JPWO2017164312A1 - Rare earth permanent magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rare earth permanent magnet using La which is high in coercive force, inexpensive in resources and abundant compared with conventional SmFe12 and SmFe11Ti. A rare earth permanent magnet according to the present invention has a main phase and a grain boundary phase, and the main phase is an RT compound having a ThMn12 type crystal structure, R is essentially La, Y, Ce, One or more rare earth elements selected from Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, T is Fe, or Fe and Co, or part thereof is M (One or more selected from Ti, V, Cr, Mo, W, Zr, Hf, Nb, Ta, Al, Si, Cu, Zn, Ga and Ge), and the grain boundary phase is The La-rich phase σ has a cubic crystal structure, the La composition ratio is 20 at% or more, and the cross-sectional area ratio of the La-rich phase σ in the grain boundary phase is 20%. That's it. [Selection figure] None

Description

  The present invention relates to a rare earth permanent magnet including La in a part of R in a rare earth permanent magnet and having a high coercive force.

  Conventionally, an Nd—Fe—B permanent magnet described in Patent Document 1 is known as a high performance rare earth permanent magnet, and is currently widely used in consumer, industrial, transportation equipment and the like. In recent years, the consumption of Nd, which is a rare element, has increased due to the spread of HV, HEV, and the like, so a rare earth permanent magnet with a lower Nd content is required.

Non-Patent Documents 1 and 2 propose rare earth permanent magnets having a ThMn ₁₂ type crystal structure. These rare earth permanent magnets have a composition with reduced or no Nd, a high magnetization, and a higher magnetocrystalline anisotropy.

JP 59-46008 A

Journal of Applied Physics, 70, 6009, 1991 Journal of Alloys and Compounds 519, 144, 2012

However, the rare earth permanent magnets disclosed in Non-Patent Documents 1 and 2 do not have a practically sufficient coercive force. In SmFe ₁₁ Ti described in Non-Patent Document 2, the coercive force is a low value of about 0.4 MA / m.

The present invention has been made in view of such a situation, and in a rare earth permanent magnet whose main phase is an RT compound having a ThMn ₁₂ type crystal structure, by using resource-rich La, An object of the present invention is to provide a rare earth permanent magnet having a higher coercive force than before without significantly reducing the magnetization.

In order to solve the above-described problems and achieve the object, the rare earth permanent magnet of the present invention is an RT compound having a main phase and a grain boundary phase, and the main phase has a ThMn ₁₂ type crystal structure, R is essential La, one or more rare earth elements selected from Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, T is Fe, Or Fe and Co, or a part thereof is M (one or more selected from Ti, V, Cr, Mo, W, Zr, Hf, Nb, Ta, Al, Si, Cu, Zn, Ga and Ge). The grain boundary phase has a La-rich phase σ, the La-rich phase σ is a cubic crystal structure, the La composition ratio is 20 at% or more, and occupies the grain boundary phase The cross-sectional area ratio of the La rich phase σ is 20% or more. To do.

  About the mechanism which expresses a coercive force higher than before, the present inventors guess as follows. Generally, it is known as a combination in which a rare earth element and a transition metal element easily react to form a compound. However, a combination of La and a transition metal element has a very low reactivity compared to other rare earth elements. Therefore, since the grain boundary phase containing La as a main component is difficult to form a compound with Fe or Co, which is a magnetic element, and easily forms a nonmagnetic phase, the nonmagnetic grain boundary phase between the main phases is magnetically magnetic between the main phases. It is expected to promote separation and develop a high coercive force. However, there have been no reports suggesting this effect so far. The reason for this is that La at room temperature has a hexagonal crystal structure and a large interfacial strain with the tetragonal main phase, which may reduce the magnetic properties of the main phase. On the other hand, at a high temperature of about 300 ° C. or higher, La has a cubic crystal structure. Therefore, the present inventors realized a La grain boundary phase having a cubic crystal structure at room temperature, and reduced the interface strain between the grain boundary phase and the tetragonal main phase, thereby increasing the rare earth permanent magnet. It was found that coercive force was developed.

