Unraveling the physical properties of K2RbMoX6 (X = Br, Cl) through first-principles characterization

Abstract

Herein, the geometric, optical, electronic, magnetic and thermoelectric (TE) attributes of K2RbMoX6 (X = Br, Cl) are brought under investigation using DFT. The geometry optimization reveals that K2RbMoX6 are stable with ferromagnetic (FM) nature in cubic phase. The thermodynamic and geometric stability of cubic halides is validated by enthalpy of formation (Δ Hf) and tolerance factor (τ). In both spin channels, semiconductor nature is observed for both materials in electronic band structures (BS) and density of states (DOS). The total magnetic moment (MTot) of K2RbMoX6 (X = Br, Cl) is 12.70 and 12.75 μB per unit cell, respectively, which is primarily originated owing to Mo-d states. The optical characteristics are explored, and we observed that optical absorption and conductivity is maximum in visible to ultraviolet region; suggesting suitable for optical devices. BoltzTraP package is utilized to explore the TE parameters in which ZT values for K2RbMoX6 (X = Br, Cl) are 0.76 and 0.94, respectively at 750 K. Overall, present research work reveals that the halide double perovskites under investigation are appropriate candidates for spintronics, TE and optical applications.

Keywords: Double perovskite halides; Electronic properties; First principles study; Optical properties; Thermoelectric materials; Wien2k