Ba/sub 1-x/K/sub x/BiO/sub 3/ thin films and grain boundary junctions prepared on MgO substrates

We have made grain boundary junctions of Ba/sub 1-x/K/sub x/BiO/sub 3/ thin film deposited on MgO bicrystal substrate. A high initial deposition temperature yielded superconductive Ba/sub 1-x/K/sub x/BiO/sub 3/ films from powder targets. We observed clear energy gap structure in the current-voltage characteristics of these junctions. In the high frequency radiation (10.5 GHz), Photon Assisted Tunneling was observed.