WO2012020617A1 - Magnetic material, magnetic shaped object, and rotating machine - Google Patents

Abstract

An objective of the present invention is to improve such magnetic characteristics of a magnetic material as magnetic moment and magnetic anisotropy. A magnetic material is employed that includes either a binary alloy denoted by a chemical formula of the form R-Fe (where R is either a 4f transition element or yttrium (Y)), or a ternary alloy of the chemical formula R-Fe-T (where R is as per the foregoing description, and T is either a 3d transition element excluding iron (Fe), or else T is aluminum (Al), silicon (Si), gallium (Ga), molybdenum (Mo), niobium (Nb), or tungsten (W), provided that if T is W, then R is either a 4f transition element other than W, or Y). The alloys include either fluorine (F) atoms, nitrogen (N) atoms, hydrogen (H) atoms, or carbon (C) atoms in doping locations in the crystal lattices thereof.

Description

Magnet materials, magnet moldings and rotating machines

The present invention relates to a structure and composition with high magnetic properties as a permanent magnet of a 4f transition element-3d transition element alloy.

The index as a high-performance permanent magnet material includes three elements of Curie temperature, magnetization, and magnetic anisotropy. As one of the methods for dramatically improving these three elements, a method of inserting atoms into a parent phase crystal is known. For example, as disclosed in Patent Document 1, by introducing nitrogen (N) atoms, which are nonmagnetic elements, into Sm ₂ Fe ₁₇ , the magnetic properties of the parent phase are improved. As described in Non-Patent Document 1, when the non-magnetic element is fluorine (F), it is predicted by calculation that R ₂ Fe ₁₇ (R is a 4f transition element) improves the magnetic characteristics most. Actually, as described in Non-Patent Document 2, it is known that the Curie temperature rises by invading F atoms.

JP 2008-78610 A

Nd ₂ Fe ₁₄ B, which has the highest performance as the parent phase of the permanent magnet material, still has a large amount of rare earth element used (Nd element with respect to Fe element is 14.3% in terms of element composition ratio). It is important to improve the magnetic properties in a composition having a smaller amount of rare earth element than this. Although Sm ₂ Fe ₁₇ N ₃ described in Patent Document 1 has improved magnetic properties as compared with the parent phase, it still has a small magnetic moment and magnetic anisotropy. Although Gd ₂ Fe ₁₇ F ₃ described in Non-Patent Document 1 makes a calculation prediction regarding an increase in magnetic moment and an increase in magnetic anisotropy energy, it does not discuss the stability of the crystal structure, but actually It is unclear whether it exists as a stable system. There is no mention of the Curie temperature. Since R ₂ Fe ₁₇ F _x described in Non-Patent Document 2 has not been subjected to elemental analysis of the F element, it is unclear whether the increase in the Curie temperature is due to the effect of F atoms, and the Curie temperature The maximum rise is as low as about 40 ° C.

An object of the present invention is to provide a magnet material that is more excellent in magnetic properties such as magnetic moment and magnetic anisotropy than conventional magnet materials.

As a result of intensive studies by the present inventor in order to solve the above-mentioned problems, the magnetic properties of the alloy are improved by arranging F atoms and N, H, or C atoms at the intrusion positions in the crystal lattice of the alloy. I found out that I can do it.

The present invention includes the following configurations.
The magnet material of the present invention includes a binary alloy represented by the chemical formula R—Fe (wherein R is a 4f transition element or Y), or a chemical formula R—Fe—T (wherein R is T is a 3d transition element excluding Fe, or Al, Si, Ga, Mo, Nb or W. However, when T is W, R is a 4f transition element other than W or Y. )), Which contains F atoms and N, H, or C atoms at the intrusion position in the crystal lattice.

According to the present invention, it is possible to provide a magnet material that has better magnetic properties than conventional magnet materials.

(A) Sm ₂ Fe ₁₇ magnetic powder, (b) 150 ° C. 24 h heat treated magnetic powder, (c) 200 ° C. 24 h heat treated magnetic powder, (d) 250 ° C. 24 h heat treated magnetic powder, (e) 300 ° C. 24 h heat treated magnetic powder, and (f) 350 The powder X-ray-diffraction pattern in room temperature of the heat processing magnetic powder for 24 degreeC is shown. (A) Secondary electron image, (b) C, (c) N, (d) O, (e) F, (f) Fe, and (g ) Sm element concentration distribution image. Analyzing crystal (a) LS7A, (b) RAP, and (c) using the LS5A measurement location A, where B, and where C energy spectrum near FK _alpha in (see FIG. 2 (a) secondary electron image) , And elemental determination results. (A) shows Sm ₂ Fe ₁₇ magnetic powder, and (b) 250 Temperature dependency of the desorbed gas in ° C. 24h heat treatment magnetic powder. (A) total ions, (b) Fe ⁺ , (c) FeH ⁺ , (d) FeOH ⁺ , (e) Sm ⁺ , (f) SmF ⁺ , (g) H The ion images of ⁺ , (h) Na ⁺ , (i) Al ⁺ , (j) Si ⁺ , and (k) Ca ⁺ are shown. (A) total ions, (b) FeO ⁻ , (c) FeO ₂ ⁻ , (d) FeO ₂ H ⁻ , (e) H ⁻ , (f) C ⁻ , ( g) Shows ion images of O ⁻ , (h) OH ⁻ , (i) F ⁻ , (j) CN ⁻ , and (k) Cl ⁻ . Shows the temperature dependence of the magnetization of Sm ₂ Fe ₁₇ magnetic powder heat-treated at each temperature in the 0.5T magnetic field. (A) Crystal lattice constant expansion rate Δa / a axis, Δc / c axis, and unit cell volume expansion rate Δv / v in Sm ₂ Fe ₁₇ H _x F _y , and (b) Curie temperature rise rate ΔT _C / The heat treatment temperature dependence of _{TC and} the heat treatment temperature dependence of (c) coercive force H _c and (d) reversal magnetic field distribution SFD of the entire sample at liquid nitrogen temperature and room temperature are shown. The correlation between the Curie temperature increase rate ΔT _C / T _C and the expansion rate Δv / v of the unit cell volume in Sm ₂ Fe ₁₇ H _α F _x is shown. Ammonium fluoride, and shows a 300 ° C. 1h heat-treated Sm ₃ magnetic field dependence of the magnetization in Fe ₂₈ Ti pulverized before and after an acidic ammonium fluoride. The dependence of the magnetic anisotropy energy of Sm ₃ Fe ₂₈ Ti at liquid nitrogen temperature and room temperature on the hydrogenation and fluorination heat treatment temperature is shown. ₃ shows powder X-ray diffraction patterns of Sm ₂ Fe ₁₇ , Sm ₂ Fe ₁₇ N ₃ , and Sm ₂ Fe ₁₇ H _α F _x . It is a perspective view which shows typically the position of the F atom which penetrate | invaded in the hexagonal crystal lattice. It is a perspective view which shows typically the position of the F atom which penetrate | invaded in the monoclinic crystal lattice. It is a perspective view which shows typically the position of F atom which invaded in the crystal lattice of a tetragonal crystal. FIG. 6 is a (001) plane view schematically showing displacement of Fe atoms when F atoms enter a hexagonal crystal lattice. It is a (003) plane view schematically showing the displacement of Fe atoms when F atoms enter the hexagonal crystal lattice.

In magnetic materials based on transition metals, magnetism is manifested by band polarization. In many cases, the 3d transition metal group having relatively strong itinerary is described by the Hubbard model, and in the 4f rare earth metal group having strong localization, the Anderson model is often used. In the Hubbard model, the electronic state and magnetic structure are determined by the competition between the gain of kinetic energy reduction due to the spatial spread of electrons and the increase of Coulomb energy due to the proximity of electrons. In the Anderson model, the electronic state and magnetic structure are determined by further considering the interaction between conduction electrons and localized electrons in the Hubbard model. The principles of the present invention generally relate to Kanamori conditions derived from a single Hubbard model of 3d transition metals. The Kanamori condition is obtained by removing the overestimation of Coulomb energy with respect to the Stoner condition.

Where U is the Coulomb energy, G (0,0) is a parameter between two electrons having a wave vector of 0 and is about the reciprocal of the 3d bandwidth, and D (E _F ) is the electron density of states at the Fermi level. Respectively. The Kanamori condition indicates that in order for ferromagnetism to occur, the bandwidth needs to be quite large, and at the same time the state density of the Fermi level must be locally increased. Since the electronic state density increases with the increase of the crystal lattice, the electronic state density changes due to the volume change of the unit cell. Therefore, when a volume change is introduced into the unit cell by forced or spontaneous force, it is expected that a large change in magnetism occurs due to a change in the density of states in the vicinity of the Fermi level.

For example, the Bethe-Slater (or Neel-Slater) curve showing the interatomic distance dependence of the magnitude of the exchange interaction in 3d transition metal alloys shows that itinerant electron magnetic interactions oscillate with interatomic distance It is a curve. In order to maximize the magnitude of the exchange interaction in the Bethe-Slater curve, α-Fe (hereinafter simply referred to as Fe) has a short interatomic distance, and Co and Ni have a wide interatomic distance. It is known that too. This is because in Fe, the itinerant nature of electrons is too strong and there are few localized electrons, so the exchange interaction is small, and in Co and Ni, the localization is too strong and the overlap of wave functions is small, so the exchange interaction is small. Means. That is, it is possible to increase the exchange interaction by increasing the interatomic distance and increasing the localization in Fe, and by reducing the interatomic distance and increasing the itinerant in Co and Ni. In addition, in the RKKY interaction that can be predicted from the Anderson model and is actually observed, the surrounding conduction electrons are subjected to spin polarization by the electric field of the electrons localized in the atoms, thereby causing the local atoms to be localized. Interacts with electrons. In the RKKY interaction, the exchange interaction oscillates according to the interatomic distance.

In the ferromagnetic fluorine compound of the present invention, F atoms and other nonmagnetic atoms (H, C, N) penetrate into the alloy of the 4f transition element-Fe element of the parent phase, so that near the Fermi level of Fe. A decrease in the density of states and an increase in the localization of Fe occur, causing the effects of increased magnetization and increased Curie temperature. Furthermore, the penetration of atoms including F atoms and the strong electronegativity of F atoms cause an improvement in magnetic anisotropy. In particular, the chemical formula R ₂ (Fe, T) ₁₇ , the chemical formula R ₃ (Fe, T) ₂₉ , the chemical formula R (Fe, T) ₁₂ (R is a 4f transition element or Y, T is a 3d transition element excluding Fe, In addition, with respect to all phases having a crystal structure based on the CaCu ₅ structure such as Al, Si, Ga, Mo, Nb or W), the magnetic characteristics of the parent phase can be obtained by introducing nonmagnetic atoms including F atoms. Improve dramatically. In general, in these structures, the N atom has the chemical formula R ₂ (Fe, T) ₁₇ N _x (0 <x ≦ 3), the chemical formula R ₃ (Fe, T) ₂₉ N _y (0 <y ≦ 4), the chemical formula R ( It is known to arrange as Fe, T) ₁₂ N _z (0 <z ≦ 1), and F atoms are arranged in the same manner as N atoms. When the introduced amount of nonmagnetic atoms is too large, the Fe band width becomes too narrow due to too strong localization, so that the Kanamori condition is not satisfied and the ferromagnetism is weakened. That is, the magnetization due to nonmagnetic atoms including F atoms and the Curie temperature increase and increase notably only in a crystal structure having a site where the distance between Fe atoms is short. In general, the value at which the positive / negative exchange interaction between Fe atoms is switched is about 0.245 nm (the distance between Fe atoms at which the exchange interaction is maximized is about 0.260 nm). In a crystal structure having an Fe interatomic distance shorter than 0.245 nm, the effect of increasing ferromagnetism by introducing F atoms is remarkable.

