The Effect of Ti Doping on the Thermoelectric Performance of Bi2Te3 and Its Chemical Stability

Bismuth telluride and its alloys are widely used as materials for thermoelectric generators (TEGs) with
excellent performance at room temperature. In this research, we synthesized Bi(22x)TixTe3-doped variants (x = 0, 0.05, 0.1, and 0.15) by using a solid-state reaction and carbon burial sintering method. Powder x-ray diffraction (XRD) showed that the cell structure formed was rhombohedral with a space group of R3m. Rietveld refinement revealed that the cell volume decreased with increasing dopant amount because Ti4þ has a smaller radius than Bi3þ. Ti doping widened the energy gap and decreased the concentration of charge carriers, which increased resistivity. The undoped sample had the highest figure of merit (zT) relative to doped samples, which was 0.46 at a temperature of 327 K. However, Ti doping in the Bi2Te3 system reduced the corrosion rate and increased hardness.