Electronic structure of grain boundaries in SrTiO₃

The formation of Schottky potential barriers and their complex interplay with current transport across electrically active grain boundaries (GBs) give rise to many novel properties of electroceramics such as the varistor behavior. The origin of the GB electrical activity lies in the defect chemistry, and associated variations in geometry, chemistry and electronic structure at GBs. Motivated by the recent experimental results of dopant identification and spatially resolved quantification of GB charge and associated space-charge across GBs in SrTiO₃, we have performed atomic-level electronic structure calculations on GBs in SrTiO₃. The first-principles density-functional embedded-cluster Discrete-Variational (DV) method is used to determine charge densities and densities of states (DOS) for several idealized models of symmetrical tilt GBs in SrTiO₃ which have been derived from a combination of atomistic lattice-static simulations and experimental electron microscopy analysis.