Comparing the Effect of In2O3 and Eu2O3 Impurities on the Structural and Optical Properties of Cerium Oxide

Abstract

     This work compares the changes in optical and structural properties of cerium oxide (CeO₂) when doped with different concentrations (3%,5%,7%, and 9%) of two oxides, In₂O₃ and Eu₂O₃. X-ray diffraction and spectrophotometry were employed in the visible, ultraviolet, and near-infrared regions. The findings demonstrated that CeO₂ doped with In₂O₃ and Eu₂O₃ thin films were polycrystalline and had a cubic structure. The crystal size increased from 20.5 to 32.15 when Eu₂O₃ doping ratio increased from 0% to 7% and then decreased to 28.46 nm at 9%. While the crystal size showed an increase from 20.5 to 21.42 nm with the increase of the In₂O₃ doping ratio, while the lattice constant measured for cubic CeO₂ changed opposite to that. The optical measurement showed that Eu₂O₃ and In₂O₃ doped CeO₂ thin films have a direct band gap with allowed transition with 3.0 eV for the undoped CeO₂. The band gap energy changed in a non-regular manner with the increase of the doping ratio of both oxides. The minimum band gap energy was 1.2 eV obtained for 7% Eu₂O₃ doped CeO₂ thin film, and the minimum band gap energy was 1.4 eV obtained for 9% In₂O₃ doped CeO₂. These results qualify them for use as absorbers in solar cell applications.