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Unexpected High-Temperature Stability of β-Zn4Sb3 Opens the Door to Enhanced Thermoelectric Performance
- Lin, Jianping, Li, Xudong, Qiao, Guanjun, Wang, Zhao, Carrete, Jesús, Ren, Yang, Ma, Lingzhi, Fei, Youjian, Yang, Baifeng, Lei, Lei, Li, Ju
- Journal of the American Chemical Society 2014 v.136 no.4 pp. 1497-1504
- molecular dynamics, temperature, thermal conductivity, zinc
- β-Zn₄Sb₃ has one of the highest ZT reported for binary compounds, but its practical applications have been hindered by a reported poor stability. Here we report the fabrication of nearly dense single-phase β-Zn₄Sb₃ and a study of its thermoelectric transport coefficients across a wide temperature range. Around 425 K we find an abrupt decrease of its thermal conductivity. Past this point, Zn atoms can migrate from crystalline sites to interstitial positions; β-Zn₄Sb₃ becomes metastable and gradually decomposes into Zn(hcp) and ZnSb. However, above 565 K it recovers its stability; in fact, the damage caused by decomposition can be repaired completely. This is key to its excellent thermoelectric performance at high temperature: the maximum ZT reaches 1.4. Molecular dynamics simulations are used to shed light on the microscopic behavior of the material.