The rare earth permanent magnet of the present invention has an RT compound having a ThMn ₁₂ type crystal structure as a main phase and uses abundant La, so that the coercive force is higher than before without significantly lowering the magnetization. Is obtained.

  A mode (embodiment) for carrying out the present invention will be described in detail. The present invention is not limited by the contents described in the following embodiments. The constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the constituent elements described below can be appropriately combined.

In the rare earth permanent magnet according to the present embodiment, the main phase is an RT compound having a ThMn ₁₂ type crystal structure. R is essentially La, and is one or more rare earth elements selected from Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. The amount of R is preferably 4.2 at% or more and 25.0 at% or less. When the amount of R is less than 4.2 at%, the main phase is not sufficiently generated, α-Fe or the like having soft magnetism is precipitated, and the coercive force is remarkably lowered. On the other hand, when R exceeds 25.0 at%, the volume ratio of the main phase decreases and the saturation magnetic flux density decreases. By setting it as this range, a saturation magnetic flux density can be improved.

In the rare earth permanent magnet according to the present embodiment, T is Fe, Fe and Co, or part thereof is M (Ti, V, Cr, Mo, W, Zr, Hf, Nb, Ta, Al, Si, Cu, An element substituted with one or more selected from Zn, Ga, and Ge. The amount of Co is preferably greater than 0 at% and less than or equal to 50.0 at% relative to the total amount of T. The saturation magnetic flux density can be improved by adding an appropriate amount of Co. Further, the corrosion resistance of the rare earth permanent magnet can be improved by increasing the amount of Co. The amount of M is preferably 0.4 at% or more and 25.0 at% or less with respect to the total amount of T. When M is less than 0.4 at% with respect to the total amount of T, soft magnetic R ₂ Fe ₁₇ or α-Fe precipitates and the volume ratio of the main phase decreases, and when it exceeds 25.0 at%, the saturation magnetic flux density is remarkably increased. descend.

  In the rare earth permanent magnet according to the present embodiment, a La rich phase σ exists in the grain boundary phase. In the case of a combination of La and a transition metal element, the reactivity is very low compared to other rare earth elements. Therefore, the La-rich phase σ containing La as a main component is less likely to form a compound with Fe or Co, which are magnetic elements, and tends to be a nonmagnetic phase. Therefore, it is expected that the nonmagnetic grain boundary phase promotes magnetic separation between the main phases and develops a high coercive force. The La rich phase σ may contain elements such as Fe and Ti in addition to La. Even when a magnetic element such as Fe is contained, the original magnetic characteristics are reduced by becoming a La solid solution, so that magnetic separation between main phases can be promoted. For this reason, the La-rich phase σ only needs to have a La composition ratio of 20 at% or more. When the La composition ratio of the La-rich phase σ is 20 at% or more, the magnetic separation effect is increased and the coercive force is increased.

  In the rare earth permanent magnet according to the present embodiment, the La rich phase σ has a cubic crystal structure. La at room temperature has a hexagonal crystal structure and a large interfacial strain with the tetragonal main phase, which may reduce the magnetic properties of the main phase. On the other hand, at a high temperature of about 300 ° C. or higher, La has a cubic crystal structure. Therefore, the present inventors realized a La grain boundary phase having a cubic crystal structure at room temperature, and reduced the interface strain between the grain boundary phase and the tetragonal main phase, thereby increasing the rare earth permanent magnet. It was found that coercive force was developed.

  In the rare earth permanent magnet according to the present embodiment, the grain boundary phase other than the La-rich phase σ includes an existing R-rich phase, an α-Fe phase, a hexagonal La phase, and the like. The cross-sectional area ratio of the La-rich phase σ occupying the grain boundary phase (portion other than the main phase) is 20% or more, preferably 21% or more, and further 24% or more, 25% or more, 54% or more, 91 % Or more is more preferable. By setting the cross-sectional area ratio of the La-rich phase σ in the grain boundary phase to 20% or more, a magnetic separation effect between the main phases and an interface strain reduction effect between the grain boundary phase and the main phase can be obtained, and the coercive force Will improve. The La rich phase σ is preferably distributed uniformly in the grain boundary phase. The ratio of the La rich phase σ in the whole grain boundary phase is preferably high.

