Solid state NMR study of phosphosilicate gels

Clayden, Nigel J.; Aronne, Antonio; Esposito, Serena; Pernice, P.

doi:10.1016/j.jnoncrysol.2004.08.105

Cited by 29 publications

(16 citation statements)

References 14 publications

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“…In general, the Si-O-Si stretching vibrations for the SiQ n units in glasses show infrared absorption bands in the domain 850-1200 cm -1 [30,31]. The broad band region for unreacted GGBFS at 900 cm -1 indicates general disorder in the silicate network reflecting the wide distribution of Q n units in an amorphous GGBFS.…”

Section: Carbonation Of Powdered Pastesmentioning

confidence: 97%

Carbonation Resistance of Alkali-Activated Slag Under Natural and Accelerated Conditions

Nedeljković

Zuo

Arbi

et al. 2018

J. Sustain. Metall.

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In this paper, carbonation resistance of alkali-activated slag (AAS) pastes exposed to natural and accelerated conditions up to 1 year was investigated. Two aspects of carbonation mechanism were evaluated. The first was the potential carbonation of the main binding phases in finely powdered AAS pastes. The second was the reactivity and diffusivity of CO 2 within the bulk AAS paste. From Fourier transform infrared spectroscopy and thermogravimetric analysis coupled with mass spectroscopy time-series measurements, it was found that powdered AAS was largely carbonated within 28 days with a CO 2 uptake of 14 wt%. The main carbonation products were calcium carbonates. Nevertheless, the bulk paste samples were highly resistant to carbonation, regardless of the exposure conditions. The findings showed that the pH value (initial pH [ 12) and strength of the samples did not decrease under accelerated carbonation compared to those of the samples exposed under natural conditions. The mineralogy of the samples in these two carbonation exposures did not alter either, except for outdoor conditions. The gel pores were dominant in the pastes (pore size in range of 2-15 nm). The dense microstructure was the main barrier for CO 2 to diffuse and further react with binding phases.

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Section: Carbonation Of Powdered Pastesmentioning

confidence: 97%

Carbonation Resistance of Alkali-Activated Slag Under Natural and Accelerated Conditions

Nedeljković

Zuo

Arbi

et al. 2018

J. Sustain. Metall.

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“…An experimental value as high as 0.01 S cm -1 at 150°C and 0.4 % RH has been reported. [11] However, P-O-Si bonds in gels are not stable towards hydrolysis, [16] which results in free phosphoric A new approach to the synthesis of fully immobilized phosphorus functionalized hybrid proton conductive gels based on phosphonic acid grafting is presented in this paper. The hybrid silicas with different amounts of phosphonic acid have been prepared and characterized using Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller surface area analysis, thermogravimetric analysis, and electrochemical techniques.…”

Section: Introductionmentioning

confidence: 99%

Hydrolytically Stable Phosphorylated Hybrid Silicas for Proton Conduction

Jin

Qiao

Costa

et al. 2007

Adv Funct Materials

112

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A new approach to the synthesis of fully immobilized phosphorus functionalized hybrid proton conductive gels based on phosphonic acid grafting is presented in this paper. The hybrid silicas with different amounts of phosphonic acid have been prepared and characterized using Fourier‐transform infrared spectroscopy, X‐ray photoelectron spectroscopy, Brunauer–Emmett–Teller surface area analysis, thermogravimetric analysis, and electrochemical techniques. The proton conductivity of the materials depend strongly on hydration, which increases by four orders of magnitude over the relative humidity (RH) range of 20 to 100 %, up to a maximum of 0.027 S cm–1 at 100 °C and 100 % RH. For the reported samples, proton conduction is believed to occur within a dynamic hydrogen‐bond network formed by functionalized P–OH groups and water molecules by the Grotthuss mechanism. However, the proton conductive sites (P–OH) are likely to be partially immobilized by strong protonic receptors (N atoms in amines), which reduces the free P–OH groups and restricts proton transfer. Hydration may cause a bonding structural rearrangement, which results in more free P–OH groups as active proton conductive sites and, therefore, greatly increased proton conductivity is observed.

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“…Absorption bands of glasses and their assignments were listed in Table 2. The bands at 400 -500 cm -1 is due to the bending vibrations of Si-O-Si and Si-O-Al linkages [19,20]. The absorption bands in the 650 -800 cm -1 is considered as Al-O stretching vibration of [AlO 4 ] tetrahedron [20,21].…”

Section: Structurementioning

confidence: 99%

“…The bands at 400 -500 cm -1 is due to the bending vibrations of Si-O-Si and Si-O-Al linkages [19,20]. The absorption bands in the 650 -800 cm -1 is considered as Al-O stretching vibration of [AlO 4 ] tetrahedron [20,21]. The broad bands in the 800 -1300 cm -1 is assigned to anti-symmetric stretching modes of the Si-O-Si bonds of the Q n units (n means the number of bridging oxygens within a tetrahedron, n = 0, 1, 2, 3 and 4) [1,22,23].…”

Section: Structurementioning

confidence: 99%

“…The broad bands in the 800 -1300 cm -1 is assigned to anti-symmetric stretching modes of the Si-O-Si bonds of the Q n units (n means the number of bridging oxygens within a tetrahedron, n = 0, 1, 2, 3 and 4) [1,22,23]. With n value increasing from 0 to 4, the absorption bands of the Q n units were centered around 850, 900, 950, 1100 and 1200 cm -1 , respectively [1,20]. -7 °C.…”

Section: Structurementioning

confidence: 99%

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