Unexpected High-Temperature Stability of beta-Zn4Sb3 Opens the Door to Enhanced Thermoelectric Performance
JP Lin and XD Li and GJ Qiao and Z Wang and J Carrete and Y Ren and LZ Ma and YJ Fei and BF Yang and L Lei and J Li, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 136, 1497-1504 (2014).
beta-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 beta-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; beta-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.
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