Water- and boron speciation in hydrous soda-lime-borate glasses

作者：Bauer U^*; Behrens H; Fechtelkord M; Reinsch S; Deubener J

来源：Journal of Non-Crystalline Solids, 2015, 423: 58-67.

DOI：10.1016/j.jnoncrysol.2015.05.004

• Glass structure
• Water-bearing glasses
• High pressure
• Spectroscopy

The structural investigation of hydrated borate glasses provides new insights on the influence of water on boron speciation using spectroscopic methods. In the present study three soda-lime-borate glasses (NCBx with x = 5, 15 and 25 corresponding to xNa(2)O, 10CaO, 90 - xB(2)O(3) in mol%) were prepared with water content up to 8 wt.%. The water speciation in the glasses was derived by near-infrared (NIR) spectroscopy while boron speciation was investigated by B-11 MAS NMR (Magic Angle Spinning Nuclear Magnetic Resonance). For the three glasses effective molar absorption coefficients were determined experimentally for the bands at 5200 cm(-1) and 4600 cm(-1), corresponding to combination modes of H2O molecules and OH-groups, respectively. In contrast to silicate glasses, in which at most similar to 2 wt.% H2O are dissociated to OH-groups, the amount of dissociated H2O may even exceed 5 wt.% in borate glasses. The fraction of tetrahedral to total boron (N-4 = B-IV / B-IV + B-III) is predominantly controlled by the ratio of Na2O + CaO / B2O3, but only weakly affected by the water content of the glasses. When increasing the H2O content from 0 to 8 wt.%, N-4 increases from 25% to 26% for NCB5 and from 42% to 47% for NCB25 glasses.

• 出版日期2015-9-1