Structural and magnetic properties of conventional and microwave treated Ni–Zr doped barium strontium hexaferrite

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 Hc decreases remarkably with increasing Ni and Zr ions content. It was found that the particle size could be effectively decreased and coercivity Hc 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.

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► Saturation magnetization increases whereas the coercivity decreases.
► The transition from hard phase to soft phase.
► Therefore, it is used for high-density magnetic recording applications.