High-Tc superconductivity in nanostructured NaxWO3-y:: sol-gel route

Tungsten trioxide, WO(3-y), infiltrated into various nanoporous matrix structures such as carbon inverse opal, carbon nanotube paper or platinum sponge, and then intercalated with alkaline ions (Li(+), Na(+)) exhibits a pronounced diamagnetic onset in ZFC magnetization in a wide range of temperatures, 125-132 K. Resistivity measurements show nonzero jump and intensive fluctuations of electrical resistance below observed transition points. The observed magnetic and electrical anomalies in nanostructured tungsten bronzes (Li(x)WO(3-y) and Na(x)WO(3-y)) suggest the possibility of localized non-percolated superconductivity.