First‐Principles Investigation of Stable Rare‐Earth Perovskite TmLiH 3 and YbLiH 3 Hydrides for Solid‐State Hydrogen Storage

Abstract

First‐principles density functional theory (DFT) computations were conducted to examine the structural, electrical, optical, mechanical, and hydrogen storage properties of the rare‐earth‐based perovskite hydrides XLiH 3 (X = Tm, Yb). The cubic structures were optimized in space group with approximately equal lattice parameters (∼3.61 Å; ∼47 Å 3 ). The stability of the cubic framework aligns with tolerance and octahedral factor criteria. Thermodynamic stability is evidenced by the negative formation energies of −0.489 and −0.456 eV/atom for TmLiH 3 and YbLiH 3 , respectively. The electronic structure analysis demonstrates metallic characteristics, indicating improved electrical conductivity and efficient charge transfer. The compounds demonstrate strong mechanical, dynamic, and thermal stability, confirmed by standard elastic‐stability assessments, phonon analyses, and ab initio molecular dynamics stability at around 300 K. The evaluation of hydrogen storage reveals gravimetric capacities of 1.69 wt.% for TmLiH 3 and 1.65 wt.% for YbLiH 3 , with substantial volumetric capacities of 107 and 107.1 g H 2 /L, respectively, and suitable desorption temperatures of 381.36 and 336.69 K.