Dresden 2020 – wissenschaftliches Programm

Die DPG-Frühjahrstagung in Dresden musste abgesagt werden! Lesen Sie mehr ...

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

CPP: Fachverband Chemische Physik und Polymerphysik

CPP 94: TEM-based Nanoanalysis and Microstructure of thin films (joint session KFM/CPP)

CPP 94.2: 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