(Bi1-xAgx)2(Te1-ySey)3粉体的机械合金化制备及其放电等离子烧结体的热电输运特性

Mechanical alloying synthesis of (Bi_(1-x)Ag_x)_2(Te_(1-y)Se_y)_3 powder and thermoelectric properties of its bulk materials prepared by spark plasma sintering

采用机械合金化制备了n型(Bi1-xAgx)2(Te1-ySey)3合金粉体,对其进行XRD分析表明Bi,Te,Ag,Se单质粉末,经2h球磨后实现了合金化;SEM分析表明随着机械合金化时间延长粉体颗粒变得均匀、细小,颗粒尺寸在微米至亚微米数量级.采用放电等离子烧结制备了块体样品,研究了合金成分和球磨时间对热电性能的影响.结果表明材料的热电性能与掺杂元素有密切关系,Ag有利于提高功率因子和降低晶格热导率,球磨10h的(Bi0.99Ag0.01)2(Te0.96Se0.04)3合金粉末的烧结块体具有最大的功率因子和最低的晶格热导率,并在323K取得最高ZT值0.52.

The powders of n-type （Bi1-xAgx）2（Te1-ySey）3 thermoelectric materials were synthesized by mechanical alloying and consolidated by spark plasma sintering. The milled powders were investigated by XRD and SEM, which shows that the pure Bi, Te, Ag and Se particles were alloyed after milling for 2 h. With the increase of the time of mechanical alloying, the size of the powder grains decreases to about 1--0.5 μm. The effects of the doped elements on the thermoelectric properties have been studied. It was found that Ag can improve the power factor and decrease the lattice thermal conductivity, the compound （Bi1-xAgx）2（Te1-ySey）3 after milling for 10 h possesses the highest value of the power factor and minimum thermal conductivity, which results in the highest value of ZT of 0.52 at 323 K.