Effect of indium doping on magnetic properties of cerium oxide nanoparticles

Ce1-xInxO2 (x = 0.0, 0.02, 0.04, 0.06, 0.10 and 0.15) nanoparticles have been successfully synthesized by sol gel method using citric acid as a gelling agent. The gel obtained was characterised using DG-DTA analysis. The XRD confirmed the fluorite phase formation and purity of the compounds. Morphological studies revealed the flaky and porous nature as seen from SEM images. TEM showed that the average particle size obtained is less than 20 nm. The existence of Ce3+/Ce+4 oxidation states is confirmed from XPS data which in turn results in the oxygen deficiency in the system. The Electrical studies displayed the typical semiconductor nature of the nano-particles. The dilute magnetic property has been studied using VSM where the existence of very weak room temperature ferromagnetism is seen in pristine sample which is found to be enhanced on indium doping where for Ce0.85In0.15O2 composition showed a super-paramagnetic nature with negligible coercivity (Hc), in magnetisation v/s field studies. The saturation magnetisation (Ms) and coercivity (Hc) are further found to be enhanced at 50 K. When compared with the bulk sample the magnetism here was found to be lowered or reduced. This suggests that the oxygen vacancies and defects in the nanostructure are responsible for the observed magnetic behaviour in the prepared compounds. [Display omitted] •Pristine and In doped CeO2 nanoparticles prepared by sol-gel method.•Doped samples display super-paramagnetic behaviour.•XPS confirmed the mixed valence state of Ce3+/Ce4+.•Nano-size and associated defects are responsible for the observed magnetism.