Investigations of TM (Ni, Co) doping on structural, optical and magnetic properties of CeO2 nanoparticles

Abstract The undoped and Ce0.95TM0.05O2 (TM: Ni, Co) nanoparticles (NPs), synthesized by co-precipitation method, have been investigated. The structural, morphological, and magnetic properties of the synthesized NPs were characterized through X-ray diffraction (XRD), Transmission electron microscopy (TEM), UV–vis absorption spectroscopy, and dc-magnetization. The particle size as obtained through XRD analysis was found in the range of 7.0–13.0 nm. The Rietveld refinement of the XRD pattern confirms the single-phase nature of NPs. The lattice parameters determined using the Rietveld refinement process was found to have minimum value (5.407 A) for Co doping as compared to pure CeO2. The value of strain is maximum for Co-doped CeO2. The particle sizes obtained by TEM show dissimilarity with the XRD outcomes. However, the defects obtained using dislocation density is larger (2.0 × 10−2) in Co-doped CeO2 NPs. The lowest value of the bandgap has been observed (∼1.6 eV) for Co-doped CeO2 NPs. The highest value of saturation magnetization was found to be 8.1 × 10−3 emu/g for Co-doped CeO2 NPs with a small coercivity of 61.5 Oe. The magnetization measurements infer that the pure and TM doped CeO2 nanoparticles show weak ferromagnetic behavior at room temperature.