Superconductivity and phase diagram in iron-based arsenic-oxides ReFeAsO1−δ (Re = rare-earth metal) without fluorine doping

  title={Superconductivity and phase diagram in iron-based arsenic-oxides ReFeAsO1−$\delta$ (Re = rare-earth metal) without fluorine doping},
  author={Zhi-An Ren and Guang-can Che and Xiaoli Dong and Jie Yang and Wei Lu and Wei Yi and Xiaoli Shen and Zheng-cai Li and Liling Sun and Fang Zhou and Zhongxian Zhao},
Here we report a new class of superconductors prepared by high-pressure synthesis in the quaternary family ReFeAsO1−δ (Re=Sm, Nd, Pr, Ce, La) without fluorine doping. The onset superconducting critical temperature (Tc) in these compounds increases with the reduction of the Re atom size, and the highest Tc obtained so far is 55 K in SmFeAsO1−δ. For the NdFeAsO1−δ compound with different oxygen concentration a dome-shaped phase diagram was found. 
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