Yazar "Iyigor, Ahmet" seçeneğine göre listele

Listeleniyor 1 - 1 / 1
  • Küçük Resim Yok
    Öğe
    Investigation of K2TiH6 and Ca2TiH6 under pressures from 0 to 20 GPa: Structural, electronic, thermodynamic, mechanical, vibrational, and hydrogen storage properties
    (Pergamon-Elsevier Science Ltd, 2025) Ermis, Salih; Iyigor, Ahmet; Kurkcu, Cihan
    In the face of the global energy crisis and increasing environmental pollution, the demand for sustainable and clean energy systems has accelerated research on hydrogen as a promising energy carrier due to its high energy density and zero-carbon emissions. However, efficient and safe storage remains a major technological challenge. In this study, the structural, electronic, elastic, thermodynamic, phonon, and hydrogen storage properties of K2TiH6 and Ca2TiH6 complex hydride compounds were systematically investigated in the 0-20 GPa pressure range using first-principles calculations based on density functional theory (DFT). Electronic band structure analyses revealed that the K2TiH6 compound exhibits a non-magnetic semiconducting character, while the Ca2TiH6 compound demonstrates ferromagnetic properties and exhibits metallic behavior. The evaluation of elastic properties revealed that both compounds meet mechanical stability criteria. Based on B/G and Poisson's ratio values, K2TiH6 exhibits brittle behavior at 0 GPa pressure but gains ductile properties at all other pressure values. Ca2TiH6, on the other hand, exhibits ductile behavior in the 0-20 GPa range. Vibrational and thermodynamic analyses revealed that an increase in temperature results in an increase in vibrational energy and entropy. Conversely, under high pressure, there is an increase in structural rigidity and a decrease in atomic disorder. It was determined that the Ca2TiH6 compound exhibits superior rigidity and ductility properties from room conditions onward. As a result of the phonon calculation, both compounds are dynamically stable. Importantly, hydrogen storage evaluations indicated gravimetric capacities of 4.58 wt% for K2TiH6 and 4.51 wt % for Ca2TiH6, with desorption temperatures of 55 K and 274 K, respectively, suggesting their suitability for low-and moderate-temperature hydrogen release applications. These findings provide valuable insights into the pressure-dependent stability and storage potential of complex hydrides, highlighting K2TiH6 and Ca2TiH6 as promising candidates for next-generation hydrogen energy systems.