Role of Co–Cr substitution on the structural, electrical and magnetic properties of nickel nano-ferrites synthesized by the chemical co-precipitation method

Nano-spinel nickel ferrites doped with Co–Cr at iron and nickel sites are synthesized by the chemical co-precipitation method and are characterized by the XRD, DC electrical resistivity and hysteresis loops measurements. The XRD analyses confirm the formation of single spinel phase and the crystallite size calculated by Schererʹs formula is found in the range of 17–19 nm. This crystallite size is small enough to obtain the suitable signal to noise ratio in the high density recording media. The values of electrical resistivity (8.28 × 107 to 29.6 × 107 ohm cm), activation energy (0.545–0.884 eV), saturation magnetization (23.67–33.49 emu g−1) and remanence (12.48–18.67 emu g−1) are increased up to a doping level of x = 0.2 and then starts to decrease. The increase in electrical resistivity, saturation magnetization and remanence suggest that the material with composition Co0.2Ni0.8Fe1.8O4 can be used for applications in microwave devices and high density recording media.