Control of magnetic anisotropy in (Bi1-xPbx) 2(AE1-yREy)2Co2O z and fabrication of magnetically aligned bulks

T. Kumagai, S. Horii, T. Okamoto, J. Shimoyama, K. Kishio, T. Uchikoshi, T. S. Suzuki, Y. Sakka, M. Mikami, R. Funahashi

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

We have successfully fabricated two different types of grain-aligned bulks of thermoelectric Bismuth-based cobalt oxides using a magnetic grain-alignment process. The Pb-doping in (Bi2Sr2O4) 0.55CoO2, which shows an easy axis of magnetization parallel to the a-axis, was effective for enhancement of magnetic anisotropy along the a-axis, while the Ca-doping in [(Bi0.5Pb 0.5)2Sr2O4]0.55CoO 2 converted the easy axis along the a-axis to that along the c-axis. Moreover, the magnetic anisotropy along the c-axis was enhanced by the partial Pr-doping for the Ca sites. The changes of their crystal structures revealed that distortion of the block layer was arisen from the substitution of the Ca-doping or the co-doping of Ca and Pr for the Sr sites in [(Bi 0.5Pb0.5)2Sr2O4] 0.55CoO2, leading to the changes of their magnetic anisotropies through locally structural distortion of the CoO2 layers. The c-axis and a-axis grain-aligned bulks were fabricated by the slip-casting method under a magnetic field of 10 T for [(Bi0.5Pb 0.5)2(Ca0.8Pr0.2)2O 4]pCoO2 and [(Bi0.75Pb 0.25)2Sr2O4]0.55CoO 2, respectively. Especially for the c-axis grain-aligned bulk, microstructure observation showed highly grain-oriented, and large reduction of resistivity was observed in a perpendicular direction to the applied field. The control of the easy axis of magnetization by a crystallochemical process is useful for the application of a magnetic grain-alignment process.

Original languageEnglish
Title of host publicationElectroceramic Materials and Applications - Proceedings of the 6th Pacific Rim Conference on Ceramic and Glass Technology
Pages291-301
Number of pages11
Publication statusPublished - 2006 Dec 1
Externally publishedYes
Event6th Pacific Rim Conference on Ceramic and Glass Technology - Maui, Hawaii, United States
Duration: 2005 Sep 112005 Sep 16

Publication series

NameCeramic Transactions
Volume196
ISSN (Print)1042-1122

Other

Other6th Pacific Rim Conference on Ceramic and Glass Technology
CountryUnited States
CityMaui, Hawaii
Period05/9/1105/9/16

ASJC Scopus subject areas

  • Ceramics and Composites
  • Materials Chemistry

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