The stuffed framework structure of SrP2N4: Challenges to synthesis and crystal structure determination

摘要

SrP2N4 was obtained by high-pressure high -temperature synthesis utilizing the multianvil technique (5 GPa, 1400 degrees C) starting from mixtures of phosphorus(V) nitride and strontium azide. SrP2N4 turned out to be isotypic with BaGa2O4 and is closely related to KGeAlO4. The crystal structure (SrP2N4, a = 17.1029(8), C = 8.10318(5) angstrom, space group P6(3) (no. 173), V = 2052.70(2) angstrom(3), Z = 24, R(F-2) = 0.0633) was solved from synchrotron powder diffraction data by applying a combination of direct methods, Patterson syntheses, and difference Fourier maps adding the unit cell information derived from electron diffraction and symmetry information obtained from P-31 solid-state NMR spectroscopy. The structure of SrP2N4 was refined by the Rietveld method by utilizing both neutron and synchrotron X-ray powder diffraction data, and has been corroborated additionally by (31)p solid-state NMR spectroscopy by employing through-bond connectivities and distance relations.