WO2016104117A1 - Rare earth thin film magnet and method for manufacturing same - Google Patents

Rare earth thin film magnet and method for manufacturing same Download PDF

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WO2016104117A1
WO2016104117A1 PCT/JP2015/084232 JP2015084232W WO2016104117A1 WO 2016104117 A1 WO2016104117 A1 WO 2016104117A1 JP 2015084232 W JP2015084232 W JP 2015084232W WO 2016104117 A1 WO2016104117 A1 WO 2016104117A1
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phase
thin film
layer
rare earth
earth thin
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PCT/JP2015/084232
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French (fr)
Japanese (ja)
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正基 中野
博俊 福永
武志 柳井
広信 澤渡
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Ｊｘ金属株式会社
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
    • C23C14/14—Metallic material, boron or silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F10/00—Thin magnetic films, e.g. of one-domain structure
    • H01F10/08—Thin magnetic films, e.g. of one-domain structure characterised by magnetic layers
    • H01F10/10—Thin magnetic films, e.g. of one-domain structure characterised by magnetic layers characterised by the composition
    • H01F10/12—Thin magnetic films, e.g. of one-domain structure characterised by magnetic layers characterised by the composition being metals or alloys
    • H01F10/14—Thin magnetic films, e.g. of one-domain structure characterised by magnetic layers characterised by the composition being metals or alloys containing iron or nickel
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/14—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for applying magnetic films to substrates
    • H01F41/20—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for applying magnetic films to substrates by evaporation
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys

Definitions

  • the present invention relates to a rare earth thin film magnet made of a Pr—Fe—B film made on a substrate of Ta or the like and a Pr—Fe—B film rare earth thin film magnet formed by the pulse laser deposition method (PLD method). Regarding the method.
  • PLD method pulse laser deposition method
  • Nd-Fe-B magnets have a relatively high maximum energy product, energy fields such as MEMS (Micro Electro Mechanical Systems) and energy harvest (energy harvesting), and medical equipment Application to fields is expected.
  • MEMS Micro Electro Mechanical Systems
  • energy harvest energy harvesting
  • Non-Patent Literature Physical Vapor Deposition
  • Patent Document 2 has an excellent composition transfer property between a target and a film by a laser ablation method using a pulsed YAG laser, and Nd is higher in film formation speed by one digit or more than a sputtering method. It is described that an Nd—Fe—B-based thin film mainly composed of 2 Fe 14 B phase can be obtained.
  • Non-Patent Document 4 It has been reported that a magnet of a rare-earth thin film manufactured by such a method has values of coercive force: about 1000 kA / m, remanent magnetization: 0.6 T, and maximum energy product (BH) max : 60 kJ / m 3 .
  • Non-Patent Document 4 the remanent magnetization and the maximum energy product are still not practical magnetic properties, and are not sufficient to drive small motors, for example, so there is a strong demand for further improvement of magnetic properties. ing.
  • Non-Patent Document 5 describes that the Pr 2 Fe 14 B phase has a larger anisotropic magnetic field than the Nd 2 Fe 14 B phase in the Pr—Fe—B system magnet and contributes to the improvement of the coercive force. .
  • This is an excellent technique for improving thermal stability, but from the viewpoint of the amount of magnetic flux generated outside, the saturation magnetization of the Pr 2 Fe 14 B phase is smaller than that of the Nd 2 Fe 14 B phase, and as a result, residual magnetization is reduced. There is a problem of becoming smaller.
  • the present invention relates to a rare earth thin film magnet of Pr—Fe—B film formed on a substrate of Ta or the like, in particular, a rare earth thin film magnet of Pr—Fe—B film having excellent magnetic properties. It is an object to form a film.
  • the present inventors have conducted intensive research. As a result, by optimizing the composition of the Pr—Fe—B film and the film formation conditions of the pulse laser deposition method, excellent magnetic properties can be obtained. It was found that a Pr—Fe—B rare earth thin film having characteristics can be formed.
  • a rare-earth thin film magnet containing Pr, Fe, and B as essential components comprising a first layer comprising a Pr phase and an ⁇ -Fe phase on a substrate, and the Pr—Fe—B on the first layer.
  • a second layer composed of a phase
  • a third layer composed of an ⁇ -Fe phase on the second layer
  • a third layer composed of a Pr—Fe—B phase and an ⁇ -Fe phase on the third layer.
  • a rare-earth thin film magnet comprising four layers.
  • the rare earth thin-film magnet according to any one of 7) The rare earth thin film magnet according to any one of 1) to 6) above, wherein the composition of the Pr—Fe—B phase in the fourth layer is Pr 2 Fe 14 B. 8)
  • the crystal grain size near the interface of the ⁇ -Fe phase in the fourth layer is 30 nm to 50 nm, and the crystal grain size near the surface is 40 nm to 80 nm.
  • the maximum energy product (BH) max is 80 kJ / m 3 or more.
  • the present invention also provides the following means. 13) A method for producing the rare earth thin film magnet according to any one of 1) to 12) above, wherein the rare earth thin film is formed by a pulse laser deposition method, and the formed rare earth thin film is heat-treated to form a crystal. And a step of magnetizing a crystallized rare earth thin film to produce a rare earth thin film magnet. 14) The method for producing a rare earth thin film magnet according to 13) above, wherein in the step of depositing the rare earth thin film, the pulse laser intensity density is 0.1 to 100 J / cm 2 .
  • the present invention has an excellent effect that a rare-earth thin film magnet of Pr—Fe—B film having excellent magnetic properties can be produced on a substrate such as Ta by a pulse laser deposition method.
  • the present invention has an excellent effect that the magnetic characteristics can be further improved by strictly controlling the manufacturing conditions.
  • the present invention can stably form a rare earth thin film magnet, and thus has an excellent effect that productivity can be improved in terms of manufacturing cost.
  • FIG. 3 is a cross-sectional TEM image of a rare earth thin film of the Pr—Fe—B film of the present invention.
  • FIG. 3 is a schematic cross-sectional view of a rare earth thin film of a Pr—Fe—B film of the present invention. It is a figure which shows the magnetization curve of the rare earth thin film magnet of the Pr-Fe-B film
  • the rare earth thin film magnet of the present invention contains Pr (praseodymium), Fe (iron), and B (boron) as essential components.
  • FIG. 1 shows a TEM image of the rare earth thin film magnet of the present invention
  • FIG. 2 shows a schematic diagram thereof.
  • a substrate such as Ta (tantalum)
  • a first layer composed of a Pr phase and an ⁇ -Fe phase
  • a second layer composed of a Pr—Fe—B phase
  • ⁇ -Fe It is characterized by having a structure in which a third layer composed of a phase and a fourth layer composed of a Pr—Fe—B phase and an ⁇ -Fe phase are sequentially laminated.
