Elastic softening and lattice dynamical insights into thermoelectric CdS _{1− <i>x</i>} Se _<i>x</i> alloys

Abstract Ternary alloys of group II–VI semiconductor are trending due to their tunable optical, electronic and thermoelectric properties. This work includes the evaluation of mechanical, thermophysical and ultrasonic behaviour of ternary alloys CdS 1− x Se x at room temperature. This analysis presents linear and nonlinear behaviour of the elastic constants of Cadmium-sulfo-selenide alloys for their different compositions using many-body Lennard-Jones potential interaction model. The mechanical and thermo-physical properties of CdS 1− x Se x have been evaluated using the second and third order elastic constants. Behaviour of propagation of ultrasonic waves in these alloys has been examined for non-destructive evaluation. For this, we have determined the longitudinal, shear, quasi-shear components of ultrasonic velocities and Debye average velocity in different crystallographic directions. Substituting Se in CdS enhances its thermoelectric potential by offering mechanical flexibility and improved anharmonic stability, reducing lattice thermal conductivity. This theoretical insight highlights CdS 1− x Se x as a promising system for doping strategies and future experimental exploration in next-generation thermoelectric materials.