Stability, lattice, transport and thermoelectric properties of \(\hbox {CdGa}_{2}\hbox {Se}_{4}\) and \(\hbox {ZnGa}_{2}\hbox {Se}_{4}\) ternaries

Structural properties of \(\hbox {CdGa}_{2}\hbox {Se}_{4}\) and \(\hbox {ZnGa}_{2}\hbox {Se}_{4}\) ternary compounds in their tetragonal phase have been investigated using the first-principles approach. These materials are stable, as supported by the computed vibrational and mechanical properties. Having established their stability, prediction of their thermal conductivity and consequently the dimensionless figure of merit was undertaken. According to the simulations results, these ternary compounds have fairly low values of lattice thermal conductivity of about 1.45 and 1.25 W/mK at room temperature for \(\hbox {CdGa}_{2}\hbox {Se}_{4}\) and \(\hbox {ZnGa}_{2}\hbox {Se}_{4}\), respectively. Their Seebeck coefficient and electrical conductivity are moderate, resulting in outstanding thermoelectric properties as backed by the dimensionless figure of merits that are beyond unity, i.e., 1.17 and 1.27 for \(\hbox {CdGa}_{2}\hbox {Se}_{4}\) and \(\hbox {ZnGa}_{2}\hbox {Se}_{4}\), correspondingly at a temperature of 1000 K. To our understanding, until now, there is lack of scientific report about thermoelectric properties of these compounds, forming the novelty of this study.