As a method for fluorinating the mother phase, ammonium fluoride (NH ₄ F), acidic ammonium fluoride (NH ₄ F · HF), ammonium silicofluoride ((NH ₄ F) ₂ SiF ₆ ), ammonium borofluoride (NH ₄ BF ₄ ) and other methods using gas generated by pyrolysis and sublimation, and nitrogen trifluoride (NF ₃ ), boron trifluoride (BF ₃ ), sulfur hexafluoride (SF ₆ ) hydrogen fluoride, There is a method using a gas such as fluorine. Depending on the reactivity of each gas, they can be mixed or used simultaneously.

For example, a ferromagnetic fluorine compound magnet having the following characteristics is synthesized by performing fluorination heat treatment at a temperature lower than 400 ° C., preferably lower than 350 ° C. by sublimation of NH ₄ F with respect to Sm ₂ Fe _17. Succeeded in doing. The principle of the present invention mainly depends on the above-described characteristics of Fe, and when a nonmagnetic atom including an F atom enters, a geometrical effect is generated as the crystal lattice volume increases, and a magnetic moment is large. There is an increase and an increase in Curie temperature.

Furthermore, the increase in magnetization and the increase in the Curie temperature are also caused by the effect of Fe localization due to the strong electronegativity of fluorine atoms. Since there is a difference in the spatial size of the intrusion position depending on the type of 4f transition element, the increase rate of magnetization and the Curie temperature increase rate are different depending on the type of 4f transition element.

Hereinafter, the present invention will be described in detail.

The present invention is a binary system of the chemical formula R—Fe (wherein R is a 4f transition element or Y) in which an F atom and an N atom, H atom or C atom are arranged at the intrusion position in the crystal lattice. Or the chemical formula R-Fe-T (wherein R is as defined above, T is a 3d transition element excluding Fe, or Al, Si, Ga, Mo, Nb or W, provided that T is W In some cases, R is a 4f transition element other than W or Y.) relates to a magnet material including a ternary alloy.

Preferably, a magnetic material comprising an alloy wherein R is a lanthanoid, particularly preferably a magnetic material comprising an alloy wherein R is Sm, Er, Tm, Pr, Nd, Tb or Dy, most preferably R is Sm or Nd. The present invention relates to a magnet material containing an alloy. In addition, the present invention preferably relates to a magnet material containing an alloy in which T is a 3d transition element excluding Fe, and particularly preferably relates to a magnet material containing an alloy in which T is Ti.

The magnetic properties can be improved by arranging F atoms and N, H, or C atoms at the intrusion position in the crystal lattice of the alloy.

1. F-Atom and H-Atom Containing Alloy As one embodiment of the present invention, a binary system of the chemical formula R—Fe in which F atoms and H atoms are arranged at the intrusion positions in the crystal lattice, or a chemical formula R—Fe—T 3 Examples thereof include a magnet material containing a base alloy.

As a method for introducing F atoms and H atoms into the intrusion position in the crystal lattice, for example, ammonium fluoride (NH ₄ F), ammonium acid fluoride (NH ₄ F · HF), ammonium silicofluoride ((NH ₄ F) ₂ SiF ₆ ), ammonium borofluoride (NH ₄ BF ₄ ) and the like, and a method of simultaneously performing hydrogenation and fluorination by heat treatment using hydrogen fluoride gas generated by thermal decomposition and sublimation. It is also possible to carry out the already known hydrogenation method and fluorination method separately. In that case, it is desirable to carry out hydrogenation in advance, since subsequent fluorination easily occurs. However, since hydrogen atoms and fluorine atoms only need to coexist at an intrusion position in the crystal lattice with an appropriate occupation ratio, they may be hydrogenated after fluorination.

The alloy used in the present invention preferably uses the chemical formula R ₂ (Fe, T) ₁₇ , the chemical formula R ₃ (Fe, T) ₂₉ , and the chemical formula R (Fe, T) ₁₂ phase. These alloys are distinguished on the basis of the CaCu ₅ structure by their three-dimensional stacking method. The present invention is applicable to all phases having a crystal structure based on the CaCu ₅ structure. Therefore, the present invention can be applied to the chemical formula RT ₅ , chemical formula RT ₇ phase, and more complex multi-component systems.

However, as an alloy in the present invention,
(1) Chemical formula R ₂ Fe ₁₇ H _α F _x (0 <α <5, 0 <x ≦ 3, and 0 <α + x ≦ 5),
(2) Chemical formula R ₃ (Fe, T) ₂₉ H _β F _y (0 <β <6 and 0 <y ≦ 4 and 0 <β + y ≦ 6) or (3) Chemical formula R (Fe, T) ₁₂ H _γ F _z (0 <γ <1, 0 <z <1, and 0 <γ + z ≦ 1)
The thing represented by these is preferable.

The upper limit of α + x, β + y, and γ + z is limited by the number of intrusion positions. The composition of the alloy in the present invention is determined by an electron probe microanalyzer (EPMA) and a time-of-flight secondary ion mass spectrometer (TOF-SIMS).

In the chemical formula (1), when R is Sm, Er or Tm and 1 ≦ x (that is, 0 <α ≦ 4, 1 ≦ x ≦ 3, and 1 <α + x ≦ 5), the alloy is 1 It becomes axial magnetic anisotropy. In the chemical formula (2), when R is Sm, Er or Tm and 2 ≦ y (that is, 0 <β ≦ 4, 2 ≦ y ≦ 4, and 2 <β + y ≦ 6), the alloy is 1 It becomes axial magnetic anisotropy. In the chemical formula (3), R is Pr, Nd, Tb or Dy, and 0.5 ≦ z (that is, 0 <γ ≦ 0.5, 0.5 ≦ z <1, and 0.5 < In the case of γ + z ≦ 1), the alloy has uniaxial magnetic anisotropy.

The alloy containing F atoms and H atoms is at least one of rare earth fluoride, rare earth oxyfluoride, iron, and iron fluoride depending on the temperature of the heat treatment for introducing F atoms and H atoms. including.

2. F-Atom and N-Atom Containing Alloy As an embodiment of the present invention, a binary alloy of the chemical formula R—Fe in which an F atom and an N atom are arranged at an intrusion position in a crystal lattice, or a chemical formula R—Fe—T A magnetic material containing a ternary alloy of Arranging F atoms and N atoms makes it possible to increase the Curie temperature, increase the magnetic moment, and improve the magnetic anisotropy.

As an alloy in the present invention,
(4) Chemical formula R ₂ Fe ₁₇ N _α F _x (0 <α <3 and 0 <x <3 and 0 <α + x ≦ 3),
(5) Chemical formula R ₃ (Fe, T) ₂₉ N _β F _y (0 <β <4 and 0 <y <4 and 0 <β + y ≦ 4) or (6) Chemical formula R (Fe, T) ₁₂ N _γ F _z (0 <γ <1, 0 <z <1, and 0 <γ + z ≦ 1)
The thing represented by these is preferable.

The upper limit of α + x, β + y, and γ + z is limited by the number of intrusion positions. The composition of the alloy in the present invention is determined by EPMA, TOF-SIMS.

In the chemical formula (4) above, when R is Sm, Er or Tm and 1 ≦ α + x (that is, 0 <α <3 and 0 <x <3 and 1 ≦ α + x ≦ 3), the alloy is 1 It becomes axial magnetic anisotropy. In the chemical formula (5) above, when R is Sm, Er or Tm and 2 ≦ β + y (that is, 0 <β <4 and 0 <y <4 and 2 ≦ β + y ≦ 4), the alloy is 1 It becomes axial magnetic anisotropy. In the chemical formula (6), R is Pr, Nd, Tb, or Dy, and 0.5 ≦ γ + z (that is, 0 <γ <1, 0 <z <1, and 0.5 ≦ γ + z ≦ 1) In this case, the alloy has uniaxial magnetic anisotropy.

Since a nitrogen atom and a fluorine atom only need to coexist at an intrusion position in the crystal lattice with an appropriate occupation ratio, the method for introducing the F atom and the N atom is not particularly limited. For example, a method of heat-treating the alloy in the presence of nitrogen trifluoride can be mentioned.

The alloy in the present invention contains at least one of rare earth nitride, rare earth fluoride, rare earth oxyfluoride, iron, and iron fluoride depending on the heat treatment temperature.

3. F- and C-atom-containing alloys As one embodiment of the present invention, a binary system of chemical formula R—Fe in which F atoms and C atoms are arranged at penetration positions in the crystal lattice, or 3 of chemical formula R—Fe—T Examples thereof include a magnet material containing a base alloy. Arranging F atoms and C atoms makes it possible to improve the thermal stability of the crystal lattice, increase the Curie temperature, increase the magnetic moment, and improve the magnetic anisotropy.

As an alloy in the present invention,
(7) Chemical formula R ₂ Fe ₁₇ C _α F _x (0 <α <3, and 0 <x <3, and 0 <α + x ≦ 3),
(8) Chemical formula R ₃ (Fe, T) ₂₉ C _β F _y (0 <β <4 and 0 <y <4 and 0 <β + y ≦ 4) or (9) Chemical formula R (Fe, T) ₁₂ C _γ F _z (0 <γ <1, 0 <z <1, and 0 <γ + z ≦ 1)
The thing represented by these is preferable.

The upper limit of α + x, β + y, and γ + z is limited by the number of intrusion positions. The composition of the alloy in the present invention is determined by EPMA, TOF-SIMS.

In the chemical formula (7), when R is Sm, Er or Tm and 1 ≦ α + x (that is, 0 <α <3 and 0 <x <3 and 1 ≦ α + x ≦ 3), the alloy is 1 It becomes axial magnetic anisotropy. In the chemical formula (8), when R is Sm, Er or Tm and 2 ≦ β + y (that is, 0 <β <4 and 0 <y <4 and 2 ≦ β + y ≦ 4), the alloy is 1 It becomes axial magnetic anisotropy. In the chemical formula (9), R is Pr, Nd, Tb or Dy, and 0.5 ≦ γ + z (that is, 0 <γ <1, and 0 <z <1, and 0.5 ≦ γ + z ≦ 1) In this case, the alloy has uniaxial magnetic anisotropy.

Since the carbon atom and the fluorine atom only need to coexist at the penetration position in the crystal lattice with an appropriate occupation ratio, the method for introducing the F atom and the C atom is not particularly limited. For example, a method of heat-treating the alloy using a hydrocarbon gas and a fluorine gas, or using a fluorocarbon can be mentioned.

The F atom and C atom containing alloy contains at least one of rare earth fluoride, rare earth oxyfluoride, iron, and iron fluoride depending on the heat treatment temperature.

4). Magnetic powder preparation (1) Preparation of parent phase alloy:
R and Fe are mixed and dissolved in a vacuum or in an inert gas or a reducing gas atmosphere to homogenize the composition (dissolution casting method). The obtained R—Fe based master alloy is coarsely pulverized in an inert gas using a ball mill.

