Effects of Calcination Conditions on Magnetic Properties in Strontium Ferrite Synthesized by the Molten Salt Method

The coercivity and the remanence of sintered M-type ferrites are highly dependent on the microstructure of the ferrite particles, particularly the size, morphology, and crystal orientation of the particles. To control the microstructures of ferrite particles, it is strongly recommended to control the nucleation and grain growth of them. In this paper, molten NaCl was used to control the crystal orientation and shape of Sr ferrite (SrFe
₁₂
O
₁₉
) particles. By changing the calcination conditions, Sr ferrite particles were obtained which had a hexagonal plate shape, and whose c-axis was aligned to the normal direction of the plate. Without any sophisticated magnetic alignment, Sr ferrite particles calcined at 1050 °C showed a saturation magnetization of 73.5 emu/g and a coercivity of 3267 G. This method was shown to be effective for developing high-performance hard ferrites.