Details
| Original language | English |
|---|---|
| Pages (from-to) | 208-217 |
| Number of pages | 10 |
| Journal | Journal of non-crystalline solids |
| Volume | 432 |
| Early online date | 22 Oct 2015 |
| Publication status | Published - 15 Jan 2016 |
Abstract
In the present study we have investigated whether the effect of water on properties of borate glasses resembles that of alkali oxide. Soda–lime–borate glasses with nominal compositions of x Na2O, 10 CaO, (90-x) B2O3 (x = 5, 15 and 25 mol%) were doped with up to 8 wt.% H2O by processing glass powder + distilled water in platinum capsules in an internally heated gas pressure vessel at 1523 K and 500 MPa. The water content of hydrous glasses was determined by Karl-Fischer titration and near-infrared spectroscopy. The glass transition temperature Tg. was derived from DTA and micropenetration experiments for which the effect of water loss at the surface of the hydrous glasses was studied. Heating glass samples at 10 K min− 1 in the DTA resulted in Tg values which are close to T12 isokom temperatures confirming the equivalence of enthalpy relaxation and viscous relaxation for borate glasses. For all three glass series it is shown that Tg strongly decreases whereas the liquid fragility strongly increases upon the addition of water. These findings reveal that H2O primarily causes breaking of B–O–B bonds rather than supporting 4-fold coordinated boron as it is well-known for alkali oxides in this concentration range.
Keywords
- Borate glasses, Thermal analysis, Viscosity, Water-bearing glasses
ASJC Scopus subject areas
- Materials Science(all)
- Electronic, Optical and Magnetic Materials
- Materials Science(all)
- Ceramics and Composites
- Physics and Astronomy(all)
- Condensed Matter Physics
- Materials Science(all)
- Materials Chemistry
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In: Journal of non-crystalline solids, Vol. 432, 15.01.2016, p. 208-217.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Water, the other network modifier in borate glasses
AU - Reinsch, S.
AU - Roessler, C.
AU - Bauer, U.
AU - Müller, R.
AU - Deubener, J.
AU - Behrens, H.
N1 - Funding Information: The financial support of the Deutsche Forschungsgemeinschaft (DFG) by the Priority Program 1594 is gratefully acknowledged.
PY - 2016/1/15
Y1 - 2016/1/15
N2 - In the present study we have investigated whether the effect of water on properties of borate glasses resembles that of alkali oxide. Soda–lime–borate glasses with nominal compositions of x Na2O, 10 CaO, (90-x) B2O3 (x = 5, 15 and 25 mol%) were doped with up to 8 wt.% H2O by processing glass powder + distilled water in platinum capsules in an internally heated gas pressure vessel at 1523 K and 500 MPa. The water content of hydrous glasses was determined by Karl-Fischer titration and near-infrared spectroscopy. The glass transition temperature Tg. was derived from DTA and micropenetration experiments for which the effect of water loss at the surface of the hydrous glasses was studied. Heating glass samples at 10 K min− 1 in the DTA resulted in Tg values which are close to T12 isokom temperatures confirming the equivalence of enthalpy relaxation and viscous relaxation for borate glasses. For all three glass series it is shown that Tg strongly decreases whereas the liquid fragility strongly increases upon the addition of water. These findings reveal that H2O primarily causes breaking of B–O–B bonds rather than supporting 4-fold coordinated boron as it is well-known for alkali oxides in this concentration range.
AB - In the present study we have investigated whether the effect of water on properties of borate glasses resembles that of alkali oxide. Soda–lime–borate glasses with nominal compositions of x Na2O, 10 CaO, (90-x) B2O3 (x = 5, 15 and 25 mol%) were doped with up to 8 wt.% H2O by processing glass powder + distilled water in platinum capsules in an internally heated gas pressure vessel at 1523 K and 500 MPa. The water content of hydrous glasses was determined by Karl-Fischer titration and near-infrared spectroscopy. The glass transition temperature Tg. was derived from DTA and micropenetration experiments for which the effect of water loss at the surface of the hydrous glasses was studied. Heating glass samples at 10 K min− 1 in the DTA resulted in Tg values which are close to T12 isokom temperatures confirming the equivalence of enthalpy relaxation and viscous relaxation for borate glasses. For all three glass series it is shown that Tg strongly decreases whereas the liquid fragility strongly increases upon the addition of water. These findings reveal that H2O primarily causes breaking of B–O–B bonds rather than supporting 4-fold coordinated boron as it is well-known for alkali oxides in this concentration range.
KW - Borate glasses
KW - Thermal analysis
KW - Viscosity
KW - Water-bearing glasses
UR - http://www.scopus.com/inward/record.url?scp=84951854635&partnerID=8YFLogxK
U2 - 10.1016/j.jnoncrysol.2015.10.010
DO - 10.1016/j.jnoncrysol.2015.10.010
M3 - Article
AN - SCOPUS:84951854635
VL - 432
SP - 208
EP - 217
JO - Journal of non-crystalline solids
JF - Journal of non-crystalline solids
SN - 0022-3093
ER -