Spinodal nano decomposition in perovskite three-way catalysts: First-principles calculations and Monte Carlo simulations

We show that self-forming perovskite three-way catalysts might occur fluctuation distribution of precious metal concentrations owing to spinodal nano-decomposition (SND). We perform ab initio calculations to evaluate the free energy of La(Fe1−x, Pdx)O3 and La(Fe1−x, Rhx)O3. In addition the fluctuation distribution is simulated by applying the Monte Carlo method mapped to the Ising model with realistic ab initio chemical pair interactions between precious metal impurities in perovskite catalysts. It is found that the SND inherently occurs in La(Fe1−x, Pdx)O3, but not in La(Fe1−x, Rhx)O3. Calculated inhomogeneous distributions of Pd atoms in La(Fe1−x, Pdx)O3 are consistent with the high-resolution X-ray energy dispersive spectroscopy measurements.