  In the rare earth permanent magnet according to the present embodiment, it is preferable to include an intrusion element X, where X is one or more elements selected from N, H, Be and C. The amount of X is preferably 0.0 at% or more and 14.0 at% or less. The coercive force can be improved by X entering the crystal lattice of the main phase. This is because the magnetocrystalline anisotropy is improved by the intruding elements.

  The rare earth permanent magnet according to the present embodiment allows the inclusion of other elements. For example, elements such as Bi, Sn, and Ag can be appropriately contained. Moreover, you may contain the impurity originating in a raw material.

  Hereinafter, preferred examples of the production method of the present invention will be described. Examples of the method for producing a rare earth permanent magnet include physical film formation methods such as sputtering and laser deposition. An example of a production method by sputtering will be described.

  First, a single element target material is prepared as a material. The rare earth thin film permanent magnet is prepared by adjusting the sputtering power of each single element target so as to obtain a desired composition ratio. Alternatively, R, T, and X alloy target materials can be prepared and sputtered. Here, the composition ratio of the alloy target material and the composition ratio of the thin film produced by sputtering may be shifted because the sputtering rates of the respective elements are different, and adjustment is necessary. Similarly, when other elements such as Bi, Sn, Ag and the like are appropriately contained, they can be contained by both methods of a single element target material and an alloy target material. On the other hand, since it is desirable to reduce impurity elements such as oxygen as much as possible, the impurity content in the target material is also reduced as much as possible.

  The target material oxidizes from the surface during storage. In particular, the rare earth target material has a high oxidation rate. Therefore, before using these target materials, it is necessary to perform sputtering sufficiently to bring out the clean surface of the target material.

  As the substrate on which the film is formed by sputtering, various metals, glass, silicon, ceramics, and the like can be selected and used. However, in order to obtain a desired crystal structure, it is desirable to select a substrate having a high melting point because it is necessary to perform processing at a high temperature. In addition to the resistance to high temperature treatment, the adhesion with rare earth thin film permanent magnets may be insufficient, and as a countermeasure, the adhesion can be improved by providing a base film such as Cr, Ti, Ta, or Mo. Usually done. A protective film such as Ti, Ta, or Mo can be provided on the rare earth thin film permanent magnet to prevent oxidation.

Since it is desirable that a film formation apparatus that performs sputtering reduces impurity elements such as oxygen, nitrogen, and carbon as much as possible, the inside of the vacuum chamber is evacuated to 10 ⁻⁶ Pa or less, more preferably 10 ⁻⁸ Pa or less. It is desirable. In order to maintain a high vacuum state, it is desirable to have a substrate introduction chamber connected to the film formation chamber. In addition, since it is necessary to perform sputtering sufficiently to bring out a clean surface of the target material before using the target material, the film forming apparatus is a shield that can be operated in a vacuum state between the substrate and the target material. It is desirable to have a mechanism. The sputtering method is preferably a magnetron sputtering method that enables sputtering in a lower-pressure Ar atmosphere for the purpose of reducing impurity elements as much as possible. Here, since the target material containing Fe and Co greatly reduces the leakage magnetic flux of magnetron sputtering and makes sputtering difficult, it is necessary to select the thickness of the target material appropriately. As the power source for sputtering, either DC or RF can be used, and can be appropriately selected depending on the target material.

  It is possible to control the amount of La in the grain boundary phase by adjusting the R ratio of the charged composition. In order to obtain a thin film having a desired composition, sputtering is performed by adjusting the film formation rate and the film formation time. When sputtering using a plurality of target materials, either multi-source simultaneous sputtering or stacked sputtering in which each target is sputtered alternately independently may be selected.

  It is necessary to perform heat treatment after the magnetic layer is formed. The atmosphere is a vacuum or Ar atmosphere, the temperature is raised in the range of 300 ° C./min to 1200 ° C./min, held at 300 ° C. to 1200 ° C. for 1 hour to 24 hours, and then 300 ° C./min to 1000 ° C./min. Cool quickly. When heat treatment is performed for a long time after the magnetic layer is formed, La is uniformly diffused into the grain boundary phase, and further, the cubic crystal structure is maintained by rapid cooling. That is, by performing this heat treatment, formation of the La rich phase σ is realized and the coercive force is improved.

