Improved electrical and thermal properties of silicon oxycarbide/spodumene composites

Novel bulk SiOC/spodumene composites have been developed by spark plasma sintering (SPS) at relatively low temperature (1200-1400 degrees C). Spodumene is a cheap and natural available lithium aluminosilicate mineral which acts as meltable/active filler. At 1300-1400 degrees C, the Al migrates toward the glassy matrix producing a Si-Al-O network and the crystallization of alpha-cristobalite. The Cfree phase also experiences a deep transformation. The epitaxial growth of few-layered graphene over SiC particles occurs at 1400 degrees C. An increase in the phonon transport is observed (36%, 1.28 - 2.14 Wm- 1K-1) associated to the reduction of the interface resistance between the partially crystallized SiO2 matrix and the SiC nano-wires/graphene-like carbon conductive phase. The electrical conductivity increases (1.14 x10- 2 - 8.1 Sm- 1) due to the densification reached and an increasing ordering degree of the tortuous Cfree phase with a high quality of interconnection and crystallization. Raman parameters are determinant to understand the thermal and electrical response.