YBa_2Cu_(2.88)Fe_(0.12)O_(7-δ)高Tc超导体的M(?)ssbauer谱研究

The study on Mossbauer spectrum of high Tc superconductor

本文研究了YBa_2Cu_(2.88)Fe_(0.12)O_(7-δ)高Tc超导体氧化物的穆斯堡尔效应,测定了Fe的价态和环境,并用点电荷模型进行了计算。Fe有三个亚晶位(Fe(1)、Fe(2)和Fe(3)),Fe(1)和Fe(3)占有YBa_2Cu_3O_(7-δ)氧化物的Cu(1)晶位,但Fe(1)周围氧的分布与Fe(3)的不同。Fe(2)占有Cu(2)晶位。Fe(1)和Fe(2)是低自旋的Fe^(+3),而Fe(3)是高自旋的Fe^(+3)。掺铁引进一些附加氧原子,它们处在Y-Ba-Cu-O体系中(001)平面的非Cu-O链上,这造成晶格趋向于四方结构。

The Mossbauer effect of YBa2Cu2.88Fe0.12O7-δ) high Tc superconducting oxide has been studied. The valence of Fe and its environment have been determined experimentally and by the calculation using point charge model. Fe has three sublattices sites Fe(1), Fe(2) and Fe(3). Fe(l) and Fe(3) occupy the sites Cu(1) in YBa2Cu3O1-δoxide, but the distribution of oxygen around Fe(1) is different from that around Fe(3). Fe(2) occupies the sites Cu(2). Fe(1) and Fe(2) are low spin Fe+3, while Fe(3) is high spin Fe+3. Doping of iron brings some extra oxygen atoms that occupy non-Cu-O chains in (001) planes in Y-Ba-Cu-O system. This makes the lattice tend to tetragonal structure.