Structural evolution of Ce1−xGdxFeAsO0.84F0.16 superconductors
Structural evolution of Ce1−xGdxFeAsO0.84F0.16 superconductors
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DOI：
10.1063/1.3565408
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发表时间：
2011-04
影响因子：
3.2
通讯作者：
Jiamin Yang;W. Ren;Li Duoli;Z. Zhang
中科院分区：
文献类型：
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作者：
Jiamin Yang;W. Ren;Li Duoli;Z. Zhang
结构参数对铁基氧铌酸盐超导体的超导电性有重要影响。采用Rietveld方法对Ce 1 −xGdxFeAsO0.84F0.16超导体的X射线衍射谱进行了精细化分析，研究了其结构演化。Gd取代Ce产生压缩晶格的内部压力。Ce/Gd-As和Ce/Gd-O/F距离的减小也表明c轴的收缩，而As-Fe-As块尺寸略有增加，这通过Gd取代的Ce/Gd-O/F-Ce/Gd块的大幅减小来补偿。Ce0.6Gd0.4FeAsO0.84F0.16的对角Fe-As-Fe角为111.13°，在Ce 1 −xGdxFeAsO0.84F0.16化合物中具有最高的Tc。这接近于理想的FeAs四面体的109.47°，它位于Fe-As-Fe键角区域，RFeAsO化合物倾向于具有最高的Tc。
Structural parameters have a critical impact on superconductivity in iron-based oxypnictide superconductors. Structural evolution study was performed on Ce1−xGdxFeAsO0.84F0.16 superconductors by the analysis of the x-ray diffraction patterns with Rietveld refinement. Substitution of Gd for Ce generates internal pressure that compresses the crystal lattice. The contraction of the c axis is also indicated by the reduction of Ce/Gd-As and Ce/Gd-O/F distances, while there is a slight increase in the As-Fe-As block size, which is compensated by a large reduction in the Ce/Gd-O/F-Ce/Gd block with Gd substitution. The diagonal Fe-As-Fe angle for Ce0.6Gd0.4FeAsO0.84F0.16, with the highest Tc among Ce1−xGdxFeAsO0.84F0.16 compounds, is 111.13°. It is close to the ideal value of 109.47° for the perfect FeAs tetrahedron, which is situated in the region of Fe-As-Fe bond angles where RFeAsO compounds tend to have the highest Tc.