Temperature Dependence of the Electrical Properties and Seebeck Coefficient of AlN-SiC Ceramics

AlN–SiC ceramics composed of AlN–SiC solid solutions were fabricated by pressureless sintering without sintering additives. The microstructure and electrical properties of the AlN–SiC ceramics were investigated for compositions between 0 and 75 mol% AlN. The AlN–SiC ceramics had a porous structure, and a 2H polytype was found in all compositions. The electrical conductivities and Seebeck coefficients of the AlN–SiC ceramics increased with temperature. The electrical conductivity of 25 mol% AlN–75 mol% SiC ceramics was the highest in all compositions: 32.7 S/m at 300°C. In contrast, the electrical conductivity of 75 mol% AlN–25 mol% SiC ceramics was much lower than that of other samples: 10−2 S/m at 300°C. The Seebeck coefficient of 50 mol% AlN–50 mol% SiC ceramics was the highest of all samples: 210 μV/K at 300°C. The electrical and thermoelectrical properties of SiC can be controlled by the formation of AlN–SiC solid solutions.