Computational study of lattice and thermoelectric properties of Rb2LiTlF6 double perovskite

We applied the density functional theory formalism to compute the lattice thermal conductivity, transport and thermoelectric properties of Rb2LiTlF6 double perovskite in the cubic phase. To gain some insights on lattice related dynamic behaviour of this material, we determined its phonon lifetimes and Grüneisen parameters within the considered frequency range. This quaternary compound has a very low value of lattice thermal conductivity, with the predicted value of 0.687 W/mK at 300 K. The highest value of dimensionless figure of merit was determined to be 5.73 × 10−3 at 800 K when hole concentration is 1020 cm−3, this low ZT value could be attributed to the wide band gap nature of this compound. Our results will serve as a benchmark for future experimental and theoretical research on lattice and thermoelectric properties of this material.