铁-镍双掺杂方钴矿的合成与热电性能

A series of single phase Ni/Fe double doped skutterudite compounds Co_3.8-xFe_xNi_0.2Sb₁₂ (x=0.05, 0.10, 0.15, 0.20) were synthesized by 5 min microwave heating for the first time. The resulting ingots were pulverized and sintered by spark plasma sintering to fabricate bulk samples, and their phase composition, grain size, element distribution, thermoelectric transport properties were investigated. The XRD patterns show that all samples are consistent with single phase of CoSb₃. The FE-SEM morphologies reveal that the size of Co_3.8-xFe_xNi_0.2Sb12 (x=0.05, 0.10, 0.15, 0.20) matrix grain is about 1∼3 μm, and the average size is about 1∼2 μm. The EDS elemental maps reveal uniform Co, Fe, Ni, and Sb distributions. The electrical transport properties are further improved by Ni/Fe double doping, with the highest power factor of 2.667x10³ μW·(m·K²)^-1. The influence of Fe doping on lattice thermal conductivity is not significant, but there is a relationship between lattice thermal conductivity and grain size, and boundary scattering is the dominant scattering mechanism. The lattice thermal conductivity of Co_3.65Fe_0.15Ni_0.2Sb₁₂ is 2.8 W·(m·K)^-1. The Co_3.7Fe_0.1Ni_0.2Sb₁₂ has the highest ZT of 0.50 at 773 K, which is obviously larger than that of Ni/Fe single or double doped samples produced via traditional techniques.