Metal oxide materials

Abstract

The invention provides certain novel metal oxide materials which exhibit superconductivity at elevated temperatures and/or which are useful in electrode, electrolyte, cell and sensor applications, or as electrochemical catalysts. The metal oxide materials are generally within the formula R n+1−u−s A u M m+e Cu n 0 w   (1) where n≧0 and n is an integer or a non-integer, 1≦m≦2, 0≦s≦0.4, 0≦e≦4, and 2n+(1/2)<w<(5/2)n+4, with the provisos that u is 2 for n≧1, u is n+1 for 0≦n<1 and where R and A are each any of or any combination of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu, Ca, Sr, Ba, Li, Na, K, Rb or Cs; M is any of or any combination of Cu, Bi, Sb, Pb, Tl or any other transition metal; Cu is Cu or Cu partially substituted by any of or any combination of Bi, Sb, Pb, Tl or any other transition metal; 0 is 0 or 0 partially substituted by any of N, P, S, Se, or F; and wherein the structure of the materials is characterised by distorted or undistorted substantially square planar sheets of Cu0 2 when n>0 and distorted or undistorted substantially square sheets of R for n>1.

What is claimed is:  
     
         1 . An oxide superconductor having the formula: 
       Bi 2 (Sr,Ca) 4 Cu 3 O 10−δ   
       wherein Bi may be partially substituted by Pb and Cu is replaceable either wholly or in part by Bi.  
     
     
         2 . An oxide superconductor having the formula: 
       Bi 2 (Sr,Ca) 4 Cu 3 O 10−δ   
       wherein Bi may be partially substituted by Pb.  
     
     
         3 . An oxide superconductor having the formula: 
       (Bi,Pb) 2 (Sr,Ca) 4 Cu 3 O 10−δ . 
     
     
         4 . An oxide superconductor having the formula: 
       (Bi 1−x Pb x ) 2 (Sr,Ca) 4 Cu 3 O 10−δ   
       wherein 0<x<1.0.