Ba6P12N17O9Br3 - A Column-Type Phosphate Structure Solved from Single-Nanocrystal Data Obtained by Automated Electron Diffraction Tomography

Oxonitridophosphate Ba6P12N17O 9Br3 was synthesized by heating a multicomponent mixture of BaBr2, BaS, phosphoryl triamide and thiophosphoryl triamide in an evacuated and sealed silica-glass ampoule to 750 °C. Ba6P 12N17O9Br3 was obtained as the main product as a nanocrystalline powder. The crystal structure was determined ab initio on the basis of electron diffraction data acquired from a single needle-shaped nanocrystal by automated diffraction tomography. Ba 6P12N17O9Br3 crystallizes in the hexagonal space group P63/m (no. 176) with unit cell parameters a = 14.654(19), c = 8.255(9) Å and Z = 2. Its structure includes triangular, column-shaped anions of ∞ 1{(P12N17O9)9-}, which are built from vertex-sharing P(O,N)4 tetrahedra with 3-rings and three-coordinate nitrogen atoms. The 1D anions are separated by Ba2+ and Br- ions, which are arranged in channels parallel to the phosphate anions along [001]. The Ba2+ ions are eight- and nine-coordinated by Br- and O/N atoms, respectively.