NMR Characterization of the Na(3)AlP(3)O(9)N and Na(2)Mg(2)P(3)O(9)N Nitridophosphates: Location of the (NaAl)/Mg(2) Substitution.

We report a solid state nuclear magnetic resonance study of (23)Na, (27)Al, and (31)P in two crystalline nitridophosphate phases, Na(3)AlP(3)O(9)N and Na(2)Mg(2)P(3)O(9)N, including two-dimensional multiple-quantum magic angle spinning (MQ-MAS) experiments on (23)Na to separate overlapping lines. The previously described single-crystal structure of Na(3)AlP(3)O(9)N gives crystallographic examples of Al(OP)(6) and P(O[Al,Na])(2)(ONa)(N[P,Na]) environments and three different environments of sodium: two Na(O)(6) and one Na(O)(6)(N). From these observations we characterize the modification of the local environment of phosphorus and show that Mg only substitutes Na in the Na2 site of the Na(2)Mg(2)P(3)O(9)N structure.