Defects and oxygen vacancies modified properties of transition metal doped Ce0.95X0.05O2 (X = Fe, Co, Ni) nanoparticles

•Transition metal doped CeO2 Nps synthesized by co-precipitation method.•Rietveld refinements of high-quality powder XRD show good convergences.•Band gap tunability was seen with transition metal doping in CeO2 Nps.•Transition metal doping influenced the photoluminescence and optical properties. In this study, pure and transition metal doped (TM = Fe, Co, and Ni), cerium oxide nanoparticles have been synthesized by the co-precipitation techniques. Rietveld refined X-ray diffraction (XRD) patterns affirm the monophase nature with cubic symmetry having an Fm3m space group and crystalline size varies in the range of 9–14 nm calculated by Debye Sherer's formulation. The morphological study has been done by scanning electron microscope (SEM) technique anticipated that agglomerated grains symmetry with the typical grain size distribution varies from 45 to 52 nm. The effect of transition metal doping on bending/stretching vibrational modes has been effectively investigated by FTIR analysis. The strong absorbance edge was seen in the UV region and shifted in the red region with the doping of transition metal ions. The tauc’s plot of UV–vis absorption uncovers the bandgap decreased from 2.87 eV to 2.42 eV on transition metal doping. The photoluminescence spectroscopy (PL) technique was used to investigate the presence of oxygen vacancies and intrinsic defects in the host CeO2 lattice when doped with transition metal ions. These imperfections induce the lattice disorder and shift in the energy bandgap from the UV to the visible region of the spectrum by affecting its electronic transitions. The CIE chromaticity coordinates of pure and transition metal doped compounds observed in the blue region might be applicable in display devices. In this manner, these materials can be fascinating for tuneable electrical and optical devices.