J. Phys. IV France 07 (1997) C1-325-C1-326
Treatment of Strontium Hexaferrite Powder Synthesized Conventionally to Produce High CoercivityS.A. Seyyed Ebrahimi1, AJ. Williams1, N. Martinez1, A. Ataie1, A. Kianvash2, C.B. Ponton1 and I.R. Harris1
1 School of Metallurgy and Materials, The University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K.
2 Department of Ceramics, Faculty of Engineering, The University of Tabriz, P.O. Box 711, Tabriz, Iran
Strontium hexaferrite powder, produced conventionally from strontium carbonate and iron oxide has been treated in nitrogen and hydrogen atmospheres and then calcined in air. Magnetic measurements after the gas treatment stage indicated a marked decrease of intrinsic coercivity and an increase in saturation magnetisation. During the calcination stage there was a recovery of the magnetic properties. The material now exhibited a remanence and saturation magnetisation close to that of the starting hexaferrite, but a very much higher intrinsic coercivity. The highest coercivity obtained was around 400 kA/m, which is very high for a hexaferrite powder, particularly one synthesized conventionally, without extensive milling. The high coercivity was attributed to a much finer grain size.
© EDP Sciences 1997