Electronic and optical characteristics of long-period stacking ordered phases in Mg-Y-Zn alloys: A first-principles study

Electronic and optical properties of long-period stacking order (LPSO) phase in Mg-Y-Zn alloy are calculated and analyzed by first principles in this paper. The electronic properties and thermodynamic stability of 14H and 18 R LPSO phases were studied by means of electron density of state (DOS), COHP analysis, electron localization function (ELF) and charge density distribution, and their optical properties, including absorption coefficient, reflectivity, refractive index, energy loss function and extinction coefficient, were discussed, and their variation trends with photon energy and related factors were analyzed. The findings indicate that both phases possess metallic characteristics and exhibit no energy gap. Furthermore, the thermodynamic stability of the 14H phase surpasses that of the 18 R phase, owing to its stronger covalent bonds metal mixed bonds. In terms of absorption coefficients, both phases display high values within the energy range of 0~19 eV, with their most potent absorption peaks occurring at photon energies of 4.48 eV and 4.8 eV for the 14H and 18 R phases, respectively. Moreover, the photon absorption rate is inversely proportional to the density of L12 clusters in both phases.