Density Functional Theory of BaFeO3-δ

The cubic perovskites based on BaFeO3-δ have recently emerged as cheap and promising materials for oxygen catalysis at both low and high temperatures [1]. Most commonly, the cubic perovskite phase is stabilized by substituting A-site and/or B-site cations, as shown in Fig. 1. This approach has led to development of several promising materials, such as Ba0.95La0.05FeO3-δ (also synthesised and studied in our lab [1]).

To further understand the high activity of the BaFeO3-δ material, we are currently studying its ground state structures using the density functional theory (DFT). By employing DFT we are able to calculate formation and migration energies of defects and vacancies to predict bulk material properties, such as the oxygen non-stoichiometry and oxygen diffusion [2,3], as shown in Fig. 1, 2 & 3. In addition, we can also analyze the electronic structure in the density of states, as shown in Fig. 4 & 5 [2,3] and the charge redistribution in defect formation, to provide physical insight into properties identified.

So far, our studies have focused on the bulk properties of BFO and its derivatives [2,3]. However, as oxygen catalysis is a surface reaction we are now extending our analysis to the surface and exploring surface stability, oxygen adsorption and surface stoichiometry.

References:

[1] C. Chen, D. Chen, Y. Gao, Z. Shao, and F. Ciucci.Computational and Experimental Analysis of Ba0.95La0.05FeO3−δ as a Cathode Material for Solid Oxide Fuel Cells.Journal of Materials Chemistry A, 2, 14154-14163 (2014) link

 

[2] Z.M. Baiyee, C. Chen, and F. Ciucci.A DFT+U study of A-site and B-site substitution in BaFeO3−δ. Physical Chemistry Chemical Physics, 17, 23511-23520 (2015) link

 

[3] C. Chen, Z.M. Baiyee, and F. Ciucci.Unraveling the Role of La A-site Substitution on Oxygen Ion Diffusion and Oxygen Catalysis in Perovskite BaFeO3by Data-driven Molecular Dynamics and Density Functional Theory.Physical Chemistry Chemical Physics, 17, 24011-24019 (2015) link