Ag掺杂SnSe化合物的制备及热电性能

SnSe是一种潜在的极具应用前景的热电材料。采用机械合金化结合放电等离子烧结的方法制备了Ag掺杂的Sn_1-xAg_xSe (0.005≤x≤0.03)多晶块体热电材料, 并借助XRD、SEM、电热输运测试系统研究了其物相组成、微结构与电热输运性能。XRD分析结果表明, 少量Ag(0.005≤x≤0.01)掺杂仍然能够成功制备出单相斜方结构SnSe化合物, 但随着Ag掺杂量的增加, 基体中出现SnAgSe₂第二相, 且第二相含量逐渐增加。掺杂Ag大幅度提高了载流子浓度, 从而使材料的综合电输运性能(功率因子)显著提高, 当Ag掺杂量x=0.02时, 功率因子提高至4.95×10^-4 W/(m·K²), 较未掺杂SnSe样品提高了36%。尽管掺杂样品的热导率均有小幅升高, 无量纲热电优值(ZT)仍获得一定改善。当Ag掺杂量x=0.02时, Sn_0.98Ag_0.02Se成分样品具有较高的热电优值, 并在823 K附近达到最高值0.82。

Synthesis and Thermoelectric Properties of Ag-doped SnSe

SnSe material is one of the most promising state-of-art thermoelectric materials. The polycrystalline Ag-doped Sn_1-xAg_xSe (0.005≤x≤0.03) bulks were prepared by mechanical alloying and spark plasma sintering technique, and the composition, microstructure and thermoelectric properties were systematically studied by XRD, SEM and thermoelectric performance measurement. XRD results show that single-phase orthorhombic SnSe-based compounds can be prepared with small amount of Ag-doping (0.005≤x≤0.01), but with Ag doping amount increasing, small quantity of secondary phase, SnAgSe₂, can be detected in the matrix. The carrier concentration and overall electrical properties (power factor) are significantly enhanced as a result of Ag doping. The power factor of Sn_0.98Ag_0.02Se increases up to 0.495×10^-3 W/(m·K²), which is about 36% higher than that of SnSe material. Although the thermal conductivity increases slightly, the dimensionless figure of merit, ZT is still optimized for the Ag-doped samples. Sn_0.98Ag_0.02Se bulk shows optimal ZT value and the highest ZT of 0.82 is obtained at 823 K, which is the highest value reported for the polycrystalline SnSe-based thermoelectric materials.