Local Optical Properties, Electron Densities, and London Dispersion Energies of Atomically Structured Grain Boundaries

Quantitative analysis of spatially resolved valence electron energy-loss spectra shows strong physical property contrasts for �5 and near �13 grain boundaries in Fe-doped SrTiO3, resulting in London dispersion interaction energies of 14 to 50 mJ=m 2 between the adjacent grains. The determination of local physical properties of grain boundary cores and the appreciable contribution of long-range London dispersion to interface energies provides new information on formation and control of interfaces in materials.