⁷Li NMR Knight Shifts in Li−Sn Compounds: MAS NMR Measurements and Correlation with DFT Calculations

Abstract

Several Li−Sn crystalline phases, LiSn, Li 7 Sn 3, Li 5 Sn 2, Li 13 Sn 5, Li 7 Sn 2, and Li 22 Sn 5, were prepared by ball-milling and studied by 7 Li MAS NMR spectroscopy with silica as a diluting agent to avoid field penetration limitations. All phases except for LiSn exhibit exchanged NMR signals at room temperature for the various types of Li present in the unit cells, in the 10 to 100 ppm range. Electronic structure calculations based on first-principles method led to a rather good correlation between the participation of the Li 2s orbital to the density of states (DOS) at the Fermi level and the corresponding NMR Knight shift for the two Li crystallographic types in the case of LiSn, and for the weighted average of the different crystallographic types in the case of the NMR-exchanged signals for the other compounds.