About this Abstract |
Meeting |
2022 TMS Annual Meeting & Exhibition
|
Symposium
|
Alloys and Compounds for Thermoelectric and Solar Cell Applications X
|
Presentation Title |
Liquid-like Ion Diffusion Leading to the Ultralow Thermal Conductivity of Ag8SiTe6 Argyrodite |
Author(s) |
Pai-Chun Wei |
On-Site Speaker (Planned) |
Pai-Chun Wei |
Abstract Scope |
Combining ultrahigh-resolution synchrotron X-ray diffraction and first-principle molecule dynamics simulations, here we report the liquid-like behavior of Ag ions leading to the ultralow thermal conductivity of Ag8SiTe6 argyrodite and a falloff in isobaric specific heat to ~ 50% of the classic Dulong-Petit limit. We show that the augmented ion diffusion at T > 260 K triggers the observed liquid-like thermal transport behavior, while the gradual localization of Ag ions at T < 260 K gives rise to consecutive symmetry breaking, lattice distortion, more solid-like transport properties. We also demonstrate the presence of soft and damped vibration modes and anomalous Stokes-anti-Stokes ratios that infers the persistently excited Ag cages with unusual statistics. These findings provide valuable insights into the argyrodite family and disclose the new state of matter that shall beckon further characterization. |
Proceedings Inclusion? |
Planned: |
Keywords |
Electronic Materials, Modeling and Simulation, Phase Transformations |