Theoretical investigations on physical properties of SrFCuCh (Ch=S and Se)

Abstract

Using first principles calculations based on full-potential linearized augmented plane-wave (FP-LAPW) method, the structural, electronic and optical properties of SrFCuCh (Ch=S and Se) have been investigated. Generalized gradient approximation (GGA-PBESol) is adopted for the exchange-correlation electron interaction. Optimized structure of studied compounds are in very good agreement with experimental results. PBESol functional underestimates the electronic band gap of these materials, whereas Tran-Blaha modified Becke-Johnson exchange potential for semiconductors with band up to 7 eV (smBJ) predicts this parameter very accurately by error of just − 1.16% (for SrFCuS) and − 1.59% (for SrFCuSe) in comparison with experimental data. These reliable obtained results are used for calculating optical and thermoelectric properties including Seebeck coefficient, electrical conductivity, thermal conductivity and figure of merit. The last ones are computed with semi-classical Boltzmann theory within the constant relaxation time approximation. Our calculations show that SrFCuS and SrFCuSe as p-type compounds are promising candidate for applications in thermoelectric devices at high temperatures. Finally, the thermodynamic properties of these materials comprising bulk modulus, heat capacities, thermal expansion and Debye temperature are calculated in wide temprature range up to 1200 K at various pressures 0 GPa, 20 GPa and 50 GPa using quasi-harmonic Debye model and they are also discussed in details.