Study on solid solubility of Gd in UO2 using X-ray diffraction

The change in solid solubility of Gd after sintering of UO2 with Gd additions has been explained based on the X-ray diffraction study. It was observed that Gd has large solid solubility in UO2 due to the same ionic radii of U4+ and Gd3+ in the lattice. On sintering, the observed reduction in the lattice parameter of UO2 with Gd addition is due to formation of oxygen ion vacancies. Two different methods were used for the preparation of specimen materials: co-precipitation and mechanical mixing. The co-precipitation route, unlike mechanical mixing route, gives atomistic mixtures where lattice parameter changes before sintering with addition of Gd.