  Although it may be used as a rare earth thin film magnet as it is, it can be a rare earth bonded magnet or a rare earth sintered magnet. Hereinafter, the manufacturing method will be described.

An example of a method for producing a rare earth bonded magnet will be described. First, a rare earth thin film magnet having a main phase of a ThMn ₁₂ type RT compound prepared by sputtering is peeled off from a substrate and pulverized to form a powder. Thereafter, the resin binder containing the resin and the present powder are kneaded by a pressure kneader such as a pressure kneader, and the rare earth bond containing the resin binder and the permanent magnet powder having the ThMn ₁₂ type RT compound as the main phase. A magnet compound (composition) is prepared. Resins include thermosetting resins such as epoxy resins and phenol resins, styrene, olefin, urethane, polyester and polyamide elastomers, ionomers, ethylene propylene copolymer (EPM), ethylene-ethyl acrylate copolymer There are thermoplastic resins such as coalescence. Among them, the resin used for compression molding is preferably a thermosetting resin, and more preferably an epoxy resin or a phenol resin. The resin used for injection molding is preferably a thermoplastic resin. Moreover, you may add a coupling agent and another additive to the compound for rare earth bond magnets as needed.

Further, the content ratio of the rare earth permanent magnet powder having the main phase of the ThMn ₁₂ type RT compound and the resin in the rare earth bonded magnet to the resin is 100% by mass, for example, 0.5% by mass to 20% by mass of the resin. % Or less is preferable. If the resin content is less than 0.5% by mass relative to 100% by mass of the rare earth permanent magnet powder, the shape retention tends to be impaired. If the resin exceeds 20% by mass, sufficiently excellent magnetic properties are obtained. It tends to be difficult to obtain characteristics.

After preparing the rare earth bonded magnet compound described above, the rare earth bonded magnet containing the rare earth permanent magnet powder and the resin having the main phase of ThMn ₁₂ type RT compound is formed by injection molding the rare earth bonded magnet compound. Can be obtained. When producing a rare earth bonded magnet by injection molding, the rare earth bonded magnet compound is heated to the melting temperature of the binder (thermoplastic resin) as necessary to obtain a fluid state, and then the rare earth bonded magnet compound is Molding is performed by injection into a mold having a shape. Then, it cools and takes out the molded article (rare earth bond magnet) which has a predetermined shape from a metal mold | die. In this way, a rare earth bonded magnet is obtained. The manufacturing method of the rare earth bonded magnet is not limited to the above-described method by injection molding. For example, the rare earth permanent magnet powder whose main phase is a ThMn ₁₂ type RT compound by compression molding a compound for rare earth bonded magnet. And a rare earth bonded magnet containing resin. When producing a rare earth bonded magnet by compression molding, after preparing the above-mentioned rare earth bonded magnet compound, the rare earth bonded magnet compound is filled into a mold having a predetermined shape, and pressure is applied to the predetermined bond from the mold. A molded product having a shape (rare earth bonded magnet) is taken out. When a compound for a rare earth bonded magnet is formed and taken out by a mold, it is performed using a compression molding machine such as a mechanical press or a hydraulic press. Then, a rare earth bond magnet is obtained by putting in a furnace such as a heating furnace or a vacuum drying furnace and curing by applying heat.

  The shape of the rare earth bonded magnet obtained by molding is not particularly limited, and changes according to the shape of the rare earth bonded magnet, for example, a flat plate shape, a columnar shape, or a cross-sectional shape depending on the shape of the mold to be used. can do. In addition, the obtained rare earth bonded magnet may be plated or painted on the surface in order to prevent deterioration of the oxide layer, the resin layer, and the like.

  When the compound for rare earth bonded magnet is molded into a desired predetermined shape, a molded body obtained by molding by applying a magnetic field may be oriented in a certain direction. Thereby, since the rare earth bonded magnet is oriented in a specific direction, an anisotropic rare earth bonded magnet having stronger magnetism can be obtained.

