Comparative study on the physical properties of rare-earth-substituted nano-sized CoFe2O4

Nanotechnology manufacturing is rapidly developing and promises that the essential changes will have significant commercial and scientific impacts be applicable in an extensive range of areas. In this area, cobalt ferrite nanoparticles have been considered as one of the competitive candidates. The present study is based on the investigation of the effect of rare-earth (RE) incorporation on the physical properties of CoFe2O4. Rare-earth ions doped cobalt ferrites with composition CoRE0.025Fe1.975O4 where RE are Ce, Er and Sm have been synthesized by citrate auto combustion technique. Characterization is achieved using X-Ray diffraction (XRD) technique for structural analysis. The obtained data show that the samples exhibit a single-phase spinel structure. RE is successfully substituted into the spinel lattice without any distortion and it acts as inhibiting agent for grain growth. Room temperature M-H curves exhibit ferrimagnetism behavior with a decrease in saturation magnetization and coercivity indicating these materials can be applicable for magnetic data storage and magneto-recording devices. The electrical conductivity is studied as a function of frequency in the temperature range of 300-700 K. The conduction mechanism is attributed to the hopping mechanism. The Seebeck coefficient S is found to be positive for Ce indicating that Co/Ce ferrite behaves as a p-type semiconductor. While it is fluctuated between positive and negative for Er/Sm-doped samples throughout the studied temperature range. The cobalt doped with Er3+ and Sm3+ exhibits degenerated semiconductor trends at higher temperatures. Such data offer a new opportunity for optimizing and improving the performance of cobalt ferrite where the physical properties are decisive.