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Proceedings Paper

Carbon-in-silica composite selective solar absorbers: a determination of composition and dielectric properties
Author(s): G. Katumba; A. Forbes
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Paper Abstract

The Bruggeman and Maxwell-Garnett effective medium approximations have been used widely to investigate optical properties of many different composite materials. In most cases, the effective medium approximation assumptions are based on random unit cell models in which some metal particles are embedded in a dielectric medium. The shapes of the embedded particles can be varied between spherical, ellipsoidal and cylindrical shapes. A new and interesting structure of connected short chains of completely amorphous carbon intermixed with short chains of silica at nanoscale level has been observed recently. A generalised Bergman representation based on an arbitrary spectral density function is currently applied on these carbon-in-silica samples with a reasonable success of fitting between experiment and theory. The curve-fitting procedure adopted here has resulted in information such as volume fraction of carbon relative to silica, percolation threshold, the thickness and effective dielectric function of the composite layer.

Paper Details

Date Published: 21 August 2009
PDF: 9 pages
Proc. SPIE 7410, Optical Modeling and Measurements for Solar Energy Systems III, 74100G (21 August 2009); doi: 10.1117/12.827960
Show Author Affiliations
G. Katumba, Council for Scientific and Industrial Research (South Africa)
A. Forbes, Council for Scientific and Industrial Research (South Africa)
Univ. of KwaZulu-Natal (South Africa)
Stellenbosch Univ. (South Africa)


Published in SPIE Proceedings Vol. 7410:
Optical Modeling and Measurements for Solar Energy Systems III
Benjamin K. Tsai, Editor(s)

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