TY - GEN A1 - Reinsch, Stefan A1 - Schadrack, Reinhard A1 - Müller, Ralf A1 - Behrens, H. A1 - Deubener, J. T1 - Bestimmung der Glastransformationstemperatur wasserhaltiger Gläser T2 - 80. Glastechnische Tagung CY - Dresden, Deutschland DA - 2006-06-12 PY - 2006 SN - 3-921089-46-8 SP - 1(?) EP - 5(?) PB - Verl. d. Dt. Glastechn. Ges. CY - Offenbach AN - OPUS4-12552 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Deubener, J. A1 - Behrens, H. A1 - Müller, Ralf A1 - Zietka, S. A1 - Reinsch, Stefan T1 - Kinetic fragility of hydrous soda-lime-silica glasses N2 - The effect of hydration on the kinetic fragility of soda-lime-silica glasses was investigated by viscometry in the glass transition range. Water-bearing glasses were prepared from industrial float glass (FG) and a ternary model glass (NCS = 16Na2O 10CaO 74SiO2 in mol%) by bubbling steam through the melt at 1480 °C and up to 7 bar. Additionally, a sodium borosilicate glass (NBS = 16Na2O 10B2O3 74SiO2 in mol%) was hydrated under equal conditions. As detected by infrared spectroscopy water dissolves in the glasses exclusively as OH-groups. The hydration resulted in a total water content CW up to ~ 0.2 wt% for FG, NCS and NBS glasses. Kinetic fragility, expressed by the steepness index m, was determined from the temperature dependence of η at the glass transition. Viscosity data from previous studies on hydrous float glasses (CW > 1 wt%) were surveyed together with literature data on the (H2O)–Na2O–CaO–SiO2, (H2O)–Na2O–SiO2 and (H2O)–SiO2 systems to expand the range of water concentration and bulk composition. We could demonstrate that m decreases for all glasses although water is dissolved as OH and should depolymerize the network. An empirical equation of the general type m = a - b logCW where a, b are fitting parameters, enables m to be predicted, for each glass series as function of the water content CW. The enlarged data base shows that the parameter B of the Arrhenius viscosity-temperature relation decreases much stronger than the isokom temperature at the glass transition. KW - Soda-lime-silica KW - Fragility KW - Viscosity KW - Water in glass PY - 2008 DO - https://doi.org/10.1016/j.jnoncrysol.2008.04.021 SN - 0022-3093 VL - 354 IS - 42-44 SP - 4713 EP - 4718 PB - North-Holland Publ. Co. CY - Amsterdam AN - OPUS4-18187 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Reinsch, Stefan A1 - Müller, Ralf A1 - Deubener, J. A1 - Behrens, H. T1 - Internal friction of hydrated soda-lime-silicate glasses N2 - The internal friction of hydrated soda-lime-silica glasses with total water content (CW ) up to 1.9 wt. % was studied by dynamic mechanical analysis (DMA) using temperature-frequency sweeps from 723 K to 273 K and from 1 s-1 to 50 s-1. Total water content and concentrations of H2O molecules (CH2O ) and OH groups (COH) in the DMA specimens were determined by infrared spectroscopy. For low water contents (CW ≈ COH < 0.25 wt. %) two discrete internal friction peaks below the glass transition (α relaxation) were assigned to the low-temperature motion of alkali ions (γ relaxation) and cooperative movements of dissimilar mobile species under participation of OH at higher temperature (βOH relaxation). For large water contents (CW > 1 wt. %), where significant amounts of molecular water are evident (CH2O > 0.15 wt. %), however, internal friction spectra change unexpectedly: the βOH peak heights saturate and a low temperature shoulder appears on the β-relaxation peak. This emerging relaxation mode (βH2O relaxation) was assigned to the motions of H2O molecules. βH2O relaxation was found to be faster than βOH but slower than γ relaxation. Activation energy of the different relaxation modes increased in the order γ < βH2O < βOH < α. KW - Internal friction KW - Glass KW - Water content PY - 2013 DO - https://doi.org/10.1063/1.4828740 SN - 0021-9606 SN - 1089-7690 VL - 139 SP - 174506-1 EP - 174506-6 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-29698 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Waurischk, Tina A1 - Reinsch, Stefan A1 - Rouxel, T. A1 - Behrens, H. A1 - Deubener, J. A1 - Müller, Ralf T1 - Vacuum crack growth in alkali silicate glasses N2 - Crack growth velocity in alkali silicate glasses was measured in vacuum across 10 orders of magnitude