An example of a method for producing a rare earth sintered magnet will be described. Similarly to the rare-earth bonded magnet, a rare-earth permanent magnet powder whose main phase is a ThMn ₁₂ type RT compound is produced and formed into a desired predetermined shape by, for example, press molding. The shape of the obtained molded body is not particularly limited, and can be changed according to the shape of the rare earth sintered magnet, such as a flat plate shape, a columnar shape, or a cross-sectional shape such as a ring shape, depending on the shape of the mold to be used. it can.

  Next, the molded body is subjected to a sintering process. The sintering holding temperature and sintering holding time need to be adjusted according to various conditions such as composition, pulverization method, difference in average particle size and particle size distribution, sintering method, and the like. Thereby, a sintered body (rare earth sintered magnet) is obtained.

  The obtained rare earth sintered magnet may be a rare earth sintered magnet having a predetermined shape by cutting into a desired size or smoothing the surface. In addition, the obtained rare earth sintered magnet may be plated or painted on the surface in order to prevent deterioration of the oxide layer, the resin layer, and the like.

Further, when a rare earth permanent magnet powder having a main phase of ThMn ₁₂ type RT compound is molded into a predetermined shape, a molded body obtained by molding by applying a magnetic field is oriented in a certain direction. Also good. Thereby, since the rare earth sintered magnet is oriented in a specific direction, an anisotropic rare earth sintered magnet having stronger magnetism can be obtained.

As mentioned above, although the form regarding the manufacturing method for implementing this invention suitably was demonstrated, next, in the rare earth permanent magnet which uses the ThMn ₁₂ type RT compound of this invention as a main phase, a composition of a main phase and a grain boundary phase A method for analyzing the crystal structure and the cross-sectional area ratio of the La-rich phase σ in the grain boundary phase will be described.

The composition of a rare earth permanent magnet whose main phase is a ThMn ₁₂ phase can be determined by ICP mass spectrometry (ICP: Inductively Coupled Plasma Mass Spectrometry). Here, the desired composition is confirmed. .

About the crystal structure of the main phase of the rare earth permanent magnet which is a sample, it is confirmed by X-ray diffractometry (XRD) that the main generated phase is attributed to the ThMn ₁₂ type crystal structure.

  The composition of the main phase is measured by energy dispersive X-ray spectroscopy (EDS: Energy Dispersive Spectroscopy). Specifically, an EDS apparatus provided with a scanning transmission electron microscope (STEM) by processing a rare earth permanent magnet into a thin piece having a thickness of 100 nm using a focused ion beam (FIB) apparatus. Is used to obtain an element mapping image, and the composition of the main phase is quantified based on the element mapping image. If there is an element that is difficult to detect with an EDS apparatus, it is supplemented by using an infrared absorption method or mass spectrometry. Here, it is confirmed that the main phase has a desired composition.

  Similar to the main phase, the composition of the grain boundary phase is measured by an EDS apparatus. After extracting La of the grain boundary phase using the element mapping image obtained by the EDS apparatus, the composition is quantified.

  The crystal structure of the grain boundary phase is judged by electron diffraction. An electron diffraction analysis is performed on a region where the La composition ratio of the grain boundary phase confirmed by the element mapping image is 20 at% or more, and the crystal structure is determined. A region where the La composition ratio is 20 at% or more and the crystal structure is cubic is defined as a La-rich phase σ.

  The cross-sectional area ratio of the La-rich phase σ occupying the grain boundary phase is a ratio between the cross-sectional area of the La-rich phase σ calculated from the element mapping image and the cross-sectional area of the entire grain boundary phase.

  The magnetic characteristics are measured by applying a magnetic field of ± 3100 kA / m in a direction perpendicular to the substrate using a vibrating sample magnetometer (VSM).

  Hereinafter, although the content of the present invention is explained in detail using an example and a comparative example, the present invention is not limited to the following examples.

