American Physical Society Acta Medica Okayama 2469-9950 96 1 2017 Preparation of new superconductors by metal doping of two-dimensional layered materials using ethylenediamine 014502 EN Xiao Miao Research Institute for Interdisciplinary Science, Okayama University Takahiro Terao Research Institute for Interdisciplinary Science, Okayama University Xiaofan Yang Research Institute for Interdisciplinary Science, Okayama University Saki Nishiyama Research Institute for Interdisciplinary Science, Okayama University Takafumi Miyazaki Research Laboratory for Surface Science, Okayama University Hidenori Goto Research Institute for Interdisciplinary Science, Okayama University Yoshihiro Iwasa Department of Applied Physics, The University of Tokyo Yoshihiro Kubozono Research Institute for Interdisciplinary Science, Okayama University We have studied new superconductors prepared by metal doping of two-dimensional (2D) layered materials, FeSe and FeSe0.5Te0.5, using ethylenediamine (EDA). The superconducting transition temperatures (T(c)s) of metal-doped FeSe and metal-doped FeSe0.5Te0.5, i.e., (EDA)(y)MxFeSe and (EDA)(y)MxFeSe0.5Te0.5 (M: Li, Na, and K), were 31-45 K and 19-25 K, respectively. The stoichiometry of each sample was clarified by energy dispersive x-ray (EDX) spectroscopy, and the x-ray powder diffraction pattern indicated a large expansion of lattice constant c, indicating the cointercalation of metal atoms and EDA. The pressure dependence of superconductivity in (EDA)(y)NaxFeSe0.5Te0.5 has been investigated at a pressure of 0-0.8GPa, showing negative pressure dependence in the same manner as (NH3)(y)NaxFeSe0.5Te0.5. The T-c-c phase diagrams of MxFeSe and MxFeSe0.5Te0.5 were drawn afresh from the T-c and c of (EDA)(y)MxFeSe and (EDA)(y)MxFeSe0.5Te0.5, showing that the T-c increases with increasing c but that extreme expansion of c reverses the T-c trend. No potential conflict of interest relevant to this article was reported.