with double cantilever beam technique. Measured and literature crack growth data were compared with calculated intrinsic fracture toughness data obtained from Young´s moduli and the theoretical fracture surface energy estimated from chemical bond energies. Data analysis reveals significant deviations from this intrinsic brittle fracture behavior. These deviations do not follow simple compositional trends. Two opposing processes may explain this finding: a decrease in the apparent fracture surface energy due to stress-induced chemical changes at the crack tip and its increase due to energy dissipation during fracture. KW - Silicate glass KW - Brittle fracture KW - Crack growth KW - Calculated intrinsic fracture toughness PY - 2021 DO - https://doi.org/10.1016/j.jnoncrysol.2021.121094 SN - 0022-3093 VL - 572 SP - 1 EP - 8 PB - Elsevier CY - Amsterdam AN - OPUS4-53144 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Deubener, J. A1 - Bornhöft, H. A1 - Reinsch, Stefan A1 - Müller, Ralf A1 - Lumeau, J. A1 - Glebova, L.N. A1 - Glebov, L.B. T1 - Viscosity, relaxation and elastic properties of photo-thermo-refractive glass KW - Ultrasonic relaxation KW - Silicates KW - Rheology KW - Structural relaxation KW - Viscosity PY - 2009 DO - https://doi.org/10.1016/j.noncrysol.2008.10.002 SN - 0022-3093 VL - 355 SP - 126 EP - 131 PB - North-Holland Publ. Co. CY - Amsterdam AN - OPUS4-18671 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schlegel, Moritz-Caspar A1 - Többens, D. A1 - Svetogorov, R. A1 - Krüger, M. A1 - Stock, N. A1 - Reinsch, H. A1 - Wallacher, D. A1 - Stewart, R. A1 - Russina, M. T1 - Conformation-controlled hydrogen storage in the CAU-1 metal-organic framework N2 - We have studied the mechanism of hydrogen storage in the aluminium based metal–organic framework CAU-1 or [Al4(OH)2 OCH3)4(O2C-C6H3NH2-CO2)3] using a complementary multidisciplinary approach of volumetric gas sorption analysis, in situ neutron diffraction and spectroscopy and ab initio calculations. The structure of CAU-1 forms two different types of microporous cages: (i) an octahedral cage with a diameter of about 10 Å and (ii) a tetrahedral cage with a diameter of about 5 Å. Though all metal sites of CAU-1 are fully coordinated, the material exhibits relatively high storage capacities, reaching 4 wt% at a temperature of 70 K. Our results reveal that hydrogen sorption is dominantly driven by cooperative guest–guest interactions and interactions between guest hydrogen molecules and organic linkers. The adsorption of hydrogen on the organic linkers leads to the contraction of the host framework structure and as a result to changes in the electronic potential surface inside the pores. This, in turn, leads to cooperative rearrangement of the molecules inside the pores and to the formation of additionally occupied positions, increasing hydrogen uptake. At the final stage we observe the formation of solid amorphous hydrogen inside the pores. KW - Hydrogen storage KW - MOF KW - X-ray diffraction KW - Neutron diffraction KW - Neutron scattering PY - 2016 DO - https://doi.org/10.1039/c6cp05310f SN - 1463-9076 SN - 1463-9084 VL - 18 SP - 29258 EP - 29267 PB - The Royal Soc. of Chemistry CY - Cambridge AN - OPUS4-37794 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bauer, Ute A1 - Behrens, H. A1 - Fechtelkord, M. A1 - Reinsch, Stefan A1 - Deubener, J. T1 - Water- and boron speciation in hydrous soda-lime-borate glasses N2 - 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 xNa2O, 10CaO, 90 - xB2O3 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 11B 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 ~ 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 (N4 = BIV / BIV + BIII) 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.