Superconducting Single Crystals of Tl2Ba2CaCu2O8 and YBa2Cu4O8: Crystal Structures in the Vicinity of Tc
Superconducting Single Crystals of Tl2Ba2CaCu2O8 and YBa2Cu4O8: Crystal Structures in the Vicinity of Tc
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DOI：
10.1107/s0108767398011465
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发表时间：
1998-11
期刊：
影响因子：
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通讯作者：
V. Molchanov;V. Simonov
中科院分区：
文献类型：
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作者：
V. Molchanov;V. Simonov
用单晶X射线衍射法研究了Tl2Ba2CaCu2O8(Tc∼110K)和YBa2Cu4O8(Tc∼70K)超导材料的结构。一些结构参数在临界温度附近表现出反常行为。最显著的结构变化是CuO5金字塔顶端的O原子向CuO2平面移动，表明Tc附近的电荷重新分布。这种尖端O原子的行为似乎是空穴掺杂高温超导体的共同结构特征。在T1处电荷重新分布的另一个效应涉及到CuO5金字塔的面内Cu-O距离和/或O-O距离的很小的减少。这两种效应都代表了在相变到超导态时对电荷(空穴)重新分布的平均结构响应。
The structures of superconducting Tl 2 Ba 2 CaCu 2 O 8 (T c ∼ 110 K) and YBa 2 Cu 4 O 8 (T c ∼70 K) were investigated by single-crystal X-ra y diffraction techniques in a wide temperature range. Some of the structure parameters show anomalous behaviour in the vicinity of the critical temperature. The most pronounced structural change is the shift of the apical O atoms in CuO 5 pyramids towards the CuO 2 planes, indicating charge redistribution near T c . This behaviour of the apical O atoms seems to be the common structural feature of hole-doped high-T c superconductors. Another effect of charge redistribution at T 1 concerns a very small decrease of in-plane Cu-O distances and/or O-O distances in CuO 5 pyramids. Both effects represent an averaged structure response to charge (hole) redistribution upon the phase transition to the superconducting state.