Synthesis and properties of barium ferrite nano-powders by chemical co-precipitation method

摘要

Nano-powders with controllable particle size, excellent magnetic properties and thermal stability of barium hexaferrite (BaFe12O19) have been synthesized via a co-precipitation/calcination technique. The phase composition, morphology and magnetic/thermal properties of the products were systematically studied. XRD patterns reveal that a long co-precipitation reaction time (5 h) and high calcination temperature (1100 degrees C) are beneficial for the formation of BaFe12O19 phase and decreasing the tendency to agglomeration. SEM micrographs show that the products show a hexagonal flake-like particle shape and the size are well controlled and maintained at single-domain particle size range area ( 460 nm), above which the coercivity will decrease abruptly for the coupling exchange among particles. The products with H-j(c) of 5934 Oe, temperature coefficient of remanence (alpha(Br)) of -0.176% K-1 and temperature coefficient of coercivity (beta(j)(Hc)) of 0.0427% K-1 were obtained when co-precipitated for 5 h and calcined at 900 degrees C for 2 h. A high saturation magnetization of 66.9 emu/g was obtained when co-precipitated for 5 h and calcined at 1100 degrees C for 2 h, approaching the theoretical saturation magnetization (72 emu/g).