Structural, mechanical, electronic, vibrational and thermoelectric properties of novel double perovskites Ba2MgPdO6 and Ba2MgPtO6 within DFT framework

The first-principles study of novel double perovskites Ba2MgPdO6 and Ba2MgPtO6 has been performed utilizing the concepts of Density Functional Theory (DFT). These materials have been studied for the first time to explore their structural, elastic, electronic, vibrational, thermodynamic and thermoelectric properties. Ba2MgPdO6 and Ba2MgPtO6 possess an FCC (Face centered cubic) crystal structure. The calculated band structure reveals the semiconducting nature of these compounds with the bandgap of 1.18eV and 1.7eV for Ba2MgPdO6 and Ba2MgPtO6 respectively. The elastic stability is predicted based on various calculated mechanical parameters such as Poisson ratio, Bulk modulus and elastic constants. The phonon dispersion curves are analyzed over the high symmetry directions of the Brillouin zone. Phonon vector representation based on Density Functional Perturbation Theory (DFPT) and phonon densities of states indicate the dynamical stability of these compounds. In addition to these properties, the thermoelectric response of Ba2MgPdO6 and Ba2MgPtO6 is investigated with the help of Boltzmann's theory. The figure of merit has been evaluated for both compounds throughout the range from 50 K to 1200 K to analyze their potential for future energy devices. The present study is aimed at providing an overview of many important properties of Ba2MgPdO6 and Ba2MgPtO6 to encourage experimental researchers to synthesize such types of compounds for modern technological devices. •Structural stability of cubic double perovskite compounds Ba2MgPdO6 and Ba2MgPtO6 has been studied.•Semiconducting nature of these compounds was confirmed by the presence of an energy band gap between the CB and VB.•Calculated elastic constants confirm the mechanical stability of double perovskites Ba2MgPdO6 and Ba2MgPtO6.•Eigen vector representation shows the individual vibrational contribution of different atoms inside a crystal structure.•Thermoelectric performance of both the compounds has been demonstrated with emphasis on figure of merit at 1200 K.