Influence on the structural characteristic of defect solid solution GdxZr1−xO2−x/2 with 0.18 ⩽ x ⩽ 0.62 under longer term annealing studied by 155Gd Mössbauer spectroscopy

Three kinds of defect solid solution GdxZr1−xO2−x/2 with 0.18 ⩽ x ⩽ 0.62, including the three single crystal samples with x = 0.21, 0.26 and 0.30, were investigated by 155Gd Mössbauer spectroscopy at 12 K. Difference in the structural characteristic under longer term annealing were confirmed by comparing the 155Gd Mössbauer parameters of the polycrystalline samples sintered one time and twice at 1773 K for 16 h in air, respectively. The results indicated that the polycrystalline samples sintered twice have relatively equilibrated structure by comparing with the three single crystal samples. After being sintered twice, basically the local structure around the Gd3+ ions does not change, but the degree of the displacements of the six 48f oxygen ions from positions of cubic symmetry becomes slightly smaller, and distribution of the Gd3+ ions in the system becomes more homogeneous.