Dislocation strain as the mechanism of phonon scattering at grain boundaries

Thermal conductivities of polycrystalline thermoelectric materials are satisfactorily calculated by replacing the commonly used Casimir model (freqeuncy-independent) with grain boundary dislocation strain model (frequency-dependent) of Klemens. It is demonstrated that the grain boundaries are better described as a collection of dislocations rather than perfectly scattering interfaces.