Structure, electronic and thermoelectric properties of XCuOTe (X: Bi, Ce, La) by density functional theory

Abstract

To lessen the energy crisis, one of the imperative ways out is to exploit the waste energy, in particular, waste heat. To make use of waste heat, among many ways the most appropriate and simplest one is the application of thermoelectric (TE) materials, as it does not require any appreciable changes in the industrial as well as domestic appliance technology. Although TE materials are recently investigated for refrigeration and power generation applications, the key issue of their limited applications is the development of high-performance TE materials. Oxytellurides are considered potential TE materials because of their aligned electronic bandgap energy. However, the exploration of a new and low cost material within a short period is very challenging. In this work, XCuOTe (X= Bi, Ce, and La) oxytellurides are investigated with a computational technique based on density functional theory (DFT) together with semi-empirical Boltzmann theory. Calculations are performed using the full potential linear augmented plane wave (FPLAPW) method implemented in WIEN2k package and BoltzTraP package. The quality of the DFT results is comprehensively dependent on the chosen form of the exchangecorrelation functionals. To obtain more precise results, different exchange-correlation functionals such as local density approximation (LDA), generalized gradient approximation (GGA), Wu-Cohen (WC-GGA) and modified Becke-Johnson (mBJ) potential are used. The obtained results for structural parameters are in good agreement with the available reported experimental and theoretical results in the literature. Based on the band structure calculations, BiCuOTe and LaCuOTe show their semiconducting behavior whereas CeCuOTe exhibits its metallic disposition. In line analysis of the obtained thermoelectric properties, results show that BiCuOTe and LaCuOTe are potential thermoelectric materials with higher Seebeck coefficients, electronic conductivities and power factor, S2a, values.