Both substituted materials with composition x=0. for comparison of the obtained values) . They reported a clear trend in the activation energies from the solid-state NMR spectral-density fitting, similar in shape to the trend observed from AC-impedance spectroscopy. Considering the high correlation among fitting parameter reproduced from their data (>|0.9|, see SI Table ) and relatively few points on the hightemperature slope (Figure ), the data does not contain the information needed to unambiguously fit activation energies (see the large difference in the values in SI Table ).