The rapid growth of the thermoelectric cooler market makes the development of novel room temperature thermoelectric materials of great importance. Ternary n-type Mg₃(Bi,Sb)₂ alloys are promising alternatives to the state-of-the-art Bi₂(Te,Se)₃ alloys but grain boundary resistance is the most important limitation. n-type Mg₃(Bi,Sb)₂ single crystals with negligible grain boundaries are expected to have particularly high zT but have rarely been realized due to the demanding Mg-rich growth conditions required. Here, we report, for the first time, the thermoelectric properties of n-type Mg₃(Bi,Sb)₂ alloyed single crystals grown by a one-step Mg-flux method using sealed tantalum tubes. High weighted mobility ∼140 cm² V⁻¹ s⁻¹ and a high zT of 0.82 at 315 K are achieved in Y-doped Mg₃Bi_1.25Sb_0.75 single crystals. Through both experimental angle-resolved photoemission spectroscopy and theoretical calculations, we denote the origin of the high thermoelectric performance from a point of view of band widening effect and electronegativity, as well as the necessity to form high Bi/Sb ratio ternary Mg₃(Bi,Sb)₂ alloys. The present work paves the way for further development of Mg₃(Bi,Sb)₂ for near room temperature thermoelectric applications.

中文翻译：

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Mg3（Bi，Sb）2单晶向高热电性能迈进

热电冷却器市场的快速增长使得新型室温热电材料的开发具有重要意义。三元n型Mg ₃（Bi，Sb）₂合金是最先进的Bi ₂（Te，Se）₃合金的有前途的替代品，但晶界电阻是最重要的限制。具有可忽略的晶界的n型Mg ₃（Bi，Sb）₂单晶预计具有特别高的zT，但由于所需的富含Mg的生长条件而很少实现。在这里，我们首次报告了n型Mg ₃（Bi，Sb）₂的热电性质用密封钽管通过一步式Mg助熔法生长的合金单晶。在掺Y的Mg ₃ Bi _1.25 Sb _0.75单晶中，实现了〜140 cm ² V ^-1 s ^-1的高加权迁移率和315 K下的0.82的高zT。通过实验角度分辨光发射光谱和理论计算，从谱带扩宽效应和电负性的观点，以及形成高Bi / Sb比三元Mg ₃（Bi的必要性）的角度，我们指出了高热电性能的起源。，Sb）_2种合金。目前的工作为进一步开发Mg ₃铺平了道路（Bi，Sb）₂用于近室温热电应用。