  • the first layer is mainly a layer in which a Pr phase and an ⁇ -Fe phase are mixed. Note that, since the amount of oxygen is large in the vicinity of the interface with the substrate, a part of the oxide phase may be formed, or a part of the Pr—Fe—B phase may be formed due to the presence of B. These phases are excluded from the components of the phase because they may be in trace amounts or may not be confirmed.
  • the average crystal grain size of each phase is preferably 10 nm to 20 nm. In the first layer, when the formed amorphous phase is crystallized by heat treatment, it is considered that crystal grain refinement occurs due to lattice matching with a Ta substrate having a significantly different lattice spacing.
  • the second layer is composed of Pr—Fe—B phase crystal grains.
  • the average crystal grain size is preferably 100 nm to 200 nm.
  • This region can be formed by depositing a stoichiometric composition such as Pr 2 Fe 14 B or a Pr-rich composition in an amorphous state and crystallizing the film by heat treatment. Further, by performing the heat treatment in a short time, the average crystal grain size can be set to 100 to 200 nm. Furthermore, this second layer has a characteristic mountain range structure.
  • the third layer is composed of an ⁇ -Fe phase.
  • the thickness is formed in a very thin region of 40 to 100 nm.
  • This third layer bears the surface of the mountain range structure of the second layer, and is formed from the ⁇ -Fe phase in the second layer when crystallized from amorphous by heat treatment after film formation. Conceivable.
  • the fourth layer has a structure in which the ⁇ -Fe phase is dispersed in a matrix composed of a Pr—Fe—B phase.
  • the formation of this layer is different from the localized ⁇ -Fe phase of the third layer, and is formed in a form in which the ⁇ -Fe phase is dispersed from the amorphous phase of the Pr—Fe—B phase found in the internal structure of the second layer. It is thought that it was done. In addition, it is considered that the crystal growth of the ⁇ -Fe phase and the crystallization of the Pr—Fe—B phase proceed simultaneously by the heat treatment.
  • the average crystal grain size of the Pr 2 Fe 14 B crystal grains in the fourth layer is preferably a fine crystal grain size of 10 nm to 50 nm in consideration of exchange coupling between the grains, and ⁇
  • the average crystal grain size of the Fe phase is also preferably a fine crystal grain size of 20 nm to 60 nm in consideration of exchange coupling between ⁇ -Fe and Pr 2 Fe 14 B crystal grains.
  • the ⁇ -Fe phase present in the fourth layer has a relatively small particle size near the interface with the third layer (average crystal particle size is 30 nm to 50 nm), and has a relatively small particle size near the surface. It has a special structure that is large (average crystal grain size is 40 nm to 580 nm). This is presumably because the growth of ⁇ -Fe crystal grains in the vicinity of the surface progressed rapidly by heat treatment in a short time.
  • the average crystal grain size of each phase described above is observed by a transmission electron microscope (TEM) for the structure crystallized by heat treatment after film formation by the pulse laser deposition method.
  • TEM transmission electron microscope
  • the distribution of the short axis length of the short crystal axis direction of the dark field image of the streak obtained by the above is taken as the short axis diameter, and the length of the short axis diameter is calculated as the arithmetic average diameter (number average diameter).
  • the rare earth thin film magnet of the present invention preferably has a thickness of 2 ⁇ m or more.
  • the film thickness is less than 2 ⁇ m, when considering application to a device, there is a concern that the influence of a demagnetizing field acts strongly and a sufficient magnetic field cannot be supplied to the outside.
  • the rare-earth thin film magnet of the present invention preferably has a coercive force of 500 kA / m or more, a residual magnetization of 0.8 T or more, and a maximum energy product (BH) max of 80 kJ / m 3 or more.
  • the rare earth thin film magnet of the present invention can be produced as follows. For example, a Pr 2.4 Fe 14 B composition target is mounted on a pulse laser deposition apparatus. Next, after exhausting the inside of the chamber until the degree of vacuum becomes 10 ⁇ 5 Pa, the target is irradiated with laser through a condenser lens. As the laser, an Nd: YAG laser (oscillation wavelength: 355 nm, repetition frequency 30 Hz) can be used. The intensity density of the laser is preferably 0.1 to 100 J / cm 2 .
  • the laser intensity density is less than 0.1 J / cm 2
  • a large amount of droplets are generated when the target is irradiated with the laser, resulting in a decrease in density and a deterioration in magnetic properties.
  • it exceeds 100 J / cm 2 etching of the target due to laser irradiation occurs remarkably, and undesirable phenomena such as stopping the ablation phenomenon occur.
  • the Pr—Fe—B amorphous phase in the film is not sufficiently crystallized, and a large amount of amorphous phase may remain.
  • the Pr 2 Fe 14 B crystal grains and ⁇ -Fe crystal grains may be coarsened to deteriorate the magnetic characteristics.
  • the pulse heat treatment has a mechanism that promotes instantaneous crystallization of a sample and realizes refinement of crystal grains by irradiating infrared rays in an extremely short time.
  • a rare earth thin film magnet can be produced by applying pulse magnetization to the crystallized thin film with a magnetic field of 7T, for example.
  • the magnetization method is not particularly limited, and a known magnetization method can be used. Accordingly, a rare-earth thin film magnet of Pr—Fe—B film having excellent magnetic properties can be manufactured on a substrate such as Ta.
  • Example 1 A Pr 2.2 Fe 14 B target having a purity of 99.9% (3N) and a relative density of 99% was mounted on a pulse laser deposition apparatus. Next, after evacuating the chamber and confirming that the vacuum degree of 10 ⁇ 5 Pa was reached, a Nd: YAG laser (oscillation wavelength: 355 nm) with a repetition frequency of 30 Hz was applied to the target rotated at about 11 rpm. Irradiated to ablate the target material.
  • a Nd: YAG laser oscilscillation wavelength: 355 nm
  • the distance between the target and the substrate was 10 mm
  • the laser intensity was 4 kW
  • the laser beam was condensed on the target surface through a condenser lens, so that the laser intensity density on the target surface was about 4 J / cm 2 .
  • Ta having a thickness of 40 ⁇ m was used for the substrate.
  • a Pr—Fe—B amorphous film having a thickness of 11 ⁇ m was formed on the Ta substrate.
  • a micrometer was used for the film thickness evaluation, and EDX (Energy Dispersive X-ray spectroscopy) was used for the composition analysis.
  • a pulse heat treatment (heat treatment temperature: about 500 to 800 ° C.) was performed at a rated output of 4 kW and a maximum output holding time of about 2 seconds to crystallize the Pr—Fe—B based amorphous phase.
  • the vertical section of the produced Pr—Fe—B rare earth thin film was observed by TEM.
  • the result is shown in FIG.
  • a fourth layer composed of an Fe—B phase and an ⁇ -Fe phase was sequentially laminated.
