CaMg sub(2)P sub(6)O sub(3)N sub(10) - A Quinary Oxonitridophosphate with an Unprecedented Tetrahedra Network Structure Type

CaMg sub(2)P sub(6)O sub(3)N sub(10) has been synthesized starting from stoichiometric amounts of Ca(N sub(3)) sub(2), Mg sub(3)N sub(2), P sub(3)N sub(5), and PON in a high-pressure/high-temperature reaction at 8 GPa and 1100 degree C. Adding small amounts of NH sub(4)Cl to the starting mixture afforded single crystals of CaMg sub(2)P sub(6)O sub(3)N sub(10), which form transparent, colorless truncated octahedra. The crystal structure [space group I4 sub(1)/acd (no. 142), a = 12.494(1), c = 23.797(2) Aa, Z = 16] was solved and refined by single-crystal X-ray diffraction analysis and confirmed by electron diffraction and transmission electron microscopy, including HRTEM image simulations. Rietveld refinement proved the phase purity of the product. FTIR analysis confirmed the absence N-H groups in the structure. Bond valence and lattice energy calculations (MAPLE) of the title compound are discussed. The crystal structure consists of polyhedral building units constructed from vertex-sharing P(O,N) sub(4) tetrahedra with condensed dreier and sechser rings. CaMg sub(2)P sub(6)O sub(3)N sub(10) has been synthesized by a high-pressure/high-temperature reaction at 8 GPa and 1100 degree C and investigated by single-crystal X-ray diffraction. The structure was confirmed by TEM investigations, including SAED and HRTEM image simulations. It represents a novel oxonitridophosphate with an unprecedented network of tetrahedra.