Effects of Zr4+-doping on the properties of (Lu, Gd)2O3: Eu transparent ceramics: Insight from the photoluminescent spectra in as-sintered and annealed state

The origin of microstructural inhomogeneity in vacuum‐sintered ZrO2‐doped Lu2O3 transparent ceramics

“…The transition from [ZrO8] to [ZrO7] unit is caused by oxygen vacancies generated during vacuum sintering at excessively high temperatures. As shown in the inset of Figure 7C, the color of the as‐sintered ceramics darkens with an increase in sintering temperature and the ZrO 2 ‐doping content, suggesting an increased oxygen vacancies concentration 37 . The new broad peak at 560 cm −1 is attributed to the disordered structure of the oxygen vacancies, which breaks the translational symmetry 38,39 .…”

“…As shown in the inset of Figure 7C, the color of the as-sintered ceramics darkens with an increase in sintering temperature and the ZrO 2 -doping content, suggesting an increased oxygen vacancies concentration. 37 The new broad peak at 560 cm −1 is attributed to the disordered structure of the oxygen vacancies, which breaks the translational symmetry. 38,39 According to an ab-initio calculation on Lu 2 O 3 with a C-type bixbyite structure, 40 positively charged oxygen vacancies (V •• O and V • O rather than neutral ones (V × O ) cause the short-range structural fluctuations associated with pronounced atomic displacements.…”