Does Mesophase Ag4+xPb2O6-z (0 <= x <= 1, 0,5 <= z <= 0,75) Appeal for a   Point Contact ATc Superconductivity?
  Weakly compacted fine particles of Ag4+xPb2O6-z which is iso-structural with Bystroem-Evers oxide Ag5Pb2O6 exhibit a novel class of physical properties, which includes an appearance of diamagnetism at t < 78 degrees Celsius, with corresponding absence of electric resistance, both events sounding for possible superconductivity. Weak compaction was performed by controlled pressing of introductory components Ag2O and PbO2. Pellets were heated from room temperature in an evacuated chamber, and solid state reaction proceeded at 340-350 degrees Celsius in an oxygen atmosphere released by reaction itself (60 < p < 100 mbar). Electric and magnetic properties appealing for an ambient temperature superconductivity may be attributed to scattering processes indicated by tunnelling of Ag-Ag clusters between states localized on the point contacts formed between adjacent particles. As compared to the work on the subject during past two decades, reproducibility of output data is satisfactory, and their correlations to the input preparation conditions appear as to be conclusive. 
Danijel Djurek (Alessandro Volta Applied Ceramics (AVAC), Kesten   brijeg 5, Remete, 10 000 Zagreb, Croatia)