“…K MoO F is one member of the rather large subgroup of oxy#uoride phases (A> B>M'4OF (A, B"an alkali ion; M'4"Ti, V), A> B>M4O F (A, B"alkali; M4"V, Nb), and A> B>M4'O F (A, B"K, Rb, Cs; M4'"Mo, W)) (3, 4) which belong to this group. Despite the two chemically distinct anion species in the case of the latter oxy#uoride subgroup, there has to date been no evidence for oxygen/#uorine ordering in any of these phases (as is also the case for many other oxy#uoride systems (5)); i.e., random anion site disorder has invariably been reported for the anion, or X, site positions (3,6).…”