Synthesis of Fe2＋-based 18H-type ferrite, Ba5Fe2−x2+Fe12+2x3+Ti3−xO31

To obtain Fe2＋-based 18H-type ferrite (Ba5Fe2−x2+Fe12+2x3+Ti3−xO31), we synthesized a series of samples in the composition range of 0≤x≤1.5 at sintering temperatures ranging from 1000 to 1200 °C. The observed phases were identified, revealing the formation of single-phase samples in the composition range of 0.2≤x≤0.8 at sintering temperatures between 1150 and 1185 °C. The Curie temperatures of the Fe2＋-based 18H-type ferrites were approximately 360 °C, exhibiting an increasing tendency as x increased. The saturation magnetizations of samples sintered at 1170 °C were found to range from 25.2 emu/g to 29.3 emu/g within the range of 0.3≤x≤1.0, displaying an increasing trend with increasing x. Additionally, a plausible arrangement of ions within the crystal structure of 18H-type ferrite crystal was proposed.