%, N4 increases from 25% to 26% for NCB5 and from 42% to 47% for NCB25 glasses. KW - Glass structure KW - Water-bearing glasses KW - High pressure KW - Spectroscopy KW - Glasstruktur KW - Wasserhaltige Gläser KW - Hoher Druck KW - Spektroskopie PY - 2015 DO - https://doi.org/10.1016/j.jnoncrysol.2015.05.004 SN - 0022-3093 VL - 423-424 SP - 58 EP - 67 PB - North-Holland Publ. Co. CY - Amsterdam AN - OPUS4-33804 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Behrens, H. A1 - Bauer, U. A1 - Reinsch, Stefan A1 - Kiefer, P. A1 - Müller, Ralf A1 - Deubener, J. T1 - Structural relaxation mechanisms in hydrous sodium borosilicate glasses N2 - Borosilicate glasses (16Na2O–10B2O3–74SiO2, NBS) with water contents up to 22 mol% H2O were prepared to study the effect of water on structural relaxation using DTA, viscometry and internal friction measurements. The results show that the glass transition temperature Tg of DTA and the isokom temperature T12, of viscometry are in excellent agreement, confirming the equivalence of enthalpy and viscous relaxation for NBS glass. Combining Tg data with water speciation data demonstrates that OH groups are mainly responsible for the decrease of Tg with increasing hydration, while molecular water plays only a minor role. Internal friction spectra at 7.125 Hz confirm the decisive influence of water on mechanical relaxation. The temperature range of α-relaxation (glass transition) strongly decreases while two β-relaxation peaks (sub-Tg) progressively appear with increasing water content. A high temperature β-relaxation peak, attributed to the presence of OH groups, shifts from 670 to 450 K as total water content increases from 0.01 to 5 wt%. A low temperature β-relaxation peak, attributed to molecular water, appears at 380 K and 330 K in glasses containing 3 and 5 wt% H2O, respectively. These findings suggest that relaxation mechanism of different hydrous species at low temperature may contribute to fatigue of stressed glasses. KW - Borosilicate glass KW - Water KW - Relaxation KW - Internal friction KW - Glass transition PY - 2018 DO - https://doi.org/10.1016/j.jnoncrysol.2018.05.025 VL - 497 SP - 30 EP - 39 PB - Elsevier B.V. AN - OPUS4-45608 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kiefer, P. A1 - Maiwald, M. A1 - Deubener, J. A1 - Balzer, R. A1 - Behrens, H. A1 - Waurischk, Tina A1 - Reinsch, Stefan A1 - Müller, Ralf T1 - Automated Analysis of Slow Crack Growth in Hydrous Soda-Lime Silicate Glasses N2 - To explore the impact of ambient and structural water on static fatigue, the initiation and growth of 3279 Vickers induced median radial cracks were automatically recorded and analyzed. We find that humidity is more efficient in initiating cracks and promoting their growth than water, which is dissolved in the glass structure. In particular for slow crack growth (< 3x10-6 m s-1), tests in dry nitrogen showed a considerable decrease in the crack growth exponent with increasing water content of the glasses. On the other hand, if tests were performed in humid air, the crack growth exponent was independent of the water content of the hydrous glasses, while stress intensity decreased slightly. These observations indicate that water promotes the processes at the crack-tip regardless of its origin. However, ambient water is more efficient. KW - Indentation fracture toughness KW - Slow crack growth KW - Automated analysis KW - Hydrous glass KW - Vickers indentation PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-513085 DO - https://doi.org/10.3389/fmats.2020.00268 VL - 7 SP - 268 AN - OPUS4-51308 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Balzer, R. A1 - Behrens, H. A1 - Reinsch, Stefan A1 - Fechtelkord, M. T1 - Structural investigation of hydrous phosphate glasses N2 - Dissolved water has major impact on the physical and chemical properties of phosphate glasses. In the present study we have investigated the structural response to water incorporation for glasses in the system Li2O–MgO–Al2O3–P2O5. Glasses containing 0–8 wt% H2O were synthesised at 500 MPa confining pressure in internally heated gas pressure vessels at 1323 K (LMP, Al-poor glass) and 1423 K (LMAP, Al-enriched glass). Water contents of glasses were determined by pyrolysis and subsequent Karl-Fischer titration (KFT) and/or by infrared spectroscopy. Density varies nonlinearly with water content implying large structural changes when adding up to 2 wt% H2O to the dry glass. Glass Transition temperatures measured by differential thermal analysis (DTA) continuously decrease with water content. The trend can be explained by depolymerisation of the phosphate network. Near-infrared spectroscopy shows that even in Al poor glasses only a minority of dissolved water is present as H2O molecules, but the largest