Optical properties of currentless radioabsorbing materials according to hexaferrite additions

Abstract
Currentless radioabsorbing materials having low reflectance and high absorptance in a wide spectral range could be used to solar dryers. One of the components included in these materials is hexaferrite addition. Influence of this component on optical properties of the smooth and porous radioabsorbing materials is investigated. The volume content of the additions into the samples do not exceed 12%. Mean pore sizes of the porous samples are varied from 0.8 mm to 5 mm. Reflectance and transmittance of the samples are measured with a spectrophotometer in the range of 0.2 µm-0.9 µm. A polarometer-ellipsometer is used for measuring polarization parameters of light with wavelength of 0.63 µm reflected by the smooth samples in the specular direction. The reflectance of the smooth sample with the 12% hexaferrite addition is the least and does not exceed 0.07 in the spectral range of 0.23 µm-0.9 µm. Without the addition, the smooth sample has the mean reflectance about 0.25-0.30. Porous sample with pore size of 0.8 mm has the least transmittance and reflectance. It is found that the hexaferrite additions have great influence on the degree of the polarization and the ellipticity of the reflected light.