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Updated: Jun 26, 2025
High Pressure Single Crystal Diffraction at PX^2
Published on: January 16, 2017
Crystal structures of two new high-pressure oxynitrides with composition SnGe4N4O4, from single-crystal electron
Philipp Gollé-Leidreiter1, Shrikant Bhat2, Leonore Wiehl3
1Glass and Mineral Materials, Fraunhofer ISC, Neunerplatz 2, Würzburg, 97082, Germany.
Abstract:
SnGe4N4O4 was synthesized at high pressure (16 and 20 GPa) and high temperature (1200 and 1500°C) in a large-volume press. Powder X-ray diffraction experiments using synchrotron radiation indicate that the derived samples are mixtures of known and unknown phases. However, the powder X-ray diffraction patterns are not sufficient for structural characterization. Transmission electron microscopy studies reveal crystals of several hundreds of nanometres in size with different chemical composition. Among them, crystals of a previously unknown phase with stoichiometry SnGe4N4O4 were detected and investigated using automated diffraction tomography (ADT), a three-dimensional electron diffraction method. Via ADT, the crystal structure could be determined from single nanocrystals in space group P63mc, exhibiting a nolanite-type structure. This was confirmed by density functional theory calculations and atomic resolution scanning transmission electron microscopy images. In one of the syntheses runs a rhombohedral 6R polytype of SnGe4N4O4 could be found together with the nolanite-type SnGe4N4O4. The structure of this polymorph was solved as well using ADT.
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