As an inexpensive method other than the above method, a reduction diffusion method in which samarium oxide powder and iron powder are mixed with granular metallic calcium and heated in an inert gas atmosphere can be used. Since the diffusion distance of Sm ₂ Fe ₁₇ is not higher than the peritectic temperature and the iron powder particle size is selected, the diffusion distance of Sm can be controlled to some extent. The casting method does not require indispensable uniform heat treatment. Since the Sm ₂ Fe ₁₇ alloy is obtained directly as a powder, a coarse pulverization step is not necessary. Further, in order to obtain a raw material powder having a smaller particle size, a microcrystalline oxide can be obtained by precipitating a hydroxide from a sulfuric acid aqueous solution of Sm and Fe and firing in the air. Magnetic powder having a particle size of several μm that does not require fine pulverization can be produced.

On the other hand, as the magnetic powder for nanocomposite magnet, ultra-quenched ribbon powder having a grain size of several μm to several tens of μm composed of a polycrystal having a crystal grain size of several tens to several hundreds of nm is required. The ribbon powder is obtained by a liquid superquenching method in which a molten mother alloy is jetted and cooled in an inert gas or reducing gas atmosphere such as argon gas on the surface of a rotating roll such as a single roll or a twin roll. As a method for obtaining a fine alloy structure, a hydrogenation, decomposition, dehydrogenation, and recombination (HDR) method is also useful.

Also, a parent phase alloy can be produced by a nanoparticle process or a thin film process. For example, the vapor phase method includes a thermal CVD method, a plasma CVD method, a molecular beam epitaxy method, a sputtering method, an EB vapor deposition method, a reactive vapor deposition method, a laser ablation method, a resistance heating vapor deposition method and the like. The liquid phase method includes coprecipitation method, microwave heating method, micelle method, reverse micelle method, hydrothermal synthesis method, sol-gel method and the like.

The mother alloy or mother alloy powder obtained by the above method needs to be coarsely pulverized as necessary. For example, there is a method of mechanically pulverizing with a ball mill or a jet mill in an inert gas atmosphere or a reducing gas atmosphere. The HDDR method is also effective, and forming a fine structure by this method is effective in coercive force expression. Of course, the coercive force is also exhibited by pulverization after the hydrogen fluoride gas treatment.

(2) Fluorination treatment, hydrogenation treatment, nitrogenation treatment, and carbonization treatment:
As a method for introducing a fluorine atom and a hydrogen atom, a nitrogen atom, or a carbon atom, there are methods as described in Examples 1 to 3 below, and all are solid-gas reactions by gas. In the solid-gas reaction process, in order to obtain a uniform composition, it is important to uniformly contact the surface of the powder with the gas. In particular, since a problem occurs when a large amount of powder is gas-treated, it is preferable to constantly flow and agitate the powder using a fluidized bed or the like. In addition, since the element intrusion reaction is diffusion-controlled, a powder having a uniform concentration distribution can be obtained more quickly as the particle size of the powder is smaller. However, if the particle size is too small, a stable flow becomes impossible, so there is a limit naturally, and a particle size of 10 μm to several 100 μm is appropriate.

Since there is a decomposition reaction of the parent phase, fluorination will occur at a temperature lower than 400 ° C., preferably lower than 350 ° C., more preferably lower than 300 ° C., and an increase in reaction rate due to heating cannot be expected. . Moreover, since it is diffusion-controlled, the reaction rate improvement by pressurization cannot be expected. However, it is conceivable to raise the reaction temperature somewhat by suppressing the decomposition by pressurization. Since microcracks enter by hydrogenation and assist in element entry, mixing with hydrogen gas is effective in terms of forming a fine structure. The diffusion rate of F atoms is extremely slow compared to other hydrogen atoms and nitrogen atoms, so heat treatment can be performed in an inert gas atmosphere after fluorination for the purpose of uniformizing the fluorine concentration distribution in the powder. May be effective.

(3) Grinding process:
In order to develop a coercive force, the coarse powder obtained in the element intrusion step is preferably finely pulverized to a mean particle size of 2 to 3 μm by a jet mill or a ball mill. In principle, it is desirable to pulverize to a single domain critical particle size of about 0.3 μm. Since the particle size after pulverization is very fine, it may be necessary to inactivate the particle surface by various methods.

The magnetic powder for nanocomposites and HDDR magnetic powder exhibit coercive force without being finely pulverized, but the particle size may be affected when molded as a magnet body, and fine pulverization may be necessary. In addition, since the particle size of the magnetic particles is related to the coercive force, adjusting the particle size distribution by fine pulverization and classification also leads to adjustment of the coercive force distribution, in the sense of increasing the performance and reliability of the magnetic particles. It is important.

5. Magnet Production As an embodiment of the present invention, a magnet molded product including a magnet material and a binder is exemplified.

(1) Binder:
Examples of the binder for hardening the magnetic powder include an inorganic binder and an organic binder. For example, a low melting point metal or a resin can be used. The resin includes a thermosetting resin and a thermoplastic resin. EP (epoxy) resin can be used as the thermosetting resin, PA (polyamide, nylon) resin, PPS (polyphenylene sulfide) resin as thermoplastic resin, NBR (acrylonitrile butadiene rubber), CPE (chlorinated) as elastomer. Polyethylene) resin and EVA (ethylene vinyl acetate) resin can be used. It can also be hardened with an inorganic compound, and is a solution of SiO ₂ precursor, CH ₃ O— (Si (CH ₃ O) ₂ —O) _m —CH ₃ (m is 3 to 5, average is 4), water , Dehydrated methyl alcohol and dibutyltin dilaurate can be mixed, impregnated and solidified.

(2) Molding method:
When manufacturing a bonded magnet using isotropic magnetic powder, how to increase the density with high productivity is an important point. Although it depends on the magnetization characteristics of the magnetic powder, any magnetization is possible in principle as long as a molded body is formed, and a necessary magnetization pattern can be realized.

When manufacturing a bonded magnet using anisotropic magnetic powder, the problem is the orientation of the magnetic powder. It is important to orient the crystal axes of the particles in the desired direction during molding and to increase the density as in the case of an isotropic magnet.

The magnetization reversal mechanism is roughly divided into a nucleation type and a pinning type. In the former case, the smaller the crystal grain size, the better the coercive force. In the latter case, the coercive force is determined by the shape and number of pinning sites. The magnet material of the present invention is expected to have both magnetization reversal mechanisms depending on the production method. It is considered that the coercive force is mainly determined by the nucleation type in the case of a crystal structure of several μm obtained by rapid cooling, and by the pinning type in the case of a crystal structure of several tens to several hundreds of nm obtained by liquid superquenching. When the magnetic powder has shape anisotropy, the direction of the magnetic powder during molding is important for increasing the coercive force. In general, it is desirable to form a direction in which the demagnetizing factor is small (the permeance factor is large) as the magnetization direction.

(3) Manufacturing process:
There are compression molding and injection molding. In compression molding, since the density of magnetic powder can be increased, a high energy product can be realized. For example, a magnetic material for a bond magnet of a ferromagnetic fluorine compound as a raw material and an EP resin are kneaded together with an additive to form a compound, which is put into a mold and press-molded. Thereafter, after heat-curing, the excess powder is washed and dropped to coat the surface. Important factors during compound production are selection of powder particles, surface treatment of powder particles, selection of resin, selection of kneading conditions, and the like. It is possible to increase the density by optimizing the particle size distribution. In order to increase the density, it is effective to increase the slipping property between the magnetic particles by using a liquid resin. When using anisotropic magnetic powder, the orientation of the magnetic powder by applying a magnetic field is added. The degree of orientation varies depending on the type of resin used, and it is important that each magnetic powder can move freely overcoming the viscosity of the binder when a magnetic field is applied.

Injection molding is characterized by the ability to form complex shapes without post-processing. As the binder, PA resin or PPS resin is used. For example, a ferromagnetic fluorine compound bond magnetic powder as a raw material and a PA resin or PPS resin are kneaded together with an additive with a kneader to form a compound in a pellet form. This compound is put into an injection molding machine, heated and melted in a cylinder, and then injected into a mold for molding. It is necessary to adjust the viscosity of the resin. When using anisotropic magnetic powder, the magnetic powder can be oriented by forming a magnetic circuit necessary for the mold. In order to produce a high-performance anisotropic injection-molded magnet, it is necessary to sufficiently orient the molten compound when it is injected into the mold.

6). Rotating machine One embodiment of the present invention includes a rotating machine having a rotor containing a magnet material. For example, examples of the PC peripheral device include a spindle motor (for HDD, CD-ROM / DVD, and FDD) and a stepping motor (CD-ROM / DVD pickup, FDD head drive). Examples of the OA include a facsimile, a copy, a scanner, and a printer. Examples of the automobile include a fuel pump, an airbag sensor, an ABS sensor, an instrument, a position control motor, and an ignition device. There are also PC game machines equipped with HDDs and DVDs, and TV set boxes that are devices that download and use digital data from the Internet or cable TV. Examples of home appliances include mobile phones, digital cameras, video cameras, MP3 players, PDAs, stereos, and the like. Other examples include air conditioners, vacuum cleaners, and power tools.

In addition, since the magnet material of the present invention has a large magnetovolume effect, a Villari effect is expected in which the strength of magnetization changes when a pressure is applied to the magnetic material. It belongs to the magnetostriction phenomenon in a broad sense and can be used industrially for sensors and actuators.

7. Chlorination The present invention also includes a method of chlorination along with hydrogenation, nitrogenation, carbonization or fluorination. A feature of the present invention is that the magnetic modification occurs due to the geometric effect accompanying the increase of the crystal lattice volume due to the penetration of F atoms. Therefore, the same effect can be expected even with Cl atoms belonging to the same group instead of F atoms.

The chlorination reaction can be carried out in the same manner as described in Examples 1 to 3 below. However, ammonium chloride (NH ₄ Cl, decomposed at 338 ° C.) thermal decomposition product, nitrogen trichloride, boron trichloride, hydrogen chloride, chlorine or the like is used as the chloride gas. Of course, these may be mixed and used simultaneously. For example, chlorination using ammonium chloride is preferably carried out at 300 ° C. or higher, particularly preferably at a decomposition temperature of 338 ° C. or higher. This does not apply when using nitrogen trichloride, boron trichloride, hydrogen chloride, or chlorine other than ammonium chloride.

Since a hydrogen atom, a nitrogen atom, a carbon atom, a fluorine atom, and a chlorine atom need only coexist at an intrusion position in the crystal lattice with an appropriate occupation ratio, the method for introducing these elements is not particularly limited.

〔Example〕
EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example, the technical scope of this invention is not limited by this.

Example 1: Alloy containing F and H atoms The R (Sm or Nd) -Fe main phase alloy takes into account the evaporation of rare earths and mixes Fe with Sm or Nd more frequently than the stoichiometric ratio. Then, it was dissolved in a vacuum, an inert gas or a reducing gas atmosphere to make the composition uniform. It was prepared by quenching after heat treatment for phase formation. Since Sm ₂ Fe ₁₇ , Sm ₃ Fe ₂₈ Ti, and NdFe ₁₁ Ti are precipitated by the peritectic reaction of Fe, it is difficult to avoid a trace amount of α-Fe in the obtained alloy. The obtained ingot of Sm ₂ Fe ₁₇ was pulverized using a jet mill in an inert gas so that the average particle diameter was 10 μm or less. Ammonium fluoride (NH ₄ F, solubility in water 45.3 mg / 100 ml (25 ° C.)) and Sm ₂ Fe ₁₇ , Sm ₃ Fe ₂₈ Ti and NdFe ₁₁ Ti magnetic powders prepared by jet milling Hydrogen fluoride gas treatment was carried out using hydrogen fluoride gas generated by thermal decomposition and sublimation of acidic ammonium fluoride (NH ₄ F · HF, solubility in water 77.7 g / 100 ml (25 ° C.)).

