La and Sc co-doped SrTiO3 as novel anode materials for solid oxide fuel cells

La and Sc co-doped SrTiO3 was synthesized via solid state reaction. The oxygen ion migration energy was investigated by first-principles calculations in SrBO3 systems (B = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Ga, Ge, As, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Cd, In, Sn and Sb) with perovskite structure. Structure with Sc showed the lowest oxygen migration energy, and thus Sc was selected as B-site dopant with the primary aim to improve the ionic conductivity of SrTiO3-based anode materials. With increasing Sc-doping amount, the electrical conductivity of La0.3Sr0.7ScxTi1-xO3-delta decreased in 25-1000 degrees C, while the ionic conductivity increased significantly between 500 and 1000 degrees C. The ionic conductivity for La0.3Sr0.7Sc0.10Ti0.90O3-delta was 1 x 10(-2) S cm(-1) and increased about 230% compared with La0.3Sr0.7TiO3-delta at 800 degrees C and under oxygen partial pressure of 10(-19) atm. Sc-doping increased the oxygen vacancy concentration and decreased the oxygen migration energy, thus facilitating the conduction process of oxygen ions in La and Sc co-doped SrTiO3. The possible charge compensation mechanism of Sc-doped La0.3Sr0.7TiO3-delta can be described as La0.3Sr0.7SCx3+ Ti0.7-2 delta-x1 Ti-0.3+2 delta-x2(3+) O-3-(delta+x(1)/2) (x = x(1) + x(2)). (C) 2008 Elsevier B.V. All rights reserved.