Temperature- and pressure-dependent phonon dynamics properties of gallium selenide telluride

Understanding the thermodynamic properties of materials is a fundamental issue in physics, and its knowledge is crucial for targeting a specific material for possible applications. In this work, we report a temperature- and pressure-dependent Raman study of bulk GaSe0.5Te0.5 alloy, besides their relevant thermodynamic parameters. Our results show a nonlinear redshift for the A1g$$ {A}_{1g} $$ and E2g$$ {E}_{2g} $$ vibrational modes as the temperature increases in the temperature range from 10 to 748 K. Such behavior is well described by considering both thermal expansion and phonon-phonon coupling contributions. By combining density functional theory (DFT) calculations and Raman spectroscopy experiments, the anharmonic constants relative to the three- and four-phonon decay processes, mode-Gruneisen parameters, Debye temperature, thermal expansion coefficient, and bulk modulus were estimated for GaSe0.5Te0.5 alloy. Furthermore, the high-pressure measurements and DFT calculations, performed in the pressure range from 0 to 26.4 GPa, show a quadratic trend for the omega A1g$$ {\omega}_{A_{1g}} $$ and omega E2g$$ {\omega}_{E_{2g}} $$ modes as a function of pressure, with the A1g$$ {A}_{1g} $$ modes being more compressible than E2g$$ {E}_{2g} $$ one, that is, partial differential omega A1g partial differential P> partial differential omega E2g partial differential P$$ \frac{\partial {\omega}_{A_{1g}}}{\partial P}>\frac{\partial {\omega}_{E_{2g}}}{\partial P} $$. No structural phase transition is observed until the maximum pressure reached in the experiment. This study took a step forward in the understanding of mechanical and thermal properties related to GaSe0.5Te0.5 alloy, whose determined parameters are important for designing new applications.