Patent ID: 8293143

Claim:
A mixed ionic/electronic conducting membrane that comprises a thin solid composition consisting of at least one component of a ceramic material (A) said thin solid composition having within said material (A) a surface concentration gradient consisting of at least one component of a ceramic and metallic material wherein said material (A) is selected from the oxides of formula (I): (M a O b ) 1-x (R c O d ) x (I), wherein M is at least one trivalent or tetravalent atom selected from the group consisting of Bi, Ce, Zr, Th, Ga, and Hf; wherein a and b are such that the structure M a O b is electrically neutral; wherein R is at least one divalent or trivalent atom selected from the group consisting of Mg, Ca, Ba, Sr, Gd, Sc, Yb, Y, Sm, Er, In, Nb, and La; wherein c and d are such that the structure R c O d is electrically neutral; and wherein x is in the range of about 0.05 to about 0.30.