Characteristics of Barium Hexaferrite Nanoparticles Prepared by Temperature-Controlled Chemical Coprecipitation

Abstract

Ba-ferrite (<TEX>$BaFe_{12}O_{19}$</TEX>) nanoparticles were synthesized by chemical coprecipitation method in an aqueous solution. The particle size and the crystallization temperature of the Ba-ferrite nanoparticles were controlled varying the precipitation temperature. The precipitate that was prepared at <TEX>$0^{\circ}C$</TEX> showed the crystal structure of Ba-ferrite in X-ray diffraction when it was calcined at the temperature above <TEX>$580^{\circ}C$</TEX>, whereas what was prepared at <TEX>$50^{\circ}C$</TEX> showed the crystallinity when it was calcined at the temperature higher than about <TEX>$700^{\circ}C$</TEX>. The particle sizes of the synthesized Ba-ferrite were in a range of about 20-30 nm when it was prepared by being precipitated at <TEX>$0^{\circ}C$</TEX> and calcined at <TEX>$650^{\circ}C$</TEX>. When the precipitation temperature increased, the particle size also increased even at the same calcination temperature. The magnetic properties of the Ba-ferrite nanoparticles were also controlled by the synthetic condition of precipitation and calcination temperature. The coercive force could be appreciably lowered without a loss of saturation magnetization when the Ba-ferrite nanoparticles were prepared by precipitation and calcination both at low temperatures.