Stoichiometric and Nonstoichiometric Surface Structures of Pyrochlore Y2Zr2O7 and Their Relative Stabilities: A First-Principles Investigation

First-principle total energy calculations were performed to investigate the atomic structures and relative stabilities of two low miller-index surfaces pyrochlore Y2Zr2O7. The stoichiometric Y2Zr2O7 (110) (100) predicted, with lowest formation energies 1.20 1.47 J/m2, respectively. Based on a thermodynamic defect model, non-stoichiometric surface further evaluated as function environmental oxygen partial pressure (pO2) temperature (T). With all results, we able construct phase diagrams for T = 300 1400 K. strong correlation between structural stoichiometry was revealed varying pO2. At given T, most stable termination would change from (Y,Zr)−rich (ns−2Y2Zr6O) O−rich ones (ns−4O_2 ns−4O_1) increasing pO2, while that (stoi−1Y1Zr_1) one (ns−5O). critical pO2 value transition moves its higher end T.