  • the average crystal grain size of the Pr phase and ⁇ -Fe phase of the first layer is 15 nm
  • the average crystal grain size of the Pr—Fe—B phase of the second layer is 150 nm
  • the Pr—Fe phase of the fourth layer The average crystal grain size of the -B phase was 30 nm
  • the average crystal grain size of the ⁇ -Fe phase was 40 nm.
  • the thickness of the third layer was 40 nm.
  • FIG. 3 shows the magnetization curve of the obtained rare earth thin film magnet.
  • the Pr—Fe—B rare earth thin film magnet produced by the pulse laser deposition method of the present invention has good magnetic properties, energy such as MEMS (Micro Electro Mechanical Systems), energy harvest (energy harvesting), etc. This is useful for magnetic devices applied in fields such as medical fields and medical equipment fields.
  • MEMS Micro Electro Mechanical Systems
  • energy harvest energy harvesting

Abstract

The present invention pertains to a rare earth thin film magnet containing Pr, Fe, and B as essential components, the rare earth thin film magnet being characterized in that a first layer comprising a Pr phase and an α-Fe phase is provided on a substrate, a second layer comprising a Pr-Fe-B phase is provided on the first layer, a third layer comprising an α-Fe phase is provided on the second layer, and a fourth layer comprising a Pr-Fe-B phase and an α-Fe phase is provided on the third layer. The present invention addresses the problem of providing a rare earth thin film magnet having good magnetic properties and a method for manufacturing the same.

Description

希土類薄膜磁石及びその製造方法Rare earth thin film magnet and manufacturing method thereof
　本発明は、Ｔａなどの基板上に作製したＰｒ－Ｆｅ－Ｂ系膜からなる希土類薄膜磁石及びパルスレーザーデポジション法（ＰＬＤ法）により形成するＰｒ－Ｆｅ－Ｂ系膜の希土類薄膜磁石の製造方法に関する。 The present invention relates to a rare earth thin film magnet made of a Pr—Fe—B film made on a substrate of Ta or the like and a Pr—Fe—B film rare earth thin film magnet formed by the pulse laser deposition method (PLD method). Regarding the method.
　近年、電子機器の軽薄短小化に伴い、優れた磁気特性を有する希土類磁石の小型化、高性能化が進められている。例えば、ネオジム－鉄－ホウ素（Ｎｄ－Ｆｅ－Ｂ）系磁石は比較的高い最大エネルギー積を有することから、ＭＥＭＳ（Micro Electro Mechanical Systems）やエナジーハーベスト（環境発電）などのエネルギー分野や、医療機器分野などへの応用が期待されている。 In recent years, as electronic devices have become lighter, thinner, and smaller, rare earth magnets having excellent magnetic properties have been reduced in size and performance. For example, since neodymium-iron-boron (Nd-Fe-B) magnets have a relatively high maximum energy product, energy fields such as MEMS (Micro Electro Mechanical Systems) and energy harvest (energy harvesting), and medical equipment Application to fields is expected.
　このような希土類磁石の薄膜は、スパッタリング法（特許文献１、非特許文献１）やパルスレーザーデポジション法（特許文献２、非特許文献２）などのＰＶＤ（Physical Vapor Deposition）法（非特許文献３）を用いて作製することが知られている。例えば特許文献２には、パルスＹＡＧレーザーを用いたレーザーアブレーション法によって、ターゲットと膜との間に優れた組成転写性があり、また、成膜速度がスパッタリング法に比べて１桁以上も高いＮｄ2Ｆｅ14Ｂ相を主とするＮｄ-Ｆｅ-Ｂ系薄膜が得られることが記載されている。 Such a rare-earth magnet thin film is formed by a PVD (Physical Vapor Deposition) method (Non-Patent Literature) such as a sputtering method (Patent Literature 1, Non-Patent Literature 1) or a pulse laser deposition method (Patent Literature 2, Non-Patent Literature 2). It is known to produce using 3). For example, Patent Document 2 has an excellent composition transfer property between a target and a film by a laser ablation method using a pulsed YAG laser, and Nd is higher in film formation speed by one digit or more than a sputtering method. It is described that an Nd—Fe—B-based thin film mainly composed of 2 Fe 14 B phase can be obtained.
　このような方法で作製した希土類薄膜の磁石は、保磁力：約１０００ｋＡ／ｍ、残留磁化：０．６Ｔ、最大エネルギー積（ＢＨ）ｍａｘ：６０ｋＪ／ｍ３の値をとることが報告されている（非特許文献４）。しかし、これらの数値の中でも残留磁化ならびに最大エネルギー積は、まだ実用化可能な磁気特性とは言えず、例えば小型のモーターを駆動するのに十分でないため、更なる磁気特性の改善が強く要求されている。 It has been reported that a magnet of a rare-earth thin film manufactured by such a method has values of coercive force: about 1000 kA / m, remanent magnetization: 0.6 T, and maximum energy product (BH) max : 60 kJ / m 3 . (Non-Patent Document 4). However, among these values, the remanent magnetization and the maximum energy product are still not practical magnetic properties, and are not sufficient to drive small motors, for example, so there is a strong demand for further improvement of magnetic properties. ing.
　薄膜特性の改善方法としては、組織・微細構造の制御や材料組成の選択などが考えられる。材料組成の選択として、希土類材料であるネオジム（Ｎｄ）に代えて、プラセオジウム（Ｐｒ）を用いたプラセオジム－鉄－ホウ素（Ｐｒ－Ｆｅ－Ｂ）系希土類薄膜が知られている。 As a method for improving thin film characteristics, control of the structure and microstructure, selection of material composition, and the like can be considered. As a selection of the material composition, a praseodymium-iron-boron (Pr—Fe—B) rare earth thin film using praseodymium (Pr) instead of the rare earth material neodymium (Nd) is known.
　また、非特許文献５には、Ｐｒ－Ｆｅ－Ｂ系磁石について、Ｐｒ2Ｆｅ14Ｂ相の異方性磁界がＮｄ2Ｆｅ14Ｂ相に比べ大きく、保磁力向上に寄与するという記載がある。これは、熱安定性向上で優れた技術であるが、外部に発生する磁束量の観点からＰｒ2Ｆｅ14Ｂ相の飽和磁化がＮｄ2Ｆｅ14Ｂ相に比べ小さく、結果的に残留磁化が小さくなるという問題がある。 Further, Non-Patent Document 5 describes that the Pr 2 Fe 14 B phase has a larger anisotropic magnetic field than the Nd 2 Fe 14 B phase in the Pr—Fe—B system magnet and contributes to the improvement of the coercive force. . This is an excellent technique for improving thermal stability, but from the viewpoint of the amount of magnetic flux generated outside, the saturation magnetization of the Pr 2 Fe 14 B phase is smaller than that of the Nd 2 Fe 14 B phase, and as a result, residual magnetization is reduced. There is a problem of becoming smaller.
