Ag5Pb2O6/CuO Composite, an Approach to Ambient Temperature Superconductivity

Bystrom-Evers compound Ag5Pb2O6 is highly conducting oxide, and it was prepared from the components Ag2O and PbO2 fired in a 300 bar O-2 atmosphere and 623 K. Compound was milled, and particles were dispersed in a powdered CuO matrix. For low concentrations of metallic particles (< 38 w/w percents), the composite is semiconductor or insulator, while for concentrations > 48 w/w percents material is metallic down to liquid helium temperatures. For intermediate concentrations, the composite exhibits properties characteristic for superconductors with transition temperatures 178 K < T (c)< 356 K, dependent on the size of dissolved metallic particles and their mutual distance. Magnetic data support a presumption of novel superconductivity. Samples were prepared with SC transition temperature T (c)=138 K, and in the temperature range 145-800 K electric resistance obeys the temperature dependence ln R similar to(T (0)/T)(1/2), and this indicates a possible 1-dimensional conduction mechanism.