NMR-Spektroskopie an den intermetallischen Verbindugen Ba$_{21}$Al$_{40}$ und Ba${\it M}_{4}$ mit ${\it M}$= Al, Ga und In

Due to the varying properties of intermetallic Compounds, these are used in many different areas. In spite of that, most of the production processes are solely experience-based [1]. To allow the creation of materials with well-defined properties, it is necessary to gain more insight into the chemical bonding and the relationship between structure, bonding and properties. This study discusses the investigation of local atomic order in Ba21Al40 and solid solutions of BaM4 with M = Al, Ga and In because material properties often depend strongly on defects and their concentration. The combination of diffraction, quantum mechanical (QM) calculations and NMR-spectroscopy has proven to be very effective for the investigation of intermetallic compounds [2,3]. Superlattice structure models for different local atomic arrangements can be created based on the crystal structure from diffraction experiments. Subsequently NMR-coupling parameters can be determined via QM-calculations and compared to experimental coupling parameters. This allows the verification, falsification or refinement of the used models.This method was used to detect that the triel-elements preferably occupy different crystallographic sites in the solid solutions Ba(Al1 xGax)4, Ba(Ga1 xInx)4 und Ba(Al1-xInx)4. The Ga-atoms favour the five-bonded (5b) position and In-atoms the (4b) position in the BaAl4-structuretype. The Al-atoms preferably occupy the other site. The NMR-Signals show that, the substitution’s influence is quite strong on the charge distribution of the neighbouring Atoms. The extraction of relevant NMR parameters from experimental data was performed with the Matlab-program Simgui, which can simulate NMR-spectra for various measurement methods and Isotopes simultaneously. Results from QM-calculations can be incorporated into the analysis of experimental NMR-data. These capabilities allow Simgui to be a simple and powerful interface between QM-calculations and NMR-spectroscopy, which might assist in future investigation of intermetallic compounds.[1] R. Nesper,. Angewandte Chemie, 103, 805-834 (1991). [2] O. Pecher, B. Mausolf, V. Peters, K. Lamberts, A. Korthaus, F. Haarmann, Chem. Eur. J., 22(49), 17833-17842 (2016). [3] O. Pecher, B. Mausolf, K. Lamberts, D. Oligschläger, U. Englert, F. Haarmann, Chem. Eur. J., 21(40), 13971-13982 (2015)