特開２０１２－２０７２７４号公報JP 2012-207274 A 特開２００９－０９１６１３号公報JP 2009-091613 A
　本発明は、Ｔａ等の基板上に成膜したＰｒ－Ｆｅ－Ｂ系膜の希土類薄膜磁石であって、特に、優れた磁気特性を有するＰｒ－Ｆｅ－Ｂ系膜の希土類薄膜磁石を安定して成膜することを課題とする。 The present invention relates to a rare earth thin film magnet of Pr—Fe—B film formed on a substrate of Ta or the like, in particular, a rare earth thin film magnet of Pr—Fe—B film having excellent magnetic properties. It is an object to form a film.
　上記の課題を解決するために、本発明者らは鋭意研究を行った結果、Ｐｒ－Ｆｅ－Ｂ系膜の組成やパルスレーザーデポジション法の成膜条件を最適化することにより、優れた磁気特性を有するＰｒ－Ｆｅ－Ｂ系希土類薄膜を成膜できるとの知見を得た。 In order to solve the above-mentioned problems, the present inventors have conducted intensive research. As a result, by optimizing the composition of the Pr—Fe—B film and the film formation conditions of the pulse laser deposition method, excellent magnetic properties can be obtained. It was found that a Pr—Fe—B rare earth thin film having characteristics can be formed.
　このような知見に基づき、本発明は、以下の手段を提供する。
　１）Ｐｒ、Ｆｅ、Ｂを必須成分とする希土類薄膜磁石であって、基板上にＰｒ相とα－Ｆｅ相とからなる第１層を備え、前記第１層の上にＰｒ－Ｆｅ－Ｂ相からなる第２層を備え、前記第２層の上に
　α－Ｆｅ相からなる第３層を備え、前記第３層の上にＰｒ－Ｆｅ－Ｂ相とα－Ｆｅ相とからなる第４層を備えることを特徴とする希土類薄膜磁石。
　２）前記第１層における各相の平均結晶粒径が１０ｎｍ～２０ｎｍであることを特徴とする上記１）記載の希土類薄膜磁石。
　３）前記第２層におけるＰｒ－Ｆｅ－Ｂ相の平均結晶粒径が１００ｎｍ～２００ｎｍであることを特徴とする上記１）又は２）記載の希土類薄膜磁石。
　４）前記第３層の厚みが４０～１００ｎｍであることを特徴とする上記１）～３）のいずれか一に記載の希土類薄膜磁石。
　５）前記第３層が山脈構造を有することを特徴とする上記１）～４）のいずれか一に記載の希土類薄膜磁石。
　６）前記第４層におけるＰｒ－Ｆｅ－Ｂ相の平均結晶粒径が１０～５０ｎｍであり、α－Ｆｅ相の平均結晶粒径が２０ｎｍ～６０ｎｍであることを特徴とする上記１）～５）のいずれか一に記載の希土類薄膜磁石。
　７）前記第４層におけるＰｒ－Ｆｅ－Ｂ相の組成がＰｒ２Ｆｅ１４Ｂであることを特徴とする上記１）～６）のいずれか一項に記載の希土類薄膜磁石。
　８）前記第４層のおけるα－Ｆｅ相の界面付近の結晶粒径が３０ｎｍ～５０ｎｍであり、表面付近の結晶粒径が４０ｎｍ～８０ｎｍであることを特徴とする上記１）～７）のいずれか一に記載の希土類薄膜磁石。
　９）膜厚が２μｍ以上あること特徴とする上記１）～８）のいずれか一に記載の希土類薄膜磁石。
　１０）保磁力が５００ｋＡ／ｍ以上であることを特徴とする上記１）～９）のいずれか一に記載の希土類薄膜磁石。
　１１）残留磁化が０．８Ｔ以上であることを特徴とする上記１）～１０）のいずれか一に記載の希土類薄膜磁石。
　１２）最大エネルギー積（ＢＨ）ｍａｘが８０ｋＪ／ｍ３以上であることを特徴とする上記１）～１１）のいずれか一に記載の希土類薄膜磁石。 Based on such knowledge, the present invention provides the following means.
1) A rare-earth thin film magnet containing Pr, Fe, and B as essential components, comprising a first layer comprising a Pr phase and an α-Fe phase on a substrate, and the Pr—Fe—B on the first layer. A second layer composed of a phase, a third layer composed of an α-Fe phase on the second layer, and a third layer composed of a Pr—Fe—B phase and an α-Fe phase on the third layer. A rare-earth thin film magnet comprising four layers.
2) The rare earth thin film magnet as described in 1) above, wherein the average crystal grain size of each phase in the first layer is 10 nm to 20 nm.
3) The rare earth thin-film magnet as described in 1) or 2) above, wherein the average crystal grain size of the Pr—Fe—B phase in the second layer is 100 nm to 200 nm.
4) The rare earth thin film magnet according to any one of 1) to 3) above, wherein the third layer has a thickness of 40 to 100 nm.
5) The rare earth thin-film magnet according to any one of 1) to 4) above, wherein the third layer has a mountain range structure.
6) The above 1) to 5), wherein the average crystal grain size of the Pr—Fe—B phase in the fourth layer is 10 to 50 nm and the average crystal grain size of the α-Fe phase is 20 to 60 nm. ) The rare earth thin-film magnet according to any one of
7) The rare earth thin film magnet according to any one of 1) to 6) above, wherein the composition of the Pr—Fe—B phase in the fourth layer is Pr 2 Fe 14 B.
8) The crystal grain size near the interface of the α-Fe phase in the fourth layer is 30 nm to 50 nm, and the crystal grain size near the surface is 40 nm to 80 nm. The rare earth thin film magnet according to any one of the above.
9) The rare earth thin film magnet according to any one of 1) to 8) above, wherein the film thickness is 2 μm or more.
10) The rare earth thin film magnet according to any one of 1) to 9) above, wherein the coercive force is 500 kA / m or more.
11) The rare earth thin film magnet according to any one of 1) to 10) above, wherein the residual magnetization is 0.8 T or more.
12) The rare earth thin film magnet according to any one of 1) to 11) above, wherein the maximum energy product (BH) max is 80 kJ / m 3 or more.
　また、本発明は、以下の手段を提供する。
　１３）上記１）～１２）のいずれか一に記載の希土類薄膜磁石を製造する方法であって、パルスレーザーデポジション法により希土類薄膜を成膜する工程、成膜した希土類薄膜を熱処理して結晶化させる工程、結晶化した希土類薄膜を着磁して希土類薄膜磁石を作製する工程、とからなることを特徴とする希土類薄膜磁石の製造方法。
　１４）希土類薄膜を成膜する工程において、パルスレーザー強度密度を０．１～１００Ｊ／ｃｍ２とすることを特徴とする上記１３）の希土類薄膜磁石の製造方法。
　１５）希土類薄膜を結晶化させる工程において、定格出力２～１０ｋＷ、最大出力の保持時間１～３秒の条件で、パルス熱処理することを特徴とする上記１３）又は１４）に記載の希土類薄膜磁石の製造方法。 The present invention also provides the following means.
