Room Temperature Resonant Ultrasound Spectroscopy of Single Crystalline SnSe

Abstract

Recently, the anisotropic single crystalline SnSe has gained tremendous interest as a promising thermoelectric material. The elastic constants of such anisotropic crystals are notoriously difficult to measure yet play a crucial role in many thermodynamic properties. We report for the first time the nine independent elastic constants of its stiffness tensor as measured by resonant ultrasound spectroscopy. Our experimental values of the elastic constants are in good agreement with those reported by the density functional theory of SnSe, except for C 12 . The Voigt−Reuss− Hill method was used to determine the isotropic polycrystalline elastic moduli from the measured elastic constants of SnSe, which were found to be in agreement with theoretical values. Notably, the heat capacity of single crystalline SnSe deduced from our measured elastic moduli is in excellent agreement with the room temperature value of heat capacity determined from thermal transport measurements.

Thermal diffusivity and its lower bound in orthorhombic SnSe

“…Using the components of the elastic tensor experimentally reported in ref. [39], we calculated the longitudinal sound velocities along b and c to be, respectively v l,b =3146 m/s and v l,c =2317 m/s (see Appendix). Remarkably, the ratio of the velocities along the two orientation corresponds to the anisotropy of thermal diffusivity in the intrinsic regime.…”

“…The sound velocities of SnSe can be computed through the 9 non-zero elastic moduli of the stiffness tensor (see Table I), which were measured by ultrasound spectroscopy in single crystalline SnSe [39].…”

Атомистическое моделирование решеточных свойств SnSe

“…В табл. 2, а) приведено сопоставление результатов расчета упругих констант и модулей Pnma-фазы SnSe с помощью DFT и ACE-потенциала в сопоставлении с экспериментальными данными [29] и результатами расчета [8]. Видно, что, как и в случае параметров кристаллической структуры, результаты расчета на основе DFT и ACEпотенциала очень близки.…”

Low pressure dependent elasticity of porous ceramics

“…Resonant Ultrasound Spectroscopy (RUS) is a widely used most efficient and precise experimental technique to determine the elastic tensor of materials with different crystal structures . Compared to other conventional mechanical testing methods, RUS has gained interest among the experimental material science fields due to its precision, ability to resolve all elastic constants in a single measurement, and of taking measurements over a range of temperatures and hydrostatic pressures.…”

“…Resonant Ultrasound Spectroscopy (RUS) is a widely used most efficient and precise experimental technique to determine the elastic tensor of materials with different crystal structures. [23][24][25][26] Compared to other conventional mechanical testing methods, RUS has gained interest among the experimental material science fields due to its precision, ability to resolve all elastic constants in a single measurement, and of taking measurements over a range of temperatures and hydrostatic pressures. In RUS, a polished rectangular parallelepiped-shaped crystal specimen is placed in between two acoustic transducers, one of which drives the sample in a swept-frequency continuous wave (CW) mode over a selected frequency range, while the other detects the sample response to the excitation (Figure 1).…”