A density functional theory study of the thermoelectric properties of K3AuO

We report for the first time the structural, electronic, lattice dynamics, mechanical and electronic transport properties of K3AuO calculated using first-principles concepts within the framework of density functional theory. Electronic transport coefficents are derived at the level of the Boltzmann's transport theory with the electronic relaxation times of K3AuO estimated using the deformation potential method. The calculated lattice constants and equilibrium volumes of K3AuO are in excellent agreement with the available experimental data. Moreover, the obtained elastic constants satisfy the elastic stability criteria and thus infer that K3AuO is mechanically stable. The calculated band gap of K3AuO is in good agreement with the experimental measured value. Furthermore, our obtained phonon spectrum do not have negative frequencies and thus indicate that K3AuO is dynamically stable. Our results also show that K3AuO possesses a low lattice thermal conductivity (k(L)) value of 0.54 W/mK at 300 K, a value which is even lower than the measured k(L) of Bi2Te3 (1.28 W/mK at 300 K). Moreover, p-doped K3AuO is found to produce a power factor which is 1 order of magnitude larger than that of practical Bi2Te3 at 300 K. A high thermoelectric figure of merit is revealed in p-type K3AuO (ZT = 2.41 at 750 K) which indicate that K3AuO is a promising candidate for thermoelectric applications. (C) 2020 Elsevier B.V. All rights reserved.