Optical properties of Ag-MgF2 cermet films

Ag-MgF2 cermet films were prepared by vacuum vapour deposition and their microstructure and optical properties were studied by X-ray diffraction, electron microscope, infrared spectrum and ultraviolet-visible spectrum. The results showed the films were mainly composed of an amorphous MgF2 matrix with embedded crystalline Ag particles. Within the IR region of lambda = 400 similar to 1600 cm(-1) the 400 similar to 600 cm(-1) absorption band was characteristic of MgF2 crystal whereas the 730 similar to 1250 cm(-1) absorption band was caused by the Ag-MgF2 cermet of composite structure. Within ultraviolet-visible region of 200 similar to 800 nm, the cermet film had low reflectance and strong absorption. The absorbance could be higher than 85% in the 215 similar to 290 nm and 340 similar to 580 nm region. In the UV region starting from 220 nm the Ag-MgF2 film has a reflectance higher than 51%. (C) 1999 Elsevier Science Ltd. All rights reserved.