Electronic structures of dynamically stable As 2 O 3 , Sb 2 O 3 , and Bi 2 O 3 crystal polymorphs

摘要: The relationships between the atomic arrangements, electronic structures, and energetics of three sesquioxides, As${}_{2}$O${}_{3}$, Sb${}_{2}$O${}_{3}$, Bi${}_{2}$O${}_{3}$, are systematically investigated by first-principles lattice-dynamics calculations. Dynamically stable structures defective fluorite family searched for including displacements along imaginary modes lattice vibrations that appear in high-symmetry structures. Experimentally reported crystal (arsenolite-As${}_{2}$O${}_{3}$, $\ensuremath{\alpha}$-Sb${}_{2}$O${}_{3}$, $\ensuremath{\beta}$-Sb${}_{2}$O${}_{3}$, $\ensuremath{\beta}$-Bi${}_{2}$O${}_{3}$) found to be formed symmetry breaking local distortion this way. Moreover, some dynamically have not yet been revealed experiments discovered. Their magnitudes their band gaps obtained. In low-symmetry valence electrons localize form an asymmetric charge distribution direction empty anion site structure. This is a common characteristic ``lone pair'' cations. formation lone pair less significant order which same trend as distortion. plays essential role determining stability, properties these sesquioxides.