Effect of holmium on the magnetic and electrical properties of barium based W-type hexagonal ferrites

A series of BaHo x Fe 16− x O 27 ( x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) W-type hexagonal ferrites were prepared by co-precipitation technique at high annealing temperature of 1320 °C. XRD reveals single W-type hexagonal phase in these ferrites. The grain size is measured by SEM analysis using line intercept method. Saturation magnetization, retentivity and coercivity were measured from MH-loops taken on VSM. It was observed that magnetization increases with the increase of Ho content due to difference in ionic radii of Ho 3+ (0.901 Å) and Fe 3+ (0.67 Å) ions. Room temperature dc resistivity increases as a function of Ho 3+ that may be due to separation between grains. The dc electrical resistivity decreases as a function of temperature which indicates the semi-conducting behavior of the samples.