Search for new superconductors by the Li-intercalation into layered perovskites

Synthesis and superconductivity of new Li-intercalated layered perovskites, Li(x)Sr(2)CuO(2)X(2) (X = Cl, Br, I) and Li(x)AB(2)M(3)O(10) (A = K, Rb, Cs; B = Ca, Sr, Ba; M = Nb, Ta), are reviewed. Li-intercalation has been carried out by the electrochemical technique. First, layered cuprates Li(x)Sr(2)CuO(2)X(2) show superconductivity with T(c) = 8.0 K and 4.5 K for X = Br and I, respectively. However, no superconductivity appears for X = Cl. Next, we have succeeded in preparing new superconductors, Li(x)CsSr(2)Nb(3)O(10) with T(c) = 5.5 K and Li(x)RbSr(2)Nb(3)O(10) with T(c) = 6 K. In the layered tantalates of Li(x)CsSr(2)Ta(3)O(10), however, no. superconductivity has been observed. (c) 2006 Elsevier B.V. All rights reserved.