Nuclear magnetic resonance studies of alkaline earth phosphosilicate and aluminoborosilicate glasses

摘要

The B-11. Al-27 Si-29 and P-31 magic angle spinning (MAS) NMR spectra of MO-P2O5, MO SiO2-P2O5 and MO(M'O-2)-SiO2-Al2O3-B2O3 (M = Mg, Ca, Sr and Ba, M' = Na) glasses were examined, in binary MO-P2O5 (M = Ca and Mg) glasses, the distributions of the phosphate sites, P(Q(n)), call be expressed by a theoretical prediction that P2O5 reacts quantitatively with MO. In the ternary 0.30MO-0.05SiO(2)-0.65P(2)O(5) glasses, the 6-coordinated silicon sites were detected. whose population increases in the order of MgO < CaO < SrO=BaO. In xCaO=0.05SiO(2) (0.95 - x)P2O5 glasses, its population increases with an increase in f (= ([P2O5] - [MO] - [B2O3] - [Na2O])/[SiO2]) and has maximum at f = 9. The signal due to the 5-coordinated silicon atoms is also observed when x is smaller than 0.45. When three network-forming oxides such as SiO2, Al2O3 and B2O3 coexist, Al2O3 reacts preferably with MO. The populations of 4-coordinated boron atoms, N-4, are expressed well with r/(1 - r), when r = ([Na2O] - [Al2O3])/([Na2O] - [Al2O3] + [B2O3]). The correlation of the Raman signal at 1210 and 1350 cm (1) with the NMR signal of Si(Q(6)) at -215 ppm is also seen. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 32]