Electrical and Thermal Properties of Nitrogen-Doped SiC Sintered Body

Abstract

In this study, the effect of nitrogen (N) doping and microstructural changes on the electrical and thermal properties of silicon carbide (SiC) were investigated. SiC powder was treated in a N₂ atmosphere at 1673, 1973 and 2273 K for 3 h and subsequently sintered by spark plasma sintering (SPS) at 2373 K for 300 s in a vacuum or in a N₂ atmosphere. The a-axis of the N₂-treated SiC powders was almost constant, while the c-axis slightly decreased with an increase in the temperature of N₂ treatment. The relative density of the SiC powder sintered body decreased from 72% to 60% with an increase in the temperature of N₂ treatment. The increase in temperature of N₂ treatment caused a decrease in the thermal and electrical conductivities of the SiC. Upon N₂ treatment at 1673 K and sintering in a N₂ atmosphere, SiC exhibited a high electrical conductivity of 1.5 × 10³ S m⁻¹ at 1123 K. SiC exhibited n-type conduction, and the highest Seebeck coefficient was −310 μV K⁻¹ at 1073 K.