Phonon dispersion in the superionic Ag8SnSe6 sample with ultralow lattice thermal conductivity

Materials with superionic behavior are a group of novel thermoelectric candidates with excellent thermoelectric performance due to their ultralow lattice thermal conductivity. In the past five years, the study of the underlying mechanism for the ultralow lattice thermal conductivity has been a hot topic in the thermoelectric community. However, there still exist large controversies about the explanation, which is caused mainly by the lack of a large single crystal for phonon studies. Here, we have got a large Ag8SnSe6 single crystal with superionic behavior. We plan to use the LET cold neutron spectrometer to map the phonon dispersions as a function of temperature. From this experiment, we expect to find the anomalies in the phonon dispersions as well as the phonon lifetimes, hence giving a thorough understanding of the ultralow lattice thermal conductivity in superionic materials.