Effect of macrostructure on the thermoelectric properties of biomorphous SiC/Si ceramics

Abstract

In this work, effect of porous macrostructure on the thermoelectric properties of biomorphous SiC/Si ceramics prepared by the liquid silicon infiltration process has been investigated. Temperature dependences of the conductivity and thermal e.m.f. have been measured within the range 20-700 °C. It has been shown that electrical resistivity of the samples decreases drastically as temperature increases over the entire temperature range, indicating semiconductor behavior. All the samples demonstrate a negative thermal e.m.f. confirming the electronic mechanism of charge transfer. It is ascertained that anisotropy of porous macrostructure of the ceramics influences considerably on their electric and thermoelectric properties. The figure of merit maximum value of 1.2×10⁻⁵ K⁻¹ at 700 °C was obtained.