The normalized cell volume (5′) is an example of such parameter. The quantity 5′ is the unit-cell volume divided by the number of ABO3 formula units in the unit cell. It measures the packing of the atoms in the structure and it is determined by the size of A and B cations and by the distortions of the octahedra. In total, 13 parameters characterizing the perovskite structures and their distortions were obtained from XRD (see full list in Table ). The formulas for defining these parameters are explained in detail in the ESI and the complex crystallographic characteristics of perovskite oxides are discussed in detail elsewhere. ICP OES (or XRF), oxygen analysis, and XPS were used to measure the A, B, and oxygen contents in the bulk and on the surface of the perovskites. compared to the bulk (0.21 and 0.22, respectively). However, there is no clear trend linking the bulk and surface compositions with the A and B elements. In total, ICP OES (or XRF), oxygen analysis, and XPS provided 6 parameters characterizing the perovskite bulk and surface compositions. Finally, the N2 physisorption provided the specific surface area of the perovskites (Table ). The values of surface area are in the range [0.60, 13.40] m 2 •g -1 .