Chemical bond properties of YBa 2Cu 3O 7 were studied by using the average ba nd-gap model. The calculated results show that the covalency of Cu(1)-O bond i s 0.406, and one of Cu(2)-O is 0.276. Mssbauer isomer shi...Chemical bond properties of YBa 2Cu 3O 7 were studied by using the average ba nd-gap model. The calculated results show that the covalency of Cu(1)-O bond i s 0.406, and one of Cu(2)-O is 0.276. Mssbauer isomer shifts of 57Fe in Y-123 were calculated by the chemical surrounding factor h v defined b y covalency and electronic polarizability. The charge-state and site of Fe were determined. The relation between the coupling constant of electron-phonon inte raction and covalency is employed to explain that the Cu(2)-O plane is more im portant than the Cu(1)-O chain on the superconductivity in the Y-123 compound s.展开更多
文摘Chemical bond properties of YBa 2Cu 3O 7 were studied by using the average ba nd-gap model. The calculated results show that the covalency of Cu(1)-O bond i s 0.406, and one of Cu(2)-O is 0.276. Mssbauer isomer shifts of 57Fe in Y-123 were calculated by the chemical surrounding factor h v defined b y covalency and electronic polarizability. The charge-state and site of Fe were determined. The relation between the coupling constant of electron-phonon inte raction and covalency is employed to explain that the Cu(2)-O plane is more im portant than the Cu(1)-O chain on the superconductivity in the Y-123 compound s.
