YBa_2Cu_3O_7的化学键性质和穆斯堡尔谱的研究

Chemical Bond Properties and Mssbauer Spectroscopy in YBa_2Cu_3O_(7-δ)

利用电介质的平均能带模型计算了YBa2 Cu3O7的化学键参数 ,得到Cu(1)—O键的平均共价性为 0 40 6,Cu(2 )—O键的平均共价性为0 2 76。应用化学环境因子计算了Fe :Y 12 3的穆斯堡尔同质异能位移 ,确定了5 7Fe在Y 12 3中的价态和占位情况。由电声子强度参数与共价性的关系说明了超导相中Cu(2 )

By using the average band gap model, chemical bond properties of YBa 2Cu 3O 7 were studied. The calculated results show that covalency of Cu(1)—O bond is 0 406, one of Cu(2)—O is 0 276. Mssbauer isomer shifts of 57 Fe in Y 123 were calculated by using the chemical surrounding factor, h v, defined by covalency and electronic polarizability. The charge state and site of Fe were represented. The relation between the coupling constant of electron phonon interaction and covalency is employed to illustrate that the Cu(2)—O plane is more important than the Cu(1)—O chain for the superconductivity in the Y 123 compounds.