Study on the effect of pressure on the properties of intrinsic point defects in monoclinic zirconia: Ab initio calculations

Abstract

First-principles calculations were performed to investigate the effects of external pressure on the properties of intrinsic point defects in monoclinic zirconia. Our results show that when the applied external pressure increases from atmospheric pressure to 14.9 GPa, the formation energies of oxygen vacancies decrease with increasing pressure, while the formation energies of the cation and anion interstitials increase all over the pressure regime investigated. Among them the most remarkable change occurs in neutral zirconium interstitial with an increase of 2.21 eV. In particular, the formation energy of zirconium vacancy depends strongly on its charge state. For all the chemical potential and Fermi level considered, the cation and anion vacancies are the most stable defects in all cases. The present calculations also reveal that the formation energies of Frenkel defects could be raised by external pressures, while the energetics of Schottky defects are not much affected. Moreover, the charge state transition of defects is found to be greatly influenced by the external pressures, and thus the stability diagram of defects in ZrO2 is strongly dependent on external pressures. Our findings suggest that external pressures should raise the concentration of oxygen vacancies significantly.

Theoretical Calculations Meet Experiment to Explain the Luminescence Properties and the Presence of Defects in m-ZrO2

“…Experimental analyses pointed out that V O entities may coexist with titanium impurities and could impact the photoluminescence intensity. , Regarding the luminescent properties, the most commonly adopted mechanism , which involves intra-site d - d electronic transitions at Ti 3+ explains the changes in the photoluminescence intensity by the reduction of Ti 4+ species due to the presence of neighboring V O species. This supposition is notably weakened by the absence of Ti 3+ species into ESR spectra …”

“…To our knowledge, such simulations have been reported for (only) intrinsic point defects in m-ZrO 2 . 20,[36][37][38][39][40][41][42][43][44] Consequently, this prompted us to revisit in-depth the impact of defects (i.e., native defects and substitution of Zr by Ti) in m-ZrO 2 on its electronic structure.…”

“…More recently, DFT has been employed to provide information on charge transition levels within the band gap, − enabling one to characterize the presence and the nature of defects in the studied structure. To our knowledge, such simulations have been reported for (only) intrinsic point defects in m -ZrO 2 . ,− Consequently, this prompted us to revisit in-depth the impact of defects ( i.e. , native defects and substitution of Zr by Ti) in m -ZrO 2 on its electronic structure.…”

First-principles study of strain effect on the formation and electronic structures of oxygen vacancy in SrFeO 2

“…Thus, the V o concentration is expected to be low in equilibrium condition. Although the E form is positive (e.g., 5.1 eV, zero strain, oxygen rich), it is comparable with the E form (zero strain, oxygen rich) of some typical TMOs, such as HfO 2 [32] (5.93 eV), ZnO [33] (5.37 eV), ZrO 2 [34] (5.97 eV), etc. The V o is often unintentionally introduced during the growth or annealing process of these TMOs.…”