Solvothermal fluorination: A new chemical fluorination method to insert fluorine into Sr2CuO3 and NdSr2Cu2O6−δ

A new chemical fluorination method to insert fluorine into Sr2CuO3 and NdSr2Cu2O6−δ under solvothermal conditions is introduced. X-ray powder diffraction and magnetic susceptibility measurements show that the fluorinated Sr2Cu(O, F)4+δ is a superconductor with superconducting transition temperature Tc = 38 K, and the fluorinated NdSr2Cu2(O, F)6+δ displays a structural change from orthorhombic structure to tetragonal structure without superconducting properties. This investigation indicates that it is feasible to insert fluorine into the structures of cuprates by solvothermal fluorination. In addition, the fluorination mechanism and the unique properties of the closed system are discussed.