Optical response of a hematite coating: ellipsometry data versus Fourier-based computations

Enguerrand Couka (1) , François Willot (1) , Patrick Callet (2, 3) , Dominique Jeulin (1)

1 CMM - Centre de Morphologie Mathématique
2 CAOR - Centre de Robotique
3 CentraleSupélec

The optical properties of a hematite-epoxy coating are predicted numerically and compared with el-lipsometry measurements. The highly-heterogeneous dispersion of nanocubic hematite particles in the epoxy resin is simulated using a previously developed two-scales random model. The local anisotropic permittivity tensor of hematite particles, and that of the epoxy, are estimated by ellipsometry measurements carried out on a macroscopic hematite and epoxy samples. Fourier-based methods using a "discrete" Green operator are used to treat complex permittivities. They predict the effective and local electric displacement field in the quasi-static approximation. The former is close to two estimates based on the Hashin-Shtrikman bounds and a self-consistent approximation. Good agreement is found between experimental data and FFT computations in the whole range of the visible spectrum.

Mots clés: Homogeneization; FFT method; Random microstructure models; Optical properties; Hematite coating; Ellipsometry

Domaines: Matériaux

Enguerrand Couka, François Willot, Patrick Callet, Dominique Jeulin. Optical response of a hematite coating: ellipsometry data versus Fourier-based computations. Advanced Science, Engineering and Medicine, 2015, 7 (11), pp.925-931. ⟨10.1166/asem.2015.1790⟩. ⟨hal-01232497⟩