As the film forming apparatus, an apparatus capable of exhausting to 10 ⁻⁸ Pa or less and having a plurality of sputtering mechanisms in the same tank was used. In this film forming apparatus, Sm, Er, Nd, La, Fe, Ti, Co, Mo, Nb single-element target materials, and Mo target materials used for the base film and protective film, depending on the configuration of the sample to be produced Installed. Sputtering was performed using a magnetron sputtering method to form an Ar atmosphere of 1 Pa, and RF and DC power supplies were used. The power of the RF and DC power sources and the film formation time were adjusted according to the sample configuration. The sputtering conditions were adjusted so that the main phase was (R ′ _1-x La _x ) T ₁₁ M. Specifically, R ′ is Sm, Er, or Nd, T is Fe, Fe, or Co, and M is Ti, Mo, or Nb so that the compositions shown in Tables 1 to 3 are obtained. The target material size is 3 inches, the substrate is a 10 mm × 10 mm Si substrate with a thermal oxide film, and sputtering is performed while rotating the substrate with a rotating mechanism of the sputtering apparatus so that the in-plane uniformity of the film is sufficiently maintained. It was.

As for the film configuration, first, Mo was deposited to a thickness of 50 nm at 200 ° C. as a base film. Next, Sm, Er, and Nd are selected as R ′, Fe is selected as T, Fe and Co are selected as Ti, Ti, Mo, or Nb is selected as M, and (R ′, La) The charge composition ratio of Sm, Er, Nd, and La was adjusted according to the examples and comparative examples described in Tables 1 to 3 with _15.3 T _78.4 M _6.3 . The Si substrate with a thermal oxide film was heated to 500 ° C., and the film was formed with a magnetic layer thickness of 1000 nm. The film was heated at 900 ° C./min in an Ar atmosphere after the magnetic layer was formed. And it heat-cooled at 500 degreeC / min-800 degreeC / min after heat processing at 900 degreeC for 10 hours. This is defined as heat treatment method A.

  On the other hand, the magnetic layer was formed under the same conditions as described above, and heat treatment was performed after the magnetic layer was formed. The heat treatment was performed under the same conditions as heat treatment method A, except that the heat treatment time was 10 minutes and cooling at 100 ° C./min. This is defined as heat treatment method B.

  A sample in which the Mo underlayer film and the magnetic layer are formed by the above-described film formation method, and then the heat treatment is not performed, and the Mo protective layer is formed by the method described later is not heat-treated.

  In order to prevent oxidation after heat treatment or after the magnetic layer was formed, Mo was again formed as a protective film at 200 ° C. to a thickness of 50 nm. Then, after cooling to room temperature in vacuum, it was taken out from the film forming apparatus.

  When heat treatment is performed for a long time after the magnetic layer is formed, La is uniformly diffused into the grain boundary phase, and further, the cubic crystal structure is maintained by rapid cooling. That is, by performing the heat treatment method A, the formation of the La rich phase σ is realized and the coercive force is improved. On the other hand, in the heat treatment method B, the coercive force is not improved because the heat treatment time and the cooling time are insufficient. Similarly, the coercive force is not improved even without heat treatment.

The prepared sample was confirmed to have a desired composition by ICP mass spectrometry, and it was confirmed by XRD that the main product phase was attributed to the ThMn ₁₂ crystal structure.

  A method for determining the main phase and the La-rich phase σ and calculating the cross-sectional area ratio will be described. With STEM-EDS, 20 locations were measured at 300 μm intervals in a 200 nm × 200 nm field of view. Elemental mapping of R ′, La, T, and M and electron beam diffraction were performed to determine the main phase, La-rich phase σ, and other grain boundary phases. The main phase was judged using an EDS apparatus because the ratio of rare earth elements to T + M elements was approximately 1:12. Also, a region where the La composition ratio is 20 at% or more and the T element ratio is less than the T element ratio of the main phase between the main phases or triple points is extracted, and the crystal structure of the region is cubic by electron diffraction. When it was a system, it was judged to be a La rich phase σ. Furthermore, the cross-sectional area of the La rich phase σ in the visual field was integrated, and the ratio with the cross-sectional area of the grain boundary phase (portion other than the main phase) was calculated. The results are listed in Table 1.

Thereafter, magnetic hysteresis was measured by applying a magnetic field of ± 3100 kA / m in the direction perpendicular to the film surface using VSM. The magnetic flux density was confirmed to be within a range of ± 5% when +2400 kA / m and +3100 kA / m were applied, and the value when +3100 kA / m was applied was defined as the saturation magnetic flux density. Table 1 shows the saturation magnetic flux density and coercivity measured in this manner.

