铁-镍双掺杂方钴矿的合成与热电性能

Synthesis and thermoelectric properties of Ni- and Fe- double doped skutterudites

摘要:

本文采用微波加热合成结合放电等离子体烧结制备了铁-镍双掺杂方钴矿Co3.8-xFexNi0.2Sb12 (x=0.05, 0.1, 0.15, 0.2)块体材料，并对其物相组成、晶粒尺寸、元素分布、热电性能等进行了系统研究。X衍射分析表明，样品X衍射峰与单相CoSb3相符；场发射扫描电镜分析表明，样品晶粒尺寸约为1~3 μm、平均尺寸约为1~2 μm，各元素均匀分布；电性能分析表明，Ni/Fe双掺杂对电输运性能有进一步改善，最高功率因子为2.667×103 μWm?1K?2；热性能分析表明，Fe掺杂对晶格热导率影响较小，晶格热导率与晶粒尺寸有关，主要热输运机制为晶界散射，Co3.65Fe0.15Ni0.2Sb12的最小晶格热导率为2.8 Wm-1K-1。Co3.7Fe0.1Ni0.2Sb12在773K获得最大热电优值0.50，显著高于传统方法制备的Ni/Fe单掺杂或者双掺杂样品。

Abstract:

In the present work, a series of single phase Fe-/Ni- double doped skutterudite compounds Co3.8-xFexNi0.2Sb12 (x=0.05, 0.1, 0.15, 0.2) were successful synthesized by 5 min microwave heating for the first time. The resulting ingots was pulverized and sintered by spark plasma sintering to fabricate bulk samples, and their phase composition, grain size, element distribution, thermoelectric transport properties have been investigated systematically. The XRD patterns show that all samples are consistent with single phase of CoSb3. The FE-SEM morphologies reveal that the size of Co3.8-xFexNi0.2Sb12 matrix grain are about 1~3 μm, the average size are about 1~2 μm. The EDS elemental maps revealing uniform Co, Fe, Ni, and Sb distributions. The electrical transport properties were further improved by Ni/Fe double doping, resulting a highest power factor of 2.667×103 μWm?1K?2. The influence of Fe doping on lattice thermal conductivity is not so significant, but there is a relationship between lattice thermal conductivity and grain size, and boundary scattering is most likely to be the dominant scattering mechanism. The lattice thermal conductivity of Co3.65Fe0.15Ni0.2Sb12 is 2.8Wm-1K-1. The Co3.7Fe0.1Ni0.2Sb12 has the highest ZT of 0.50 at 773 K, which are obviously larger than those of Ni- /Fe- single or double doped samples produced via traditional techniques.