| 研究実績の概要 |
The purpose of this research is to prepare the core/shell nanocomposite magnetic particles for the development of high performance permanent magnets. The first attempt is to prepare the single crystal Sm-Co alloy nanoparticles with narrow composition distribution for use as the core of core/shell particles. In this study, in order to improve the magnetic properties of Sm-Co nanopowder prepared by the induction thermal plasma process, the effect of heat treatment on the phase transformation and magnetic properties of Sm-Co nanopowder was investigated. The Sm-Co nanopowder was annealed at 873, 973, 1073, and 1173 K. The X-ray diffraction results indicate that uniform Sm-Co nanopowder with a dominant SmCo5 phase can be prepared at annealing temperatures higher than 1073 K. The coercivity of the Sm-Co nanopowder annealed at 1173 K was measured to be 1.5 MA/m. The Sm-Co nanoparticles can be sufficiently oriented by an external magnetic field. Although perfect crystal orientation could not be achieved in the annealed nanopowder due to necking, short-time heat treatment promoted the formation of the hard magnetic phase and suppressed necking. The results of this study demonstrate the importance of the rapid heat treatment effect during particle formation in the induction thermal plasma process for preparing dispersible Sm-Co nanoparticles with high coercivity and improved anisotropic magnetic behavior.
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