23Na NMR Spectroscopy of Solids: Interpretation of Quadrupole Interaction Parameters and Chemical Shifts

Abstract

Quadrupole coupling constants (QCC), asymmetry parameters of the electric field gradients (η), and isotropic chemical shifts (δ cs ) of sodium-23 were determined by computer simulation of the central transition line shapes of the 23 Na MAS NMR spectra of a series of crystalline sodium compounds in which sodium has exclusively oxygen atoms as nearest neighbors. The relations between the crystal structure and the above parameters were discussed qualitatively for typical examples. The bond-valence method is applied to derive empirical models for the calculation of a «shift parameter» (A) and of oxygen atomic charges (model I) from which QCC and η were calculated by a simple point charge model