Application to the Plastic-Magnet Using SrFe₁₂O₁₉ Particles Prepared by the Glass-Ceramic Method

Abstract

High coercivity SrFe₁₂O₁₉ particles were prepared by the glass-ceramic method using the glass with composition y=1 in the system 46.94[(1-y)BaO⋅ySrO]⋅7.14B₂O₃⋅11.43SiO₂.24.49Fe₂O₃ (mo1%), and plastic-magnets were fabricated with the obtained particles.
SrFe₁₂O₁₉ particles (≈0.3μm in diam.) were obtained by leaching the sample after a heat treatment of the glass (y=1) at 875°C for 5 hr. The particles showed very high coercive force of 6080 Oe and σs=52 emu/g.
SrFe12O19 plastic-magnet fabricated by the roll method consisted of random assembly. Values of magnetic properties were _BH_C=1030 Oe, Br=1150G, and (B⋅H)max=0.3 M G⋅Oe, however a SrFe₁₂O₁₉ plastic-magnet fabricated by the injection molding under applying magnetic field exhibited slightly preferred orientation with the values of _BH_C=1551 Oe, Br=1743 G, and (B⋅H)max=0.7 M G⋅Oe.