Fig. 1. Density functional theory calculations.
a Calculated Gibbs free energy for oxygen vacancy formation (Gvf-O) of Pr0.5(Ba/Sr)0.5TO3−δ (T = Mn, Fe, Co, and Ni) from the surface AO (green bar) and BO2 (purple bar) networks and the predicted phase change under reducing condition. b Schematic illustration of the most stable structure configurations of Pr0.5(Ba/Sr)0.5TO3−δ (T = Mn, Fe, Co, and Ni) slab models used for the calculations of oxygen vacancy formation energy values from AO and BO2 networks.