First-principles calculations of defects near a grain boundary in MgO

The electronic structure of oxygen vacancy and proton defects close to grain boundaries in MgO are calculated using first principles methods. These defects, in various charge states, favorably segregate to grain boundaries and can trap electrons. The interplay between electron and defect segregation provides a mechanism for charge to build up at boundaries, for example, under irradiation or applied electrical voltage. The theoretical calculations presented provide insight into the complex electronic properties of metal-oxide grain boundaries that can be difficult to obtain by experiment alone but which are important for many applications.