KMg 6 (P 2 O 7 ) 2 P 3 O 10 : A novel phosphate with two distinct anions

A novel mixed-anion phosphate, KMg6(P2O7)2P3O10, has been synthesized by spontaneous crystallization technique with K2O–P2O5–Li2O as a flux. Single-crystal X-ray analysis reveals that KMg6(P2O7)2P3O10 features two kinds of isolated anions, [P2O7] dimers and [P3O10] trimers. Such coexisting of two distinct anions in one polyphosphate, which has somewhat conflict with Pauling's parsimony (V) rule, is very rare in alkali metal and alkali-earth metal phosphates. This finding enriches the structural chemistry of phosphates and provides new perspective on the design of multiple anion materials. The thermal stability and a.c. conductivity of KMg6(P2O7)2P3O10 are also discussed in this paper.