核壳结构对Zn0.98Al0.02O热电性能的影响

Influence of core-shell structure on thermoelectric properties of Zn0.98Al0.02O

摘要:

ZnO由于其优异的电学性能被认为是非常具有应用前景的高温氧化物热电材料,但它较高的热导率一直限制着其热电性能的提升。本文我们通过共沉淀法制备了Al掺杂的ZnO颗粒,并在其表面包覆了不同厚度的TiO₂,得到了Zn_0.98Al_0.02O@TiO₂纳米核壳异质结构粉体,采用放电等离子体(SPS)烧结技术烧结制备了热电陶瓷材料。包覆TiO₂之后,材料的电学和热学性能均得到调控,其中包覆15%TiO₂的样品的功率因子在1023 K比未包覆样品的功率因子提高了10%,而且其热导率在1023 K比未包覆样品的热导率降低了将近30%。由于电学和热学的同时优化,使最大ZT值由未包覆时的0.030提高到了包覆之后的0.043,提高了43%,这一结果表明氧化钛包覆氧化锌的核壳结构是提高氧化锌热电性能的有效途径。

Abstract:

ZnO is considered as a promising oxide thermoelecreic material based on its excellent electrical properties, however, its thermoelectric properties is hard to improve limited by its high thermal conductivity. In this paper, Al doped ZnO powders were fabricated by co-precipitation, and then coated with different quantity TiO₂, forming Zn_0.98Al_0.02O@TiO₂ core-shell heterogeneous structure, at last sintered to ceramics by SPS. The electrical and thermal properties both were optimized with TiO₂ coating. The power factor of 15 wt% TiO₂ coated sample was improved about 10% than that of the uncoated sample at 1023 K, and the thermal conductivity of 15 wt% TiO₂ coated sample was depressed about 30% than that of the uncoated sample. As a result, the maximum ZT value was enhanced about 43% from 0.030 of the uncoated sample to 0.043 of 15 wt% TiO₂ coated sample at 1023 K, which shows that Zn_0.98Al_0.02O@TiO₂ core-shell heterogeneous structure is an effective approach to enhance the thermoelectric properties of ZnO.