SrBO ₃ (B = V, Ru) (110) And (001) Surface Structure And Stabilization Mechanism

The cubic SrVO3and SrRuO3surfaces were investigated systematically by the first-principles density functional theory (DFT) plane-wave pseudopotential method. We usedthe CASTEP code to perform relevant calculations of atomic structures, electronicstructures, and thermodynamic stabilities of bulk crystals as well as five (110) polarsurfaces of each system. Furthermore, we also considered the influence of (001) surfaceon stability phase diagram of (110) terminations.The detailed calculation results indicate that for each of SrVO3and SrRuO3twostoichiometric terminations of (110) polar surface undergo significant changes in atomicand electronic structures with respect to bulk materials. For the SrBO (B=V, Ru)terminations, an anomalous filling of conduction band was observed, and this surfacepossesses metallic characteristics. For the O2termination, two surface oxygen atoms closeto each other and form a peroxo bond. For the three nonstoichiometric BO-, Sr-and O-terminated surfaces with metallic characteristics, their electronic structures are verysimilar to bulk crystal. Charge redistribution results for the five terminations confirmedthat the changes in electronic structure and surface composition are responsible for theirpolarity compensation. An investigation of thermodynamic stability diagram indicatedthat no distinct stability domains can be localized for O2-terminationed surfaces of SrBO3(B=V, Ru) and SrRuO termination of SrRuO3. Furthermore, three nonstoichiometric(110) terminations and two nonpolar (001) terminations (SrO and BO2) can be stabilizedin some given regions.