Transparent silica aerogels

Pajonk, G.M.

doi:10.1016/s0022-3093(98)00131-8

Cited by 137 publications

(102 citation statements)

References 24 publications

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“…Secondly, the scattering contribution from surface inhomogeneity is assumed to be small compared to the bulk contribution. 9 This assumption can break down especially for thin aerogel samples, which can be observed in Figure 4 (where there is a larger discrepancy between model and experiment for thin samples).…”

Section: Resultsmentioning

confidence: 95%

“…[1][2][3][4] In particular, the optical transparency of silica aerogel in the solar spectrum is crucial for many solar related applications [5][6][7][8] and has been studied extensively. [9][10][11][12][13][14][15][16][17][18] J. Fricke et al showed that the optical transparency of silica aerogels is tied closely to its microstructure which acts as Rayleigh scattering centers.…”

Section: Introductionmentioning

confidence: 99%

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Modeling silica aerogel optical performance by determining its radiative properties

et al. 2016

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Silica aerogel has been known as a promising candidate for high performance transparent insulation material (TIM). Optical transparency is a crucial metric for silica aerogels in many solar related applications. Both scattering and absorption can reduce the amount of light transmitted through an aerogel slab. Due to multiple scattering, the transmittance deviates from the Beer-Lambert law (exponential attenuation). To better understand its optical performance, we decoupled and quantified the extinction contributions of absorption and scattering separately by identifying two sets of radiative properties. The radiative properties are deduced from the measured total transmittance and reflectance spectra (from 250 nm to 2500 nm) of synthesized aerogel samples by solving the inverse problem of the 1-D Radiative Transfer Equation (RTE). The obtained radiative properties are found to be independent of the sample geometry and can be considered intrinsic material properties, which originate from the aerogel’s microstructure. This finding allows for these properties to be directly compared between different samples. We also demonstrate that by using the obtained radiative properties, we can model the photon transport in aerogels of arbitrary shapes, where an analytical solution is difficult to obtain.

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Section: Resultsmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Modeling silica aerogel optical performance by determining its radiative properties

et al. 2016

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“…As a result, dried samples keep the porous texture of the wet stage. In general, aerogels have a high specific surface area, a very low apparent density and a low refraction index [20,80,52]. Furthermore, the thermal properties of aerogels may undertake a structural evolution when aged in a liquid medium and/or heat treated during the synthesis process.…”

Section: Synthesismentioning

confidence: 99%

Aerogel insulation for building applications: A state-of-the-art review

Bætens

Jelle

Gustavsen

2011

Energy and Buildings

917

465

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Aerogels are regarded as one of the most promising high performance thermal insulation materials for building applications today. With a thermal conductivity down to 13 mW/(mK) for commercial products they show remarkable characteristics compared to traditional thermal insulation materials. Also the possibility of high transmittances in the solar spectrum is of high interest for the construction sector. With the proper knowledge they give both the architect and engineer the opportunity of re-inventing architectural solutions. Within this work, a review is given on the knowledge of aerogel insulation in general and for building applications in particular.

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“…To convert a gel into an aerogel, the solvent is removed by extraction with supercritical CO 2 or by the direct conversion of the solvent in supercritical state in order to prevent the structure collapse caused by capillary forces [Fricke 1986]. The chemistry of aerogel materials is relatively f lexible: their pore size and surface area can be tailored during the synthesis by changing the solvent and catalysts [Rao et al 1993, Pajonk 1998, Stolarski et al 1999]. Furthermore, different functional groups can be implemented in the structure of silica aerogels by surface modification or by reaction during sol-gel processes Schubert 1997, Husing et al 1998].…”

Section: Introductionmentioning

confidence: 99%