Highly resolved Al-27 NMR spectra of aluminosilicate solutions

The first highly resolved Al-27 NMR spectra of alkaline aluminosilicate sol utions have been recorded and are discussed. The linewidths and number of r esolved lines are shown to depend critically on several factors, especially the pH and Si:Al ratio. At least thirteen separate peaks or bands are obse rved at pH approximate to 10.35 and Si:Al=1:1. A substantial range of anion ic species, comparable to those found for alkaline silicate solutions, is t hus shown to exist in dynamic equilibrium. Tentative assignments of some ba nds are presented, based on Al-27 and Si-29 shift comparability, Al-27 line widths and Al-27 spin-lattice relaxation measurements. Relative intensities of the various Al-27 signals are given for the pH approximate to 10.35 sol ution.