13) A method for producing the rare earth thin film magnet according to any one of 1) to 12) above, wherein the rare earth thin film is formed by a pulse laser deposition method, and the formed rare earth thin film is heat-treated to form a crystal. And a step of magnetizing a crystallized rare earth thin film to produce a rare earth thin film magnet.
14) The method for producing a rare earth thin film magnet according to 13) above, wherein in the step of depositing the rare earth thin film, the pulse laser intensity density is 0.1 to 100 J / cm 2 .
15) The rare earth thin film magnet as described in 13) or 14) above, wherein in the step of crystallizing the rare earth thin film, pulse heat treatment is performed under conditions of a rated output of 2 to 10 kW and a maximum output holding time of 1 to 3 seconds. Manufacturing method.
　本発明は、パルスレーザーデポジション法によって、Ｔａ等の基板上に優れた磁気特性を有するＰｒ－Ｆｅ－Ｂ系膜の希土類薄膜磁石を作製することができるという優れた効果を有する。また、本発明は、製造条件を厳密に制御することにより、磁気特性をさらに向上させることができるという優れた効果を有する。本発明は、安定して希土類薄膜磁石を成膜することができるので、製造コストの点から生産性を向上できるという優れた効果を有する。 The present invention has an excellent effect that a rare-earth thin film magnet of Pr—Fe—B film having excellent magnetic properties can be produced on a substrate such as Ta by a pulse laser deposition method. In addition, the present invention has an excellent effect that the magnetic characteristics can be further improved by strictly controlling the manufacturing conditions. The present invention can stably form a rare earth thin film magnet, and thus has an excellent effect that productivity can be improved in terms of manufacturing cost.
本発明のＰｒ－Ｆｅ－Ｂ膜の希土類薄膜の断面ＴＥＭ画像である。3 is a cross-sectional TEM image of a rare earth thin film of the Pr—Fe—B film of the present invention. 本発明のＰｒ－Ｆｅ－Ｂ膜の希土類薄膜の断面模式図である。FIG. 3 is a schematic cross-sectional view of a rare earth thin film of a Pr—Fe—B film of the present invention. 本発明のＰｒ－Ｆｅ－Ｂ膜の希土類薄膜磁石の磁化曲線を示す図である。It is a figure which shows the magnetization curve of the rare earth thin film magnet of the Pr-Fe-B film | membrane of this invention.
　本発明の希土類薄膜磁石は、Ｐｒ（プラセオジム）、Ｆｅ（鉄）、Ｂ（ホウ素）を必須成分として含有する。図１に本発明の希土類薄膜磁石のＴＥＭ画像を示し、図２にその模式図を示す。図１や図２に示されるように、Ｔａ（タンタル）などの基板上に、Ｐｒ相とα－Ｆｅ相とからなる第１層、Ｐｒ－Ｆｅ－Ｂ相からなる第２層、α－Ｆｅ相からなる第３層、Ｐｒ－Ｆｅ－Ｂ相とα－Ｆｅ相とからなる第４層、が順次積層した構造を備えることを特徴とするものである。 The rare earth thin film magnet of the present invention contains Pr (praseodymium), Fe (iron), and B (boron) as essential components. FIG. 1 shows a TEM image of the rare earth thin film magnet of the present invention, and FIG. 2 shows a schematic diagram thereof. As shown in FIGS. 1 and 2, on a substrate such as Ta (tantalum), a first layer composed of a Pr phase and an α-Fe phase, a second layer composed of a Pr—Fe—B phase, α-Fe It is characterized by having a structure in which a third layer composed of a phase and a fourth layer composed of a Pr—Fe—B phase and an α-Fe phase are sequentially laminated.
　前記第１層は、主として、Ｐｒ相とα－Ｆｅ相とが混在した層となっている。なお、基板との界面付近では酸素量が多いため、一部酸化物相が形成したり、また、Ｂの存在によって、一部Ｐｒ－Ｆｅ－Ｂ相が形成したりすることが考えられるが、これらの相は微量であったり、確認できない場合もあるので、相の構成要素から除外している。
　それぞれの相の平均結晶粒径は、１０ｎｍ～２０ｎｍであることが好ましい。第１層は、成膜したアモルファス相を熱処理によって結晶化する際、格子間隔が著しく異なるＴａ基板上との格子整合を行うために、結晶粒の微細化が生ずるものと考えられる。 The first layer is mainly a layer in which a Pr phase and an α-Fe phase are mixed. Note that, since the amount of oxygen is large in the vicinity of the interface with the substrate, a part of the oxide phase may be formed, or a part of the Pr—Fe—B phase may be formed due to the presence of B. These phases are excluded from the components of the phase because they may be in trace amounts or may not be confirmed.
The average crystal grain size of each phase is preferably 10 nm to 20 nm. In the first layer, when the formed amorphous phase is crystallized by heat treatment, it is considered that crystal grain refinement occurs due to lattice matching with a Ta substrate having a significantly different lattice spacing.
　前記第２層は、Ｐｒ－Ｆｅ－Ｂ相の結晶粒で構成されている。その平均結晶粒径は、好ましくは、１００ｎｍ～２００ｎｍである。この領域は、Ｐｒ２Ｆｅ１４Ｂといった化学量論組成、若しくは、それよりもＰｒリッチな組成がアモルファス状態で成膜され、これを熱処理により結晶化することで形成することができる。また、熱処理を短時間で行うことにより、平均結晶粒径を１００～２００ｎｍとすることができる。さらに、この第２層は、特徴的な山脈構造を有する。 The second layer is composed of Pr—Fe—B phase crystal grains. The average crystal grain size is preferably 100 nm to 200 nm. This region can be formed by depositing a stoichiometric composition such as Pr 2 Fe 14 B or a Pr-rich composition in an amorphous state and crystallizing the film by heat treatment. Further, by performing the heat treatment in a short time, the average crystal grain size can be set to 100 to 200 nm. Furthermore, this second layer has a characteristic mountain range structure.
　前記第３層は、α－Ｆｅ相から構成されている。その厚みは４０～１００ｎｍと極めて薄い領域で形成されている。この第３層は、第２層の山脈構造の表面を担っており、成膜後、熱処理によってアモルファスから結晶化する際、第２層中のα-Ｆｅ相に由来して形成されたものと考えられる。 The third layer is composed of an α-Fe phase. The thickness is formed in a very thin region of 40 to 100 nm. This third layer bears the surface of the mountain range structure of the second layer, and is formed from the α-Fe phase in the second layer when crystallized from amorphous by heat treatment after film formation. Conceivable.