Hydrogen fluoride gas treatment was performed in a gas flow format using a tubular furnace. In order to absorb the generated surplus gas, a trap mechanism was provided downstream of the reactor. The sample was spread thinly on a glassy carbon (GC) boat. However, the material of the sample container may be platinum or nickel other than carbon. A GC boat containing ammonium fluoride powder was disposed upstream and downstream. The amount of ammonium fluoride charged depends on the size of the reaction space, the gas flow rate, the heat treatment temperature, and the heat treatment time. This time, a quartz tube having a radius of 28 mm and a length of 1200 mm was used, and 10 g of ammonium fluoride and ammonium acid fluoride were arranged upstream and 10 g respectively downstream of the magnetic powder 20 g. After evacuating with a rotary pump, Ar was flowed at 200 ml / min. To heat the electric furnace. Heat treatment was performed at 150 ° C., 200 ° C., 250 ° C., and 300 ° C. so that the reaction time was 24 hours.

In selecting the heat treatment temperature, the low temperature side where the decomposition / oxidation reaction of Sm ₂ Fe ₁₇ is relatively small is selected, and the temperature is preferably lower than 300 ° C. Further, in the selection of the heat treatment time, sufficient diffusion can be expected even in a short time because hydrogenation and fluorination proceed simultaneously. However, it greatly depends on the magnetic powder size, the crystal grain size, the surface state of the magnetic powder, the structure shape, and the like. It is expected that hydrogen fluoride and fluorination will be accelerated by mixing ammonium fluoride and acidic ammonium fluoride and magnetic powder and placing them on the GC boat, but the hydrogen fluoride generation source and magnetic powder are in direct contact with each other. Thus, an excessively strong redox diffusion reaction occurs, and the outer periphery of the magnetic powder is decomposed into rare earth fluoride, rare earth oxyfluoride, iron fluoride, iron, and the like. It is necessary to select appropriately depending on the particle size of the magnetic powder to be used.

When mixing, vacuum replacement may be performed at the end of the heat treatment for the purpose of removing unreacted products. The sample was stored in a vacuum container in a polyethylene container because unreacted material may be attached. However, since hydrogenated and fluorinated magnetic powders are extremely stable at room temperature, glass bottles may be used if the amount of unreacted material does not matter.

Since this method is a solid-gas reaction and a low-temperature reaction, non-uniformity of the reaction becomes a problem. Therefore, it is desirable to introduce a fluidized bed or the like so that the reaction proceeds evenly.

The following shows the analytical results for representative Sm ₂ Fe _17. Similar results were obtained with Sm ₃ Fe ₂₈ Ti and NdFe ₁₁ Ti.

FIG. 1 shows (a) Sm ₂ Fe ₁₇ magnetic powder, (b) 150 ° C. 24 h heat treated magnetic powder, (c) 200 ° C. 24 h heat treated magnetic powder, (d) 250 ° C. 24 h heat treated magnetic powder, (e) 300 ° C. 24 h heat treated magnetic powder, (F) The powder X-ray diffraction pattern at room temperature of the heat-treated magnetic powder at 350 ° C. for 24 hours is shown. In order to observe the structural change of the product due to the difference in heat treatment temperature, powder X-ray diffraction was performed. The diffraction peaks are SmFe ₃ for ◯, Fe for △, FeF ₂ (rutile type, space group P4 ₂ / mnm) ▽, SmF ₃ (β-YF ₃ type, space group Pnma) and SmOF (strained CaF ₂ type, space). Group R-3m) is indicated by □, and Sm ₂ Fe ₁₇ is indicated by no mark. However, samarium oxyfluoride is represented by SmOF because phases of various composition ratios and structures are known, and their diffraction peaks are located in diffuse diffraction and are difficult to distinguish. (A) In Sm ₂ Fe ₁₇ magnetic powder, diffraction peaks corresponding to a small amount of Fe and SmFe ₃ were observed in addition to Sm ₂ Fe ₁₇ of the main phase. Sm ₂ Fe ₁₇ is produced by the peritectic reaction of Fe and liquid phase, and the difference between the melting point and the peritectic temperature of Fe is large, so the Fe initial phase remains even after the solidification. Although phase growth is performed by high-temperature heat treatment, it is difficult to avoid a small amount of foreign phase formation. The formation of FeF ₂ was observed in (b) 150 ° C. 24 h heat treated magnetic powder and (c) 200 ° C. 24 h heat treated magnetic powder. In (d) 250 ° C. 24 h heat treated magnetic powder, (e) 300 ° C. 24 h heat treated magnetic powder, and (f) 350 ° C. 24 h heat treated magnetic powder, the diffraction peak of FeF ₂ is buried in diffuse diffraction and cannot be clearly observed. It was not able to be confirmed even if division analysis was carried out. Furthermore, it was observed that the diffuse diffraction increases from around 25 degrees to around 35 degrees and around 45 degrees as the heat treatment temperature increases. The low angle side corresponds to SmF ₃ , SmOF, etc., and the high angle side corresponds to the diffuse diffraction of Fe. By heat treatment in an oxidizing atmosphere higher than 150 ° C., it is estimated that a part of Sm ₂ Fe ₁₇ was decomposed and Sm and Fe were precipitated as fine crystal grains, and a part of them was oxidized and fluorinated. . Thus, at least rare earth fluoride, rare earth oxyfluoride, iron, and iron fluoride are generated as heterogeneous phases. As a result of analyzing the reciprocal width of the diffuse diffraction by the Scherrer method, the average size of the precipitated crystals was about 5 nm, and the heat treatment temperature dependence was hardly observed.

FIG. 2 shows (a) secondary electron image, (b) C, (c) N, (d) in a crystal grain cross section of 250 ° C. 24 h heat treated magnetic powder measured by an electron probe micro analyzer (EPMA). Element concentration distribution images of O, (e) F, (f) Fe, (g) Pr, and (h) Sm are shown, respectively. However, the element concentration is expressed in weight percentage (wt%). (B) C atoms and (c) N atoms, which are known as intruding elements into Sm ₂ Fe ₁₇ , are within the crystal grains at the resolution of EPMA (C atoms: 0.0x-1 wt%, N atoms: ˜1 wt%). In FIG. 5, the concentration was the same before and after the heat treatment, and the penetration of C atoms and N atoms by the heat treatment could not be confirmed. It was observed that (d) O atoms, (e) F atoms, (f) Fe atoms, and (h) Sm atoms show non-uniform distribution within the crystal grains by heat treatment. Presence of SmF ₃ , SmOF, and Fe is observed as fine crystal grains of about 5 nm from the half-value width of diffuse diffraction in powder X-ray diffraction (see Fig. 1), and these phases are mixed in the EPMA observation scale. Observed in the same area. In particular, in the O and F concentration distribution, a correlated region can be confirmed in the outer periphery of the magnetic powder, and the F concentration tends to be high in the region where the O concentration is high. It is estimated that the outer periphery of the magnetic powder is easily oxidized, and the oxidized phase is fluorinated by heat treatment to produce SmF ₃ , SmOF and the like. Further, it has been observed that the O concentration in the outer periphery of the magnetic powder is higher in the 250 ° C. 24 h heat treated magnetic powder than in the Sm ₂ Fe ₁₇ magnetic powder, and oxidation is considered to occur mainly during the heat treatment. The effect of moisture adhering to the magnetic powder surface is suggested. Considering the concentration ratio of each element, (e) it is presumed that the blue region in the F concentration distribution image corresponds to a phase having Sm ₂ Fe ₁₇ symmetry. However, since incurred hem of the FK _alpha FeL _alpha, suffer the effects of element concentration distribution of Fe with low concentrations of F region (see FIG. 3).

FIG. 3 shows a place A, a place B, and a place C (measured using spectral crystals (a) LS7A (diffraction grating), (b) RAP (rubidium acid phthalate), and (c) LS5A (diffraction grating). energy spectrum near FK _alpha in FIGS. 2 (a) see secondary electron image), and elemental quantitative results are shown, respectively. However, in order to make the spectrum shape symmetrical, the unit of the horizontal axis is converted from wavelength to energy and displayed. In the function approximation, since the energy range is narrow, convolution of the resolution function of the apparatus is ignored and approximation is performed by three Lorentz functions (FK _α , FeL _α1 , FeL _α2 ). Further, since it is a spectral crystal, 2λ is observed in (a). Result, the skirt of the peak of FeL _alpha in any of analyzing crystal was found to be incurred FK _alpha. The lower limit of detection of F atoms was found to be about 3 wt% to about 4 wt% in terms of weight percentage. Assuming the Sm ₂ Fe ₁₇ F _x structure, it cannot be detected when x ≦ 2 to 2.7. Location A, where B, and the location quantified ZAF correction result using a standard sample in C, the elemental ratio at any location Sm: has a Fe ~ 2:17, also, F atom location A, and Detection was not possible at location B, and 17 at% was detected at location C. Considering that the electron beam beam diameter is 1 μm, the penetration of the electron beam into the metal material, and the escape depth of the characteristic X-ray is about 2 μm to 3 μm, Sm ₂ Fe ₁₇ is decomposed at the place C, and FeF ₂ , SmF ₃ , SmOF, etc. are presumed to be mixed.

As a result, the penetration of C atoms and N atoms into Sm ₂ F ₁₇ can be denied in the range of EPMA detection resolution.

In order to verify the presence or absence of H atoms and F atoms that could not be detected by EPMA, two mass spectrometry methods were implemented.

A temperature-programmed desorption gas analysis was performed to infer invading elements from the analysis of the element species generated from the entire sample.

