title: Pressure-induced isostructural phase transition and correlation of FeAs coordination with the superconducting properties of 111-type Na(1-x)FeAs.
abstract: The effect of pressure on the crystalline structure and superconducting transition temperature (T(c)) of the 111-type Na(1-x)FeAs 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 FeAs(4) 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-x)FeAs 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-Fe-As 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.
authors.affiliation: Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Qingqing
authors.initials: Q
authors.lastname: Liu
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Yu
authors.forename: Xiancheng
authors.initials: X
authors.lastname: Wang
authors.forename: Zheng
authors.initials: Z
authors.lastname: Deng
authors.forename: Yuxi
authors.initials: Y
authors.lastname: Lv
authors.forename: Jinlong
authors.initials: J
authors.lastname: Zhu
authors.forename: Sijia
authors.initials: S
authors.lastname: Zhang
authors.forename: Haozhe
authors.initials: H
authors.lastname: Liu
authors.forename: Wenge
authors.initials: W
authors.lastname: Yang
authors.forename: Lin
authors.initials: L
authors.lastname: Wang
authors.forename: Hokwang
authors.initials: H
authors.lastname: Mao
authors.forename: Guoyin
authors.initials: G
authors.lastname: Shen
authors.forename: Zhong-Yi
authors.initials: ZY
authors.lastname: Lu
authors.forename: Yang
authors.initials: Y
authors.lastname: Ren
authors.forename: Zhiqiang
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authors.lastname: Chen
authors.forename: Zhijun
authors.initials: Z
authors.lastname: Lin
authors.forename: Yusheng
authors.initials: Y
authors.lastname: Zhao
authors.forename: Changqing
authors.initials: C
authors.lastname: Jin