Effect of Pressure on Mechanical and Thermal Properties of SnSe2

Density functional theory based computations are used to investigate the pressure effect (0–20 GPa) on mechanical and thermal properties of SnSe2. It is noted that SnSe2 obeys mechanical stability criteria in the pressure range of 0–20 GPa. The elastic constant dependence on pressure is greater in out of plane direction as compared to in plane direction. At 20 GPa the out of plane elastic constant increases by 1.86 times as compared to the in plane elastic constants which increase by 55 %. An analysis of values of Poisson’s ratio and ratio of bulk modulus to shear modulus (B/G) indicates that SnSe2 is brittle and the brittleness decreases with increase in pressure. The hardness increases by 1.33 times at 20 GPa and the Debye temperature is enhanced by 1.24 times as compared to corresponding values of these parameters at 0 GPa. The minimum lattice thermal conductivity exhibits a slight increase with pressure. The material is more isotropic at higher pressure which is revealed from the computed anisotropic factor. Free energy of SnSe2 increasers with pressure increase. Heat capacity of SnSe2 first increases with pressure increase and then decreases with further increase in pressure. Entropy of SnSe2 decreases with pressure increase.