Structural evolution and phase diagram of the superconducting iron selenides ${\rm{L}}{{\rm{i}}_x}{( {{{\rm{C}}_{\rm{2}}}{{\rm{H}}_{\rm{8}}}{{\rm{N}}_2}} )_y}{\rm{F}}{{\rm{e}}_2}{\rm{S}}{{\rm{e}}_2}( {x = 0\sim 0.8} )$

Linlin Zhao,1,2 Da Wang,1 Qingzhen Huang,3 Hui Wu,3 Ruijin Sun,1,2 Xiao Fan,1,2 Yanpeng Song,1,2 Shifeng Jin,1,4,* and Xiaolong Chen1,4,5,6,† 1Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China 2University of Chinese Academy of Sciences, Beijing 100049, China 3NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland, 20899, USA 4School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 101408, China 5Collaborative Innovation Center of Quantum Matter, Beijing, 100190, China 6Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China