Eu掺杂YBa_(2-x)Eu_xCu_3O_(7-δ)超导体的X射线衍射研究

X-ray Diffraction Studies on Eu Doped YBa_(2-x)Eu_xCu_3O_(7-δ) Superconductors

Eu掺杂(取代)导致Y系YBa2Cu3O7-δ(YBCO)超导材料临界电流密度增强,晶格应变被认 为是主要原因。本文研究了Eu掺杂YBa2-xEuxCu3O7-δ超导体的结构和应变,并从容忍因子讨论了 钙钛矿单元的结构稳定性和晶格畸变,以及结构与电输运的相互关系;当x<0．15时,样品中没有 杂相。我们发现Eu3+／Eu2+离子优先替代Ba位的Ba,对电输运几乎没有影响。研究还表明氧含量 对超导转变温度Tc几乎没有影响。进一步研究了所有正常态样品的自旋能隙打开温度与超导输 运及结构变化之间的关系。

Eu doped YBa2-xEuxCu3O7-δ superconductors with x〈 0.5 were synthesized and studied. The microstructure of YBa2-xEuxCu3O7-δ superconductors was characterized by X - ray diffraction with Rieweld refinements. Eu may occupy Y- site, Ba - sites and Cu - site,which depends on its content. The orthorhombic strain vary with the content of Eu, which may affect the electronic transportation. We found that Eu^3＋/Eu^2＋ ions prefer to replace Ba at Ba sites, which gives little influence on superconductivity. The spin gap temperature, Ts, in the normal state decreases with increasing the Eu contetn.