研究者詳細 - 竹澤　昌晃

論文 - 竹澤　昌晃

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Magnetic domain control of amorphous ribbons for highly sensitive fluxgate sensors 査読有り

Miyata H., Yamamoto R., Morimoto Y., Takezawa M.

IEEJ Transactions on Fundamentals and Materials 137 ( 8 ) 466 - 469 2017年08月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2017 The Institute of Electrical Engineers of Japan. We observed the repeatability of changes in the magnetic domains of three types of amorphous ribbons. These ribbons were cut at their edges and annealed to control their domain structures. The domain change of the cut samples had good repeatability. Moreover, jitter noise in the fluxgate-sensor output for the amorphous ribbon decreased. A decrease in the magnetization-reversal jitter could be achieved through magnetic domain-structure control of the sensor core, which could improve the sensitivity of the fluxgate.

DOI： 10.1541/ieejfms.137.466

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CiNii Article

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Nd-Fe-B 系焼結磁石の圧縮応力による磁区構造変化査読有り

竹澤昌晃, 森本祐治, 江島潤, 中野善和, 荒木健

電気学会論文誌 A(基礎・材料・共通部門誌) 137 ( 7 ) 367 - 373 2017年07月

The high squareness Sm-Co magnet having Hcb=10.6 kOe at 150°C 査読有り

Machida H., Fujiwara T., Kamada R., Morimoto Y., Takezawa M.

AIP Advances 7 ( 5 ) 056223 全6ページ 2017年05月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2017 Author(s).The relationship between magnetic properties and magnetic domain structures of Sm(Fe, Cu, Zr, Co)7.5 magnet was investigated. The developed Sm-Co magnet, which is conducted homogenization heat treatment at ingot state, high temperature short time sintering and long time solid solution heat treatment showed the maximum energy product, [BH]m of 34.0 MGOe and the coercivity, Hcb of 11.3 kOe at 20°C respectively. Moreover, Hcb of 10.6 kOe at 150°C was achieved. Heat treated ingot has clear 1-7 phase in mother phase from optical microscope observation. Kerr effect microscope with magnetic field applied was used to investigate magnetic domain structure. Reverse magnetic domains were generated evenly but generation of them from inside grain were not observed. Cell structure was observed by scanning transmission electron microscope and composition analysis was conducted by energy dispersive X-ray spectroscopy. Cell size was approximately 150 ∼ 300 nm, Fe and Cu were clearly separated and concentrated to 2-17 phase and 1-5 phase respectively. Moreover, Cu concentration went up to 40 at% in 1-5 phase. That means the gap of domain wall energy between 1-5 phase and 2-17 phase was increased due to microstructure control by conducting heat treatment for compositional homogeneity.

DOI： 10.1063/1.4976334

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ナノスケール磁性体の構造・組織解析と創製の研究動向

竹澤昌晃

電気学会論文誌 A(基礎・材料・共通部門誌) ( 電気学会 ) 137 ( 1 ) 26 - 27 2017年01月

Influence of misorientation angle between easy-axes of adjacent grains on magnetic domain propagation in Nd-Fe-B sintered magnet 査読有り

T. Maki, R. Uchikoshi, R. Ishii, T. Nishiuchi, M. Takezawa

Proceedings of the 24th International Workshop on Rare-Earth and Future Permanent Magnets and their Applications 24 637 - 640 2016年08月

Magnetics and optics research

Munekata H., Nakamura Y., Okamoto S., Sekiguchi K., Shiratsuchi Y., Takezawa M.

Japanese Journal of Applied Physics ( Japanese Journal of Applied Physics ) 55 ( 7 ) 2016年07月

Analysis of thermal demagnetization behavior of Nd–Fe–B sintered magnets using magnetic domain observation (共著) 査読有り

M. Takezawa, S. Ikeda, Y. Morimoto, H. Kabashima

AIP Advances 6 ( 5 ) 056021 2016年03月

The hysteresis properties analysis of Fe-4 wt% Si prepared by high purity metallurgy (共著) 査読有り

Z. Lei, T. Horiuchi, I. Sasaki, C. Kaido, M. Takezawa, S. Hata, Y. Horibe, T. Ogawa, H. Era

Journal of the Magnetics Society of Japan 40 ( 1 ) 8 - 12 2016年01月

Relationship between Microstructure and Magnetic Domain Structure of Nd-Fe-B Melt-Spun Ribbon Magnets(共著) 招待有り査読有り

M. Takezawa, H. Taneda, Y. Morimoto

Frontiers of Materials Science 9 ( 2 ) 206 - 210 2015年06月

Nd-Fe-B系焼結磁石の高温下における減磁過程の磁区観察

竹澤昌晃, 荻本紘史, 森本祐治

粉体および粉末冶金 ( 粉体粉末冶金協会 ) 62 ( 2 ) 67 - 71 2015年02月

Study on magnetic properties and domain structures of Fe-(5, 6) wt% Si alloys prepared with high purity metallurgy 査読有り

Lei Z., Horiuchi T., Mimura Y., Sasaki I., Kaido C., Takezawa M., Kubo S., Ogawa T., Era H.

