Effect of Transition Metal (Gd, Dy) Co-doping on Structural, Optical, and Magnetic Properties of CeO₂ Nanoparticles by Solid-State Reaction

Ce_(2-x–y)Gd_xDy_yO_2-δ nanoparticles with x = 0.02 and y = 0.02, 0.04, 0.06, and 0.08 with a size range of 15.81 to 40.42 nm have been obtained by annealing the solid-state reaction-derived nanocrystalline powders. Correlations between Gd and Dy doping and lattice expansion were found; lattice parameters increased from 5.423 to 5.468 Å. When Gd and Dy content increased, optical investigations showed unexpected bandgap behaviour that did not follow the predicted reduction. Red, green, blue, and violet emissions have been identified via photoluminescence analysis. SEM and EDS verified the homogenous elemental distribution of spherical nanoparticles. With a growing magnetic moment and coercive field, magnetic measurements showed paramagnetic activity.