Pressure-Induced Isostructural Phase Transition and Correlation of FeAs Coordination with the Superconducting Properties of 111-Type Na1鈥?i>xFeAs

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• 作者：Qingqing Liu ; Xiaohui Yu ; Xiancheng Wang ; Zheng Deng ; Yuxi Lv ; Jinlong Zhu ; Sijia Zhang ; Haozhe Liu ; Wenge Yang ; Lin Wang ; Hokwang Mao ; Guoyin Shen ; Zhong-Yi Lu ; Yang Ren ; Zhiqiang Chen ; Zhijun Lin ; Yusheng Zhao ; Changqing Jin
• 刊名：Journal of the American Chemical Society
• 出版年：2011
• 出版时间：May 25, 2011
• 年：2011
• 卷：133
• 期：20
• 页码：7892-7896
• 全文大小：821K
• 年卷期：v.133,no.20(May 25, 2011)
• ISSN：1520-5126

文摘

The effect of pressure on the crystalline structure and superconducting transition temperature (T_c) of the 111-type Na_1鈥?i>xFeAs system using in situ high-pressure synchrotron X-ray powder diffraction and diamond anvil cell techniques is studied. A pressure-induced tetragonal to tetragonal isostructural phase transition was found. The systematic evolution of the FeAs₄ tetrahedron as a function of pressure based on Rietveld refinements on the powder X-ray diffraction patterns was obtained. The nonmonotonic T_c(P) behavior of Na_1鈥?i>xFeAs is found to correlate with the anomalies of the distance between the anion (As) and the iron layer as well as the bond angle of As鈥揊e鈥揂s for the two tetragonal phases. This behavior provides the key structural information in understanding the origin of the pressure dependence of T_c for 111-type iron pnictide superconductors. A pressure-induced structural phase transition is also observed at 20 GPa.