Investigation of the structural, electronic, mechanical, and optical properties of X2MgH6 (X=Ba, Sr) hydrides for hydrogen storage

Abstract

This study examines the structural, electronic, mechanical, and optical characteristics of X₂MgH₆ hydrides (where X=Ba, Sr) for hydrogen storage applications. These compounds, featuring a double perovskite crystal structure, show significant promise for hydrogen storage owing to their thermodynamic stability and robust mechanical attributes. First principles calculations using density functional theory (DFT) indicate negative formation enthalpies, verifying their thermodynamic stability. The electronic characteristics, such as band gaps and density of states, affect the materials' electrical conductivity and chemical reactivity. Mechanical evaluations using elastic constants and modulus data demonstrate that Sr₂MgH₆ possesses higher strength and stiffness compared to Ba₂MgH₆. Furthermore, optical traits like UV absorption and visible light reflectivity point to possible uses in optoelectronic and photonic technologies. This research advances the comprehension of complex hydrides and supports the advancement of hydrogen storage systems, essential for the global shift toward sustainable energy.