Example 1
As shown in Table 1, Sm is selected for R ′ and Ti is selected for M so that the composition of the main phase is (R ′ _1-x La _x ) Fe ₁₁ M. A Sm _0.9 La _0.1 ) Fe ₁₁ Ti ThMn ₁₂ crystal structure thin film permanent magnet was obtained. The obtained thin film permanent magnet was evaluated by the evaluation method described above. The results are shown in Table 1.

(Example 2)
A thin film permanent magnet was produced in the same manner as in Example 1 except that (Sm _0.7 La _0.3 ) Fe ₁₁ Ti was used. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 3)
A thin film permanent magnet was produced in the same manner as in Example 1 except that (Sm _0.5 La _0.5 ) Fe ₁₁ Ti was used. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 4)
A thin film permanent magnet was produced in the same manner as in Example 1 except that Er was selected as R ′ and (Er _0.9 La _0.1 ) Fe ₁₁ Ti was used. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 5)
A thin film permanent magnet was prepared in the same manner as in Example 1 except that Mo was selected as M and (Sm _0.9 La _0.1 ) Fe ₁₁ Mo was used. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 6)
A thin film permanent magnet was produced in the same manner as in Example 1 except that Fe and Co were selected as T and (Sm _0.9 La _0.1 ) Fe ₁₀ CoTi was used. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 1)
An SmFe ₁₁ Ti thin film permanent magnet was produced in the same manner as in Example 1. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 2)
A thin film permanent magnet of (Sm _0.95 La _0.05 ) Fe ₁₁ Ti was produced in the same manner as in Example 1. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 3)
A thin film permanent magnet of (Sm _0.9 La _0.1 ) Fe ₁₁ Ti was produced in the same manner as in Example 1 except that heat treatment was performed by heat treatment method B. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 4)
A thin film permanent magnet was produced in the same manner as in Example 1 except that (Sm _0.9 La _0.1 ) Fe ₁₁ Ti was used and heat treatment was not performed. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

Further, when the intruding element X is N, nitriding can be performed at a stage after the heat treatments A and B. The thin film permanent magnet was nitrided at 500 ° C. for 24 hours in nitrogen gas at 1 atm. By setting N ′ as R ′ and N as an intruding element, a higher saturation magnetic flux density could be obtained. The results are shown in Table 2.

(Example 7)
A thin film permanent magnet is formed in the same manner as in Example 1 except that R ′ is Nd and N is intruded as an intruding element by the above method to obtain (Nd _0.9 La _0.1 ) Fe ₁₁ TiN _1.5. Produced. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 2.

(Example 8)
A thin film permanent magnet was prepared in the same manner as in Example 7 except that (Nd _0.5 La _0.5 ) Fe ₁₁ TiN _1.5 was used. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 2.

Example 9
A thin film permanent magnet was produced in the same manner as in Example 7 except that Fe and Co were selected as T and (Nd _0.9 La _0.1 ) Fe ₁₀ CoTiN _1.5 was used. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 2.

(Comparative Example 5)
An NdFe ₁₁ TiN _1.5 thin film permanent magnet was produced in the same manner as in Comparative Example 1 by making R ′ Nd and N as an intruding element by the above method. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 2.

(Comparative Example 6)
A thin film permanent magnet was prepared in the same manner as in Comparative Example 2 except that R ′ was Nd and N was invaded by the above method to form (Nd _0.95 La _0.05 ) Fe ₁₁ TiN _1.5. Produced. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 2.

(Comparative Example 7)
A thin film permanent magnet was prepared in the same manner as in Comparative Example 3 except that R ′ was Nd, and N was invaded as the intruding element by the above method to obtain (Nd _0.9 La _0.1 ) Fe ₁₁ TiN _1.5. Produced. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 2.

(Comparative Example 8)
A thin film permanent magnet was produced in the same manner as in Comparative Example 4 except that (Nd _0.9 La _0.1 ) Fe ₁₁ TiN _1.5 was used. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 2.

