This peak was also observed by Barth et al, who discussed the interpretation of this peak as being due to partial ordering of the Mg vacancies. Therefore, neither the compound nor the reported (partial) ordering is new. In addition, a second structure is known to form from this composition, reported in 2008 in a different structure. The predicted compound KNaTi 2 (PO 5 ) 2 is a cation ordered version of a series of titanyl phosphates that have been studied by various groups, for example Norberg et al. reported one such disordered version with a very similar stoichiometry to that predicted here in 2003. The predicted ordering causes only minimal changes to the PXRD peak intensities, and while it may be possible to discern it with careful measurements, and comparison between models, these were not done, so there is no evidence of the ordered phase. It is likely the previously reported disordered phase was made.