Raman micro-spectroscopic map of plastic strain in indented amorphous silica
Résumé
Glassy materials are known to exhibit a plastic behavior, in particular in confined geometries. In contrast to metals the plasticity of glasses is characterized by a strong coupling between volumetric and shear strain. We use Raman micro-spectroscopy to estimate the residual densification after indentation in amorphous silica. Using a specific experimental design, the micro-metric resolution of this technique is obtained both at the surface and in-depth. Taking advantage of the high sensitivity to density of the defect lines D1 and D2 associated to vibration modes of three and four-membered silica tetrahedra rings, we obtain a spatially resolved three-dimensional map of indentation induced densification. These local experimental data constitute a guide for a more accurate description of the plastic behavior of silica.