SmBa(1-x)Ca(x)Co(2)O(5+d) Layered Perovskite Cathodes for Intermediate Temperature-operating Solid Oxide Fuel Cells

In SmBa(1-x)Ca(x)Co(2)O(5+d) (x = 0.01, 0.03, 0.1, and 0.2, SBCCO) oxide systems calcined at 1100°C for 8 h, the XRD patterns of the SBCCO single phase were maintained in the cases of SmBa(0.97)Ca(0.03)Co(2)O(5+d) (SBCCO-0.97) and SmBa(0.99)Ca(0.01)Co(2)O(5+d) (SBCCO-0.99) compositions. In SmBa(0.8)Ca(0.2)Co(2)O(5+d) (SBCCO-0.8) and SmBa(0.9)Ca(0.1)Co(2)O(5+d) (SBCCO-0.9), CaCoSmO(4) existed with the pattern SBCCO. SBCCO structures were identified as orthorhombic crystal structures because they showed splitting of the X-ray diffraction (XRD) peaks at 23.4°, 47.9°, and 59.1°.Typical metallic conduction behaviors were found in all measured compositions except SBCCO-0.8, which showed a metal-insulator transition (MIT) behavior. Compared to other SmBa(1-x)Ca(x)Co(2)O(5+d) compositions, SBCCO-0.8 showed the highest electrical conductivity of 460 S/cm at 500°C. In particular, SBCCO-0.9 was found to have an excellent ASR characteristic of about 0.077 Ωcm(2) at 700°C. The activation energy of SBCCO-0.9 was the lowest among SBCCO oxide systems with a value of 0.77 eV.