Modelling of point defects in monoclinic zirconia

Luminescence of rare earth-doped Si–ZrO2 co-sputtered films

“…Fig. 3 shows possible components that could make up the visible PL spectra of the film samples for 488.0 nm excitation, including emissions related to oxygen vacancy defects or interstitial oxygen defects [2,14,21,22] in ZrO 2 or YSZ, SiQO surface state emissions [23] related to small SiO x (xo2) regions within the film samples and the following Er 3+ emissions: 2 H 11=2 ! 4 I 15=2 , 4 S 3=2 !…”

“…The T-defects would correspond to the oxygen vacancies distributed to be on opposite cube corners with relaxed oxygens surrounding the vacancies along the [1 0 0] edges [22]. The positively charged oxygen vacancy V þ 4 is surrounded by four Zr nearest neighbors, which are moved apart (0.1 Å ) from the vacant site and the remaining electron (related to the vacancy) is strongly localized near the vacant site [21]. The doubly positively charged oxygen vacancy V 2þ 4 is also surrounded by four Zr neighbors but further displaced (an additional 0.1 Å ).…”

“…The doubly positively charged oxygen vacancy V 2þ 4 is also surrounded by four Zr neighbors but further displaced (an additional 0.1 Å ). In the case of the O 0 3 interstitial defect the lattice oxygen relaxes to accommodate the interstitial, distorting the original triple-planar O-Zr 3 group into a slight pyramid with its apex pointing away from the interstitial [21]. The excitation wavelength in this case is not resonant with any Er 3+ energy level and neither is the V-type center defect level, so there is no excitation of the energy levels of the Er 3+ ions that could produce emission in the visible.…”

Luminescence of Er-doped silicon oxide–zirconia thin films

“…Band B can be related also to V + -defects in ZrO 2 , positively charged electron-trapping oxygen vacancies with the surrounding Zr neighboring ions slightly displaced [30,31]. Band C would correspond to V 2+ -defects in ZrO 2 , doubly positively charged electron-trapping oxygen vacancies with the surrounding Zr neighboring ions more displaced [32,33]. Band D, the weakest, would correspond to O 0 3 interstitial defects in ZrO 2 , where the lattice oxygen relaxes to accommodate the interstitial, distorting the original triple-planar O-Zr 3 group into a slight pyramid with its apex pointing away from the interstitial [32,33].…”

“…Band C would correspond to V 2+ -defects in ZrO 2 , doubly positively charged electron-trapping oxygen vacancies with the surrounding Zr neighboring ions more displaced [32,33]. Band D, the weakest, would correspond to O 0 3 interstitial defects in ZrO 2 , where the lattice oxygen relaxes to accommodate the interstitial, distorting the original triple-planar O-Zr 3 group into a slight pyramid with its apex pointing away from the interstitial [32,33]. The G8 sample presents an additional band with band center at 492 nm (band E), also reported previously [30,34] and assigned to F-type oxygen vacancies coordinated by normal cations [30] or C-defects (heptacoordinated Zr 3+ ions in trigonally distorted cubes that serve as electron traps) [35] (see inset of Fig.…”