SnxBi0.5-xSb1.5Te3热电材料的组织与性能研究

Structures and Thermoelectric Properties Research of SnxBi0.5-xSb1.5Te3 Thermoelectric Materials

摘要:

通过真空熔炼、球磨制粉、冷压成形和常压烧结制备具有高热电优值的p型SnxBi0.5-xSb1.5Te3热电材料。研究了Sn含量对SnxBi0.5-xSb1.5Te3热电材料晶体结构、微观形貌和热电性能的影响。结果表明：SnxBi0.5-xSb1.5Te3热电材料晶体结构为R-3m空间群斜方晶系的六面体层状结构；添加合金元素Sn，Bi0.5Sb1.5Te3基热电材料产生大量的纳米结构缺陷。合金元素Sn含量增加， SnxBi0.5-xSb1.5Te3热电材料载流子浓度和DOS有效质量增加，有效地提高电导率和功率因子；同时声子散射增强，显著地降低晶格热导率。在300K时，Sn0.015Bi0.485Sb1.5Te3的功率因子达3.10 mW?m-1?K-2，晶格热导率为0.358 W?m-1?K-1，ZT值为1.25。并且在300～400 K温度范围内，Sn0.015Bi0.485Sb1.5Te3的ZT值为1.25～1.33。

Abstract:

The p-type SnxBi0.5-xSb1.5Te3 thermoelectric materials with high ZT values have been prepared by vacuum melting, ball milling, cold-pressing and ambient pressure sintering. The effect of Sn content on the crystal structure, microscopic appearance, thermoelectric properties for SnxBi0.5-xSb1.5Te3 materials was investigated. As a result, the crystal structure of SnxBi0.5-xSb1.5Te3 thermoelectric materials is the rhombohedral structure; Bi0.5Sb1.5Te3 based thermoelectric materials contain more nanostructure defects with adding alloying element Sn. The addition of the alloying element Sn can increase carrier concentration and DOS effective mass to improve the electrical conductivity and power factor (PF). While, the reduction in lattice thermal conductivity is attributed to the enhanced phonon scattering. Eventually, the power factor reaches 3.10 mW·m-1·K-2, the lattice thermal conductivity is 0.358 W·m-1·K-1 and the ZT value is 1.25 at 300 K for Sn0.015Bi0.485Sb1.5Te3. And，in the temperature range of 300～400K，the ZT values for the Sn0.015Bi0.485Sb1.5Te3 are 1.25～1.33.