In-situ polymer-derived SiC/Si(B)OC ceramic nanocomposites: A sustainable potential candidate for high-temperature thermoelectric applications

Abstract

• The free carbon within polymer-derived SiOC ceramics develops into an interconnected conductive network. • Incorporating B 4 C led to partial substitution of carbon layers with boron atoms, catalyzing graphitization and creating additional holes. • Incorporating B 4 C facilitated the in-situ formation and grain growth of SiC nanocrystals. • Enhanced SiC crystallinity, increased carbon graphitization, and the presence of BC 3 units collectively led to a significant boost in electrical conductivity. Polymer-derived ceramics are potential candidates for the next generation of high-temperature thermoelectrics due to their exceptional high-temperature stability and chemical resistance, characteristics that are absent in conventional thermoelectric intermetallic compounds. In this work, we prepared polymer-derived SiC/Si(B)OC ceramic nanocomposites by introducing B 4 C particles into polysiloxane, followed by high-temperature pyrolysis, and explored their microstructural evolution and thermoelectric properties. The addition of B 4 C has a catalytic effect on the growth of SiC and the graphitization of carbon, resulting in the establishment of a more efficient conduction network. Consequently, the electrical conductivity at room temperature increases from 81 S m −1 in the sample without B 4 C to 1103 S m −1 in the sample with the addition of 1 wt% B 4 C. The introduction of B 4 C leads to a higher content of the crystalline SiC phase, which in turn contributes to an enhanced Seebeck coefficient. Finally, a remarkable increase in ZT was observed. The highest ZT of 8.9 × 10 −4 was achieved in the sample with 1 wt% B 4 C at 1100 K. Although there is still a considerable distance to cover in achieving suitable ZT values in polymer-derived ceramics, this study provides a straightforward strategy for enhancing electrical transport properties.

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