High-temperature piezoresistive C / SiOC sensors
- 1Technical University Darmstadt, Institute of Material Science, Jovanka-Bontschits-Strasse 2, 64287 Darmstadt, Germany
- 2Forschungszentrum Jülich, Institute of Energy and Climate Research, Wilhelm-Johnen-Strasse, 52425 Jülich, Germany
Abstract. Here we report on the high-temperature piezoresistivity of carbon-containing silicon oxycarbide nanocomposites (C / SiOC). Samples containing 13.5 vol% segregated carbon have been prepared from a polysilsesquioxane via thermal cross-linking, pyrolysis and subsequent hot-pressing. Their electrical resistance was assessed as a function of the mechanical load (1–10 MPa) and temperature (1000–1200 °C). The piezoresistive behavior of the C / SiOC nanocomposites relies on the presence of dispersed nanocrystalline graphite with a lateral size ≤ 2 nm and non-crystalline carbon domains, as revealed by Raman spectroscopy. In comparison to highly ordered carbon (graphene, HOPG), C / SiOC exhibits strongly enhanced k factor values, even upon operation at temperatures beyond 1000 °C. The measured k values of about 80 ± 20 at the highest temperature reading (T = 1200 °C) reveal that C / SiOC is a primary candidate for high-temperature piezoresistive sensors with high sensitivity.