The resonance level leading to the high Seebeck coefficient has been found in indium (In) doped SnTe nanocomposites. In this study, we optimized the doping amount of indium in Sn1-xInxTe alloys under a traditional synthesis process, followed by melting, quenching and the hot-pressing method. On increasing the doping of In, the Seebeck coefficients for all samples increased and the highest power factor of 26 μW cm-1 K-2 at 848 K was obtained for x = 0.25%. Based on the optimized In-doped SnTe composition, which shows the highest thermoelectric figure of merit, Selenium (Se) was introduced as the second doping element to further reduce the lattice thermal conductivity and the cost of raw materials; thus, Sn0.99In0.01Te1-ySey alloys were synthesized. The lowest thermal conductivity of 1.9 W m-1 K-1 at 873 K was observed for the y = 20% sample, which is significantly lower than that for the optimized In-doped sample (2.4 W m-1 K-1). In the end, the 1.00% In-doped SnTe alloy and 1.00% In & 10% Se co-doped SnTe alloy exhibited the highest figures of merit, zT, of ∼0.9 at 873 K. In addition, the highest average figure of merit, zTave, of ∼0.5 was achieved for the 1.00% In & 10% Se co-doped SnTe alloy, which was higher than that of In single-doped nanocomposite and better than that previously reported In & Se co-doped ingot. It is known that a high average figure of merit is preferable in the case of a large temperature difference between the hot and the cold junctions.
Bibliographical noteFunding Information:
The work is financially supported by the National Basic Research Program of China of 2013CB632506, the Natural Science Fund of China under grant no. 51501105, 51672159, 51611540342, the Young Scholars Program of Shandong University under grant no. 2015WLJH21, the China Postdoctoral Science Foundation under grant no. 2015M580588 and 2016T90631, the Postdoctoral Innovation Foundation of Shandong Province under grant No. 201603027, the Fundamental Research Funds of Shandong University under grant No. 2015TB019, and the Foundation of the State Key Laboratory of Metastable Materials Science and Technology under grant No. 201703. JH, HK, and WK acknowledge support under the framework of the international cooperation program managed by the National Research Foundation of Korea (2016K2A9A2A06005099, FY2017).
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All Science Journal Classification (ASJC) codes
- Inorganic Chemistry