29Si NMR studies of the transformation of silicate anions in the system Na2O·SiO2·nH2O (n= 9,5) in crystals, melts, and solution

Abstract

A combined solid- and liquid-state ²⁹Si NMR study shows that the monomeric silicate anions of crystalline sodium silicate hydrates Na₂H₂SiO₄·nH₂O (n= 8,4) upon melting undergo rapid condensation to distinct oligomer species, and that recrystallization of the melt involves hydrolysis of the oligomers and reconstitution of the initial monomeric silicate structure.