Nanocluster Model sp2-C SiOC glass 5 nm The Fate of Carbon in Polymer-Derived SiCO Ceramics Hans-Joachim Kleebe Colorado School of Mines DMR-0304968 This research is close a collaboration between CSM and SRI International, Dr. Yigal Blum, who processed these novel materials. Polymer-derived ceramics reveal exceptional properties at elevated service temperatures such as high resistivity against crystallization and, in particular, viscoelastic behavior of C-rich SiCO materials. Nanocluster model of C-rich SiCO (HRTEM image to the left corresponds to the PHMS material doped with 60% DVB). This model is consistent with recent SAXS data obtained as well as the viscoelastic behavior of similar polymer-derived carbon-rich SiCO materials. Strain versus time diagrams comparing the creep response of SiO2 with C-rich SiCO (high-carbon, HC and low-carbon content, LC). In the C-containing materials, the initial strain is re-covered when the applied stress is removed [A. Scarmi, et a., J. Non-Cryst. Solids, (2005) in press].