Investigation of magnetic properties of MnZn-substituted strontium ferrite nanopowders prepared via conventional ceramic technique followed by a high energy ball milling

Strontium ferrite powders with substitution of Mn2+ and Zn2+ ions for Fe3+ ions according to the formula SrMnxZnxFe12−2xO19, wherein x ranging from 0 to 1 with a step of 0.2, has been pre-milled via conventional ceramic method and calcined at 1200 °C for 4 h in the air. In order to get nanopowders, the obtained powders were milled again in a high energy SPEX mill for 1 h and 15 min. XRD study was performed to investigation the phases and structural properties of samples. Lattice parameters and mean crystallite sizes of the milled powders were determined from the XRD data and Scherrer׳s formula. Size of particles was studied by TEM. The DC electrical resistivities of the milled samples have been measured by the two-point probe method. In addition, room temperature magnetizations and coercivities of the samples in a magnetic field of 14.7 kOe have been determined from the hysteresis loops. The behavior of magnetizations of samples has been discussed based on core-shell model and according to the site occupation of substituted cations on the sublattices. The discussion of site occupation also supports the increase of lattice parameters as x increases.