FIG. 4 shows the temperature dependence of the desorption gas of (a) Sm ₂ Fe ₁₇ magnetic powder and (b) 250 ° C. 24 h heat-treated magnetic powder, respectively. In consideration of the chemical used and the temperature change of the amount of desorbed gas, the composition formula corresponding to each mass-to-charge ratio m / z is as follows: m / z = 1 is H ⁺ , m / z = 2 is H ₂ ⁺ , m / Z = 16 is O ⁺ , CH ₄ , NH ₂ ⁺ , m / z = 17 is OH ⁺ , NH ₃ ⁺ , m / z = 18 is H ₂ O ⁺ , NH ₄ ⁺ , m / z = 19 is F ⁺ , M / z = 20 is estimated as HF ⁺ , m / z = 28 is estimated as N ₂ ⁺ , and m / z = 44 is estimated as N ₂ O ⁺ , CO ₂ ⁺ , C ₃ H ₈ ⁺ . For m / z = 85, N ₂ F ₃ ⁺ is considered, but the details are unknown. In (a), it was observed that a desorbed gas having a mass-to-charge ratio m / z = 1, 2, 16, 17, 18, 44 was generated in a temperature range from about 100 ° C. to about 300 ° C. It is estimated that water adhering to the magnetic powder is mainly desorbed. In addition, it was observed that a desorbed gas having a mass-to-charge ratio m / z = 2 was generated in a temperature range of about 320 ° C. to about 500 ° C. Sm ₂ Fe ₁₇ H _x is known to release H atoms in a temperature range of about 350 ° C. to about 550 ° C., and is presumed to be due to H atoms contained in a trace amount in the main phase. Actually, it has been confirmed that the Curie temperature of the purchased Sm ₂ Fe ₁₇ magnetic powder is about 4 ° C. to 12 ° C. higher than the literature value, and supports the presence of H atoms contained in a trace amount. (B) can be divided into four temperature regions based on the type and generation pattern of the degassing gas. In the temperature region I (0 ° C. to about 120 ° C.), a desorption gas having a mass-to-charge ratio m / z = 1, 2, 16, 17, 18, 44 was observed at a peak around 100 ° C. This is thought to be the detachment of water adhering to the magnetic powder. In the temperature region II (about 120 ° C. to about 400 ° C.), the temperature of the desorbed gas having a mass-to-charge ratio m / z = 1, 2, 16, 17, 18, 19 reaches about 400 ° C. with a peak around 200 ° C. Observed to occur in the region. It is presumed to be a desorbed gas generated by thermal decomposition of ammonium hydrogen fluoride remaining on the sample surface. However, it was observed that the desorbed gas having a mass-to-charge ratio m / z = 19,20 behaves differently and increased in the temperature range from 210 ° C. to 400 ° C. Although it is considered that F atoms are desorbed from Sm ₂ Fe _17, there is a possibility that the decomposition mode of the remaining ammonium hydrogen fluoride is complicatedly changed. In temperature region III (about 400 ° C to about 540 ° C), a desorption gas having a mass-to-charge ratio of m / z = 2,28 is generated, which is related to decomposition of the ammonia component generated by decomposition of ammonium hydrogen fluoride. It seems to be. In the temperature region IV (about 540 ° C. to 680 ° C.), it was observed that desorbed gas having a mass-to-charge ratio m / z = 19, 28, 85 increased. Although it is presumed to be related to a gas generated by decomposition of ammonium hydrogen fluoride, details are unknown.

A time-of-flight secondary ion mass spectrometer (TOF-SIMS) was used to analyze a trace amount and local element concentration distribution mainly of H atoms and F atoms.

FIG. 5 shows (a) total ions, (b) Fe ⁺ , (c) FeH ⁺ , (d) FeOH ⁺ , (e) Sm ⁺ , (f) SmF ⁺ , and 250 ° C. for 24 h. (G) Ion images of H ⁺ , (h) Na ⁺ , (i) Al ⁺ , (j) Si ⁺ , and (k) Ca ⁺ are shown, respectively. From the ion images of (b) Fe ⁺ and (e) Sm ⁺ , it was observed that the Fe element and the Sm element showed a non-uniform composition distribution. In particular, from the ion images of (b) Fe ⁺ and (f) SmF ⁺ , it was observed that many Fe atoms, Sm atoms, and F atoms were segregated on the outer periphery of the crystal grains. From the comparison of the ion images of (c) FeH ⁺ and (d) FeOH ⁺ , it was found that a large amount of O element was also present in the outer periphery of the crystal grains. Presumed to be fine Fe, SmF ₃ and SmOF generated by decomposition and precipitation of Sm ₂ Fe ₁₇ during the heat treatment. Furthermore, it was found that most of the fine crystal grains existed as Fe, SmF ₃ and SmOF. Given these, Sm ₂ Fe ₁₇ was oxidized, it would not be able to maintain a structure with symmetry of Sm ₂ Fe ₁₇ during the heat treatment. At least rare earth fluoride, rare earth oxyfluoride, iron, and iron fluoride are generated as different phases. Even if the oxidation of the outer periphery of the magnetic powder can be suppressed, it may be difficult to avoid the decomposition of the outer periphery of the magnetic powder due to the contact between the HF gas and the magnetic powder. At the center of the crystal grain, each ion of (f) SmF ⁺ and (g) H ⁺ was observed at an intensity higher than the background compared to the resin part. That is, F atoms and H atoms were detected in a region assumed to be a phase having symmetry of Sm ₂ Fe ₁₇ . (H) Na ⁺ , (i) Al ⁺ , (j) Si ⁺ , and (k) Ca ⁺ observed in the same region are trace impurities that are mixed during the production of Sm ₂ Fe ₁₇ magnetic powder. Further, (j) a large amount of Si ⁺ ions were detected from the outer periphery of the magnetic powder, and it seems that the quartz tube used in the fluorination treatment was attacked by hydrogen fluoride and adhered to the magnetic powder as silicon fluoride gas.

FIG. 6 shows (a) total ions, (b) FeO ⁻ , (c) FeO ₂ ⁻ , (d) FeO ₂ H ⁻ , (250 ° C. for 24 h heat treated magnetic powder measured using TOF-SIMS. e) The ion images of H ⁻ , (f) C ⁻ , (g) O ⁻ , (h) OH ⁻ , (i) F ⁻ , (j) CN ⁻ , and (k) Cl ⁻ are shown, respectively. There is a correlation between the ion images of (e) H ⁻ and (g) O ⁻ , and the O concentration tends to increase corresponding to the H concentration. The comparison between the samples is only a reference level, but the influence of the background in the apparatus can be ignored to some extent by comparing the H concentration by the difference between the resin portion around the magnetic powder and the crystal grains. In that case, it appears that the H concentration in the crystal grains before and after the treatment hardly changes. Each ion of (f) C ⁻ and (j) CN ⁻ has the same size as the background within the crystal grain, and C atoms and N atoms are present inside the crystal grain within the range of the TOF-SIMS detection resolution. I found that it doesn't exist. (I) It was observed that F ^- ions were strongly segregated on the outer periphery of the crystal grains, and that small crystals were present at a high concentration even inside the crystal grains. Small crystal grains are almost decomposed and presumed to exist as SmF ₃ , FeF ₂ , SmOF and the like.

As a result of the above, heat treatment of the Sm ₂ Fe ₁₇ magnetic powder using hydrogen fluoride gas gave Sm ₂ Fe ₁₇ H _α F _x (0 <α <5, 0 <x ≦ 3, and 0 <α + x ≦ 5 ) Was obtained as a suitable composition. The upper limits of α and x are naturally limited by the number of intrusion positions. Similarly, the chemical formula R ₃ (Fe, T) ₂₉ H _β F _y (0 <β <6 and 0 <y ≦ 4 and 0 <β + y ≦ 6), chemical formula R (Fe, T) ₁₂ H _γ F _z (0 <γ <1, 0 <z <1, and 0 <γ + z ≦ 1) is obtained. In order to experimentally obtain the α, β, γ, x, y, z values of the prepared sample, the following method is possible.

The first is to separate the heterogeneous phase of the synthesized magnetic powder with a ball mill or jet mill, etc., and to separate it according to the structure and composition by methods such as magnetic attraction and centrifugation, and then the weight and chemical composition of the target phase before and after treatment. It depends on the analysis method. Second, using TOF-SIMS and elemental determination in the target phase. The third is the identification of F atom position and occupancy by wide-angle X-ray absorption fine structure (EXAFS) measurement and X-ray / neutron Rietveld analysis. In addition, since it is a magnetic material, it can also be identified from magnetic measurements. By combining the above methods, it is possible to identify with higher accuracy.

FIG. 7 shows the temperature dependence of the magnetization of Sm ₂ Fe ₁₇ magnetic powder heat-treated at various temperatures in a 0.5T magnetic field. The magnetization of Sm ₂ Fe ₁₇ magnetic powder is a temperature change of a standard ferromagnet according to mean field theory. However, an increase in magnetization at 200 ° C. or higher means that Fe is generated by phase decomposition by a trace amount of oxygen contained in dilute He as a measurement atmosphere. The Curie temperature is 120 ° C. from the polarization point. It was observed that the Curie temperature increased according to the heat treatment temperature and reached a maximum of 260 (140 ° C. increase) in the heat treated magnetic powder at 200 ° C. for 24 hours. In the case of heat treated magnetic powder at 200 ° C. for 24 hours, two Curie temperatures were observed at about 190 ° C. and 260 ° C. in the temperature curve of magnetization, and it was found that the method of decreasing the magnetization was slow compared to other heat treated magnetic powder. This means that although it is represented mainly by two phases depending on the way of atom penetration into Sm ₂ Fe ₁₇ , it still has a distribution in atom penetration. It is presumed to be caused by a complex diffusion reaction of hydrogenation and fluorination, and details of the diffusion reaction mechanism are not well understood at present. In addition, magnetization jumps were observed in the temperature range from −100 ° C. to −60 ° C., and it was found that the temperature range where the jumps occurred correlated with an increase in the Curie temperature. It is known that the magnetization jump in this temperature region is a change in magnetic anisotropy related to the localization of Fe. It is a magnetic transition having a scale as an evaluation criterion of atom penetration other than the Curie temperature. That is, it has a certain correlation with the expansion rate of the crystal lattice. In the heat-treated magnetic powder at 350 ° C. for 24 hours, Sm ₂ Fe ₁₇ is completely phase-decomposed into Fe, SmF ₃ , SmOF, etc., and what is observed is the temperature change of Fe. If the temperature dependence of the magnetization is significantly different from the Brillouin function in this thermomagnetic property evaluation, it is suggested that multiple phases contribute to the temperature dependence of the magnetization. Provides a measure of whether the diffusion is uniform.

FIG. 8 shows (a) crystal lattice constant expansion rate Δa / a axis, Δc / c axis, and unit cell volume expansion rate Δv / v, and (b) Curie temperature increase in Sm ₂ Fe ₁₇ H _x F _y . The dependence of the rate ΔT _C / T _{C on} the heat treatment temperature is shown. In addition, the heat treatment temperature dependence of (c) coercive force H _c and (d) switching field distribution (SFD) of the entire sample at liquid nitrogen temperature (Liq.N), room temperature (RT). Each is shown. However, the standard for the expansion rate and the rate of increase is Sm ₂ Fe ₁₇ magnetic powder. SFD is a dimensionless quantity derived by dividing the half width of the peak obtained by differential analysis of the magnetic field dependence of magnetization by the coercive force. This amount gives a measure of the distribution of the magnetization reversal field of the permanent magnet material. In the case of the low coercive force as in this case, the smaller the value, the harder the magnetic material, and the larger the value, the softer the magnetic. (A) It was observed that the a-axis expansion ratio Δa / a of the crystal lattice constant takes a maximum value when the heat treatment temperature is 200 ° C. and gradually decreases with heat treatment at a higher temperature. It was observed that the c-axis expansion ratio Δc / c of the crystal lattice constant takes a minimum value when the heat treatment temperature is 200 ° C. and gradually increases with heat treatment at a higher temperature. This is presumed that atoms invaded by heat treatment at 200 ° C. for 24 hours are desorbed by heat treatment at a higher temperature. (B) The Curie temperature rise rate also exhibits the same behavior as the a-axis expansion rate Δa / a and the unit cell volume expansion rate Δv / v of the crystal lattice constant, and the maximum value when the heat treatment temperature is 200 ° C. However, it was observed that the temperature decreased gradually with heat treatment at higher temperatures. This suggests that there is a correlation between the crystal lattice constant and the Curie temperature. (C) It was observed that the coercive force Hc gradually decreased from a heat treatment at 200 ° C. or higher where atomic penetration increases. (D) It was observed that SFD also gradually increased from the heat treatment at 200 ° C. or higher where atomic penetration increases, and suddenly becomes a large value at 350 ° C. heat treatment in which Sm ₂ Fe ₁₇ is completely decomposed. Magnetization reversal occurs when Fe, which is soft magnetism generated by decomposition during heat treatment, is mixed in the crystal structure (especially the outer periphery of the crystal) of the Sm ₂ Fe ₁₇ structure having a coercive force generation mechanism of reversed domain nucleation type. It occurs easily, and it is considered that the coercive force decreases and the SFD increases.

