MAS NMR studies of ternary silicate glasses

Abstract

A series of silicate glasses based on PbO-B₂O₃-SiO₂, PbO-Al₂O₃-Si_O, Bi₂O₃-Al₂O₃-SiO₂ and PbO-PbF₂-SiO₂ have been studied using solid-state magic-angle-spinning (MAS) NMR of ²⁹Si, ²⁷Al and ¹¹B nuclei. Al is found to be always four-coordinated in all these glasses. Si is present mostly as Q ₂ or Q ₃. Four-coordinated boron dominates the ¹¹B spectra. Calculated partial charges on Al, Si and B have been used to provide a rationale for the observed spectral features.