Zur Synthese und Kristallstruktur schichtartiger Chalkogenide der Hauptgruppenmetalle

  • About the synthesis and crystal structure of layered main group metal chalcogenides

K├╝pers, Michael; Dronskowski, Richard (Thesis advisor); Oppel, Iris Marga (Thesis advisor)

Aachen (2019)
Dissertation / PhD Thesis

Dissertation, RWTH Aachen University, 2019

Abstract

This doctoral thesis investigates the synthesis and crystal structures of different layered main group metal chalcogenides. In the first part, the synthesis and crystal structure of Ge4Se3Te are presented, a compound that is known for more than 50 years, but its structure has remained unknown. During this thesis high quality single crystals where synthesised, and the crystal structure of Ge4Se3Te could be determined for the first time. It consists of Se/Te-Ge-Ge-Se/Te layers with unexpected Ge-Ge interactions. The second part of the thesis deals with the polymorphism of In2Se3. Seven different polymorphs were synthesised and structurally characterised, which will help to understand the extraordinary physical properties of this material. In the third part, the Sb2Te3-Sb2Se3 system was structurally characterised by single crystal diffraction. The system crystallises in the Bi2Te3 structure type with A2-Sb-A1-Sb-A2 layers (A: Se/Te mixed sites). A preferred incorporation of Se inside the layer (A1) and unexpected chalcogenide-chalcogenide interactions are observed. In the last part the results of the thesis are discussed in terms of layer-layer distances and compared with literature. While in most layered chalcogenides, the layer-layer distance is in accordance with the van der Waals radius, it was observed, that chalcogenides with a group 5 metal show significantly to small layer-layer distances.

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