A mechanically robust;  high electrically and low thermally conducting silicon oxycarbide ceramic composite by spark plasma sintering

doi:10.1039/D5TC00653H

A mechanically robust; high electrically and low thermally conducting silicon oxycarbide ceramic composite by spark plasma sintering

2025-07-27

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Shreyasi Chattopadhyay

DOI：10.1039/D5TC00653H

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Silicon oxycarbide (SiOC) ceramics derived from pyrolysis of polymer precursors are important for their aerospace; automotive and electronics applications. Here; we investigate the structural and functional properties of a Si–O–C composite obtained via a high-temperature spark plasma sintering process of SiOC powders; derived from the pyrolysis of a polysiloxane polymer. Structural characterization reveals the presence of turbostratic carbon; SiO2; and SiC domains in the Si–O–C matrix composite. Mechanically; it shows a hardness of ∼5.5 GPa and a Young's modulus of ∼40 GPa. The composite shows semiconducting behavior at room temperature with electrical conductivities of ∼95 S cm−1 (in-plane) and ∼215 S cm−1 (out-of-plane); p-type charges with a carrier density of ∼1021 cm−3 and a mobility of ∼0.25 cm2 V−1 s−1; which remains almost temperature independent. The temperature coefficient of resistivity is found to be a very low value of −0.0012 °C−1. We also measured a cross-plane thermal conductivity of ∼1.14 W m−1 K−1 at 300 K which exhibits temperature-independent behavior. Our observations are valuable for designing oxycarbide ceramic-based energy efficient devices for advanced applications.

Keywords:

SiOC ceramics

spark plasma sintering

turbostratic carbon

electrical conductivity

thermal conductivity

A mechanically robust; high electrically and low thermally conducting silicon oxycarbide ceramic composite by spark plasma sintering

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