to form an amorphous material. 4 Manganese ferrite, barium ferrite,
and 70 to 92.5 mol% of ferrite selected from cobalt ferrite, and 30 to 7.5 mol% of oxides, and less than 10 mol% of the oxides are boron oxide (B ₂ O ₃ ), germanium oxide (GeO ₂ ), Antimony oxide (Sb ₂ O ₃ ), vanadium pentoxide (V ₂ O ₅ ),
Tantalum pentoxide (Ta ₂ O ₅ ) and lead oxide (PbO)
A mixture is prepared in which the remainder of the oxide is bismuth oxide (Bi ₂ O ₃ ), and the mixture is placed in an oxidizing atmosphere with an oxygen partial pressure of 0.2 to 10 atm. A ferromagnetic amorphous amorphous oxide magnetic material characterized in that it is heated and melted at a temperature of 1300°C to 1600°C, and then rapidly cooled from a temperature of at least 1200°C at a rate of 5°C or more per second to become amorphous. Manufacturing method. 5 Manganese ferrite, barium ferrite,
and 70 to 92.5 mol% of ferrite selected from cobalt ferrite and bismuth oxide (Bi ₂ O ₃ ) 30
After preparing a mixture having a composition consisting of ~7.5 mol % and heating and melting the mixture at a temperature of 1300 °C to 1600 °C in an oxidizing atmosphere with an oxygen partial pressure of 0.2 to 10 atm, 5 per second from temperatures above
A method for producing a ferromagnetic amorphous oxide magnetic material, characterized in that the material is rapidly cooled to become amorphous at a rate of 0.degree. 6 Manganese ferrite, barium ferrite,
and 70 to 92.5 mol% of ferrite selected from cobalt ferrite, and 30 to 7.5 mol% of oxides, and less than 10 mol% of the oxides are boron oxide (B ₂ O ₃ ), germanium oxide (GeO ₂ ), Antimony oxide (Sb ₂ O ₃ ), vanadium pentoxide (V ₂ O ₅ ),
Tantalum pentoxide (Ta ₂ O ₅ ) and lead oxide (PbO)
A mixture is prepared in which the remainder of the oxide is bismuth oxide (Bi ₂ O ₃ ), and the mixture is placed in an oxidizing atmosphere with an oxygen partial pressure of 0.2 to 10 atm. After heating and melting the material to a temperature of 1,300°C to 1,600°C within a temperature range of 1,300°C to 1,600°C, the material is rapidly cooled from a temperature of at least 1,200°C at a rate of 5°C or more per second to form an amorphous material, and the amorphous material is further heated at a temperature below its crystallization temperature. A method for producing a ferromagnetic amorphous oxide magnetic material characterized by improving magnetic properties.