High oxide ion conductive ceria based solid electrolyte

摘要

PROBLEM TO BE SOLVED: To introduce an oxygen deficiency and to simultaneously improve oxide ion conductivity and reduction resistance by specifying the composition of a fluorite type ceria compound consisting of La, Sr, Ba, Ce and O and providing a specified effective index. SOLUTION: This high oxide ion conductive ceria-base solid electrolyte comprises a fluorite type ceria compound of the formula (La1-xMx)yCe1-yO2-z (wherein M is Sr or Ba, 1=x=0.5, 0.1y0.2 and 0.05z0.15). When the average ionic radius of all cations constituting the ceria compound, the average ionic radius of the cations except Ce, the ionic radius of Ce and the ionic radius of oxygen are represented by Rc, Rd, Rce and Ro, respectively, the solid electrolyte has an effective index of 0.925 to 1.20 represented by the equation (effective index)=(Rd/Rce)*(Rc/Ro), wherein the symbol * shows integration, Rd=RM*x+RLa*(1-x), Rc=Rd*y+Rce*(1-y), Ro=1.4*(1-z), Rce=0.97, RLa is 1.18 which is the ionic radius of La, RM is the average ionic radius of Sr and Ba and 1.187=Rd=1.30 .