Enhanced Room-Temperature Ferromagnetism on Co-Doped CeO2 Nanoparticles: Mechanism and Electronic and Optical Properties

The present study reports the effect of Co doping on the structural, optical, magnetic, and electronic properties of CeO2 nanoparticles (NPs) synthesized by a simple low-temperature co-precipitation method. Co doping was introduced by adding CoCl3 with different mole percentages (0%, 2%, 4%, and 6%) to cerium nitrate, which resulted in room-temperature ferromagnetism (RTFM). TEM and XRD analysis showed that the Co-doped CeO2 NPs are monodispersed with face centered cubic structure. The 6% Co-doped CeO2 NPs showed a coercivity value of 155 Oe and saturation magnetization of 0.028 emu/g at room temperature. The electronic structures of the as-prepared CeO2 and Co-doped CeO2 NPs were investigated by X-ray absorption near-edge structure (XANES) spectroscopy. The XANES spectra at Ce M- and L-edges clearly indicated a decrease in the valency state of Ce ions from Ce4+ to Ce3+ upon Co doping. This causes redistribution of oxygen ions and Co–Co bonding. The XANES study revealed that Co doping plays a prominent ro...