amount is present as OH Groups formed by hydrolysis of P–O–P bonds. The network is stabilised by aluminium which is predominantly six-coordinated in these glasses as shown by 27Al MAS NMR spectroscopy. With increase of Al in the glasses, breaking up of the Phosphate network through hydrolysis is depressed, i.e. much lower OH Contents are formed at same total water content. Network depolymerisation upon addition of H2O is evident also from 31P MAS NMR spectroscopy. While Phosphate tetraheda are crosslinked by two to three bridging oxygen in dry glasses, diphosphate Groups are dominant in glasses containing 8 wt% H2O. T2 - 2. INT. CONF. ON PHOSPHATE GLASSES CY - Oxford, UK DA - 26.07.2017 KW - water speciation KW - phosphate glasses KW - infrared spectroscopy KW - NMR spectroscopy KW - high pressure PY - 2019 DO - https://doi.org/10.13036/17533562.60.2.041 SN - 1753-3562 VL - 60 IS - 2 SP - 49 EP - 61 PB - Society of Glass Technology CY - Sheffield AN - OPUS4-48122 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Balzer, R. A1 - Behrens, H. A1 - Waurischk, Tina A1 - Reinsch, Stefan A1 - Müller, Ralf A1 - Kiefer, P. A1 - Deubener, J. A1 - Fechtelkord, M. T1 - Water in Alkali Aluminosilicate Glasses N2 - To understand the influence of water and alkalis on aluminosilicate glasses, three polymerized glasses with varying ratios of Na/K were synthesized [(22. 5-x)Na2O-xK2O-22.5 Al2O3-55 SiO2 with x = 0, 7.5, and 11.25]. Subsequently, these glasses were hydrated (up to 8 wt% H2O) in an internally heated gas pressure vessel. The density of hydrous glasses linearly decreased with water content above 1 wt%, consistent with the partial molar volume of H2O of 12 cm3/mol. Near-infrared spectroscopy revealed that hydroxyl groups are the dominant species at water content of <4 wt%, and molecular water becomes dominating at water content of >5 wt%. The fraction of OH is particularly high in the pure Na-bearing glass compared to the mixed alkali glasses. 27Al magic angle spinning-NMR spectroscopy shows that aluminum is exclusively fourfold coordinated with some variations in the local geometry. It appears that the local structure around Al becomes more ordered with increasing K/Na ratio. The incorporation of H2O reinforces this effect. The differential thermal analysis of hydrous glasses shows a significant mass loss in the range of glass transition already during the first upscan, implying the high mobility of water in the glasses. This observation can be explained by the open structure of the aluminosilicate network and by the low dissociation enthalpy of H2O in the glasses (≈ 8 kJ/mol). The effect of the dissolved H2O on the glass transition temperature is less pronounced than for other aluminosilicate glasses, probably because of the large fraction of Al in the glasses. KW - NMR spectroscopy KW - Alkali aluminosilicate glasses KW - Water speciation KW - Glass transition KW - Infrared spectroscopy PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-509497 DO - https://doi.org/10.3389/fmats.2020.00085 VL - 7 SP - 85 AN - OPUS4-50949 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Waurischk, Tina A1 - Müller, Ralf A1 - Reinsch, Stefan A1 - Kiefer, P. A1 - Deubener, J. A1 - Balzer, R. A1 - Behrens, H. T1 - Crack Growth in Hydrous Soda-Lime Silicate Glass N2 - Stable crack growth was measured for nominal dry and water-bearing (6 wt%) soda-lime silicate glasses in double cantilever beam geometry and combined with DMA studies on the effects of dissolved water on internal friction and glass transition, respectively. In vacuum, a decreased slope of logarithmic crack growth velocity versus stress intensity factor is evident for the hydrous glass in line with an increase of b-relaxation intensity indicating more energy Dissipation during fracture. Further, inert crack growth in hydrous glass is found to be divided into sections of different slope, which indicates different water related crack propagation mechanism. In ambient air, a largely extended region II is observed for the hydrous glass, which indicates that crack growth is more sensitive to ambient water. KW - Internal friction KW - Soda-lime silicate glass KW - Water content KW - Stable crack growth KW - DCB geometry KW - Stress intensity factor PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-506829 DO - https://doi.org/10.3389/fmats.2020.00066 VL - 7 SP - Articel 66 AN - OPUS4-50682 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Reinsch, Stefan A1 - Rössler, C. A1 - Bauer, Ute A1 - Müller, Ralf A1 - Deubener, J. A1 - Behrens, H. T1 - Water, the other network modifier in borate glasses 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 T-g. 