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通过测量YBa2Cu3-xMxO7-y(M=Zn,Ni,x=0,0.025,0.05,0.075,0.1,0.15,0.2,0.3)系列样品的晶体结构、正常态电子输运性质、超导电性以及O含量,给出了Zn择优取代Cu(2)的更直接证据;同时,观察到掺Zn系统中的由正交相Ⅰ到正交相Ⅱ的结构相变以及Ni取代Cu带来的电子局域化效应。研究结果表明,具有正二价态的Zn对Cu(2)具有择优取代性,而具有正二价和正三价的Ni并不具有明显的择优取代。对Cu(2)的取代引起超导临界温度的显著变化,但对正常态电子输运性质的影响不明显;对Cu(1)的取代更显著地影响了晶体结构和正常态电子输运性质,同时对Tc产生抑制,我们认为,YBa2Cu307中的高温超导电性以及正常态输运性质是由CU-O平面和Cu-0链共同承担,而Cu-O平面和Cu-0链之间的耦合强度决定着该系统的超导电性的强弱。The crystal structure, electronic transport properties in normal states, and superconductivity of a series of sample YBa2Cu3-xMxO7-y, (M = Zn,Ni, 0≤x≤0.3) have been studied, and a more direct evidence of preferential substitution of Zn for Cu(2) is obtained. In addition, an orthor-hombic(Ⅰ)-to-orthorhmbic(Ⅱ) structural transition in Zn-doped system as well as the effect of electronic localization in Ni-doped system is observed. The investigation shows that the Zn2+ may replace Cu(2) preferentially, but no such replacement for Cu by Ni was found. The role of Cu-O planes and chains on superconductivity is discussed. The importance of the coupling between Cu-O sheets and chains for high Tc superconductivity are noticed.
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