Stresses and optical constants in BaF2-PrF3 thin films deposited using electron-beam evaporation

Although thin films of praseodymium fluoride (PrF3) have a good transparency and the lower refractive index n and extinction coefficient k in the spectral range of thermal infrared as a substitution for radioactive thorium fluoride (ThF4), the higher tensile stress presented in the layers will deteriorate the reliability and durability of the interference multilayers. In our investigation, a new infrared low-index evaporation material, the admixture of PrF3 with barium fluoride (BaF2) was explored. The stresses and optical constants were presented for thin films deposited using electron beam evaporation from the sintered pellets of PrF3 admixed with BaF2.