　前記第４層は、Ｐｒ－Ｆｅ－Ｂ相からなるマトリックス中に、α－Ｆｅ相が分散する組織を有している。この層の形成は、第３層の局在したα－Ｆｅ相とは異なり、第２層内部組織で見られたＰｒ－Ｆｅ－Ｂ相のアモルファス相からα－Ｆｅ相が分散した形で形成されたものと考えられる。また、熱処理によって、α－Ｆｅ相の結晶粒成長とＰｒ－Ｆｅ－Ｂ相の結晶化が同時に進行すると考えられる。 The fourth layer has a structure in which the α-Fe phase is dispersed in a matrix composed of a Pr—Fe—B phase. The formation of this layer is different from the localized α-Fe phase of the third layer, and is formed in a form in which the α-Fe phase is dispersed from the amorphous phase of the Pr—Fe—B phase found in the internal structure of the second layer. It is thought that it was done. In addition, it is considered that the crystal growth of the α-Fe phase and the crystallization of the Pr—Fe—B phase proceed simultaneously by the heat treatment.
　前記第４層中のＰｒ２Ｆｅ１４Ｂ結晶粒の平均結晶粒径は、その粒間での交換結合性を考慮すると１０ｎｍ～５０ｎｍの微細な結晶粒径であることが好ましく、また、α－Ｆｅ相の平均結晶粒径も、α－ＦｅとＰｒ２Ｆｅ１４Ｂ結晶粒の交換結合性を考慮すると、２０ｎｍ～６０ｎｍの微細な結晶粒径であることが好ましい。
　さらに、第４層中に存在するα－Ｆｅ相は、第３層との界面付近では、粒径が比較的小さく（平均結晶粒径が３０ｎｍ～５０ｎｍ）、表面付近では、粒径が比較的大きい（平均結晶粒径が４０ｎｍ～５８０ｎｍ）という特殊な組織を有する。これは、短時間での熱処理により、表面付近のα－Ｆｅの結晶粒の成長が早く進行したためと考えられる。 The average crystal grain size of the Pr 2 Fe 14 B crystal grains in the fourth layer is preferably a fine crystal grain size of 10 nm to 50 nm in consideration of exchange coupling between the grains, and α− The average crystal grain size of the Fe phase is also preferably a fine crystal grain size of 20 nm to 60 nm in consideration of exchange coupling between α-Fe and Pr 2 Fe 14 B crystal grains.
Further, the α-Fe phase present in the fourth layer has a relatively small particle size near the interface with the third layer (average crystal particle size is 30 nm to 50 nm), and has a relatively small particle size near the surface. It has a special structure that is large (average crystal grain size is 40 nm to 580 nm). This is presumably because the growth of α-Fe crystal grains in the vicinity of the surface progressed rapidly by heat treatment in a short time.
　上述した、各相の平均結晶粒径は、パルスレーザーデポジション法によって成膜した後、熱処理により結晶化させた組織について、透過電子顕微鏡（ＴＥＭ：Transmission Electron Microscope）による観察を行い、そのＴＥＭ観察により得られた筋状組織の暗視野像の短い結晶軸方向の軸の長さを短軸径として分布を取り、該短軸径の長さを算術平均径（個数平均径）として、算出して求める。 The average crystal grain size of each phase described above is observed by a transmission electron microscope (TEM) for the structure crystallized by heat treatment after film formation by the pulse laser deposition method. The distribution of the short axis length of the short crystal axis direction of the dark field image of the streak obtained by the above is taken as the short axis diameter, and the length of the short axis diameter is calculated as the arithmetic average diameter (number average diameter). Ask.
　本発明の希土類薄膜磁石は、膜厚２μｍ以上であることが好ましい。膜厚が２μｍ未満であると、デバイスへの応用を考慮した際、反磁界の影響が強く作用し、外部に十分な磁界を供給できないというという懸念がある。また、本発明の希土類薄膜磁石は、保磁力が５００ｋＡ／ｍ以上、残留磁化が０．８Ｔ以上、最大エネルギー積（ＢＨ）ｍａｘが８０ｋＪ／ｍ３以上、であることが好ましい。 The rare earth thin film magnet of the present invention preferably has a thickness of 2 μm or more. When the film thickness is less than 2 μm, when considering application to a device, there is a concern that the influence of a demagnetizing field acts strongly and a sufficient magnetic field cannot be supplied to the outside. The rare-earth thin film magnet of the present invention preferably has a coercive force of 500 kA / m or more, a residual magnetization of 0.8 T or more, and a maximum energy product (BH) max of 80 kJ / m 3 or more.
　本発明の希土類薄膜磁石は、以下のようにして、作製することができる。
　例えば、Ｐｒ２．４Ｆｅ１４Ｂ組成のターゲットをパルスレーザーデポジション装置に装着する。次に、チャンバー内を真空度が１０－５Ｐａとなるまで排気した後、前記ターゲットに集光レンズを通してレーザーを照射する。レーザーには、Ｎｄ：ＹＡＧレーザー（発振波長：３５５ｎｍ、繰り返し周波数３０Ｈｚ）を使用することができる。レーザーの強度密度は０．１～１００ Ｊ／ｃｍ２とするのが好ましい。レーザー強度密度が０．１Ｊ／ｃｍ２未満であると、レーザーがターゲットに照射した際、ドロップレットが大量発生して、密度の低下、ひいては磁気特性の劣化が生じる。一方、１００Ｊ／ｃｍ２を超えると、レーザー照射によるターゲットのエッチングが著しく生じ、アブレーション現象が停止するなどの好ましくない現象が生じる。 The rare earth thin film magnet of the present invention can be produced as follows.
For example, a Pr 2.4 Fe 14 B composition target is mounted on a pulse laser deposition apparatus. Next, after exhausting the inside of the chamber until the degree of vacuum becomes 10 −5 Pa, the target is irradiated with laser through a condenser lens. As the laser, an Nd: YAG laser (oscillation wavelength: 355 nm, repetition frequency 30 Hz) can be used. The intensity density of the laser is preferably 0.1 to 100 J / cm 2 . When the laser intensity density is less than 0.1 J / cm 2 , a large amount of droplets are generated when the target is irradiated with the laser, resulting in a decrease in density and a deterioration in magnetic properties. On the other hand, if it exceeds 100 J / cm 2 , etching of the target due to laser irradiation occurs remarkably, and undesirable phenomena such as stopping the ablation phenomenon occur.
