Clarifying the gel-to-glass transformation in Al2O3-SiO2 systems

Liu, Shujiang; Boffa, Vittorio; Yang, Dongliang; Fan, Zhenkun; Meng, Fanpeng; Yue, Yuanzheng

doi:10.1016/j.jnoncrysol.2018.03.049

Cited by 8 publications

(5 citation statements)

References 26 publications

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“…Assuming a constant surface tension with T, the key term of this equation is thus related to the glass viscosity η at high T. We suggested that the observe difference is mostly related to η(T) that is likely higher for 50% and element distribution maps shown in Figure 5 have confirmed this view. In particular the high thermal stability of laser-induced phase separation could be related to immiscibility, which has been reported for example in annealed solgel glasses containing >10 mol% Al 2 O 3 and this immiscibility appears to increase with Al 2 O 3 content as reported in 47,48 . This immiscibility can be ascribed to the difference in the coordination number between oxygen ions bonded to Si and those bonded to Al.…”

Section: Discussionmentioning

confidence: 62%

Femtosecond laser direct writing in SiO₂‐Al₂O₃ binary glasses and thermal stability of Type II permanent modifications

et al. 2020

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We investigate the potential of fabricating thermally stable refractive index contrasts using femtosecond (fs) near-infrared (IR) radiation in aluminosilicate glasses. A set of pure SiO 2-Al 2 O 3 glasses are manufactured, characterized (density and Raman) and investigated after being irradiated by fs laser within the Type II regime. The formation of nanogratings is identified and studied using quantitative birefringence measurements. Their thermal stability is then investigated through 30min step isochronal annealing (up to 1250°C). For both SiO 2 and 50SiO 2-50Al 2 O 3 compositions, the normalized birefringence does not decrease when tested up to 1100°C, while for the 4,6 mol% GeO 2-SiO 2 erased for 20% at 1000°C.

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Section: Discussionmentioning

confidence: 62%

Femtosecond laser direct writing in SiO₂‐Al₂O₃ binary glasses and thermal stability of Type II permanent modifications

et al. 2020

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“…Indeed, precipitation of Al 2 O 3 from the sol was always observed when the surfactant was added after the second step. Nevertheless, depending on the synthesis conditions and sol composition, phase separation might occur in the final membrane material when the molar ratio of the alumina reach to 10% [27,28,29].…”

Section: Introductionmentioning

confidence: 99%

Surfactant-Assisted Fabrication of Alumina-Doped Amorphous Silica Nanofiltration Membranes with Enhanced Water Purification Performances

Janowska

Boffa

et al. 2019

Nanomaterials

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Surfactant-templated 5 mol% Al2O3-doped silica membranes nanofiltration membranes were synthesized via the sol-gel method, and afterward, were optimized, and tested with respect to the permeability and rejection rate. The disordered silica network was stabilized by doping 5 mol% alumina. Tetraethyl orthosilicate and aluminum isopropoxide were used as the silica and alumina precursors, respectively. Cetyltrimethylammonium bromide (CTAB) was used not only as a pore-forming agent, but also to control the reaction rate of the aluminum isopropoxide, thus obtaining highly homogeneous materials. The results about filtration of model solutions showed that the optimized membranes are featured by both a relatively high water permeability (1.1–2.3 L·m−2·h−1 ·bar−1) and a high rejection for salts (74% for NaCl, and >95% for MgSO4 and Na2SO4) and organic pollutants (e.g., about 98% for caffeine). High rejection of divalent ions and organic molecules was also observed when a real wastewater effluent was filtered. The influence of the synthesis conditions on the membrane performance is discussed.

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“…Otherwise, it has been shown that the addition of Al2O3 to the SiO2 gel allows avoiding the dependence of glass transition temperature (Tg) on hydroxyl concentration. This effect is due to the highly cross-linked structure in alumina-silica gels [33] .Indeed, previous studies confirm by NMR spectroscopy the formation of the chemical bond Si-O-Al in alumina-silica gels rather than Al-O-Al linking with Al2O3 content lower than 14 mol% [34] . Lithium silicate gels were also studied.…”

Section: Introductionmentioning

confidence: 82%

Structural study of the effect of mineral additives on the transparency, stability, and aging of silicate gels

Felss

Gharzouni

Colas

et al. 2020

J Sol-Gel Sci Technol

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The objective of this work is to evaluate to structural evolution of silicate gel in function of time and mineral additives. A comparison between fresh and aged silicate gel synthesized by silica and potassium hydroxide was carried out using FTIR, Raman and 29 Si MAS-NMR spectroscopies. Then, different additives such as NaOH, AlOOH, Li2B4O7 and HCl were incorporated in the silica solution. Their effect on the aspect, transparency, Q n polymerization and stability of silicate gels was studied. The structural study has shown that the quantification of Q n species is difficult using FTIR and Raman spectroscopy because of the existence of several contributions in the same spectral region of silicate species. More precise informations were given by 29 Si NMR spectroscopy which has demonstrated the increase of Q 3 species in the detriment of Q 4 revealing the depolymerization of the structure over time. The study of effect of additives reveals that HCl, AlOOH and Li2B4O7 do not permit to improve the stability of the gel due to the formation of several networks. However, promising results of stability and transparency were obtained using NaOH with a molar ratio of former to modifier of 2.52.

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Clarifying the gel-to-glass transformation in Al2O3-SiO2 systems

Cited by 8 publications

References 26 publications

Femtosecond laser direct writing in SiO₂‐Al₂O₃ binary glasses and thermal stability of Type II permanent modifications

Femtosecond laser direct writing in SiO₂‐Al₂O₃ binary glasses and thermal stability of Type II permanent modifications

Surfactant-Assisted Fabrication of Alumina-Doped Amorphous Silica Nanofiltration Membranes with Enhanced Water Purification Performances

Structural study of the effect of mineral additives on the transparency, stability, and aging of silicate gels

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Clarifying the gel-to-glass transformation in Al2O3-SiO2 systems

Cited by 8 publications

References 26 publications

Femtosecond laser direct writing in SiO2‐Al2O3 binary glasses and thermal stability of Type II permanent modifications

Femtosecond laser direct writing in SiO2‐Al2O3 binary glasses and thermal stability of Type II permanent modifications

Surfactant-Assisted Fabrication of Alumina-Doped Amorphous Silica Nanofiltration Membranes with Enhanced Water Purification Performances

Structural study of the effect of mineral additives on the transparency, stability, and aging of silicate gels

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Femtosecond laser direct writing in SiO₂‐Al₂O₃ binary glasses and thermal stability of Type II permanent modifications

Femtosecond laser direct writing in SiO₂‐Al₂O₃ binary glasses and thermal stability of Type II permanent modifications