The electronic conductivity and thermodynamic stability of mixed n-type and p-type doped SrTiO3 have been investigated at anodic solid oxide fuel cell (SOFC) conditions using density functional theory (DFT) calculations. In particular, constrained ab initio thermodynamic calculations have been performed to evaluate the phase stability and reducibility of various Nb- and Ga-doped SrTiO3 at synthesized and anodic SOFC conditions. The density of states (DOS) of these materials was analyzed to study the effects of n- and p-doping on the electronic conductivity. In agreement with experimental observations, we ﬁnd that the transformation from 20% Nb-doped Sr-deﬁcient SrTiO3 to a non-Sr-deﬁcient phase occurs at high temperature and low oxygen partial pressure, which leads to a signiﬁcant improvement in electronic conductivity. A mixed ionic/electronic conductor is obtained when doping 20% Nb-doped SrTiO3 with small amounts of Ga (10%) in a reducing environment and high temperature. Doping with higher concentrations of Ga, e.g., 20%, diminishes the electronic conductivity of the material. These ﬁndings suggest that independent of the speciﬁc dopant, mixed ionic/electronic conductivity can be obtained in perovskite oxides under reducing conditions and high temperatures by doping the B-site with small amounts of both n-type and p-type dopants.
Published in Physical Review B, Volume 84, 2011, pages 205102-1-205102-9.
Suthirakun, S., Ammal, S. C., Xiao, G., Chen, F., zur Loye, H.-C., Heyden, A. (2011). “Density Functional Theory Study on the Electronic Structure of n- and p-type Doped SrTiO3 under Anodic Solid Oxide Fuel Cell Conditions”, Physical Review B, 84, 205102-1-205102-9. DOI: 10.1103/PhysRevB.84.205102
©Physical Review B 2011, APS physics.