Alkali Metals in Focus: Investigations on the Structural Chemistry of Alkali Metal Trielides

• Applicant: Dr. Stefanie Gärtner
• Subject Area: Solid State and Surface Chemistry, Material Synthesis
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 468336522

The project will continue to focus on the role of the various alkali metals in the structure formation of Zintl phases. The alkali metal-thallium system studied so far will be expanded to include the lighter triel indium and the influence of the element gold will also be examined in more detail. Alkali metal-thallium compounds exhibit a very rich structural chemistry. Thereby, the proportion of alkali metal does not necessarily indicate the thallium substructure formed. Especially for the heavier representatives of the first group of the PSE in combination with thallium, the number of compounds characterized so far has been very limited. In the alkali metal-rich region, isolated clusters are found for which it could be shown in this project, that the use of mixed alkali metals, and particularly the use of the heavy representatives K-Cs, allows the observation of new Zintl phases. In the first part of the follow-up project, this concept is further expanded for the range between A:Tl 1:1 and 2:1. The thallides Na2K21Tl19 and Na9K16Tl25.25. known from the literature serve as starting phases in which permutation with heavy alkali metals is carried out to realize new electron-precise Zintl phases. Compared to the comparably larger number of thallide clusters found in these phases, only a few representatives of isolated clusters In48- and Tl117-in alkali metal indides are known for the lighter homologue indium with. Therefore, the second subproject deals with the (partial) substitution of thallides with indium in order to realize mixed Tl/In clusters. The third subproject will focus on mixed alkali metals and additionally gold in thallides and indides. Due to the high electron affinity of gold, the formation of intermetalloid clusters competes with the formation of aurides. This area needs to be investigated experimentally more in detail. In the project to date, further expertise has generally been gained regarding the characterization of these very sensitive compounds, which strongly absorb X-rays. In addition to measurements on laboratory diffractometers, the use of synchrotron radiation is to be established in the follow-up investigations. Overall, the structural chemistry of the trielides is to be expanded during the continuation application, and the characterization methods used to date are also to be refined. The aim is to make a substantial contribution to the knowledge of the Zintl phases of triels with alkali metals.

• DFG Programme: Research Grants