Optical properties of Co and Co-Fe-Cr thin films deposited from an aerosol on glass substrates

Thin films of Co and Co-Fe-Cr metal oxide films were prepared by deposition of an aerosol generated pneumatically from aqueous nitrate solutions. As substrates commercial gray glass has been used. Thermogravimetric (TG, DTG) and DTA measurements of initial nitrate components and their homogenized mixture were performed, and optical properties of deposited films important for privacy purposes (reflectance, transmittance), in the UV-visible and near-infrared regions up to 4761 nm as well as their surface roughness were measured. The reflectance values, defined at 550 nm wavelength, were 20-30% for Co-oxide films and 20-25% for Co-Fe-Cr films compared to 10-15% reported in literature. Transmittance values were 14-28% and 24-36%, respectively. For the substrate (uncoated gray glass) also used as a reference, these corresponding values were 5 and 57%. The surface roughness R_a correlates with the main deposition parameters, such as temperature and time of deposition, and the molarity of solutions used. Crystallinity in Co-oxide films has been detected by X-ray measurements.