FIG. 9 shows the correlation between the Curie temperature increase rate ΔT _C / T _C and the unit cell volume expansion rate Δv / v in Sm ₂ Fe ₁₇ fluorinated with HF. However, the unit cell volume is a value at room temperature. In the linear approximation, the origin was forcibly passed to reduce the approximation error (increase the R factor). In hydrogenation and fluorination, in addition to ammonium fluoride and acidic ammonium fluoride, ammonium silicofluoride ((NH ₄ F) ₂ SiF ₆ ) and ammonium borofluoride (NH ₄ BF ₄ ) are used to react. The degree of was adjusted. When the volume expansion rate Δv / v of the unit cell is taken on the horizontal axis and the Curie temperature rise rate ΔT _C / T _C is taken on the vertical axis, the slope of Sm ₂ Fe ₁₇ H _x F _y synthesized by HF is 16.0 (± 0 .9). Sm ₂ Fe ₁₇ H _x C _y N _z , whose Curie temperature rose by a maximum of 36% and whose unit cell volume expanded by a maximum of 1.9% , N are almost independent of each other and are known to have a relationship of 13.3 (± 0.6). The linear relationship is mainly related to the localization of Fe atoms caused by atoms entering Sm ₂ Fe ₁₇ . Therefore, the expansion rate of the unit cell volume is correlated with the amount of penetration of H atoms and F atoms. Although the approximation error is large because the number of data points is small and the distribution of measurement points is biased, the slope of Sm ₂ Fe ₁₇ H _x F _y tends to be larger than that of Sm ₂ Fe ₁₇ H _x C _y N _z. is there. This difference in magnetovolume effect may reflect the degree of localization of Fe atoms due to the strong electronegativity of F atoms. The above correlation is also observed in principle in the chemical formula R ₂ (Fe, T) ₁₇ F _x , the chemical formula R ₃ (Fe, T) ₂₉ F _y , and the chemical formula R (Fe, T) ₁₂ F _z . It is expected.

Since the measured average particle diameter of the magnetic powder was 10 μm, the coercive force is slight, but it is estimated that a significant coercive force is exhibited by grinding from about 2 μm to about 3 μm. In principle, it is desirable to pulverize to a single domain critical particle size (about 0.3 μm). However, since problems in process such as oxidation occur, it is desirable that the particle size is 1 μm or more.

For example, FIG. 10 shows the magnetic field dependence of magnetization before and after pulverization of Sm ₃ Fe ₂₈ Ti heat-treated with ammonium fluoride and ammonium acid fluoride at 300 ° C. for 1 h. The pulverization was performed by wet pulverization in a cyclohexane solvent using a ball mill. After removing the solvent, it was aligned with stearic acid and measured. However, secondary agglomeration of magnetic powder is caused by ball milling and the degree of magnetic powder orientation is lowered, and saturation magnetization is evaluated to be low due to contamination with impurities. Sufficient dispersion and crushing treatment and removal of impurities are necessary. The increase in coercive force and generation of large hysteresis were confirmed by grinding. In order to further increase the coercive force, it is necessary to improve the reverse domain nuclear reversal magnetic field, and it is effective to suppress oxidation by Zn, Sn, and their alloys, and surfactants.

By treating Sm ₂ Fe ₁₇ with hydrogen fluoride, the magnetic anisotropy changes from in-plane anisotropy to uniaxial anisotropy, and has the potential as a permanent magnet material. This is because the 4f electron orbit responsible for the magnetism of Sm has a cigar shape, and the same effect is expected for Er and Tm. In other words, when the crystal field acting on the rare earth element is considered, in the chemical formula R ₂ (Fe, T) ₁₇ H _α F _x (1 ≦ x), the chemical formula R ₃ (Fe, T) ₂₉ H _β F _y (2 ≦ y) When the rare earth element R is Sm, Er, or Tm, uniaxial magnetic anisotropy is obtained. On the other hand, when the rare earth element R is Pr, Nd, Tb, Dy in the chemical formula R (Fe, T) ₁₂ H _γ F _z (0.5 ≦ z), the uniaxial magnetic anisotropy is obtained. In order to experimentally obtain the values of α, β, γ, x, y, and z of the prepared sample, the above-described method can be used. Uniaxial magnetic anisotropy can be evaluated by orientation and fixation in a magnetic field, and it is desirable to evaluate a single-phase sample that has been pulverized, crushed and separated in order to increase accuracy.

For example, FIG. 11 shows the heat treatment temperature dependence of hydrogenation and fluorination of the liquid nitrogen temperature and the magnetic anisotropy energy of Sm ₃ Fe ₂₈ Ti at room temperature. A sample oriented using a stearic acid (melting point 68 ° C. to 71 ° C.) in a 2T magnetic field was evaluated in the vertical direction and the parallel direction, and the enclosed area was derived as the magnetic anisotropy energy. However, since the measuring device can only apply a magnetic field up to ± 6T, the intersection of both curves was calculated by extrapolation using the saturation asymptotic rule, and the enclosed area was derived. Therefore, there are some errors. It was found that the magnetic anisotropy energy tends to increase with increasing hydrogenation and fluorination heat treatment temperatures. Thus, magnetic anisotropy increases by hydrogenation and fluorination. Uniaxial magnetic anisotropy can also be analyzed using micromagnetic evaluation means such as ferromagnetic resonance, Mossbauer, neutrons, and nuclear magnetic resonance.

In addition, a large amount of α-Fe, which is inevitably decomposed and generated by a part of Sm ₂ Fe ₁₇ due to the influence of a trace amount of oxygen in the treatment with hydrogen fluoride, tends to exist on the surface of the magnetic powder. As a result, since it contributes as a reverse domain nucleus at the time of magnetization reversal, it is desirable to form a Zn—Fe alloy or Sn—Fe alloy that is a paramagnetic phase by mixing Zn, Sn, etc. in order to develop a coercive force. Moreover, such a low melting point metal and a low melting point alloy can bind magnetic powders and increase the packing density to increase the magnetic flux density.

Example 2: F atom and N atom containing alloy In a present Example, the method of implementing nitrogenation and fluorination is demonstrated. In Sm ₂ Fe ₁₇ , it has been intensively studied and clarified that fluorine atoms are discharged out of the crystal lattice at a temperature higher than 300 ° C. and nitrogen atoms are taken into the crystal lattice from around 300 ° C. Therefore, it is difficult to carry out nitrogenation and fluorination at the same time, and it is necessary to carry out nitrogenation first in view of the stability of the system. However, chemical formula R ₂ (Fe, T) ₁₇ , chemical formula R ₃ (Fe, T) ₂₉ , chemical formula R (Fe, T) ₁₂ (where R is a 4f transition element or Y, T In a system of 3d transition elements other than Fe, or Al, Si, Ga, Mo, Nb, W), the absorption and emission temperatures of fluorine atoms and nitrogen atoms are different, so it cannot be generally said. Hereinafter, for example, a method of fluorinating Sm ₂ Fe ₁₇ after nitriding will be described in detail. However, the scope of the present embodiment is not limited depending on whether or not it can be performed simultaneously. It is essential that nitrogen atoms and fluorine atoms coexist with an appropriate occupation ratio at the intrusion position in the crystal lattice. Therefore, there is no problem in mixing nitrogen gas and fluorine gas, using each gas separately, and using nitrogen and fluorinated gas or solid.

The R (Sm or Nd) —Fe-based main phase alloy was produced in the same manner as in Example 1. Of course, it is not limited by the manufacturing method of the alloy. Nitrogenation and fluorination used nitrogen trifluoride (NF ₃ , purity 99.99% or more) gas. As the reaction apparatus, a Ni reaction vessel having a sufficient wall thickness was used. In addition, Ni-based alloys such as Inconel and Monel can be used. Stainless steel was used for the sample container. In advance, a sample container was placed in the reaction container, and nitrogen trifluoride was introduced at a temperature higher than the working temperature, and a passivation process was performed for a sufficient time.

For example, in this example, the following procedure was used. A sample 5 g was thinly spread and placed in a stainless steel container (5 cm × 7 cm). The operation of evacuation (0.4 kPa) and Ar (purity 99.9995% or more) replacement was performed three times. After raising the temperature to 120 ° C. in dilute Ar, vacuuming and Ar replacement were performed again for the purpose of removing moisture. Thereafter, the temperature was raised to a temperature T ₁ for nitrogenation, and nitrogen trifluoride gas was introduced. The introduced nitrogen trifluoride gas is mixed and adjusted in advance with Ar, and the concentration is about 10% in terms of ideal gas. The treated pressure was 90 kPa. Nitrogen trifluoride was introduced and held for 1 hour, furnace cooled to a temperature T ₂ for fluorination, and held for 4 hours. The selection of the processing temperatures T ₁ and T _{2 and} the selection of each holding time dominate the penetration rate occupancy and the atomic diffusion. When the nitrogenation has completely progressed, the position where the fluorine atom penetrates disappears and the fluorination does not occur. Therefore, appropriate adjustment is necessary. After holding, sufficient exhaust treatment was performed, and the furnace was cooled in an Ar atmosphere and released to the atmosphere at 40 ° C. or lower.

Table 1 shows the Curie temperature of Sm ₂ Fe ₁₇ heat-treated at each temperature. Thus, it was found that the Curie temperature differs depending on the difference in heat treatment temperature. Since the difference in the heat treatment temperature causes a difference in the degree of nitridation and fluorination, it indicates that the Curie temperature rises by nitridation and fluorination. By fluorination, the Curie temperature of Sm ₂ Fe ₁₇ N ₃ exceeds 470 ° C. FIG. 13 shows powder X-ray diffraction patterns of Sm ₂ Fe ₁₇ , Sm ₂ Fe ₁₇ N ₃ , and Sm ₂ Fe ₁₇ N _α F _x . It was found that the diffraction pattern had the same symmetry as the Th ₂ Zn ₁₇ structure, and the peak angle shifted to the lower angle side as the Curie temperature increased. This indicates that there is a correlation between the Curie temperature and the size of the crystal lattice, which is one manifestation of the magnetic volume effect.

From detailed composition analysis by TOF-SIMS, N atoms and F atoms were detected from the region presumed to be the parent phase at the center of the crystal grains. It is unavoidable to avoid some decomposition and generation of Sm and Fe due to non-uniformity of the Sm ₂ Fe ₁₇ phase during nitrogenization and fluorination, and the outer periphery of the magnetic powder after fluorination has SmN, SmF ₃ , SmOF, Fe, FeN, FeF ₂ and FeF ₃ were present. That is, depending on the heat treatment temperature, at least one of rare earth nitride, rare earth fluoride, rare earth oxyfluoride, iron, and iron fluoride is included when nitriding and fluorinating rare earth iron It will be. O atoms are caused by moisture adhering to the outer periphery of the magnetic powder and oxidation during heat treatment, and are unavoidably mixed. Desirably, it is an atom to be excluded. By increasing the heat treatment time, it is possible to advance the nitrogenation and fluorination to the inside of the crystal grains. When the heat treatment time is short, N atoms and F atoms penetrate and diffuse from the outer periphery of the crystal grains, so that N and F atoms inevitably have a concentration gradient from the grain boundary toward the parent phase center. Will have. Since the diffusion rate of F atoms is slower than that of N atoms, the concentration non-uniformity tends to be large in F atoms.

