shows that different arrangements of cations along the chains become accessible as temperature increases. The order-disorder transition occurs around 400 K and can be visualised by calculating the change in the heat capacity with increasing temperature, Figure . At the annealing temperature of 573 K used by Nie et al., over 40% of cations along the chains are no longer found in the ground state configuration, compared to 75% at the fully random limit. The MC simulations predict that the fully-random limit is not reached at temperatures below the melting point, determined to be 688.15 K by Starosta et al. Assuming that the arrangement of cations is frozen during cooling, this would suggest significant disorder is present in the final synthesized absorber.