Synthesis and superconducting properties of the strontium copper oxy-fluoride Sr(sub 2)CuO(sub 2)Fe(sub 2+delta)

High-pressure synthesis provides strontium copper oxy-fluoride and establishes the compound's property of superconductivity. Proof that F avoids equatorial sites suggests the role of oxy-fluorides in forming high temperature copper oxide superconductors. F site preference promotes exchange of O and F ions and creates structural properties needed to support superconductivity.