Bridgman Growth of Mg<sub>2</sub>Sn<sub>1–<i>x</i></sub>Bi<sub><i>x</i></sub>Single Crystals and Anisotropic Thermoelectric Properties
Yuan-Yuan Su, Qiqi Wang, Kefeng Liu, Shun Zhou, Xiao‐Cun Liu, Sheng‐Qing Xia
Abstract
Mg 2 X-based (X = Si, Ge, Sn) phases are promising for thermoelectric applications due to their nontoxicity, low cost, and high performance. Substantial experimental work has already been carried out based on the polycrystalline samples; however, studies on related single-crystal growth and corresponding properties are still very limited owing to the high volatility and reactivity of Mg, which makes it very challenging to obtain high-quality single crystals with big sizes. In this report, for the first time, the Bridgman method was successfully applied in the single-crystal growth of the Bi-doped Mg 2 Sn materials. The crystals are of high quality and related anisotropic thermoelectric properties were systematically investigated. The Bi-doped Mg 2 Sn 0.99 Bi 0.01 single crystal exhibited a maximum zT value of 0.58 along the [111] orientation at 623 K, which is about 30 times that of the pristine Mg 2 Sn single crystal.