Theoretical investigation of X2NaIO6 (X= Pb,Sr) double perovskites for thermoelectric and optoelectronic applications

Abstract

The full-potential linearized augmented plane wave (FP-LAPW) method was used to evaluate the structural, optical, electronic, and thermoelectric (TE) characteristics of X2NaIO6 (X = Pb, Sr) cubic double perovskite oxides. Pb2NaIO6 and Sr2NaIO6 revealed the semiconductor behavior with a direct band gap (Eg) of 3.75 eV and 5.48 eV, respectively. Furthermore, the optical parameters like absorption coefficient α(ω), reflectivity R(ω), optical conductivity σ(ω), extinction coefficient k(ω), dielectric constants, and refractive index n(ω) are calculated. Electrical conductivity (σ), figure of merit (ZT), Seebeck coefficient (S), thermal conductivity (k), and power factor (PF) are investigated for their thermoelectric (TE) features by using the Boltz-Trap package. Sr2NaIO6 attained the maximum value of ZT (0.7728) with PF of 206.3. Results of cubic X2NaIO6(X = Pb,Sr) double perovskite oxides revealed their potential application in TE and optoelectronic devices.