DFT-focused estimation of mechanical, thermoelectric and thermodynamic properties of ACdF3 (A=K, Rb, Cs) fluroperovskites

Structural, electronic, mechanical, thermodynamic and thermoelectric properties of Alkaline fluroperovskites ACdF(3) (A=K, Rb, Cs) have been explored using the FP-LAPW method from the perspective of density functional theory (DFT) as employed in the Wien2k package within the generalized gradient approximation (GGA) as well as the local spin density approximation (LSDA). The volume optimization calculations of these materials agree well with experimental as well as available theoretical values. From the energy dispersion curves as well as DOS plots, all the investigated alkali fluroperovskites are found to have an indirect bandgap in Gamma-M direction using both approximations. The second-order elastic constants as well as mechanical properties such as Young's modulus, shear modulus, density, anisotropic factor, B/G(H) ratio are also computed for these materials. In order to study the thermal and vibrational effects on the studied fluroperovskites, we have employed the quasi-harmonic Debye model that uses a set of energy versus volume calculations. The effects of temperature as well as pressure on the structural parameters are also studied using the non-equilibrium Gibbs function. The transport properties of these perovskites have been investigated using BoltzTrap Code. Comparatively, a good figure of merit of these compounds reveals their possible use in thermoelectric applications.