Structural, mechanical, electronic, optical, gravimetric, and thermodynamic properties of AYH3 (A = K, Rb) compounds: A DFT study

초록

This work presents a comprehensive density functional theory (DFT) investigation of Yttrium-based perovskite hydrides AYH3 (A = K, Rb) for solid-state hydrogen storage. First-principles calculations confirm both compounds crystallize in cubic structures and exhibit thermodynamic stability, evidenced by negative formation energies of-0.458 eV/atom for KYH3 and-0.437 eV/atom for RbYH3. Hydrogen storage evaluation reveals KYH3 achieves a superior gravimetric capacity of 2.31 wt% compared to 1.70 wt% for RbYH3, with desorption temperatures of 338 K and 323 K respectively. Electronic structure analysis using both GGA-PBE and HSE06 functionals confirms metallic behavior for both materials, which could promote favorable charge-carrier mobility for storage applications. Mechanical property assessment indicates brittle characteristics with Pugh's ratios below 1.75. The comprehensive analysis identifies KYH3 as the more promising candidate, combining enhanced hydrogen storage capacity with practical thermal properties for potential application in hydrogen storage systems.

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