Fe掺杂GdBa_2Cu_(3-x)Fe_xO_(7-δ)超导体系的正电子湮没研究  

Positron annihilation study on Fe-doped GdBa_2Cu_(3-x)Fe_xO_(7-δ) superconductor systems

作　　者：陈镇平[1] 张国芳[2] 薛人中[1] 石开[1] 李涛[1] 王春梅[1] 薛运才[1] 

机构地区：[1]郑州轻工业学院技术物理系,郑州450002 [2]南阳师范学院物理与电子工程学院,南阳473061

出　　处：《核技术》2011年第3期183-187,共5页Nuclear Techniques

基　　金：国家自然科学基金(10875107);河南省自然科学基金(082300440080)资助

摘　　要：利用X射线衍射(XRD)、正电子湮没等实验技术对Fe掺杂稀土超导体系GdBa2Cu3–xFexO7–δ(x=0.00–0.30)的晶体结构、局域电子密度ne以及超导电性进行了系统研究。实验结果表明,当Fe掺杂量在x=0.10附近时,体系的晶体结构发生了正交-四方相变。随Fe含量的增加,体系的超导转变温度逐渐降低,且超导转变宽度在正交-四方相变前后有明显变化,四方相结构样品的超导转变宽度明显增加。正电子实验结果表明,体系发生正交-四方相变时,体系的局域电子密度出现较大变化,并且超导转变温度Tc随局域电子密度ne的减小而减小。研究结果证明了体系的结构相变和局域电子结构对超导电性具有重要影响。The crystal structure, local electron density and superconductivity were investigated by X-ray diffraction, positron annihilation and other methods for Fe-doped GdBa2Cu3-xFexO7-δ（x=0.00-0.30） systems. The results showed that the crystal structure of the samples evolved a phase transition from orthorhombic to tetragonal near x=0.10. The superconducting transition temperature Tc decreased with increasing Fe doping amounts, and the superconducting transition width changed strikingly for O-T phase transition samples. The width increased markedly for the tetragonal phase ones. The results from the positron experiments indicated that the local electron density displayed a noticeable change when the O-T phase transition took place in the systems. It was found that the superconducting transition temperature Tc decreased with the local electron density. These findings manifest that the crystal phase transition and the local electron density can strongly affect the superconductivity in the Fe doped GdBa2Cu3-xFexO7-δ systems.

关 键 词：正电子湮没 结构相变 超导电性 局域电子密度 

分 类 号：O511[理学—低温物理]