Doping of low-Tg phosphate glass with Al2O3, B2O3 and SiO2: Part I-effect on glass property and stability

A zinc alkali pyrophosphate system 46.6ZnO-20Na(2)O-33.5P2O(5) presenting low-T-g (339 degrees C) and good thermal stability has been doped with (1-4) mol% of Al2O3, B2O3 and SiO2 to improve the stability of the glass with a minimal increase in glass transition temperature (T-g). XRD and 1D P-31 solid state NMR were used to monitor the isothermal crystallization process occurring at 130 degrees C above T-g. If the Al2O3 and B2O3 doping significantly improved thermal stability, this property was marginally affected by SiO2 doping. Viscosity measurements were performed to observe the crystallization effects induced by the doping. It is noteworthy that the T-g values of all the doped compositions with improved stability presented in this work are below 400 degrees C. Raman spectroscopy, 1D P-31, Al-27 B-11 and Si-29 solid state NMR were carried out to determine the structural modifications and coordination states of the doping elements all along the composition line. (C) 2016 Elsevier B.V. All rights reserved.