Abstract: This invention is directed to a method for making multiphase copper oxide based materials which have a phase having a zero resistance transition temperature above about 200K. The method comprises subjecting a copper oxide based material precursor to an oxygenation in an atmosphere comprising more than about 20% oxygen by volume at a temperature less than about 200.degree. C. for a time sufficient to form the material. The invention also is directed to maintaining the properties of a copper oxide based material having a zero resistance transition temperature above 150K.

Abstract: Superconducting films and devices are provided which exhibit an AC to DC conversion effect of an RF AC input signal. The films can be microscopically inhomogeneous with granular or columnar microstructures in layered or nonlayered structures, which provide the conversion effect with and without an applied magnetic field. The films also can be multilayer films which provide the conversion effect with a magnetic field applied to the films. The multilayer films are substantially compositionally homogeneous within the layers and the microscopically inhomogeneous films are substantially compositionally homogeneous throughout, but include structural inhomogeneities.