Synthesis of oxide superconductors by soft-chemical techniques

Our recent works on the synthesis of oxide superconductors using soft-chemical techniques are reviewed. First, Li-intercalaiion into layered perovskites has been carried out. We have found new Li-intercalated superconductors of the Ruddlesden-Popper phase of LixSr2CuO2X2 (X = Br, I) with T-c = 7-8 K and the Dion-Jacobson phase of Li(x)ASr(2)Nb(3)O(10) (A =Rb, Cs) with T-c similar to 6 K. However, no superconductivity has appeared in Aurivillius phases of LixBi4Ti3O10 and LixBi2MO6 (M = Mo, W). Next, we have succeeded in preparing insulating La2CuO4 with the Nd2C6O4-type (T') structure and superconducting Ba0.6K0.4BiO3 by the direct precipitation from molten alkaline-metal hydroxides at a temperature as low as 260-350 degrees C. (C) 2007 Elsevier B.V. All rights reserved.