THIN FILMS OF GAS-EVAPORATED Co FOR USE IN PHOTOTHERMAL CONVERSION

Selective surfaces for an efficient solar energy photothermal conversion were obtained by evaporation of Co in a gaseous atmosphere. A bell jar system was used with a Tungsten basket and a gas mixture consisting of oxygen and helium. Using a KBr substrate we performed spectral measurements of the transmittance from 0.38 µm to 20 µm obtaining λc ≈ 2.5 µm. The film observed in a transmission electron microscope revealed a small particles structure for which the filling factor was measured. The results justified the application of the Maxwell Garnett theory