High temperature dependent elastic properties of single crystalline SnSe

Abstract

In recent years, single crystalline SnSe has been widely studied as a thermoelectric material which exhibits a high thermoelectric figure of merit (ZT ~ 2.6 at T > 900 K). The efficiency has been enhanced due to the significantly low thermal conductivity, arising from the strong lattice anharmonicity of the layered orthorhombic crystal structure. A study of the thermo-elastic properties of single crystalline SnSe is essential to gain a better understanding of the lattice anharmonicity and the low thermal conductivity. The highly anisotropic orthorhombic crystal structure of SnSe results in nine independent elastic constants. This work seeks to investigate the temperature dependent elastic constants of single crystalline SnSe, using resonant ultrasound spectroscopic (RUS). Here, we report the experimentally observed elastic constants and their variation at elevated temperature from room temperature to ~775 K. The temperature dependent elastic and thermal properties have been derived from the elastic constants and compared to independent heat capacity data.