Preparation and Magnetic Properties of Acicular Ba - Ferrite Powder

Acicular α-FeOOH and Ba(OH)₂ㆍ8H₂O are starting materials in this study. This paper presents the characteristics of the contents of citric acid and heating condition for preparing acicular barium ferrite powder. They control particle shape, crystalline phase, magnetic properties of acicular barium ferrite powder. So the effects of the contents of citric acid and heating condition are studied. The experimental condition for starting materials were 800~1000 ℃ in firing and 0~40 wt. % citric acid, respectively. Ba-ferrite particles fired at the range of 800 ℃ to 900 ℃ were maintained as acicular particle shape, but there were mixed particles of acicular and round shape after fired at 950 ℃. Ba-ferrite powder of the single phase was obtained in firing at 900~1000 ℃ and with 20 wt.% citric acid. There were unreacted phase of α-Fe₂O₃ and BaFe₂O₄ phases as a second phase in case of sintering at below 850 ℃. Acicular barium ferrite powder of single phase was also produced in firing at 900 ℃ with 20 wt.% citric acid. The saturation magnetization of single phase of acicular BaFe₁₂O_(19) powder was about 51 emu/g and coercivity was about 4200 Oe.