To gauge the preference for La/Pr ordering at the experimental measurement temperature of 800 ˚C, a Boltzmann average of the Pr site occupancy was calculated from the cell energies of all structures at each composition, as shown in Fig. . For all x compositions, at 800˚C there is only a weak preference for Pr ordering on the M(2) site, as the thermal energy (kBT = 0.107 eV) is larger than the energy difference between most of the configurations. The occupancy of the M(1) and M(2) sites is therefore close to the random solution limit of 0.5:0.5.