Impacts of Tb substitution at cobalt site on structural, morphological and magnetic properties of cobalt ferrites synthesized via double sintering method

Cobalt ferrites substituted with terbium (Tb) at cobalt (Co) and iron sites were fabricated by double sintering method and were characterized by the XRD, fourier transform infrared (FTIR) spectroscopy, scanning electron microscope and hysteresis loops measurements. The XRD analyses confirm the formation of single spinel phase for x=0.0 and thereafter a small peak of secondary phase occurred. The lattice parameter was found to increase by increasing Tb contents and this was attributed to the larger ionic radius of Tb ions as compared to Co ions. FTIR revealed two absorption bands which are characteristic feature of spinel ferrites. The morphology studies exhibit the inhomogeneous grain size distribution. The saturation magnetization was found to exist in the range of 63–67 emu/g and coercivity in the range of 405–435 Oe. The observed variation in saturation magnetization was attributed to the redistribution of cations due to the substitution of terbium at cobalt sites. The incorporation of terbium in cobalt ferrites substantially decreased the coercivity and remanence. The smaller values of coercive field suggest that these materials are potential candidates to be useful in high density data storage devices.