Infrared Properties of Pt/Al2O3 Cermet Films.

摘要

The room temperature transmittance and front reflectance of mid- and near-infrared radiation by thin Pt/AI2O3 cermet films prepared by electron beam evaporation onto sapphire substrates were measured using a Fourier transform spectrometer. The high value of the dc percolation threshold for the Pt.AI2O3 system is evidence for correlations in the positions of the particles that can be described by coated-grain topologies. The data were compared with the predictions of five effective medium models, which feature different microstructural topologies. Effective medium theories are commonly used to model the optical properties of granular composite materials such as cermet films. If one considers a two-component metal-insulator composite material over the complete range of composition, a characteristic parameter relevant to both the electrical and optical properties is the percolation threshold.