The Effect of Milling Time and Sintering Temperature on Crystallization of BaFe12O19 Phase and Magnetic Properties of Ba-Hexaferrite Magnet

Abstract

Barium hexaferrite samples were prepared by mechanical alloying using the stoichiometric amounts of BaCO3 and Fe2O3 precursors followed by heat treatment applied in the temperature range 700-1150 degrees C. It was found that the high energy ball mill with a milling rate enabled to obtain powders with the finer particles at the reduced milling time mechanical alloying of the initial powders linked to the formation of barium hexaferrite phase. The exothermic reaction peaks corresponding to the formation of BaFe12O19 phase shift from 928 degrees C to 793 degrees C for the increased milling time up to 6 h. This was resulted in improved magnetic properties that the M-s value of the as-blended sample sintered at 800 degrees C rised from 31.16 emu/g to 53.46 emu/g after milling for 6 h. The saturation magnetization and remanence values of the samples mechanically alloyed for 3 h and sintered at 1150 degrees C also increased to 63.57 emu/g and 31.26 emu/g, respectively, more than for 800 degrees C and 900 degrees C. The increase in the annealing temperature favours the formation of BaFe12O19 phase in the samples.