Insights into structural, elastic, mechanical, opto-electronic, and thermoelectric properties of rubidium-based fluoroperovskites RbXF3 (X = Zn, Cd, Hg)

Abstract

In this study, we investigate the structural, electronic, optical, thermoelectric, elastic, and mechanical characteristics of Rb-based perovskites RbXF3 (X = Zn, Cd, Hg) by using ab-initio calculations based on density functional theory and semi-classical Boltzmann theory through the FP-LAPW method in WIEN2k. The ground-state computations were performed by using three approximations of the GGA, i.e., PBE-GGA, WC-GGA, PBE-sol GGA, and LSDA, as exchange correlation potentials. The optimized structural data obtained were consistent with the results for similar compounds. All samples were found to be indirect band gap semiconductors along the direction of high Γ-M symmetry, and the conclusions were consistent with those obtained for similar compounds in past studies. Furthermore, we explored the elastic constants of the fluoroperovskites to inspect their mechanical behavior by using the IRelast approach. The dependencies of ε(ω), optical conductivity σ(ω), loss function L(ω), and refractive index n(ω) of the materials on the spectral frequency provide a fundamental basis for attaining optical characteristics that are suitable for use in applications of optoelectronics. The Seebeck coefficient, electrical and thermal conductivities, power factor, and figure of merit of the samples were also calculated by using semi-classical Boltzmann theory in BoltzTraP code. The results of thermoelectric computations showed that the Rb-based fluoroperovskite compounds investigated here have promising thermoelectric properties.