Composite films of Ni particles embedded in an Al2O3 matrix have been produced by controlled coevaporation. The optical properties of the Ni/Al2O3 composites measured over the range of the solar spectrum are in good accord with the predictions of Maxwell-Garnett theory provided the Ni volume fraction is ≲0.2. The composite films have excellent spectral selectivity for the absorption of solar radiation, with a solar absorptivity of 0.94 obtained for a film produced with a composition gradient. Low-temperature emissivities of ∼0.1 have been obtained with composite films evaporated on highly reflecting metal substrates.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)