| Summary: | Research on harvesting alternative energy sources is of interest to meet human demands for energy while reducing environmental pollution caused by the extensive use of fossil fuels. Thermoelectric materials are a promising technology for converting heat into electricity. Among thermoelectric materials, the binary bismuth telluride system (Bi-Te) is widely used. To produce high-quality Bi-Te systems with low materials consumption, spark plasma sintering (SPS) is commonly applied. Because SPS is a fast low-temperature process, controlling the ratio and crystallization of Bi-Te is critical for effective energy conversion. Here, we investigated the quality of Bi-Te systems formed by SPS compaction of raw powders with an in-depth examination of the oxidation effects on their thermoelectric performance. With increasing measurement temperature (300→420 K), the mechanically mixed sample and a commercial Bi2Te3 alloy (sintered at 533 K) showed differences in Seebeck coefficients (0.245→0.267 and 0.223→0.246 mVK−1, respectively). The alloy sample showed a decreased figure of merit (0.863→0.331) while that of the mechanically mixed sample (0.543→1.671) increased with temperature. This was related to the degree of oxygen impurity in each Bi-Te process based on XPS analysis. This study proposes that the integration of oxygen species to Bi-Te can be considered to maximize the thermoelectric efficiency at the specified temperature.
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