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 T-g values which are close to T-12 isokom temperatures confirming the equivalence of enthalpy relaxation and viscous relaxation for borate glasses. For all three glass series it is shown that T-g 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. (C) 2015 Elsevier B.V. All rights reserved. KW - Wasserhaltige Gläser KW - Viskosität KW - Boratgläser KW - Thermische Analyse KW - Viscosity KW - Borate glasses KW - Thermal analysis KW - Water-bearing glasses PY - 2016 DO - https://doi.org/10.1016/j.jnoncrysol.2015.10.010 SN - 0022-3093 VL - 432 SP - 208 EP - 217 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-35123 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Balzer, R. A1 - Behrens, H. A1 - Schuth, S. A1 - Waurischk, Tina A1 - Reinsch, Stefan A1 - Müller, Ralf A1 - Fechtelkord, M. A1 - Deubener, J. T1 - The influence of H2O and SiO2 on the structure of silicoborate glasses N2 - To understand the impact of dissolved water on structure and properties, four boron-rich glasses of molar compositions 15-x Na2O x CaO 15 SiO2 70 B2O3 (with x=0, 7.5, 10) and 10 Na2O 15 SiO2 75 B2O3 were prepared and subsequently hydrated (up to 8 wt% H2O). Density measurements show a non-linear trend upon hydration implying large structural changes in particular at water contents<2 wt%. Near-infrared spectroscopy shows hydroxyl groups are the dominant species in all glasses upon the entire range of water content. Molecular H2O is detectable only at total water contents>2 wt%. 11B MAS NMR spectra show that the abundance of BO4 species is mainly controlled by ratio of (Na2O+CaO)/B2O3 while incorporation of water plays a minor role. Compared to borate glasses, the efficiency of formation of BO4 tetrahedra is favored by crosslinking of the network by SiO4-units. The glass transition temperatures, determined by differential thermal analysis, decreases continuously with water content due to breakage of B-O-B bonds by hydrolysis. However, compared to Silicates and aluminosilicates, the effect of dissolved water is less pronounced which can be explained by weaker B-O-B bonds in comparison to Si-O-Si bonds. KW - High pressure KW - Water speciation KW - Silicoborate glasses KW - Infrared spectroscopy KW - NMR spectroscopy PY - 2019 DO - https://doi.org/10.1016/j.jnoncrysol.2019.05.030 VL - 519 SP - 38 EP - 51 PB - Elsevier B.V. AN - OPUS4-48748 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kiefer, P. A1 - Balzer, R. A1 - Deubener, J. A1 - Behrens, H. A1 - Waurischk, Tina A1 - Reinsch, Stefan A1 - Müller, Ralf T1 - Density, elastic constants and indentation hardness of hydrous soda-lime silica glasses N2 - The effect of structural water on density, elastic constants and microhardness of water-bearing soda-lime-silica glasses of up to 21.5 mol% total water is studied. It is found that the Poisson ratio and the water content are positively correlated, while density and the elastic moduli decrease with increasing water content. Vickers hardness decreases by approximately 27% from the dry to the most hydrous glass. For water fractions <3 mol%, the dependencies are non-linear reflecting the non-linear change in the concentrations of OH and H2O molecules dissolved, whereas for water fractions >3 mol% linear dependencies are found. To distinguish the effect of structural water and environmental water, indentations were performed in toluene, nitrogen gas and air. Timedependent softening was evident for testing dry glasses in humid atmospheres as well as for tests of hydrous glasses in dry atmospheres. This indicates that the response times of dissolved water species are effectively equal in both scenarios. KW - Elastic constants KW - Soda-lime-silica KW - Glass KW - Water content KW - Microhardness PY - 2019 DO - https://doi.org/10.1016/j.jnoncrysol.2019.119480 SN - 0022-3093 SN - 1873-4812 VL - 521 SP - 119480 PB - Elsevier B.V. AN - OPUS4-48758 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bauer, Ute A1 - Behrens, H. A1 - Reinsch, Stefan A1 - Morin, E. I. A1 - Stebbins, J. F. T1 - Structural investigation of hydrous sodium borosilicate glasses N2 - The structural properties of a borosilicate glass with nominal 16 mol% Na2O, 10 mol% B2O3 and 74mol% SiO2 and water contents between 0 and 8wt% H2O (0–22 mol% H2O)were investigated with IR, Raman and 11BMAS NMR spectroscopy. In addition to the pronounced OH stretching vibration band of weakly H-bonded species at 3580 cm−1 the MIR spectra show a triplet at 2900, 2350 and 1750 cm−1, similar as observed in water-bearing silicate glasses. These bands are assigned to OH groups and water molecules which are strongly H-bonded, to non-bridging oxygen. Water species contents determined from absorption bands in the NIR at 5200 cm−1 (molecular H2O), 4700 cm−1 (B\\OH), and 4500 cm−1 (Si\\OH) indicate that hydroxyl groups dominate up to ~6 wt% total H2O. Based on the absorption coefficients known from literature for silicate and borate glasses the B\\OH/Si\\OH ratio is estimated to be ≈0.8. As indicated by density, Raman and NMR data the incorporation ofwater has strong structural impacts in particular at low water contents up to 3 wt% H2O. While the nominally dry glasses still contain a significant fraction (12%) of three-fold coordinated boron, almost all boron is four-fold coordinated in hydrous glasses. The increase of band components in the Raman spectra near 900 cm−1 relative to the region N 1050 cm−1 gives evidence for depolymerization of the network upon hydration. Fitting of the spectra with Gaussians implies that silica tetrahedra with two non-bridging oxygen (Q2) are preferentially formed by reactionwithwater on expense of tetrahedra linked to four tetrahedra (Q4). KW - Glass structure KW - Borosilicate glasses KW - Water-bearing glasses KW - Spectroscopy PY - 2017 DO - https://doi.org/10.1016/j.jnoncrysol.2017.03.023 SN - 0022-3093 SN - 1873-4812 VL - 465 SP - 39 EP - 48 PB - Elsevier B. V. AN - OPUS4-40805 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Paskin, A. A1 - Couasnon, T. A1 - Perez, J. P. H. A1 - Lobanov, S. S. A1 - Blukis, R. A1 - Reinsch, Stefan A1 - Benning, L. G. T1 - Nucleation and Crystallization of Ferrous Phosphate Hydrate via an Amorphous Intermediate N2 - The fundamental processes of nucleation and crystallization are widely observed in systems relevant to material synthesis and biomineralization; yet most often, their mechanism remains unclear. In this study, we unravel the discrete stages of nucleation and crystallization of Fe3(PO4)2·8H2O (vivianite). We experimentally monitored the formation and transformation from ions to solid products by employing correlated, time-resolved in situ and ex situ approaches. We show that vivianite crystallization occurs in distinct stages via a transient amorphous precursor phase. The metastable amorphous ferrous phosphate (AFEP) intermediate could be isolated and stabilized. We resolved the differences in bonding environments, structure, and symmetric changes of the Fe site during the transformation of AFEP to crystalline vivianite through synchrotron X-ray absorption spectroscopy at the Fe K-edge. This intermediate AFEP phase has a lower water content and less distorted local symmetry, compared to the crystalline end product vivianite. Our combined results indicate that a nonclassical, hydration-induced nucleation and transformation driven by the incorporation and rearrangement of water molecules and ions (Fe2+ and PO4 3−) within the AFEP is the dominating mechanism of vivianite formation at moderately high to low vivianite supersaturations (saturation index ≤ 10.19). We offer fundamental insights into the aqueous, amorphous-to-crystalline transformations in the Fe2+−PO4 system and highlight the different attributes of the AFEP, compared to its crystalline counterpart. KW - Nucleation KW - Crystallization KW - Vivianite KW - Ferrous phosphate hydrate PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-580696 DO - https://doi.org/10.1021/jacs.3c01494 SN - 0002-7863 VL - 145 IS - 28 SP - 15137 EP - 15151 PB - ACS Publications AN - OPUS4-58069 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -