These structural features suggest a possible distribution of Fe (III) and (IV) in both types of octahedra based on the different sizes of the two ions. The larger cation, Fe (III), would be mainly located in the larger octahedra [Fe1O6] while the smaller one, Fe (IV), will occupy the Fe2 position. Considering that the relation between Fe1 and Fe2 sites is 1:2, the limit of this ordered distribution would be 1Fe (III):2Fe (IV) which corresponds to a BaFeO2.83 composition. This could explain the increase in the Fe1-O2 distance, as the Fe (III) content increases from 2.96 to 2.86 compositions, while Fe2-O remains almost constant. When the amount of Fe (III) is higher than 33 %, a fraction of this cation must also occupy the [Fe2O6] octahedra, inducing an increase in the average Fe-O distance and in the octahedra degree of distortion, as can be seen in the O-BaFeO2.63 phase.