高填充量BaxEuyCo4Sb12方钴矿热电性能研究

摘要

利用熔融法和等离子放电烧结(sPs)制备单相双原子填充BaxEuyCo4Sb12方钴矿材料并测试其高温热电性能.实验发现,在高填充量下(x+y＞40％),材料在高温时具有高的功率因子(＞60 W/(cm·K2)).在方钴矿的晶格空洞中同时引入Ba和Eu两种填充原子,能增强晶格声子散射,从而大幅降低方钴矿的晶格热导.实验证实,BaxEuvC04Sb12体系的晶格热导显著降低,其室温晶格热导最低达1.7 W/(m·K).与此对应的是双原子填充BaxEuyCo4Sb12方钴矿材料的热电优值(ZT值)明显增大,其中Ba0.19Eu0.23Co4Sb12的ZT值在850 K时达到了1.3.%Filled skutterudite is one of the most promising thermoelectric materials for power generation applications.We report the high-temperature thermoelectric properties including electrical conductivity,Seebeck coefficient,and thermal conductivity in single-phased polycrystalline dual-element-filled skutterudites BaxEuyCo4Sb12(0＜x＜0.2,0＜y＜0.3).The double-filled skutterudites are synthesized by the melting-quenching-annealing method and the bulk pellects are sintered by spark plasma sintering (SPS).High total filling fractions (x+y＞40％) with very large power factor of BaxEuyCo4Sbl2over 60μW/(cm·K2) at high temperature is obtained.The combination of Ba and Eu fillers inside the voids of the skutterudite structure provides a broad range of resonant phonon scattering and consequently a strong suppression in the lattice thermal conductivity is observed.The lattice thermal conductivity values for BaxEuyCo4Sb12 system are dramatically decreased and the lowest value is about 1.7 W/(m·K) at room temperature.Consequently,enhanced thermoelectric figure of merits (ZT) for Ba and Eu dual-element-filled CoSb3 skutterudites are obtained at elevated temperatures,in particular ZT=1.3 at 850 K for Ba0.19Eu0.23Co4Sb12.