Microstructure and Optical Absorption Properties of Cu-MgF₂ Nanoparticle Cermet Film

The microstructure and optical absorption spectra of 10-30vol% Cu-MgF₂ nanoparticle cermet films prepared by co-evaporation in vacuum are examined. The results show that the Cu-MgF₂ cermet films are mainly composed of amorphous MgF₂ matrix with embedded fcc-Cu nanoparticles of average size 12-24 nm. The results also show that the optical absorption of the films decreases as the wavelength increases in the range of 200-800 nm. The surface plasmon resonance absorption peaks of Cu nanoparticles in 10, 20, and 30vol% Cu-MgF₂ films appear at 578, 588, and 606nm, respectively, and the interband transition absorption of Cu starts from 590 nm downwards. Based on the Maxwell-Garnett theory, the experimental optical absorption properties of the films have been quantitatively evaluated.