Mg_2Si基热电材料的稀土掺杂优化

Optimization of Mg_2Si by doping the rare earth elements

采用机械研磨-电场激活压力辅助合成(FAPAS)技术,快速合成了稀土Sc和Y掺杂的Mg2Si基热电材料,所得试样组织均匀、致密,试样的平均晶粒尺寸为1.5～2μm,微量稀土元素不改变基体材料的组织形貌。分析表明两种稀土元素均在不同程度改善热电性能,其中掺杂0.427%(摩尔分数)Sc和0.173%(摩尔分数)Y的试样的综合电功率因子在378和468K分别达到未掺杂试样的2.67和2.03倍;掺杂0.173%(摩尔分数)Y的试样的热导率相对于未掺杂降低了20%,其无量纲热电优质系数ZT相对于后者提高了1.30倍,ZTmax为0.23,明显高于未掺杂试样的0.18。

The rare earth elements（Sc,Y） doped Mg_2 Si based thermoelectric materials were prepared by field-activated and pressure-assisted synthesis（FAPAS）. The samples by this method own uniform and compact struc- ture, the average grain size was about 1.5-2μm, micro-content of rare earth element did not change the morphology o{ matrix. The two dopants enhanced the thermoelectric properties at varying degrees, the power {actor of samples doped with 0. 427mol%Sc and 0. 173mol%Y were 2.67 times and 2.03 times of that of non-doped Mg_2Si at 378 and 468K respectively, and the thermal conductivity of the latter reduced by 20%. Thus, the figure of merit ZT of O. 173mol%Y doping sample reaches to 1.30 times of the pure Mg_2Si, its ZT_max-0. 23, obviously higher than 0.18 belonging to the latter.