Optical properties of aluminum oxide powder modified by nanoparticles and prospects for its use in solar power and space industry

Abstract

Studies on the phase composition, diffuse reflectance spectra (ρλ) and solar absorptance (αs) and their changes after modification of aluminum oxide powder by nanoparticles of cerium dioxide, magnesium oxide, silicon dioxide, titanium dioxide and zinc oxide are presented. The diffuse reflectance spectra and solar absorptance αs of nanoparticles used for modification were studied.In its initial state, Al2O3 was found to exhibit high reflectivity. The obtained value of the solar absorptance, 0.074, was significantly less than that of the widely used white reflective powders – ZnO and TiO2. After modification by nanoparticles of wide-band compounds, MgO and SiO2, the reflectivity of Al2O3 powder changed slightly. Modification by SiO2 nanoparticles at a concentration of 1 wt % decreased the solar absorptance to 0.064. At small concentrations (0.1–1 wt. %) of nanoparticles of semiconductor compounds, CeO2, TiO2 and ZnO, the absorption edge of Al2O3 powder shifted to a longer wavelength region of the spectrum. At 10 wt % concentration of nanoparticles, the absorption edge of Al2O3 powder shifted to a value close to the absorption edge of the initial nanopowders.Such nano-micropowder systems can be used to develop new materials with improved optical properties for solar power and space technology applications, as well as other applications that need high reflectance and low solar absorptance. New data on shifts of the main absorption edge after modification by semiconductor nanoparticles can be useful in developing new materials for photocatalysis.