　上記のようにレーザー照射されたターゲット表面では、化学反応と溶融反応が起きて、プルームと呼ばれるプラズマが発生する。このプルームが、対向する基板上に到達することで、Ｐｒ―Ｆｅ―Ｂ系アモルファス相の薄膜を形成することができる。そして次にこのようにして成膜したＰｒ－Ｆｅ－Ｂ系アモルファス膜を結晶化させるため、成膜後に定格出力２～１０ｋＷ、最大出力の保持時間１～３秒の条件でパルス熱処理を施して、Ｐｒ－Ｆｅ－Ｂ系アモルファス母相を結晶化させる。
　ここで、定格出力２ｋＷ未満、保持時間１秒未満の熱処理では、膜中のＰｒ－Ｆｅ－Ｂ系アモルファス相の結晶化が十分でなく、アモルファス相が多く残存することがある。一方、定格出力１０ｋＷを超、保持時間３秒超の熱処理では、Ｐｒ２Ｆｅ１４Ｂ結晶粒やα－Ｆｅ結晶粒が粗大化して、磁気特性は劣化することがある。なお、パルス熱処理とは、赤外線を極短時間で照射することで、試料の瞬時の結晶化を促し、結晶粒の微細化を実現する機構を有する。 On the target surface irradiated with the laser as described above, a chemical reaction and a melting reaction occur, and a plasma called a plume is generated. When this plume reaches the opposing substrate, a Pr—Fe—B amorphous phase thin film can be formed. Then, in order to crystallize the Pr—Fe—B-based amorphous film thus formed, pulse heat treatment was performed after the film formation under conditions of a rated output of 2 to 10 kW and a maximum output holding time of 1 to 3 seconds. The Pr—Fe—B amorphous matrix is crystallized.
Here, in the heat treatment with a rated output of less than 2 kW and a holding time of less than 1 second, the Pr—Fe—B amorphous phase in the film is not sufficiently crystallized, and a large amount of amorphous phase may remain. On the other hand, in the heat treatment exceeding the rated output of 10 kW and the holding time of more than 3 seconds, the Pr 2 Fe 14 B crystal grains and α-Fe crystal grains may be coarsened to deteriorate the magnetic characteristics. Note that the pulse heat treatment has a mechanism that promotes instantaneous crystallization of a sample and realizes refinement of crystal grains by irradiating infrared rays in an extremely short time.
　その後、この結晶化薄膜に対して、たとえば、磁界７Ｔでパルス着磁を施すことで、希土類薄膜磁石を作製することができる。なお、本発明においては、着磁の方法に特に制限はなく、公知の着磁方法を用いることができる。これより、Ｔａなどの基板上に、優れた磁気特性を有するＰｒ－Ｆｅ－Ｂ膜の希土類薄膜磁石を製造することができる。 Then, a rare earth thin film magnet can be produced by applying pulse magnetization to the crystallized thin film with a magnetic field of 7T, for example. In the present invention, the magnetization method is not particularly limited, and a known magnetization method can be used. Accordingly, a rare-earth thin film magnet of Pr—Fe—B film having excellent magnetic properties can be manufactured on a substrate such as Ta.
　以下、実施例および比較例に基づいて説明する。なお、本実施例はあくまで一例であり、この例によって何ら制限されるものではない。すなわち、本発明は特許請求の範囲によってのみ制限されるものであり、本発明に含まれる実施例以外の種々の変形を包含するものである。 Hereinafter, description will be made based on examples and comparative examples. In addition, a present Example is an example to the last, and is not restrict | limited at all by this example. In other words, the present invention is limited only by the scope of the claims, and includes various modifications other than the examples included in the present invention.
（実施例１）
　純度９９．９％（３Ｎ）、相対密度９９％のＰｒ２．２Ｆｅ１４Ｂターゲットをパルスレーザーデポジション装置に装着した。次に、チャンバー内を真空に排気して、１０－５Ｐａの真空度に到達したことを確認後、約１１ｒｐｍで回転させたターゲットに繰り返し周波数３０ＨｚのＮｄ：ＹＡＧレーザー（発振波長：３５５ｎｍ）を照射しターゲット物質をアブレーションした。 (Example 1)
A Pr 2.2 Fe 14 B target having a purity of 99.9% (3N) and a relative density of 99% was mounted on a pulse laser deposition apparatus. Next, after evacuating the chamber and confirming that the vacuum degree of 10 −5 Pa was reached, a Nd: YAG laser (oscillation wavelength: 355 nm) with a repetition frequency of 30 Hz was applied to the target rotated at about 11 rpm. Irradiated to ablate the target material.
　このときターゲットと基板との距離を１０ｍｍ、レーザー強度を４ｋＷとし、レーザービームを集光レンズを通してターゲット表面に集光させることで、ターゲット表面でのレーザー強度密度を４Ｊ／ｃｍ２程度とした。基板には厚さ４０μｍのＴａを用いた。このようにして、Ｔａ基板上にＰｒ－Ｆｅ－Ｂアモルファス膜を厚さ１１μｍ成膜した。なお、膜厚評価にはマイクロメーターを使用し、組成分析にはＥＤＸ（Energy Dispersive X-ray spectroscopy）を用いた。次に、定格出力４ｋＷ、最大出力の保持時間約２秒にて、パルス熱処理（熱処理温度：約５００～８００ ℃）を行って、Ｐｒ－Ｆｅ－Ｂ系アモルファス相を結晶化させた。 At this time, the distance between the target and the substrate was 10 mm, the laser intensity was 4 kW, and the laser beam was condensed on the target surface through a condenser lens, so that the laser intensity density on the target surface was about 4 J / cm 2 . Ta having a thickness of 40 μm was used for the substrate. In this manner, a Pr—Fe—B amorphous film having a thickness of 11 μm was formed on the Ta substrate. A micrometer was used for the film thickness evaluation, and EDX (Energy Dispersive X-ray spectroscopy) was used for the composition analysis. Next, a pulse heat treatment (heat treatment temperature: about 500 to 800 ° C.) was performed at a rated output of 4 kW and a maximum output holding time of about 2 seconds to crystallize the Pr—Fe—B based amorphous phase.
　作製したＰｒ－Ｆｅ－Ｂ系希土類薄膜について、ＴＥＭにより、その垂直断面を観察した。その結果を図１に示す。図１に示すように、Ｔａ基板上に、Ｐｒ相とα－Ｆｅ相とからなる第１層、Ｐｒ－Ｆｅ－Ｂ相からなる第２層、α－Ｆｅ相からなる第３層、Ｐｒ－Ｆｅ－Ｂ相とα－Ｆｅ相とからなる第４層、が順次積層した構造を備えていた。また、第１層のＰｒ相とα－Ｆｅ相の平均結晶粒径は１５ｎｍであり、第２層のＰｒ－Ｆｅ－Ｂ相の平均結晶粒径は１５０ｎｍであり、第４層のＰｒ－Ｆｅ－Ｂ相の平均結晶粒径は３０ｎｍ、α－Ｆｅ相の平均結晶粒径は４０ｎｍであった。また、第３層の厚みは４０ｎｍであった。 The vertical section of the produced Pr—Fe—B rare earth thin film was observed by TEM. The result is shown in FIG. As shown in FIG. 1, on a Ta substrate, a first layer composed of a Pr phase and an α-Fe phase, a second layer composed of a Pr—Fe—B phase, a third layer composed of an α-Fe phase, Pr— A fourth layer composed of an Fe—B phase and an α-Fe phase was sequentially laminated. The average crystal grain size of the Pr phase and α-Fe phase of the first layer is 15 nm, the average crystal grain size of the Pr—Fe—B phase of the second layer is 150 nm, and the Pr—Fe phase of the fourth layer. The average crystal grain size of the -B phase was 30 nm, and the average crystal grain size of the α-Fe phase was 40 nm. The thickness of the third layer was 40 nm.
