Abstract

Al-substituted M-type hexaferrite is a high anisotropy material. In this paper, we report the coprecipitation synthesis of SrAl4Fe8O19 powder and the effects of preheating temperature and calcining time on the anisotropy and magnetic property of the powders. The XRD analysis indicated that the SrAl4Fe8O19 powder requests a calcining time of 3 h for formation of pure hexagonal platelike particle, and preheat treatment at 300 °C was favorable for the formation of single phase SrAl4Fe8O19. Calculation of c/a value with XRD data indicated that the Al-substitution and preheat treatment induced notable increase of the atomic lattice anisotropy. SEM analysis revealed that shape anisotropy of the samples decreases with the preheating. Magnetic measurement indicates that coercivity decrease and magnetization increase as decrease in shape anisotropy, but have no concern with the atomic lattice anisotropy. The no-preheated sample has a maximum coercivity up to 3.9947 kG and the sample preheated at 400 °C has a maximum magnetization up to 32.266 A·m2·kg-1. The present article discusses some important patents related to catalysis of Mg-containing spinel compounds.

Keywords: SrAl4Fe8O19, powder, coprecipitation method, shape anisotropy, magnetic property