Furthermore, even when the R amount and M amount of the charged composition were changed, high magnetic properties were obtained. Even when M = Nb, a ThMn ₁₂ crystal structure was obtained, and high magnetic properties could be obtained. The results are shown in Table 3.

(Example 10)
Other than selecting Ti as M, charging composition to (R ′, La) _9.7 T _84.2 M _6.1, and main phase composition to (Sm _0.9 La _0.1 ) Fe ₁₁ Ti Produced a thin film permanent magnet in the same manner as in Example 1. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 3.

(Example 11)
Ti is selected for M, and the charged composition is (R ′, La) _15.3 T _80.4 M _4.3 , and the main phase composition is (Sm _0.9 La _0.1 ) Fe _11.5 Ti _{0 A} thin film permanent magnet was produced in the same manner as in Example 1 except that the _thickness was set to _.5 . Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 3.

(Example 12)
A thin film permanent magnet was produced in the same manner as in Example 10 except that Nb was selected as M and (Sm _0.9 La _0.1 ) Fe ₁₁ Nb was used. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 3.

(Example 13)
A thin film permanent magnet was produced in the same manner as in Example 11 except that Nb was selected as M and (Sm _0.9 La _0.1 ) Fe _11.5 Nb _0.5 was used. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 3.

Furthermore, even when the heat treatment time of the heat treatment method A was set to a short time on the basis of Example 1, the La composition ratio of the La rich phase σ was 20 at% or more, and the result that the magnetic characteristics were improved was obtained. . The results are shown in Table 4. Table 4 shows saturation magnetic flux density (mT), coercive force HcJ (kA / m), La composition ratio of La-rich phase σ, cross-sectional area ratio of La-rich phase σ in the grain boundary phase, and heat treatment time (hours). Show.

(Example 14)
A thin film permanent magnet similar to that of Example 1 was prepared and heat treatment similar to heat treatment time A was performed except that the heat treatment time was 3 hours. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 4.

(Comparative Example 9)
A thin film permanent magnet similar to that of Example 1 was prepared, and a heat treatment similar to the heat treatment time A was performed except that the heat treatment time was 15 minutes. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 4.

(Examples 1-3, Comparative Examples 1-4)
As the cross-sectional area ratio of the La-rich phase σ occupying the grain boundary phase increased, it was confirmed that the coercive force was improved.

(Examples 4 to 6)
It was confirmed that the same result as Sm was obtained when R ′ was changed to Er. It was also confirmed that the same result as Ti was obtained when M was Mo. It was confirmed that the same results as Fe were obtained when T was changed to Fe and Co.

(Examples 10, 11, 12, 13)
Even when the amount of R was reduced, the amount of M was reduced, and M was Nb, the coercive force did not change much and a high saturation magnetic flux density was obtained.

(Examples 7-9, Comparative Examples 5-8)
Even when N was intruded as an intruding element, the same results as in Examples 1 to 6 were obtained.

(Example 14)
By changing the heat treatment time of the heat treatment method A, the La composition ratio of the La-rich phase σ can be adjusted, and the effect of improving the coercive force was obtained.

(Comparative Example 9)
By changing the heat treatment time of the heat treatment method A, the La composition ratio of the grain boundary phase becomes 20 at% or less, so that the magnetic separation effect is low and the coercive force is low.

Claims (2)

Having a main phase and a grain boundary phase;
The main phase is an RT compound having a ThMn ₁₂ type crystal structure;
R is essential La, and is one or more rare earth elements selected from Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu,
T is selected from Fe, or Fe and Co, or a part thereof from M (Ti, V, Cr, Mo, W, Zr, Hf, Nb, Ta, Al, Si, Cu, Zn, Ga and Ge One or more elements),
The grain boundary phase has a La rich phase σ,
The La-rich phase σ has a cubic crystal structure with a La composition ratio of 20 at% or more,
A rare earth permanent magnet having a cross-sectional area ratio of the La-rich phase σ in the grain boundary phase of 20% or more.   The rare earth permanent magnet according to claim 1, wherein the main phase further contains an intruding element X (X is one or more elements selected from N, H, Be, and C).