Cation displacements and the structures of the superconducting pyrochlore osmates AOs(2)O(6) (A = K, Rb, and Cs)
Cation displacements and the structures of the superconducting pyrochlore osmates AOs(2)O(6) (A = K, Rb, and Cs)
复制标题
超导烧绿石锇酸 AOs(2)O(6) 的阳离子位移和结构（A = K、Rb 和 Cs）
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
M. Weller
中科院分区：
文献类型：
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作者：
R. Galati;C. Simon;P. Henry;M. Weller
在2K<；T<；500K变温条件下，对A=K、Rb和Cs的β-焦绿石AOs2O6和ANbTeO6进行了粉末中子衍射研究。当A=K，A=Rb时，晶格参数随温度变化的反常行为与碱金属阳离子在~80K以下发生的局部静态位移有关，这些位移在8b位置附近是随机的，如空间群FD-3M所模拟的；对于任何高于2K的样品，没有证据表明对称性从FD-3M开始下降；对于非超导ANbTeO_6，A=K，Rb和Cs，观察到类似的结构和晶格参数行为，K离子在~30K以下局域化。
Variable temperature, 2 K<T<500 K, powder neutron diffraction studies of the beta-pyrochlores AOs2O6 and ANbTeO6, A=K, Rb, and Cs, have been undertaken. Anomalous behaviors in the lattice parameter variations as a function of temperature for the superconducting osmates with A=K, and to a lesser extent for A=Rb, are associated with local, static displacements of the alkali metal cation, which occur below ~80 K. These displacements are random around the 8b position as modeled in the space group Fd-3m; no evidence for decrease in symmetry from Fd-3m was observed for any sample above 2 K. For the nonsuperconducting ANbTeO6, A=K, Rb, and Cs, phases, similar structural and lattice parameter behaviors are observed with localization of the potassium ions in KNbTeO6 below ~30 K.