From the above results, Sm ₂ Fe ₁₇ N _α F _x can be synthesized by heat-treating Sm ₂ Fe ₁₇ in a nitrogen trifluoride atmosphere, and an increase in the Curie temperature was confirmed. Besides increasing the Curie temperature, we observed an increase in magnetic moment and an improvement in magnetic anisotropy. Separately conducted with regard Sm ₃ Fe ₂₈ Ti, and NdFe ₁₁ Ti, it was observed almost the same tendency.

Since the measured magnetic powder had an average particle size of 10 μm, the coercive force was slight, but it is estimated that a significant coercive force is exhibited by grinding from about 2 μm to about 3 μm. In principle, it is desirable to pulverize to a single domain critical particle size (about 0.3 μm). However, since problems in process such as oxidation occur, it is desirable that the particle size is 1 μm or more. When nitrogen atoms and fluorine atoms enter Sm ₂ Fe ₁₇ , the magnetic anisotropy changes from in-plane anisotropy to uniaxial anisotropy, and has the potential as a permanent magnet material. This is because the 4f electron orbit responsible for the magnetism of Sm has a cigar shape, and the same effect is expected for Er and Tm. In other words, when the crystal field acting on the rare earth element is considered, in the chemical formula R ₂ (Fe, T) ₁₇ N _α F _x (1 ≦ α + x), the chemical formula R ₃ (Fe, T) ₂₉ N _β F _y (2 ≦ β + y) When the rare earth element R is Sm, Er, or Tm, uniaxial magnetic anisotropy is obtained. On the other hand, when the rare earth element R is Pr, Nd, Tb, Dy in the chemical formula R (Fe, T) ₁₂ N _γ F _z (0.5 ≦ γ + z), the uniaxial magnetic anisotropy is obtained. Uniaxial magnetic anisotropy can be evaluated by the method described in Example 1. In order to experimentally obtain the values of α, β, γ, x, y, and z of the prepared sample, the analysis method described in Example 1 can be used.

Example 3: F-atom and C-atom-containing alloy In this example, a method for carbonization and fluorination will be described. In Sm ₂ Fe ₁₇ , it has been intensively studied and clarified that fluorine atoms are discharged out of the crystal lattice at a temperature higher than 300 ° C., and carbon atoms are taken into the crystal lattice from around 300 ° C. Therefore, it is difficult to carry out carbonization and fluorination at the same time, and it is necessary to carry out carbonization first in view of the stability of the system. Moreover, since carbonization increases the thermal stability of the crystal lattice more than nitrogenation, it is desirable to carry out carbonization first. However, chemical formula R ₂ (Fe, T) ₁₇ , chemical formula R ₃ (Fe, T) ₂₉ , chemical formula R (Fe, T) ₁₂ (where R is a 4f transition element or Y, T In 3d transition elements other than Fe, or Al, Si, Ga, Mo, Nb, W) systems, the absorption and emission temperatures of fluorine atoms and carbon atoms are different, so it cannot be generally stated. Hereinafter, for example, a method of fluorinating Sm ₂ Fe ₁₇ after carbonization will be described in detail. However, the scope of the present embodiment is not limited depending on whether or not it can be performed simultaneously. It is essential that the carbon atom and the fluorine atom coexist with an appropriate occupation ratio at the intrusion position in the crystal lattice. Therefore, there is no problem if it is a substance that can be carbonized or fluorinated (such as solid, gas, liquid, etc.) such as hydrocarbon gas and fluorine gas. However, since hydrocarbon gas and fluorine gas react violently, it is desirable not to carry out mixing of both gases for safety, and there are few advantages in terms of process and characteristics. It is more efficient and effective to use the fluorocarbon from the beginning. Sm ₃ Fe ₂₈ Ti and NdFe ₁₁ Ti were also separately carried out in substantially the same manner as Sm ₂ Fe ₁₇ .

The R (Sm or Nd) —Fe-based main phase alloy was produced in the same manner as in Example 1. Of course, it is not limited by the manufacturing method of the alloy. In this embodiment, butane (C ₄ H ₁₀ , purity 99.5% or more) is used as the gas to be carbonized, and fluorine (F ₂ , purity 99.5% or more) is used as the gas to be fluorinated. Carried out. A sample 5 g was thinly spread and placed in a stainless steel container (5 cm × 7 cm). The operation of evacuation (0.4 kPa) and Ar (purity 99.9995% or more) replacement was performed three times. After raising the temperature to 120 ° C. in dilute Ar, vacuuming and Ar replacement were performed again for the purpose of removing moisture. Thereafter, the temperature was raised to a temperature T ₁ of the for carbonization was introduced butane. The introduced butane had a concentration of 100% and was maintained at a treatment pressure of 90 kPa for 1 hour. Butane gas was exhausted sufficiently to form an Ar atmosphere, and the furnace was cooled to a temperature T ₂ for fluorination. After reaching the temperature T ₂ , F ₂ gas having a concentration of 10% (in terms of ideal gas) mixed with Ar in advance was introduced. The treatment pressure was 90 kPa and held for 4 hours. The selection of the heat treatment temperatures T ₁ and T _{2 and} the selection of the respective holding times dominate the penetration ratio and the atomic diffusion. When complete nitrification proceeds, there is no position where fluorine atoms enter, and therefore fluorination does not occur. The heat treatment conditions need to be appropriately adjusted according to the shape of the parent phase alloy such as the grain size and the surface state of the grains. T ₁ is preferably 300 ° C. or higher, and T ₂ is preferably 300 ° C. or lower. In this example, T ₁ was selected to be 350 ° C., and T ₂ was selected to be 250 ° C. After holding, sufficient exhaust treatment was performed, and the furnace was cooled in an Ar atmosphere and released to the atmosphere at 40 ° C. or lower.

From detailed composition analysis by TOF-SIMS, C atoms and F atoms were detected from a region presumed to be the parent phase at the center of the crystal grains. During carbonization and fluorination, it is difficult to avoid some decomposition and generation of Sm and Fe due to non-uniformity of the Sm ₂ Fe ₁₇ phase. SmF ₃ , SmOF, Fe, FeF ₂ and FeF ₃ were present. O atoms are caused by moisture adhering to the outer periphery of the magnetic powder and oxidation during heat treatment, and are unavoidably mixed. Desirably, it is an atom to be excluded. By increasing the heat treatment time, carbonization and fluorination can proceed to the inside of the crystal grains. When the heat treatment time is short, C atoms and F atoms enter and diffuse from the outer periphery of the crystal grains, so that C atoms and F atoms inevitably have a concentration gradient from the grain boundary toward the parent phase center. Will have. Since the diffusion rate of F atoms is slower than that of C atoms, the concentration non-uniformity tends to be large in F atoms.

From the above results, Sm ₂ Fe ₁₇ C _α F _x can be synthesized by heat-treating Sm ₂ Fe ₁₇ using butane and fluorine gas, and an increase in the Curie temperature was confirmed. Besides increasing the Curie temperature, we observed an increase in magnetic moment and an improvement in magnetic anisotropy. Separately conducted with regard Sm ₃ Fe ₂₈ Ti, and NdFe ₁₁ Ti, it was observed almost the same tendency.

Since the measured magnetic powder had an average particle size of 10 μm, the coercive force was slight, but it is estimated that a significant coercive force is exhibited by grinding from about 2 μm to about 3 μm. In principle, it is desirable to pulverize to a single domain critical particle size (about 0.3 μm). However, since problems in process such as oxidation occur, it is desirable that the particle size is 1 μm or more. When nitrogen atoms and fluorine atoms enter Sm ₂ Fe ₁₇ , the magnetic anisotropy changes from in-plane anisotropy to uniaxial anisotropy, and has the potential as a permanent magnet material. This is because the 4f electron orbit responsible for the magnetism of Sm has a cigar shape, and the same effect is expected for Er and Tm. In other words, when the crystal field acting on the rare earth element is considered, in the chemical formula R ₂ (Fe, T) ₁₇ C _α F _x (1 ≦ α + x), the chemical formula R ₃ (Fe, T) ₂₉ C _β F _y (2 ≦ β + y) When the rare earth element R is Sm, Er, or Tm, uniaxial magnetic anisotropy is obtained. On the other hand, in the chemical formula R (Fe, T) ₁₂ C _γ F _z (0.5 ≦ γ + z), when the rare earth element R is Pr, Nd, Tb, Dy, uniaxial magnetic anisotropy is obtained.

Uniaxial magnetic anisotropy can be evaluated by the method described in Example 1. Α, β,
In order to experimentally obtain the values of γ, x, y, and z, the analysis method described in Example 1 can be used.

Example 4: Magnetic powder production (1) Formation of parent phase alloy:
In this example, magnetic powder obtained by pulverizing an SmFe-based ribbon obtained by quenching a mother alloy with a composition adjusted was used as the magnetic powder of the 4f transition element-3d transition element of the parent phase. The SmFe-based master alloy was mixed with Sm and Fe and dissolved in a vacuum or in an inert gas or reducing gas atmosphere to make the composition uniform (dissolution casting method). The obtained master alloy was coarsely pulverized in an inert gas using a ball mill so that the average particle diameter was about 10 μm.

(2) Hydrogenation treatment, nitrogenation treatment, and fluorination treatment:
In the present invention, heat treatment was performed at 250 ° C. for 24 hours using hydrogen fluoride gas or nitrogen trifluoride by the method described in Example 1 and Example 2.

Example 5: Chlorination Magnetic powder produced in Example 1 was used as magnetic powder. That is, magnetic powders of Sm ₂ Fe ₁₇ , Sm ₃ Fe ₂₈ Ti, and NdFe ₁₁ Ti produced by jet mill grinding were used.

The hydrogen chloride gas treatment was carried out in a gas flow format using a tubular furnace using ammonium chloride. In order to absorb the generated surplus gas, a trap mechanism was provided downstream of the reactor. The sample was spread out thinly on a glassy carbon (GC) boat. However, the material of the sample container can be used as long as it is resistant to hydrogen chloride in addition to carbon. A GC boat containing ammonium fluoride powder was disposed upstream and downstream. The amount of ammonium chloride charged depends on the size of the reaction space, the gas flow rate, the heat treatment temperature, and the heat treatment time. This time, a quartz tube having a radius of 28 mm and a length of 1200 mm was used, and 10 g of ammonium chloride was arranged upstream and downstream of 20 g of magnetic powder. After evacuating with a rotary pump, Ar was flowed at 200 ml / min. To heat the electric furnace. Heat treatment was performed at 250 ° C., 300 ° C., 350 ° C., 400 ° C., and 450 ° C. so that the reaction time was 24 hours. In selecting the heat treatment temperature, a low temperature at which the decomposition / oxidation reaction of Sm ₂ Fe ₁₇ is relatively small is desirable, but a temperature higher than 300 ° C. at which ammonium chloride is decomposed is selected. In addition, in the selection of the heat treatment time, due to the presence of hydrogen, chlorine atoms can be expected to diffuse sufficiently even in a short time. However, it greatly depends on the magnetic powder size, the crystal grain size, the surface state of the magnetic powder, the structure shape, and the like. It is expected that hydrogen chloride and chlorination will be accelerated if ammonium chloride and magnetic powder are mixed and placed on the GC boat, but the redox is too strong because the hydrogen fluoride source and magnetic powder are in direct contact. A diffusion reaction occurs, and the outer periphery of the magnetic powder is decomposed into rare earth chloride, rare earth acid chloride, iron chloride, iron and the like. It is necessary to select appropriately depending on the particle size of the magnetic powder to be used. At the time of mixing, vacuum substitution may be performed at the end of the heat treatment for the purpose of removing unreacted products. The sample was stored in a vacuum container in a polyethylene container because unreacted material may be attached. However, since the chlorinated magnetic powder is extremely stable at room temperature, it may be a glass bottle. Since this method is a solid-gas reaction, non-uniformity of the reaction becomes a problem. Therefore, it is desirable to introduce a fluidized bed or the like so that the reaction proceeds evenly.

