Defect mediated changes in structural, optical and photoluminescence properties of Ni substituted CeO2

Local and long range structure, optical and photoluminescence properties of sol-gel synthesized Ce1-xNixO2 nanostructures have been studied. The crystal structure, lattice strain and crystallite size have been analyzed. A decrease in lattice parameter may be attributed to substitution of Ce with smaller Ni ion. UV-Vis measurement is used for studying the effect of Ni substitution on bandgap and disorder. The bandgap decreases with Ni substitution and disorder increases. The PL spectra show five major peaks attributed to various defect states. The PL emission decreases with Ni substitution owing to increase in defects which acts as emission quenching centers. The lattice disorder and defects have been studied using Raman spectroscopy. Raman measurement shows that oxygen vacancies related defects are increasing with Ni substitution which causes changes in optical and PL properties. Local structure measurements show that Ni substitution leads to oxygen vacancies which does change host lattice structure notably. Ce4+ to Ce3+ conversion increases with Ni substitution.