The significance of anti-fluorite Cs₂NbI₆ via its structural, electronic, magnetic, optical and thermoelectric properties

The structural, electronic, magnetic, optical and thermoelectric properties of anti-fluorite Cs₂NbI₆ were investigated using full potential augmented plane wave method of density functional theory. Structurally, Cs₂NbI₆ was found to be cubic in ground state from values of tolerance factor (1.04) and formation energy (−22.3 eV). While, it's ferromagnetic nature was predicted from volume optimization process. In spin down channel, the compound was explored as indirect band gap (E_g(Γ-X) = 1.97 eV) semiconductor, while it changes to metallic in upper spin channel. Nb-d and I-p states were exposed as the main cause of spin dependent electronic nature (half-metallicity). The origin of magnetism in Cs₂NbI₆ was explained on basis of crystal field theory. The calculated magnetic moment (1.001 μ_B) was found in reasonable agreement with experimental value. The optimum absorption and optical conductivity spectra in semiconductor state explored Cs₂NbI₆ as suitable for optoelectronic devices. Furthermore, the transport properties were calculated using BoltzTrap code. The nature of carriers was predicted as n type from negative values of Seebeck coefficients. Where, the figure of merit (ZT) was found to increase up to 0.85 at 900 K. The present work not only explores Cs₂NbI₆ as potential optoelectronic and thermoelectric material, but can also inspire more experimental research on this important compound.