Preparation of the Orthorhombic Li-x(C2H8N2)(y)Fe2Se2 Superconductor by Amine Exchange Method

摘要

A new FeSe-based superconductor Li-x(C2H8N2)(y)Fe2Se2 with Tc=30 K was successfully synthesized by substituting ethylenediamine(en) for ammonia molecules in Li-x(NH3)(y)Fe2Se2. The XRD pattern indicates that the intercalation compound is an orthorhombic structure with lattice parameters a=3.8517(7)angstrom, b=3.9188(7)angstrom, c=21.4862(6)angstrom at room temperature, which is different from the tetrahedral phase Li-x(C2H8N2)(y)Fe2Se2 with Tc=45 K synthesized by solvothermal method. Compared with the precursor Li-x(NH3)(y)Fe2Se2, the Li-x(C2H8N2)(y)Fe2Se2 underwent a structure transition from tetrahedral to orthorhombic during the amine exchange reaction accompanying by the decrease of Tc, indicating that Tc is influenced by structure.