Extended Data Table 1 Structural parameters from the Rietveld refinements

From: Reversible Mn2+/Mn4+ double redox in lithium-excess cathode materials

  1. The Rietveld refinements are shown in Figs. 1b and 5a. The crystallographic information file of \({Fm}\bar{3}m\) LiFeO2 (ICSD collection code 51208) was used as an input file. A pseudo-Voigt fit was used (U,V,W = 8.0691, −0.9697, 1.3778 for Li2Mn2/3Nb1/3O2F, and 5.8736, −1, 1.4118 for Li2Mn1/2Ti1/2O2F). The atomic occupancies were initially set to the atomic ratio obtained from elemental analysis by direct-current plasma emission spectroscopy and an ion-selective electrode, based on which the lattice parameters were first refined. We then further refined the lattice parameters and the atomic occupancies together. Transition-metal occupancies were first refined freely. Then O and F occupancies were individually refined with a constraint of their occupancies summing to 1. Finally, all atomic occupancies including Li occupancy were simultaneously refined with the additional constraint that the total transition-metal occupancy should stay unchanged during this final process. However, as O and F are difficult to distinguish by XRD, and Li cannot be seen clearly, their occupancy values are more subject to error.
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