2001 Fiscal Year Final Research Report Summary
PREPARATION AND CHARACTERIZATION OF Nd-Fe-B FILMS WITH HIGH COERCIVITY
| Project/Area Number |
12650310
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Electronic materials/Electric materials
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| Research Institution | Nagoya Institute of Technology |
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Principal Investigator |
OKUDA Takashi Nagoya Institute of Technology, Faculty of Engng., Prof., 工学部, 教授 (60233459)
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| Co-Investigator(Kenkyū-buntansha) |
ADACHI Nobuyasu Nagoya Institute of Technology, Faculty of Eng., Res. Assoc., 工学部, 助手 (90262956)
OHSATO Hitoshi Nagoya Institute of Technology, Faculty of Eng., Prof., 工学部, 教授 (20024333)
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| Project Period (FY) |
2000 – 2001
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| Keywords | Thin Film Permanent Magnet / Nd_2Fe_<14>B / Crystallization by Heat Treatment / Substrate Temperature / Perpendicular Magnetic Film / Columnar Structure / Single Domain Particle / High Coercivity |
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| Research Abstract |
In order to develop thin film permanent magnet (TFPM) necessary for miro- or nanb-devices, preparation and characterization of Nd-Fe-B films with very high coercivity have been investigated. As the high coercivity is the most important material requisite for TFPM, we concentrated to find target composition which may result high coercivity. We prepared the films by RF-sputtering with subsequent heat treatment. As-deposited films were in amorphous state and magnetically very soft with strong in-plane magnetic anisotropy. We found that some of the as-deposited films prepared under special conditions have very weak out-of-plane anisotropy. In those films heat treated under appropriate conditions, Nd_2Fe_<14>B phase crystallizes with c-axis oriented along the film normal. We named such a phenomenon as self-texturing crystal growth.
As the c-axis is magnetic easy direction, the film is easily magnetized perpendicular to the film plane. The films show prominent permanent magnet characteristics: coercivity higher than 15kOe, residual flux density of 9kG, and maximum energy product (BH)_<max> as high as 20.1MGOe. Such a high coercivity may be resulted from Nd_2Fe_<14>B crystallites of which size is as large as single domain size and c-axis is orienting along film normal. We consider that such a fine crystallite size maybe in relation with nucleation density in self-texturing crystal growth.
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