Single-layer TiO_x reconstructions on SrTiO_3 (111): (7~(1/2) × 7~(1/2))R19.1°, (13~(1/2) × 13~(1/2))R13.9°, and related structures

摘要

The atomic structures of two reconstructions, (root 7 x root 7)R19.1 degrees and (root 13 x root 13)R13.9 degrees, on the SrTiO3 (111) surface were determined using a combination of density functional theory and scanning tunneling microscopy data and APW + lo density functional theory minimizations and simulations. These reconstructions belong to the same structural family made up of an interconnected, single layer of edge-sharing TiO6 and TiO5[] octahedra. This family of reconstructions between 0.5 and 1.5 excess TiO2, representing the lowest-reported TiO2 coverages for reconstructions on this surface. This family is found to include the previously-solved (2 x 2)a reconstruction. They all follow a simple rule for surface composition, which serves as a tool for better understanding and predicting the structure of other reconstructions of arbitrary surface unit cell size on SrTiO3 (111). This reconstruction family and the calculations of surface energies for different hypothesis structures also shed light on the structure of Schottky defects observed on these reconstructed SrTO3 (111) surfaces.