Effect of Sn–Ni substitution on the structural, electrical and magnetic properties of mixed spinel ferrites

Abstract

Abstract Nanocrystalline spinel ferrites with nominal composition Co 0.5 Mn 0.5 Fe 2−2 x Sn x Ni x O 4 ( x = 0.0, 0.2, 0.4 and 0.6) are prepared by the co-precipitation method. The samples are characterized by X-ray diffraction (XRD), energy dispersive X-ray fluorescence (ED-XRF), dc electrical resistivity and hysteresis loops measurements. The powder XRD patterns confirm the single spinel phase and the crystallite size is found in the range of 17–18 nm. The lattice constant ( a ), X-ray density ( ρ X-ray ) and porosity ( P ) are also calculated from XRD data. The elemental composition of the synthesized samples is determined by ED-XRF analysis. The dc electrical resistivity ( ρ ) of all samples is measured in the temperature range of 303–723 K and is found to decrease with temperature, indicating the semiconducting nature of the synthesized materials. The room temperature electrical resistivity increases from 10.22 to 40.01 × 10 7 Ω cm with dopant concentration while the drift mobility ( μ d ) decreases from 21.3 to 1.42 × 10 −12 cm 2 V −1 S −1 . The saturation magnetization ( M s ) increases from 18.33 to 38.39 emu g −1 up to x = 0.2 and then decreases, while the coercivity ( H c ) decreases continuously with dopant concentration. The increase in the dc electrical resistivity and saturation magnetization make the synthesized materials suitable for their applications in microwave devices and high density recording media, respectively.