However, the spectra reveal an additional Na signal at around 1 ~ 3 ppm with a significant quadrupolar broadening with CQ~1 MHz and additional disorder. Furthermore, the MQMAS spectra demonstrate a clear difference between the x = 0.5 and the x = 0.75 composition: while for x = 0.5 a distribution of Na signals with small CQ (< 0.5 MHz) is observed within an isotropic shift range as wide as 10 ppm (δiso= 0 and ~ 10 ppm), the chemical shift range for x = 0.75 is restricted between 0 and -5 ppm. This indicates that different Na environments form with more Al substitution. We used the extracted Na sites from the MQMAS spectra to fit the 1D Na MAS NMR spectra of both compositions (Figure , Table and S18). To assign the different experimentally observed Na signals to different Na sites and local environments, we calculated the expected NMR parameters for the DFT structures of NaAlCl4, Na2ZnCl4, as well as Na1.75Zn0.75Al0.25Cl4 with solely Na1 or solely Na2 vacancies, the two energetically favored structures. The results (summarized in Figure , Table ) are in good agreement with the experimental signals for the x = 0.75 composition considering the degree of disorder and strain from the ball milling syntheses and therefore are allowing for an assignment of the either be caused by the disorder in the system or by partial motional averaging, which may take place by limited local Na + motion as indicated from the MD calculations.