Study of the hydrolysis of combined Al³⁺ and Ga³⁺ aqueous solutions: Formation of an extremely stable GaO₄Al₁₂(OH)₂₄(H₂O) polyoxycation

Abstract

Abstract 71 Ga and 27 Al NMR and clay mineral pillaring studies were used to investigate the hydrolysis of Al(H 2 O) –Ga(H 2 O) solutions, mixed in an Al:Ga mole ratio of 12:1, and confirmed the formation of the previously proposed GaO 4 Al 12 (OH) 24 (H 2 O) polyoxycation. This species has been found to be formed in marked preference to both AlO 4 Al 12 (OH) 24 (H 2 O) and the previously identified GaO 4 Ga 12 (OH) 24 (H 2 O) ions, and further to have a much higher thermal stability in solution than either of these. It is suggested that the reason for the increased stability of the ‘GaAl 12 ’ species is that the substitution of a larger metal into the central tetrahedral position has resulted in the formation of a less distorted structure.