TY - CONF A1 - Behrens, H. A1 - Bauer, Ute A1 - Reinsch, Stefan A1 - Müller, Ralf A1 - Morin, E. I. A1 - Stebbins, J. F. A1 - Kiefer, P. A1 - Deubener, J. T1 - Effect of water on structure and dynamics of sodium borosilicate glasses N2 - Borosilicate glass has a wide range of technical applications due to its high chemical durability and thermal-shock resistivity. Here the effect of H2O on 16 Na2O, 10 B2O3,74 SiO2 glass is studied over a wide range of water contents from 0 to 8 wt.%. MIR spectra give evidence for the coexistence of strongly and weakly H-bonded hydrous species. Evaluation of NIR bands at 5200 cm-1 (molecular H2O), 4700 cm-1 (B-OH), and 4500 cm-1 (Si-OH) reveal that OH groups dominate up to ~6 wt.% H2O, with B-OH/Si-OH of ≈ 0.8. The incorporation of low amounts of H2O has strong impact on structure. NMR spectra of nominally dry glasses indicate a significant fraction (12 %) of 3-coordinated boron, but almost all boron is 4-coordinated after addition of 3 wt.% H2O. Raman spectra show that hydration results preferentially in transformation of Q4 to Q2 while Q3 remain unchanged, probably stabilized by bonding to BO4 tetrahedra. Viscosity measurements and differential thermal analysis give consistent results, confirming strong decrease of the glass transition temperature with addition of water from 849 K (dry) to 540 K (5 wt% H2O). An additional relaxation mechanism in hydrous glasses is inferred from dynamic mechanical analysis and is assigned to cooperative processes involving hydrous species. It is postulated that this relaxation mechanism plays an important role in crack growth kinetics. T2 - 9th International Conference on Borate Glasses, Crystals and Melts CY - Oxford, UK DA - 24.07.2017 KW - Borosilicate glass KW - Water speciation KW - Sub-Tg relaxation KW - High water bearing glass PY - 2017 AN - OPUS4-44355 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Behrens, H. A1 - Bauer, Ute A1 - Reinsch, Stefan A1 - Müller, Ralf A1 - Morin, E. I. A1 - Stebbins, J. F. A1 - Kiefer, P. A1 - Deubener, J. T1 - Effect of water on structure and dynamics of sodium borosilicate glasses N2 - Borosilicate glass has a wide range of technical applications due to its high chemical durability and thermal-shock resistivity. Here the effect of H2O on 16 Na2O, 10 B2O3,74 SiO2 glass is studied over a wide range of water contents from 0 to 8 wt.%. MIR spectra give evidence for the coexistence of strongly and weakly H-bonded hydrous species. Evaluation of NIR bands at 5200 cm-1 (molecular H2O), 4700 cm-1 (B-OH), and 4500 cm-1 (Si-OH) reveal that OH groups dominate up to ~6 wt.% H2O, with B-OH/Si-OH of ≈ 0.8. The incorporation of low amounts of H2O has strong impact on structure. NMR spectra of nominally dry glasses indicate a significant fraction (12 %) of 3-coordinated boron, but almost all boron is 4-coordinated after addition of 3 wt.% H2O. Raman spectra show that hydration results preferentially in transformation of Q4 to Q2 while Q3 remain unchanged, probably stabilized by bonding to BO4 tetrahedra. Viscosity measurements and differential thermal analysis give consistent results, confirming strong decrease of the glass transition temperature with addition of water from 849 K (dry) to 540 K (5 wt% H2O). An additional relaxation mechanism in hydrous glasses is inferred from dynamic mechanical analysis and is assigned to cooperative processes involving hydrous species. It is postulated that this relaxation mechanism plays an important role in crack growth kinetics. T2 - 12th Pacific Rim Conference on Ceramic and Glass Technology including Glass & Optical Materials Division Meeting CY - Waikoloa, USA DA - 21.05.2017 KW - Borosilicate glass KW - Water speciation KW - Sub-Tg relaxation KW - High water bearing glass PY - 2017 AN - OPUS4-44383 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -