Quantitative x-ray diffraction techniques have been used to estimate the mean square thermal displacements of atoms in the interface region, and to measure the thermal expansion coefficients parallel and normal to the interface plane for the large-angle $\Sigma =13\mathrm{}$ ($\theta =22.6\mathrm{}°$) [001] twist grain boundary in Au. The thermal properties of the grain boundary are shown to be much different from those of the bulk material, which indicates that the effective interatomic potential for an atom in the grain boundary is different from that in bulk Au.

• Received 20 June 1988

DOI:https://doi.org/10.1103/PhysRevLett.61.2237