Orientation-phase-space-averaged properties of grain boundaries

The orientation-phase-space-averaged excess volume associated with grain boundaries in nanocrystalline Pd has been deduced from a rule-of-mixtures analysis of density and thermal expansion coefficient measurements. The atomic density is found to fluctuate along the grain-boundary core with an amplitude that could be reduced by low-temperature annealing of the sample. The scaling relation between resistivity and crystallite size changes significantly below approximately 7nm, suggesting that, in this limit, the intrinsic nature of a grain boundary becomes coupled to its spatial extent.