Zintl相Mg₃X₂(X= Sb, Bi)基热电材料以其无毒性、价格低及性能高等优点而备受关注。与多晶相比, Mg₃X₂晶体在揭示材料本征热电性能、各向异性性质及电声输运调控策略等方面极具研究价值。本文系统归纳与总结近年Mg₃X₂基晶体的生长及热电性能发展现状。针对Mg₃X₂晶体生长过程中Mg元素易挥发和活泼金属性的难点, 多种技术如合适的温度冷却法、定向凝固法、助熔剂法、助熔剂坩埚下降法等被开发运用于生长Mg₃X₂晶体, 其中助熔剂坩埚下降法在获得大尺寸块状晶体方面更有竞争力。n型和p型Mg₃Sb₂晶体都呈现出各向异性的热电性能。调控晶体生长速度、Mg元素自补偿含量、杂质元素掺杂与固溶含量等手段, 都会影响Mg₃X₂晶体的电学性能和热学性能。目前p型和n型Mg₃Sb₂基晶体的最高ZT值可分别达到0.68和0.82。本文综述了Zintl相Mg₃X₂基晶体生长与热电性能的研究进展, 发现助熔剂坩埚下降法是制备大尺寸Mg₃X₂基晶体的关键, 通过元素掺杂及固溶方法调控载流子浓度和能带结构可以进一步提高Mg₃X₂基晶体性能。该生长方法和研究思路对将来Mg₃X₂基晶体制备与热电性能深入研究具有重要指导意义。

Zintl phase Mg₃X₂ (X=Sb, Bi) based thermoelectric materials have attracted much attention because of their non-toxic, low cost and high performance. Compared with polycrystalline materials, the Mg₃X₂ crystals are of great value in revealing material’s intrinsic and anisotropic thermoelectric properties, as well as providing effective strategies for enhancing electrical and thermal transport properties. Therefore, the recent progress of single crystal growth and thermoelectric properties for Mg₃X₂ crystals are systematically summarizes in this paper. Due to the volatility and causticity of Mg element, several different methods such as slow cooling method, directional solidification method, flux method, and flux Bridgman method are widely used for synthesizing Mg₃X₂ crystals, in which the flux Bridgman method is more competitive to prepare large size bulk crystals. Researchers found that both n-type and p-type Mg₃Sb₂ crystals show an anisotropy thermoelectric transport property. The crystal growth rate, the concentration of self-doped Mg element, the concentration of impurity doping or alloying elements have a great impact on both electrical and thermal transport properties for Mg₃Sb₂ crystals. So far, the p-type and n-type Mg₃Sb₂ crystals with ZT value of 0.68 and 0.82 are achieved, respectively. This paper reviews the recent progress of growth and thermoelectrics properties of Zintl phase Mg₃X₂-based crystals, revealing that the flux Bridgman method is the most effective method to produce large-sized Mg₃X₂-based crystals. Tuning chemical composition of Mg₃X₂-based crystal by doping and forming solid solution for optimal carrier concentration and band structure engineering is expected to further improve the thermoelectric performance of Mg₃X₂-based crystal. The above-mentioned growth method and research strategies provide a significant guidance for the in-depth understanding of the Mg₃X₂-based crystal in the future.