Simulation Studies of the Phase Stability of the Ruddlesden–Popper Phases

Atomistic simulation techniques are used to examine the stability of Ruddlesden–Popper (R–P) phases Sr(n = 1, 2, 3, 4 and ∞). Various sets of empirical pair potentials are employed to determine the formation energies of the R–P phases. Formation energies are also calculated with Density Functional Theory (DFT). The tendency of a given R–P phase to dissociate into a lower order R–P phase plus SrTiO₃ perovskite is found to increase with increasing n. The results obtained are compared with experiment and previous computational studies. The stability of intergrowth phases with respect to the pure R–P compounds is examined. In all cases the intergrowths are calculated to be thermodynamically less stable than the pure R–P phase, but the differences are in some cases negligible. Finally, the energy for SrO partial Schottky disorder in strontium titanate is computed taking the formation of R–P phases into account.