First-principles investigation of Yttrium (Y)-based hydrides YCdXH6 (X= Mn, Tc) for hydrogen storage

This paper reports on the structural, electronic, mechanical, optical, and thermodynamic properties of YCdXH 6 (X = Mn, Tc) complex hydrides. The findings presented in this work are based on first-principles calculations. An ab initio approach based on density functional theory was adopted, and the WIEN2k program was used to evaluate the physical characteristic of the system. The stability of YCdMnH 6 and YCdTcH 6 is confirmed, where structural analysis for thermodynamic stability and phonon dispersion for dynamic stability both prove stability at the optimized lattice parameters 6.8095 Å and 7.0023 Å. Both compounds are indirect band gap semiconductors based on electronic band structure analysis performed using the PBE-GGA and mBJ-GGA functional. The results of mechanical simulations confirm that these substances are stable and brittle with anisotropic properties. Furthermore, high potential for optoelectronic application is suggested by the dielectric constants and optical results. For energy application purposes, the gravimetric hydrogen storage capacities were calculated to be 2.31%, and 1.98% for YCdMnH 6 , and YCdTcH 6 , respectively. We demonstrate through our computational investigation that YCdMnH 6 and YCdTcH 6 hydrides are thermally stable, with the formation enthalpy of −2.64 eV/atom and −2.63 eV/atom. According to the present analysis, YCdXH 6 compounds demonstrate applicability for use in solid-state hydrogen storage, sustainable energy conversion systems, and optoelectronic devices.