A first-principles investigation of the stabilities and electronic properties of SrZrO₃(1 1 0) (1 × 1) polar terminations

The stabilities and electronic properties of SrZrO₃(1 1 0) (1 × 1) polar terminations were investigated systematically by the first-principles density functional theory method. Five possible polar surfaces, i.e. O-deficient, O-rich, stoichiometric, SrO-rich and SrO-deficient ones, were considered. The calculated results indicated that the charge neutralization and polarity compensation condition could be achieved by charge redistributions of surface atoms. For the O-deficient (1 1 0) termination, some filled electronic states were separated from the original conduction bands, while a surface reconstruction was found for the O-rich (1 1 0) surface. The remaining three (1 1 0) terminations remained insulated. Furthermore, a stability diagram involving seven different terminations was constructed using the surface grand potential technique, in which the effect of the chemical environment was included. The calculated results indicated that three (1 1 0) (O-rich, SrO-rich and stoichiometric) and 2 (0 0 1) (ZrO₂ and SrO) terminations could be stabilized in distinct areas, whereas the O-deficient surface was unstable within the whole region. Finally, we drew a comparison of stability behaviors between SrZrO₃(1 1 0) (1 × 1) polar surfaces and the counterparts of ATiO₃(A = Ba, Pb, Sr) and BaZrO₃ materials.