Structural studies of magnesium nitride fluorides by powder neutron diffraction

Samples of ternary nitride fluorides, Mg3NF3 and Mg2NF have been prepared by solid state reaction of Mg3N2 and MgF2 at 1323–1423K and investigated by powder X-ray and powder neutron diffraction techniques. Mg3NF3 is cubic (space group: Pm3m) and has a structure related to rock-salt MgO, but with one cation site vacant. Mg2NF is tetragonal (space group: I41/amd) and has an anti-LiFeO2 related structure. Both compounds are essentially ionic and form structures in which nitride and fluoride anions are crystallographically ordered. The nitride fluorides show temperature independent paramagnetic behaviour between 5 and 300K.