Raman study on structure of U1−yGdyO2−x (y=0.005, 0.01, 0.03, 0.05 and 0.1) solid solutions

•Investigation of structural character of U1−yGdyO2−x solid solutions.•Defect structures in U1−yGdyO2−x solid solutions were evaluated by Raman spectroscopy.•Oxygen deficiency due to Gd content causes Raman band related to oxygen vacancy.

The U1−yGdyO2−x solid solutions with y = 0.005, 0.01, 0.03, 0.05 and 0.1 were characterized by Raman spectroscopy to investigate the defect structure induced by oxygen vacancies. The oxygen deficiencies of solid solutions were estimated by the relation between the doping level and a lattice parameter calculated from X-ray diffraction patterns. Raman mode shifts to higher wavenumber with increasing doping level showed that crystal lattice disorder due to oxygen vacancies. The frequency shifts and relative ratio of Raman modes were enabled to be the indicator for composition, defect and oxygen vacancy of U1−yGdyO2−x solid solutions.