서강대학교

초록/요약

Rare-earth magnetic material with small size and high magnetic properties has been a desirable research target for wide usage in modern industry and technology. To increase maximum energy product, bottom-up synthesis method of magnetic spin exchange coupled magnets with a well dispersion of hard/soft phase and elaborate particle size can be a breakthrough compared to conventional rough synthetic approach. This work presented a chemical strategy with thermal decomposition and reduction/diffusion process to synthesize magnetic spin exchange coupled nanocomposite magnet of Co/SmCo5. Co/SmCo5 nanocomposite was prepared by 3-dimensional alternative arrangement of hard phase SmCo5 magnetic nanoparticles and soft phase Co magnetic nanoparticles to get higher magnetic properties. The compacted hard (SmCo5)/soft (Co) phase magnetic spin exchange coupled nanocomposite showed large coercivity value, higher magnetization and enhancement of maximum energy product due to magnetic spin exchange interaction. For effective magnetic spin exchange interaction, hard and soft magnetic materials were synthesized as nanoparticle size because they had to have a diameter within magnetic domain wall size. Particle size and ideal mass ratio between Co and Sm source were adjusted, which resulted in increase in maximum energy product almost twice compared to pure SmCo5 based magnetic material. Though fabricating the nanocomposite, the magnetic properties could be enhanced much more higher by hot pressing and di-upsetting process. This study can be further applied to the synthesis of other bimetal based magnetic spin exchange-coupled magnetic materials.