First-principles study of lutetium-based double hydride perovskites (Cs₂CaLuH₆, Cs₂SrLuH₆, Cs₂BaLuH₆) as promising...

The double hydride Cs₂XLuH₆ (X = Ca, Sr, Ba) perovskites are explored to determine the scope of these materials in hydrogen fuel cells and related applications. The DFT-based physical properties like thermoelectric, optoelectronic, vibrational, mechanical, and thermodynamic properties are calculated by applying hybrid complex HSE06 functional. The vibrational and thermodynamic stability of these materials are verified by positive (real) modes of phonons in the dispersion curves. The electronic properties illustrate the metallic behavior of these materials that make these materials favorable for hydrogen storage applications. The mechanical properties illustrate the compatibility, reliability, stability, and easy transportation of these materials for hydrogen storage applications. The peak value of Seebeck coefficient is listed as $4.82\times {10}^{-5}V/K$ for Cs₂CaLuH₆. The highest value of gravimetric ratio for hydrogen energy storage is found to be 4.07 wt% for Cs₂BaLuH₆. The highest calculated tolerance factors is 0.92 for Cs₂BaLuH₆. All these novel and significant properties confirmed Cs₂BaLuH₆ double hydride perovskites as the potential candidates for future energy applications like hydrogen fuel cell.

In the present article, optoelectronic and other physical properties of the materials under consideration are calculated by applying first principles DFT based in the framework of CASTEP simulation code. The electronic properties have been calculated using the HSE06.