M-type hexaferrites of component B0.5Sr0.5Fe12-2xNixZrxO19 were investigated. The XRD patterns show single phase of the magnetoplumbite barium strontium ferrite and no other phases were present. Significant increase in line broadening of the XRD patterns was observed indicating a decrease of grain size. The samples exhibit well defined crystallization; all of them are hexagonal platelet grains. As the substitution level increased x = 0.2-0.8 mol%, the grains are agglomerated and the average diameter increased. The H-c decreases remarkably with increasing Ni and Zr ions content. It was found that the particle size could be effectively decreased and coercivity H-c could easily be controlled by varying the concentration (x) without significantly decreasing saturation magnetization. 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. (C) 2011 Elsevier Ltd. All rights reserved.