EELS Characterization of Silicon Oxycarbide Glasses

Abstract

Abstract Anionic modification of silicate-based glasses with carbon has recently attracted the attention of many research groups due to the beneficial effect on mechanical properties and both thermal and chemical stability. These carbon containing glasses, termed silicon oxycarbide glasses, can be synthesized from various organically modified silica gels or from preceramic polymers after a pyrolysis process in an inert atmosphere. The oxycarbide network is often mixed with a free carbon phase, and so the local environment around C atoms exhibits a complex distribution. In the ideal silicon oxycarbide phase, carbon atoms would be present only in carbidic units (forming only Si-C bonds). The carbon phases and the chemical bonding in the silicon oxycarbide have been investigated by high resolution electron microscopy (HREM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR). Electron Energy Loss Spectroscopy (EELS) is an important analytical technique that can be used to further characterize the local chemistry and electronic structure of these glasses.