Dresden 2020 – wissenschaftliches Programm
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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 14: TEM-based Nanoanalysis and Microstructure of thin films (joint session KFM/CPP)
KFM 14.2: Vortrag
Donnerstag, 19. März 2020, 14:30–14:50, HSZ 301
A Novel High-Pressure Tin Oxynitride Sn2N2O — •Philipp Gollé-Leidreiter1, Shrikant Bhat2, Leonore Wiehl1, Ute Kolb1, and Ralf Riedel1 — 1Technische Universität Darmstadt — 2Photon Science DESY
The crystal structure of a novel high pressure high temperature tin oxynitride phase (Sn2N2O) was solved via Automated electron Diffraction Tomography (ADT) [1]. The new phase was synthesized from a Sn-N-O precursor at 20 GPa and 1200-1500∘C. Due to strong overlaps of symmetrically non-equivalent reflections, the unknown structure could not be solved based on X-ray powder diffraction data. Using the ADT method three dimensional electron diffraction data from a single nanocrystal can be collected in a TEM [2]. The crystal is tilted in 1∘ steps and diffraction patterns are measured sequentially. Thereby, the reconstructed reciprocal space delivers the unit cell as well as the space group. The intensities of the reflections can be extracted and used to solve the crystal structure via approaches like *direct methods*. The new phase crystallizes in space group Pbcn with the unit cell parameters: a=7.8Å, b=5.53Å, c=5.54Å. The crystal structure could be solved and refined applying kinematic and dynamic theory. It is a Rh2S3 type structure where the Sn atoms are sixfold coordinated by O and N atoms. The refined structure compares very well with DFT calculations. This shows the value ADT can provide for the structure solution of high pressure and high temperature materials.
[1]Bhat S, et al. (2019) Chem. Eur. J. 10.1002/chem.201904529
[2]Kolb U, et al. (2019) doi.org/10.1107/S2052520619006711