Ca-substitution and O-doping effects in superconducting Cu(Ba0.8Sr0.2)2(Yb1−xCax)Cu2O6+z obtained from neutron diffraction refinements
Ca-substitution and O-doping effects in superconducting Cu(Ba0.8Sr0.2)2(Yb1−xCax)Cu2O6+z obtained from neutron diffraction refinements
复制标题
通过中子衍射细化获得的超导 Cu(Ba0.8Sr0.2)2(Yb1−xCax)Cu2O6+z 中的 Ca 取代和 O 掺杂效应
DOI：
10.1103/physrevb.60.4378
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发表时间：
1999
影响因子：
3.7
通讯作者：
R. Tellgren
中科院分区：
文献类型：
--
作者：
M. Karppinen;H. Yamauchi;K. Fujinami;T. Nakane;K. Peitola;H. Rundlöf;R. Tellgren
利用中子衍射和超导量子干涉装置实验，研究了${\mathrm{C}\mathrm{u}(\mathrm{B}\mathrm{a}} {{0.8}{\mathrm{Sr}} {0.2}{)}_{2}({\mathrm{Yb}} {1\ensuremath{-}x}{\mathrm{Ca}} {x}){\mathrm{Cu}}_{2}{\mathrm{O}} {6+z}$ $(\mathrm{Cu}\ensuremath{-}1212:P)$体系在$0l~xl~0.35$和$0lzl1的宽取代范围内的钙和氧掺杂效应。比较了两种不同方式在{\ maththrm {CuO}}_{2}$平面上引入空穴的有效性，包括增加{{T}_{c}$的能力，以及通过键价和计算从中子衍射数据中估计的空穴产量。氧掺杂提高空穴浓度的效率较低，且在一定空穴浓度下，钙取代比氧掺杂获得更高的${T}_{c}$值。两种不同的空穴掺杂方式也表现出不同的${T}_{c}$与Cu-O键长关系。结果表明，平面内Cu-O键的空穴分布和${\ mathm {CuO}}_{2}$平面的平整度在确定超导性能方面可能起着重要的作用。
Distinct calcium and oxygen doping effects were studied in the ${\mathrm{C}\mathrm{u}(\mathrm{B}\mathrm{a}}_{0.8}{\mathrm{Sr}}_{0.2}{)}_{2}({\mathrm{Yb}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}){\mathrm{Cu}}_{2}{\mathrm{O}}_{6+z}$ $(\mathrm{Cu}\ensuremath{-}1212:P)$ system by means of neutron diffraction and superconducting quantum interference device experiments in the wide substitution ranges of $0l~xl~0.35$ and $0lzl1.$ The effectiveness of the two different ways to introduce holes into the ${\mathrm{CuO}}_{2}$ planes was compared both in respect to the capability to increase ${T}_{c}$ and in terms of the hole production as estimated from neutron-diffraction data via bond-valence-sum calculation. Oxygen doping was found to increase the hole concentration less efficiently, and further, at a certain hole concentration value higher ${T}_{c}$ values were obtained with calcium substitution than with oxygen doping. The two different hole-doping methods exhibited also different ${T}_{c}$ vs Cu-O bond length relations. As a conclusion, the possible roles of the hole distribution in the in-plane Cu-O bond and the flatness of the ${\mathrm{CuO}}_{2}$ planes in determining the superconducting properties were recognized.