Influence of magnetostriction on the lattice constants of the secondary phases in Nd-Fe-B sintered magnets studied by synchrotron X-ray diffraction

Shintaro Kobayashi; Andrés Martín-Cid; Kentaro Toyoki; Hiroyuki Okazaki; Satoshi Hirosawa; Tetsuya Nakamura

doi:10.1063/1.5129849

Influence of magnetostriction on the lattice constants of the secondary phases in Nd-Fe-B sintered magnets studied by synchrotron X-ray diffraction

Shintaro Kobayashi, Andrés Martín-Cid, Kentaro Toyoki, Hiroyuki Okazaki, Satoshi Hirosawa, Tetsuya Nakamura

International Center for Synchrotron Radiation Innovation Smart (SRIS)

Research output: Contribution to journal › Article › peer-review

4 Citations (Scopus)

Abstract

We investigated the structural influence of Nd₂Fe₁₄B phase magnetostriction on the Nd-rich secondary phases of hcp-Nd₂O₃, fcc-NdO_x, dhcp-Nd, and fcc-Nd, in Nd-Fe-B bulk-sintered magnets. The temperature dependence of the secondary phase lattice constants was evaluated by synchrotron X-ray diffraction using rod-shaped isotropic (randomly oriented) and anisotropic (c-axis oriented) Nd-Fe-B-Cu sintered magnets. The lattice constants of each secondary phase in the rod-shaped isotropic and anisotropic samples exhibited an invar-type expansion below the Nd₂Fe₁₄B phase Curie temperature (T_C), despite the phases not showing ferromagnetic ordering at T_C - and peak broadening was seen for the secondary phases below T_C. Since such volume expansion has not been seen in powdered sintered magnets, we viewed it as a phenomenon particular to rod-shaped sintered magnets. These results indicated that the Nd₂Fe₁₄B phase spontaneous volume expansion induced the volume expansion observed in all the constituent phases of the bulk sintered magnets.

Original language	English
Article number	125154
Journal	AIP Advances
Volume	9
Issue number	12
DOIs	https://doi.org/10.1063/1.5129849
Publication status	Published - 2019 Dec 1

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title = "Influence of magnetostriction on the lattice constants of the secondary phases in Nd-Fe-B sintered magnets studied by synchrotron X-ray diffraction",

abstract = "We investigated the structural influence of Nd2Fe14B phase magnetostriction on the Nd-rich secondary phases of hcp-Nd2O3, fcc-NdOx, dhcp-Nd, and fcc-Nd, in Nd-Fe-B bulk-sintered magnets. The temperature dependence of the secondary phase lattice constants was evaluated by synchrotron X-ray diffraction using rod-shaped isotropic (randomly oriented) and anisotropic (c-axis oriented) Nd-Fe-B-Cu sintered magnets. The lattice constants of each secondary phase in the rod-shaped isotropic and anisotropic samples exhibited an invar-type expansion below the Nd2Fe14B phase Curie temperature (TC), despite the phases not showing ferromagnetic ordering at TC - and peak broadening was seen for the secondary phases below TC. Since such volume expansion has not been seen in powdered sintered magnets, we viewed it as a phenomenon particular to rod-shaped sintered magnets. These results indicated that the Nd2Fe14B phase spontaneous volume expansion induced the volume expansion observed in all the constituent phases of the bulk sintered magnets.",

author = "Shintaro Kobayashi and Andr{\'e}s Mart{\'i}n-Cid and Kentaro Toyoki and Hiroyuki Okazaki and Satoshi Hirosawa and Tetsuya Nakamura",

note = "Funding Information: We thank S. Kawaguchi for providing useful comments on the synchrotron XRD and T. Fukagawa and T. Nishiuchi of Hitachi Metals, Ltd. for supplying Nd-Fe-B sintered magnets. This work has been performed with the approval of the SPring-8 Program Advisory Committee (Proposal Nos. 2018A1009, 2018B1016, 2018B1333, 2019A1007). This work is partially supported by ESICMM Grant Number 12016013 and ESICMM is funded by Ministry of Education, Culture, Sports, Science and Technology (MEXT). Some analysis was conducted using the Rietan-FP program.29 Publisher Copyright: {\textcopyright} 2019 Author(s).",

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T1 - Influence of magnetostriction on the lattice constants of the secondary phases in Nd-Fe-B sintered magnets studied by synchrotron X-ray diffraction

AU - Kobayashi, Shintaro

AU - Martín-Cid, Andrés

AU - Toyoki, Kentaro

AU - Okazaki, Hiroyuki

AU - Hirosawa, Satoshi

AU - Nakamura, Tetsuya

N1 - Funding Information: We thank S. Kawaguchi for providing useful comments on the synchrotron XRD and T. Fukagawa and T. Nishiuchi of Hitachi Metals, Ltd. for supplying Nd-Fe-B sintered magnets. This work has been performed with the approval of the SPring-8 Program Advisory Committee (Proposal Nos. 2018A1009, 2018B1016, 2018B1333, 2019A1007). This work is partially supported by ESICMM Grant Number 12016013 and ESICMM is funded by Ministry of Education, Culture, Sports, Science and Technology (MEXT). Some analysis was conducted using the Rietan-FP program.29 Publisher Copyright: © 2019 Author(s).

PY - 2019/12/1

Y1 - 2019/12/1

N2 - We investigated the structural influence of Nd2Fe14B phase magnetostriction on the Nd-rich secondary phases of hcp-Nd2O3, fcc-NdOx, dhcp-Nd, and fcc-Nd, in Nd-Fe-B bulk-sintered magnets. The temperature dependence of the secondary phase lattice constants was evaluated by synchrotron X-ray diffraction using rod-shaped isotropic (randomly oriented) and anisotropic (c-axis oriented) Nd-Fe-B-Cu sintered magnets. The lattice constants of each secondary phase in the rod-shaped isotropic and anisotropic samples exhibited an invar-type expansion below the Nd2Fe14B phase Curie temperature (TC), despite the phases not showing ferromagnetic ordering at TC - and peak broadening was seen for the secondary phases below TC. Since such volume expansion has not been seen in powdered sintered magnets, we viewed it as a phenomenon particular to rod-shaped sintered magnets. These results indicated that the Nd2Fe14B phase spontaneous volume expansion induced the volume expansion observed in all the constituent phases of the bulk sintered magnets.

AB - We investigated the structural influence of Nd2Fe14B phase magnetostriction on the Nd-rich secondary phases of hcp-Nd2O3, fcc-NdOx, dhcp-Nd, and fcc-Nd, in Nd-Fe-B bulk-sintered magnets. The temperature dependence of the secondary phase lattice constants was evaluated by synchrotron X-ray diffraction using rod-shaped isotropic (randomly oriented) and anisotropic (c-axis oriented) Nd-Fe-B-Cu sintered magnets. The lattice constants of each secondary phase in the rod-shaped isotropic and anisotropic samples exhibited an invar-type expansion below the Nd2Fe14B phase Curie temperature (TC), despite the phases not showing ferromagnetic ordering at TC - and peak broadening was seen for the secondary phases below TC. Since such volume expansion has not been seen in powdered sintered magnets, we viewed it as a phenomenon particular to rod-shaped sintered magnets. These results indicated that the Nd2Fe14B phase spontaneous volume expansion induced the volume expansion observed in all the constituent phases of the bulk sintered magnets.

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Influence of magnetostriction on the lattice constants of the secondary phases in Nd-Fe-B sintered magnets studied by synchrotron X-ray diffraction

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