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A6: Characterization
Rock-salt chalcogenides such as AgSbTe2 are promising thermoelectric materials due to their anomalously low thermal conductivity. Previous work has shown that this low conductivity is due to phonon scattering, but the cause of this scattering has remained elusive: possibilities include intrinsic phonon anharmonicity and scattering from vacancies, cation disorder, and local atomic displacements. We present x-ray and neutron elastic diffuse scattering measurements, which show large atomic displacements from the rock-salt structure with nanoscale order. We discuss the contribution of this disorder to the thermal conductivity.
Research supported by the U.S. Department of Energy (DOE), Basic Energy Sciences (BES), Materials Sciences and Engineering Division and performed in part at beamline 33-BM-C at the Advanced Photon Source, Argonne National Laboratory. Use of the Advanced Photon Source, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory, was supported by the U.S. DOE under Contract No. DE-AC02-06CH11357. Research performed in part at ORNL's Spallation Neutron Source, sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy.