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    A precise prediction for the hydrogen storage ability of perovskite XPH3 (X=Li, Na, K) hydrides: First-principles study
    (Elsevier Ltd., 2024) Murtaza, Hudabia; Ain, Quratul; Issa, Shams A.M.; Zakaly, Hesham M.H.; Munir, Junaid
    Hydrogen storage remains a significant barrier to creating a sustainable hydrogen economy, as many current materials fail to meet the high safety, efficiency, and capacity requirements. Current hydrogen storage technologies frequently exhibit low gravimetric densities and slow absorption/desorption rates, which limit their practical applicability in energy systems. This manuscript reports the first principles analysis on the physical features of alkali-based perovskite hydrides LiPH3, NaPH3, and KPH3, along with their hydrogen storage potential. Volume optimization curves, negative formation enthalpies and tolerance factor manifested the complete structural and geometric stability of these studied hydrides. Brittle, higher resistance to indentation, endurance towards high temperatures and anisotropic behavior are revealed through mechanical attributes for LiPH3, NaPH3, and KPH3. Higher longitudinal velocities are observed in crystallographic planes. The directional velocities for XPH3 (X = Li, Na, K) reflect an anisotropic nature in each crystallographic plane. The electronic band structure, TDOS and PDOS elaborates the metallic behavior of these studied hydrides. These hydrides' optical characteristics showed that they have good optical conductivity in the UV spectrum, along with minimal polarization and dispersion in the UV region. The hydrogen storage capacities for LiPH3 (6.83 wt%), NaPH3 (5.00 wt%), and KPH3 (3.95 wt%) signifies that all perovskite hydrides have shown promising results for hydrogen storage but LiPH3 is the strongest contender for hydrogen storage with highest gravimetric ratio (6.83 wt%) and volumetric storage (93.39 gH2/L) as it fulfills the energy storage demand mentioned by US-DOE of metal hydrides for year 2025. © 2024 Hydrogen Energy Publications LLC
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    A spin-polarized analysis of the half-metallicity, mechanical, structural and optoelectronic attributes of full-Heusler XVCo2 (X = B and P) alloys
    (Royal Society of Chemistry, 2024) Firdous, Faiza; Ain, Quratul; Issa, Shams A. M.; Zakaly, Hesham M. H.; Munir, Junaid
    Cobalt-based Heusler alloys possess high Curie temperatures with half-metallic characteristics, which make them excellent candidates for spintronic applications. These types of Heusler alloys are perfect for the fabrication of magnetic sensors and memory-based devices. Herein, an in-depth first principles analysis of the physical attributes of XVCo2 (X = B and P) was performed. The mBJ functional was employed to treat electron-ion interaction within their crystal structures. The crystal structure of XVCo2 (X = B and P) was optimized, and relaxation parameters for both alloys were analyzed. Their ground-state energies at minimum volume were also computed. The Thomas Charpin methodology was employed to compute elastic constants for XVCo2 (X = B and P), and mechanical properties of both alloys were obtained. For both alloys, metallic behavior was recorded in spin up channels, while indirect bandgaps of 0.38 eV and 1.73 eV were calculated in spin down channels for BVCo2 and PVCo2, respectively. Both studied alloys showed 100% polarization at the Fermi level. Furthermore, their bonding character was analyzed via electron density plots. The optical characteristic obtained from a complex dielectric equation revealed higher dispersion in the visible range for BVCo2 and PVCo2, making these materials excellent candidates for spintronics and optoelectronic devices. © 2024 The Royal Society of Chemistry.