First-principles study of physical properties of perovskites XZnH₃ (X = Ca, Sr, Ba) hydrogen storage materials

Abstract In this study, the density functional theory (DFT) has been employed to investigate the structural, electronic, optical, mechanical, and thermodynamic properties of novel hydride perovskite assemblies XZnH 3 (where X = Ca, Sr, Ba). The lattice parameters of XZnH 3 (X = Ca, Sr, Ba) were calculated as 3.91 Å, 3.97 Å, and 4.11 Å respectively, which is consistent with the existing results. The negative formation enthalpy indicates thermodynamic stability for all three hydrides. Phonon spectra show dynamic stability for SrZnH 3 and BaZnH 3 , while CaZnH 3 exhibits dynamic instability due to imaginary frequencies. The electronic band structure and density of states indicate that the XZnH 3 perovskites exhibit metallic behavior. The hydrogen storage performance analysis revealed that the weight hydrogen storage capacities of the three compounds were 2.81 wt%, 1.94 wt%, and 1.47 wt% , respectively, indicating that they are potential hydrogen storage materials. The optical properties show that CaZnH 3 and SrZnH 3 possess the higher conductivity and the least amount of energy loss than BaZnH 3 . Evaluate the mechanical properties of compounds using Young’s modulus, shear modulus, elastic constant, and Poisson’s ratio. This study provides valuable insights into hydrogen storage materials.