2015 IEEE International Magnetics Conference, INTERMAG 2015 2015年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

© 2015 IEEE.The hysteresis loss of silicon iron alloy is highly connected to the crystal defects caused by impurities, stress and so on, which contribute to a pinning effect of magnetic domain wall displacement and rotation, thus results in an increase of iron loss<sup>[1]</sup>. Therefore, highly pure silicon iron alloy is always desired among industries and researchers. In order to obtain high purity iron silicon alloy in the experiment, highly pure raw iron and silicon with a purity of 99.99 wt% were utilized, and a method called CCLM (Cold Crucible Levitation Melting), which is popular for high purity metallurgy of various materials, was introduced to melt raw materials. In CCLM furnace, during melting by electromagnetism induction heating, the melted alloy can avoid contacting the crucible because it is levitated by magnetic force simultaneously that can effectively reduce impurities of the alloy than other metallurgy.

DOI： 10.1109/INTMAG.2015.7156862

Scopus

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Magnetic domain observation of Nd-Fe-B sintered magnet at elevated temperature 査読有り

Takezawa M., Ogimoto H., Morimoto Y.

Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy 62 ( 2 ) 67 - 71 2015年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

Magnetization reversal and its propagation in sintered Nd-Fe-B magnets were clearly observed at elevated temperature up to 150 °C using a Kerr microscope, image processing, and photo editing. Simultaneous magnetization reversal in several grains along the easy axis direction occurred at elevated temperature, and the extent of simultaneous magnetization reversal increased with temperature. This indicates that reduction in the coercivity of Nd-Fe-B sintered magnets at elevated temperatures is attributable to decrease in anisotropy and insufficient pinning of domain walls at grain boundaries.

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研究グループ紹介：九州工業大学大学院工学研究院先端機能システム工学研究系竹澤研究室

竹澤昌晃

電気学会論文誌. A ( The Institute of Electrical Engineers of Japan ) 135 ( 11 ) NL11_2 - NL11_2 2015年01月

Relationship Between Output of a Fluxgate Sensor and Magnetization Process of Its Core 査読有り

H. Miyata, R. Yamamoto, Y. Morimoto, M. Takezawa

IEEE Transactions on Magnetics 50 ( 11 ) 1 - 4 #4005804 2014年11月

Relationship between Sensor Output of a Fluxgate Magnetic Sensor and the Magnetic Domain Structure of its Core 査読有り

H. Miyata, Y. Morimoto, M. Takezawa

Journal of the Magnetics Society of Japan 38 ( 4 ) 169 - 173 2014年07月

Analysis of the Demagnetization Process of Nd-Fe-B Sintered Magnets at Elevated Temperatures by Magnetic Domain Observation Using a Kerr Microscope 査読有り

M. Takezawa, H. Ogimoto, Y. Kimura, Y. Morimoto

Journal of Applied Physics 115 ( 17 ) 17A733 2014年05月

Analysis of Magnetization Reversal Process of Nd-Fe-B Sintered Magnets by Magnetic Domain Observation Using Kerr Microscope 査読有り

M. Takezawa, Y. Kimura, Y. Morimoto and J. Yamasaki

IEEE Transactions on Magnetics 49 ( 7 ) 3263 - 3264 2013年07月

Easy Axis Orientation of Nd-Fe-B Melt-Spun Magnets Caused by Hot-Rolling 査読有り

Masaaki Takezawa, Toshio Mihara, Yuji Morimoto, Jiro Yamasaki, Masaaki Yagi

電気学会論文誌Ａ(基礎・材料・共通部門誌) 132 ( 10 ) 818 - 821 2012年10月

Magnetic Domain Observation of Nd−Cu-Diffused Nd-Fe-B Magnets with Submicron Grains by Kerr Effect Microscopy 査読有り

M. Takezawa, Y. Nagashima, Y. Kimura, Y. Morimoto, J. Yamasaki, N. Nozawa, T. Nishiuchi and S. Hirosawa

J. Appl. Phys. 111 ( 7 ) 07A714 2012年02月

Investigation of Easy Axis Orientation of Nd-Fe-B Melt-Spun Ribbons Produced by hot Rolling and Influence of Ti-C Addition 査読有り

M. Takezawa, Y. Nakanishi, Y. Morimoto, J. Yamasaki and M. Yagi

J. Appl. Phys. 111 ( 7 ) 07A703 2012年02月

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