磁 気 Magnetic properties were evaluated, and an increase in Curie temperature, an increase in magnetization, and an improvement in magnetic anisotropy were observed.

Example 6: Nanocoat treatment In this example, in order to suppress oxidation / decomposition of the mother phase during fluorination, a fluorination treatment was examined on the magnetic powder constructed around a thin fluoride film.

A processing solution for forming a rare earth fluoride or alkaline earth metal fluoride coating film was prepared as follows. In this example, PrF ₃ was used. After dissolving Pr acetate or Pr nitrate (4 g) in 100 ml of water, 90% of the equivalent amount required for PrF ₃ to form hydrofluoric acid diluted to 1% is gradually added with stirring. Gel-like PrF ₃ was produced. After removing the supernatant by centrifugation, add the same amount of methanol as the remaining gel, and repeat the agitation / centrifugation operation 3 to 10 times to remove the anion, and the almost transparent colloidal PrF ₃ methanol solution (Concentration: PrF ₃ / methanol = 1 g / 5 ml) was prepared.

The process of forming the rare earth fluoride or alkaline earth metal fluoride coating film on the magnetic powder was performed by the following method. The magnetic powder was produced by the same method as in Example 1. In this example, Sm ₂ Fe ₁₇ and Nd ₂ Fe ₁₇ phase magnetic powders were used. It grind | pulverized in the inert atmosphere using the jet mill until the average particle diameter of magnetic powder became 10 micrometers or less. 10 ml of PrF ₃ coat film forming solution was added to 100 g of magnetic powder having an average particle diameter of 10 μm, and mixed until it was confirmed that the entire magnetic powder was wet. The magnetic powder subjected to the PrF ₃ coating film formation treatment was subjected to methanol removal of the solvent under a reduced pressure of 2 to 5 torr. The magnetic powder from which the solvent had been removed was transferred to a quartz boat and heat-treated at 200 ° C. for 30 minutes and 350 ° C. for 30 minutes under a reduced pressure of 1 × 10 ⁻³ Pa. As a result, 2 wt% of PrF ₃ was treated with respect to the magnetic powder weight.

The magnetic powder having a PrF ₃ film formed thereon by the above method was hydrogenated, nitrogenated or carbonized, and fluorinated by the same method as in Examples 1 to 3. It was found that the reaction occurs uniformly by forming a film of PrF ₃ around the magnetic powder. We also observed signs that hydrogen with a small ion radius was preferentially taken into the magnetic powder. Details of the effect of the PrF ₃ film are unknown at present, but it is presumed that it contributes effectively for purposes such as reaction uniformity, atomic selective diffusion, and decomposition suppression.

Example 7: Change in particle size In Examples 1 to 3, since the chemical reaction proceeds by atomic diffusion generated from the outer periphery of the magnetic powder accompanying the solid-gas reaction, the crystal particle size is uniform in chemical reaction, that is, the element It greatly affects the uniformity of concentration distribution. In general, since diffusion is controlled by temperature and time, naturally, particle size control is necessary in mass production. However, even in the research stage, since the diffusion rate of F atoms in the Fe-based alloy is extremely slow, particle size control is a factor that cannot be ignored. Therefore, in this example, the particle size dependence of magnetic properties was examined. The magnetic powder was produced by the same method as in Example 1, and the particle size was adjusted using a jet mill and a ball mill. Classification was not performed, and the average particle size was evaluated using a laser diffraction particle size distribution analyzer. Although the dispersion was very large, magnetic powders having approximate average particle diameters of 100 μm, 50 μm, 25 μm, 10 μm, 5 μm, and 3 μm were prepared. As a result of fluorination of these with F ₂ gas, a uniform composition was obtained as the particle size decreased. However, the smaller the particle size, the greater the effect of oxidation, and the degree of oxidation inhibition greatly affects the uniformity of the composition. The composition evaluation can be performed by chemical analysis or various methods described in Example 1. In this example, since the uniformity of the composition appears in magnetism, the temperature dependence of magnetization was mainly evaluated. In this example, typical Sm ₂ Fe ₁₇ magnetic powder was prepared. Chemical formula R ₂ (Fe, T) ₁₇ , chemical formula R ₃ (Fe, T) ₂₉ , chemical formula R (Fe, T) ₁₂ (where R is 4f transition element or Y, and T is a 3d transition element other than Fe, or Al, Si, Ga, Mo, Nb, or W), there is a particle size dependence of chemical reaction and element concentration distribution.

Hereinafter, the displacement of Fe atoms when F atoms enter the crystal lattice will be described with reference to the drawings.

FIG. 13A is a perspective view schematically showing a position of an F atom that has entered a hexagonal crystal lattice having a Th ₂ Zn ₁₇ type structure.

In this figure, R is a 4f transition element or Y (the same applies to FIGS. 13B and 13C).

FIG. 13B is a perspective view schematically showing the position of an F atom that has entered the monoclinic crystal lattice having an Nd ₃ (Fe, Ti) ₂₉ type structure.

In this figure, T is a 3d transition element other than Fe, or Al, Si, Ga, Mo, Nb, or W (the same applies to FIG. 13C).

FIG. 13C is a perspective view schematically showing the position of an F atom that has entered a tetragonal crystal lattice having a ThMn ₁₂ type structure.

FIG. 14A is a (001) plane view schematically showing the displacement of Fe atoms when F atoms enter the hexagonal crystal lattice.

FIG. 14B is a (003) plane view schematically showing displacement of Fe atoms when F atoms enter the hexagonal crystal lattice.

14A and 14B, the elements constituting the crystal lattice are Sm, Fe, and F. In the figure, Fe is located at the apex of the hexagon.

When F atoms enter the crystal lattice, Fe atoms constituting the hexagon are displaced toward the center of the hexagon. Thereby, the density of states in the vicinity of the Fermi level of Fe decreases, and the localization of Fe increases. Also, the magnetization increases and the Curie temperature rises. Furthermore, magnetic anisotropy is improved by the strong electronegativity of F atoms.

Claims (16)

1. A binary alloy represented by the chemical formula R—Fe (wherein R is a 4f transition element or Y), or a chemical formula R—Fe—T (wherein R is as defined above, T is 3d transition elements other than Fe, or Al, Si, Ga, Mo, Nb or W. However, when T is W, R is a 4f transition element other than W or Y. A magnet material comprising an alloy, wherein the alloy contains an F atom and an N atom, an H atom or a C atom at an intrusion position in a crystal lattice.
2. The alloy is
   Chemical formula R ₂ Fe ₁₇ N _α F _x (0 <α <3 and 0 <x <3 and 0 <α + x ≦ 3),
   Chemical formula R ₃ (Fe, T) ₂₉ N _β F _y (0 <β <4 and 0 <y <4 and 0 <β + y ≦ 4) or chemical formula R (Fe, T) ₁₂ N _γ F _z (0 < γ <1, and 0 <z <1, and 0 <γ + z ≦ 1)
   The magnet material according to claim 1, wherein
3. The alloy is represented by the chemical formula R ₂ Fe ₁₇ N _α F _{x where} R is Sm, Er or Tm, 0 <α <3, 0 <x <3, and 1 ≦ α + x ≦ 3. The magnet material according to claim 2, wherein:
4. The alloy has the chemical formula R ₃ (Fe, T) ₂₉ N _β F _y (R is Sm, Er or Tm, 0 <β <4, 0 <y <4, and 2 ≦ β + y ≦ 4. The magnet material according to claim 2, which is represented by:
5. The alloy has the chemical formula R (Fe, T) ₁₂ N _γ F _z (R is Pr, Nd, Tb or Dy, 0 <γ <1, 0 <z <1, and 0.5 ≦ γ + z ≦ 1. The magnet material according to claim 2, wherein the magnet material is expressed by:
6. The alloy is
   Chemical formula R ₂ Fe ₁₇ H _α F _x (0 <α <5 and 0 <x ≦ 3 and 0 <α + x ≦ 5),
   Chemical formula R ₃ (Fe, T) ₂₉ H _β F _y (0 <β <6 and 0 <y ≦ 4 and 0 <β + y ≦ 6) or chemical formula R (Fe, T) ₁₂ H _γ F _z (0 < γ <1, and 0 <z <1, and 0 <γ + z ≦ 1)
   The magnet material according to claim 1, wherein
7. The alloy is represented by the chemical formula R ₂ Fe ₁₇ H _α F _{x, where} R is Sm, Er or Tm, 0 <α ≦ 4, 1 ≦ x ≦ 3, and 1 <α + x ≦ 5. The magnet material according to claim 6.
8. The alloy has the chemical formula R ₃ (Fe, T) ₂₉ H _β F _y (R is Sm, Er or Tm, 0 <β ≦ 4, 2 ≦ y ≦ 4, and 2 <β + y ≦ 6). The magnet material according to claim 6, which is represented by:
9. The alloy has the chemical formula R (Fe, T) ₁₂ H _γ F _z (R is Pr, Nd, Tb or Dy, 0 <γ ≦ 0.5, 0.5 ≦ z <1, and 0.5 The magnetic material according to claim 6, wherein <γ + z ≦ 1.
10. The alloy is
    Chemical formula R ₂ Fe ₁₇ C _α F _x (0 <α <3 and 0 <x <3 and 0 <α + x ≦ 3),
    Chemical formula R ₃ (Fe, T) ₂₉ C _β F _y (0 <β <4 and 0 <y <4 and 0 <β + y ≦ 4) or chemical formula R (Fe, T) ₁₂ C _γ F _z (0 < γ <1, and 0 <z <1, and 0 <γ + z ≦ 1)
    The magnet material according to claim 1, wherein
11. The alloy is represented by the chemical formula R ₂ Fe ₁₇ C _α F _{x, where} R is Sm, Er or Tm, 0 <α <3, 0 <x <3, and 1 ≦ α + x ≦ 3. The magnet material according to claim 10.
12. The alloy has the chemical formula R ₃ (Fe, T) ₂₉ C _β F _y (R is Sm, Er or Tm, 0 <β <4, 0 <y <4, and 2 ≦ β + y ≦ 4. The magnet material according to claim 10, which is represented by:
13. The alloy has the chemical formula R (Fe, T) ₁₂ C _γ F _z (R is Pr, Nd, Tb or Dy, 0 <γ <1, 0 <z <1, and 0.5 ≦ γ + z ≦ 1. The magnetic material according to claim 10, which is expressed by:
14. The alloy according to any one of claims 1 to 13, wherein the alloy further includes at least one selected from the group consisting of rare earth nitrides, rare earth fluorides, rare earth oxyfluorides, iron and iron fluorides. Magnet material.
15. A magnet molded product comprising the magnet material according to any one of claims 1 to 14 and a binder.
16. A rotating machine comprising a rotor including the magnet material according to any one of claims 1 to 14.

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