Zn-Sb双掺杂Mg_2(Si,Sn)合金的热电性能

Thermoelectric Property of Zn-Sb Doped Mg_2(Si,Sn) Alloys

Mg_2(Si,Sn)合金热电材料具有成本低廉、环境友好等优点,作为一种绿色环保的中温区热电材料一直受到广泛关注。在Mg_2(Si,Sn)基材料中掺杂大剂量Sb可诱发Mg空位,从而有效降低材料的热导率,但同时Seebeck系数也会降低。研究采用高温熔炼及真空热压法成功合成了Mg_(2.12-y)Si_(0.4)Sn_(0.5)Sb_(0.1)Zn_y(y=0～0.025)试样,通过在大剂量Sb掺杂的Mg_2(Si,Sn)基材料中添加Zn元素,研究了大剂量Sb和微量Zn双掺杂对材料电声输运特性的综合影响。研究结果表明,Zn-Sb双掺杂可通过有效抑制材料电子热导率的方法大幅降低Mg_2(Si,Sn)合金材料的总热导率,与此同时明显提高掺Zn试样的塞贝克系数以弥补其电导率的损失,维持材料较为优异的电学性能。最终,热导率的大幅优化及电学性能的维持实现了材料综合热电性能的显著提升,其中,成分为Mg_(2.095)Si_(0.4)Sn_(0.5)Sb_(0.1)Zn_(0.025)的材料在823 K下热电优值ZT达到1.42。

As a type of medium-temperature thermoelectric materials,Mg2(Si,Sn)alloy thermoelectric materials have been widely concerned because of the low cost and environmental friendliness.Heavily Sb doping can effectively induce Mg vacancy so as to reduce the thermal conductivity in Mg2(Si,Sn)-based materials,but at the same time lead to a decrease of Seebeck coefficient.In this study,high-quality Mg2.12-ySi0.4Sn0.5Sb0.1Zny(y=0-0.025)samples were successfully synthesized by high temperature melting and vacuum hot-pressing method.Zn element was introduced into the heavily Sb-doped Mg2(Si,Sn)material to investigate the double doping effect on the electroacoustic transport properties.The results show that Zn-Sb double doping could effectively reduce the total thermal conductivity of Mg2(Si,Sn)-based materials by obviously suppressing the electronic thermal conductivity and at the same time enhance the Seebeck coefficient of Zn-doped samples,so as to compensate for the loss of electrical conductivity,and maintain high electrical performance.Significantly optimized thermal conductivity and electrical performance ultimately improve the thermoelectric figure of merit ZT of the material.At 823 K,the maximum ZT of Mg2.095Si0.4Sn0.5Sb0.1Zn0.025 reached 1.42.