Patent ID: 6875528

Claim:
A ceramic composition as a mixed conducting oxide in perovskite structure, said composition being expressed by the following general formula (1): {Ln 1−a A a }{B x B′ y B″ z }O (3−δ) (1) where Ln represents one or a combination of elements selected from the group of Y and lanthanoids; A represents one or a combination of elements selected from the group of Ba, Sr, and Ca; B represents one or a combination of elements selected from the group of Co, Fe, Cr, and Ga, B always containing Fe or Co, the sum of the molar numbers of Cr and Ga being within the range of 0% to 20% of the total molar number x of B; B′ represents one or a combination of elements selected from the group of Nb, Ta, Ti, and Zr, B′ always containing Nb or Ta, the sum of the molar numbers of Ti and Zr being within the range of 0% to 20% of the total molar number y of B′; B″ represents one or a combination of elements selected from the group of Cu, Ni, Zn, Li, and Mg; 0.8≦ a≦ 1; 0< x; 0< y≦ 0.5; 0≦ z≦ 0.2 0.98≦ x+y+z≦ 1.02; and δ represents a value which is so determined as to meet charge neutralization conditions.