Publication Type
Journal
Journal Name
Physical Review Materials
Publication Date
Page Number
045403
Volume
4
Issue
4
Abstract
Materials with simple crystal structure usually exhibit substantial lattice thermal conductivity (κlatt) due to a scarcity of strong phonon-phonon scattering channels. Yet here we find simple CsCl-structure TlBr to have an extremely low room temperature κlatt∼0.5W/m-K, while at low temperature we find a high κlatt of 155W/m-K. This extreme range of conductivity behavior results from lattice-instability-related anharmonicity, effective only at temperatures above ∼30K. Manipulating these instabilities (e.g., pressure, strain) may yield a pathway to ultralow thermal conductivity via intrinsic phonon resistance in similar materials.
