Plasma oxidation of the high Tc superconducting perovskites

Abstract

A near room-temperature plasma oxidation process is shown to restore superconductivity and metalliclike behavior in oxygen deficient La2-x Srx CuO4-y and YBa2Cu3O 7-x compounds. In the YBa2Cu3O7-x compound the conversion from an oxygen deficient n-type tetragonal to the p-type orthorhombic phase with a concomitant factor of 5×105 increase in room-temperature conductivity is also accomplished. This process is of technological importance because oxygen can be restored in these materials at temperatures compatible with device processing. Of scientific interest, the process allows us to carefully control the oxidation state and thereby systematically study the 90 and 55 K superconducting transitions in YBa 2Cu3O7-x.