　その後、磁界７Ｔでパルス着磁を施して希土類薄膜磁石を作製した。得られた希土類薄膜磁石について、ＶＳＭ（Vibrating Sample Magnetometer）により磁気特性を測定した。その結果を、保磁力（ｉＨｃ）は、５１６ ｋＡ／ｍ、残留磁化（Ｂｒ）は、１．０４ Ｔ、最大エネルギー積（ＢＨ）ｍａｘは、１１４ ｋＪ／ｍ3と、良好な磁気特性が得られた。得られた希土類薄膜磁石における磁化曲線を図３に示す。 Thereafter, pulsed magnetization was applied with a magnetic field of 7T to produce a rare earth thin film magnet. The magnetic characteristics of the obtained rare earth thin film magnet were measured by a VSM (Vibrating Sample Magnetometer). As a result, the coercive force ( i H c ) is 516 kA / m, the remanent magnetization (B r ) is 1.04 T, the maximum energy product (BH) max is 114 kJ / m 3, and a good magnetic property is obtained. Characteristics were obtained. FIG. 3 shows the magnetization curve of the obtained rare earth thin film magnet.
　本発明のパルスレーザーデポジション法で作製されるＰｒ－Ｆｅ－Ｂ系の希土類薄膜磁石は、良好な磁気特性を有することから、ＭＥＭＳ（Micro Electro Mechanical Systems）、エナジーハーベスト（環境発電）などのエネルギー分野や医療機器分野などに応用される磁気デバイスに有用である。 Since the Pr—Fe—B rare earth thin film magnet produced by the pulse laser deposition method of the present invention has good magnetic properties, energy such as MEMS (Micro Electro Mechanical Systems), energy harvest (energy harvesting), etc. This is useful for magnetic devices applied in fields such as medical fields and medical equipment fields.

Claims (12)

  1. 　Ｐｒ、Ｆｅ、Ｂを必須成分とする希土類薄膜磁石であって、基板上にＰｒ相とα－Ｆｅ相とからなる第１層を備え、前記第１層の上にＰｒ－Ｆｅ－Ｂ相からなる第２層を備え、前記第２層の上にα－Ｆｅ相からなる第３層を備え、前記第３層の上にＰｒ－Ｆｅ－Ｂ相とα－Ｆｅ相とからなる第４層を備えることを特徴とする希土類薄膜磁石。 A rare-earth thin film magnet containing Pr, Fe, and B as essential components, comprising a first layer comprising a Pr phase and an α-Fe phase on a substrate, and a Pr—Fe—B phase on the first layer. A fourth layer comprising a third layer comprising an α-Fe phase on the second layer, and comprising a Pr—Fe—B phase and an α-Fe phase on the third layer. A rare earth thin film magnet comprising:
  2. 　前記第１層における各相の平均結晶粒径が１０ｎｍ～２０ｎｍであることを特徴とする請求項１記載の希土類薄膜磁石。 2. The rare earth thin film magnet according to claim 1, wherein an average crystal grain size of each phase in the first layer is 10 nm to 20 nm.
  3. 　前記第２層におけるＰｒ－Ｆｅ－Ｂ相の平均結晶粒径が１００ｎｍ～２００ｎｍであることを特徴とする請求項１又は２記載の希土類薄膜磁石。 3. The rare earth thin film magnet according to claim 1, wherein the average crystal grain size of the Pr—Fe—B phase in the second layer is 100 nm to 200 nm.
  4. 　前記第３層の厚みが４０～１００ｎｍであることを特徴とする請求項１～３のいずれか一項に記載の希土類薄膜磁石。 The rare-earth thin film magnet according to any one of claims 1 to 3, wherein the third layer has a thickness of 40 to 100 nm.
  5. 　前記第３層が山脈構造を有することを特徴とする請求項１～４のいずれか一項に記載の希土類薄膜磁石。 The rare-earth thin film magnet according to any one of claims 1 to 4, wherein the third layer has a mountain range structure.
  6. 　前記第４層におけるＰｒ－Ｆｅ－Ｂ相の平均結晶粒径が１０～５０ｎｍであり、α－Ｆｅ相の平均結晶粒径が２０ｎｍ～６０ｎｍであることを特徴とする請求項１～５のいずれか一項に記載の希土類薄膜磁石。 6. The average crystal grain size of Pr—Fe—B phase in the fourth layer is 10 to 50 nm, and the average crystal grain size of α-Fe phase is 20 nm to 60 nm. The rare earth thin film magnet according to claim 1.
  7. 　前記第４層におけるＰｒ－Ｆｅ－Ｂ相の組成がＰｒ２Ｆｅ１４Ｂであることを特徴とする請求項１～６のいずれか一項に記載の希土類薄膜磁石。 7. The rare earth thin film magnet according to claim 1, wherein the composition of the Pr—Fe—B phase in the fourth layer is Pr 2 Fe 14 B.
  8. 　前記第４層のおけるα－Ｆｅ相の界面付近の結晶粒径が３０ｎｍ～５０ｎｍであり、表面付近の結晶粒径が４０ｎｍ～８０ｎｍであることを特徴とする請求項１～７のいずれか一項に記載の希土類薄膜磁石。 8. The crystal grain size in the vicinity of the α-Fe phase interface in the fourth layer is 30 nm to 50 nm, and the crystal grain size in the vicinity of the surface is 40 nm to 80 nm. The rare earth thin film magnet according to item.
  9. 　膜厚が２μｍ以上であること特徴とする請求項１～８のいずれか一項に記載の希土類薄膜磁石。 9. The rare earth thin film magnet according to claim 1, wherein the film thickness is 2 μm or more.
  10. 　保磁力が５００ｋＡ／ｍ以上であることを特徴とする請求項１～９のいずれか一項に記載の希土類薄膜磁石。 The rare earth thin film magnet according to any one of claims 1 to 9, wherein the coercive force is 500 kA / m or more.
  11. 　残留磁化が０．８Ｔ以上であることを特徴とする請求項１～１０のいずれか一項に記載の希土類薄膜磁石。 The rare-earth thin film magnet according to any one of claims 1 to 10, wherein the remanent magnetization is 0.8 T or more.
  12. 　最大エネルギー積が８０ｋＪ／ｍ３以上であることを特徴とする請求項１～１１のいずれか一項に記載の希土類薄膜磁石。 The rare earth thin film magnet according to any one of claims 1 to 11, wherein the maximum energy product is 80 kJ / m 3 or more.
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