On the relationship between microstructure and densification of silica gels

Grandi, S.; Mustarelli, Piercarlo; Tomasi, Corrado; Sorarù, Gian Domenico; Spanò, Guido

doi:10.1016/j.jnoncrysol.2004.06.003

Cited by 7 publications

(10 citation statements)

References 17 publications

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“…The first weight loss is easily assigned to the evolution of ethanol or water physically adsorbed and/or H-bonded to the silica matrix [33,34]. This last statement is also confirmed by our recent work [35] that showed thermal analyses of a simple xerogel silica synthesized with a very similar solgel recipe but without PEG. The assignment of the other losses is not trivial.…”

Section: Materials Of Class IIsupporting

confidence: 78%

Synthesis and characterization of SiO2–PEG hybrid materials

Grandi¹,

Magistris²,

Mustarelli³

et al. 2006

Journal of Non-Crystalline Solids

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Section: Materials Of Class IIsupporting

confidence: 78%

Synthesis and characterization of SiO2–PEG hybrid materials

Grandi¹,

Magistris²,

Mustarelli³

et al. 2006

Journal of Non-Crystalline Solids

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“…As a consequence, the emitting centers sense different local environments because of the modification of the chemical surroundings induced by the aging or the regeneration. It was reported, for example, that a bimodal distribution of the pore diameter can be observed in SiO 2 xerogel samples: the regeneration procedure, and, to somehow extent, the aging process, increases the diameter of the micropores (diameter b 2 nm) and decreases the one of the mesopores (2 b diameter b 50 nm) [25]. The change in the pore diameter distribution affects the observed spectroscopic features because of the modification of the distribution of different OH groups.…”

Section: Discussionmentioning

confidence: 99%

Photoluminescence characterization of aged and regenerated mesoporous silica

Carbonaro¹,

Ricci²,

Corpino³

et al. 2011

Journal of Non-Crystalline Solids

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The investigation of the photoluminescence features of aged and regenerated mesoporous silica is reported. The emission spectrum of aged samples displays a blue band peaked at about 450 nm at room temperature with excitation channels at 250 and 200 nm. No UV emission band is detected. The regenerated samples recover the optical transparency of the samples, the vibrational properties in the 3000-3800 cm(-1) but for the isolated silanols band and the UV-blue emission features. Indeed beside the blue band peaked around 450 nm a UV band centred at 340 nm is reported whose relative contribution depends on the excitation wavelength. The aging and regeneration processes are discussed in view of the attribution of the observed emission features to specific surface defects. (C) 2010 Elsevier B.V. All rights reserved

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“…An IV-type curve, illustrating that aerogels are typical mesoporous materials, is presented in Figure 3 a. An H1-type hysteresis loop indicates that there are a large number of spherical pores stacked in succession [ 18 , 19 ]. An I-type curve and most microporous materials belonging to this category are shown in Figure 3 b.…”

Section: Resultsmentioning

confidence: 99%

One-Dimension Diffusion Preparation of Concentration-Gradient Fe2O3/SiO2 Aerogel

Zhang¹,

Wang²,

Zhou³

et al. 2018

Molecules

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Concentration-gradient Fe2O3/SiO2 aerogels were prepared by placing an MTMS (methyltrimethoxysilane)-derived SiO2 aerogel on an iron gauze with an HCl atmosphere via one-dimensional diffusion, ammonia-atmosphere fixing, supercritical fluid drying and thermal treatment. The energy dispersive spectra show that the Fe/Si molar ratios change gradually from 2.14% to 18.48% with a height of 40 mm. Pore-size distribution results show that the average pore size of the sample decreases from 15.8 nm to 3.1 nm after diffusion. This corresponds well with TEM results, indicating a pore-filling effect of the Fe compound. In order to precisely control the gradient, diffusion kinetics are further studied by analyzing the influence of time and position on the concentration of the wet gel. At last, it is found that the diffusion process could be fitted well with the one-dimensional model of Fick’s second law, demonstrating the feasibility of the precise design and control of the concentration gradient.

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On the relationship between microstructure and densification of silica gels

Cited by 7 publications

References 17 publications

Synthesis and characterization of SiO2–PEG hybrid materials

Synthesis and characterization of SiO2–PEG hybrid materials

Photoluminescence characterization of aged and regenerated mesoporous silica

One-Dimension Diffusion Preparation of Concentration-Gradient Fe2O3/SiO2 Aerogel

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