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Proceedings Paper

Spectral density analysis of the optical properties of Ni-Al2O3 nano-composite films
Author(s): Gunnar A. Niklasson; Tobias K. Boström; Enis Tuncer
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Paper Abstract

Thin films consisting of transition metal nanoparticles in an insulating oxide exhibit a high solar absorptance together with a low thermal emittance and are used as coatings on solar collector panels. In order to optimise the nanocomposites for this application a more detailed understanding of their optical properties is needed. Here we use a highly efficient recently developed numerical method to extract the spectral density function of nickel-aluminum oxide (Ni-Al2O3) composites from experimental data on the dielectric permittivity in the visible and near-infrared wavelength ranges. Thin layers of Ni-Al2O3 were produced by a sol-gel technique. Reflectance and transmittance spectra were measured by spectrophotometry in the wavelength range 300 to 2500 nm for films with thicknesses in the range 50 to 100 nm. Transmission electron microscopy showed crystalline Ni particles with sizes in the 3 to 10 nm range. The spectral density function shows a multi-peak structure with three or four peaks clearly visible. The peak positions are influenced by particle shape, local volume fraction distributions and particle-particle interactions giving rise to structural resonances in the response of the composite to an electromagnetic field.

Paper Details

Date Published: 3 October 2011
PDF: 11 pages
Proc. SPIE 8168, Advances in Optical Thin Films IV, 81680S (3 October 2011); doi: 10.1117/12.898174
Show Author Affiliations
Gunnar A. Niklasson, Uppsala Univ. (Sweden)
Tobias K. Boström, NORUT Northern Research Institute AS (Norway)
Enis Tuncer, GE Global Research Ctr. (United States)

Published in SPIE Proceedings Vol. 8168:
Advances in Optical Thin Films IV
Michel Lequime; H. Angus Macleod; Detlev Ristau, Editor(s)

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