The experimental Al 1D NMR spectrum shown in Fig. shows 3 distinct peaks corresponding to disordered four-, five-, and six-fold coordinated (Al(IV), Al(V) and Al(VI)) Al environments with a ratio of 50%, 38%, and 12% ± 2% respectively. The presence of the Al(V) signal at 40 ppm and the low intensity of the Al(VI) signal at 11 ppm are strong indicators of the amorphous nature . It is expected that a distribution of asymmetric Al environments, combined with the quadrupolar nature of the Al nucleus (𝐼 = 5/2), would lead to large quadrupolar coupling constants (𝐶 $ ) and a wide range of isotropic chemical shifts, as evidenced by the broad peaks shown in the 1D NMR spectrum in Fig. . The 2D MQMAS (multi quantum MAS) NMR shows three signals spreading along the isotropic diagonal line and horizontally along the MAS dimension, highlighting the spread of quadrupolar coupling constants and a chemical shift distribution (Fig. ).