The growth of Ba/sub 1-x/K/sub x/BiO/sub 3/ superconducting single crystals with the large Meissner effect

The growth of Ba/sub 1-x/K/sub x/BiO/sub 3/ single crystals with a large (50-70%) volume of superconducting phase measured by the Meissner effect is described. A narrow range of temperatures and solution concentrations exists to grow single crystals with a large volume of the Meissner state and a sharp diamagnetic transition at T/spl ap/30 K. In addition the powder synthesis of Ba/sub 1-x/K/sub x/BiO/sub 3/ polycrystals with large (/spl gsim/50%) Meissner effect is described. Some of theses experimental results contradict the traditional BCS model of superconductivity.