Preparation and magnetic properties of Ni-Zr doped barium strontium hexaferrite

M-type Hexaferrites B0.5Sr0.5Fe12-2xNixZrxO19 were synthesized and investigated. The XRD patterns show single phase of the magnetoplumbite barium strontium ferrite and no other phases were present. The samples exhibit well defined crystallization; all of them are hexagonal platelet grains. As the substitution level increased from x = 0.2 to 0.8 mol%, the grains are agglomerated and the average diameter increased. This suggests that Ni-Zr substitution increases the grain size, as observed in the FE-SEM micrographs. The results of magnetic measurement revealed that M-s of barium strontium hexaferrite increased when the value of x increased from 0 to 0.4 mol% and then decreased with the increasing Ni-Zr content. The H-c decreases remarkably with increasing Ni and Zr ions content. Hard magnetic material is converted into soft magnetic material when the substitution level is increased from 0.2 to 0.8 mol%. In particular, Ba0.5Sr0.5Fe12-2xNixZrxO19 with x = 0.2, 0.4, 0.6, 0.8 mol% has suitable magnetic characteristics with particle size small enough for high-density magnetic recording applications.