Using the deconvolution of the 1D Na MAS NMR spectrum (Figure ) we can estimate a NZAC composition of Na10.88Na20.87Zn0.75Al0.25Cl4 for the nominal x = 0.75 sample, which is in good agreement with the Na1/Na2 occupancies derived from XRD analyses (Figure ). Thus, we conclude that in the case of x = 0.75 both layers of Na1 or Na2 vacancies form during the high-energy ball milling synthesis.