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用熔融退火结合放电等离子烧结(SPS)技术制备了具有不同Ga填充含量的GaxCo4Sb12方钴矿化合物,研究了不同Ga含量对其热电传输特性的影响规律.Rietveld结构解析表明,Ga占据晶体学2a空洞位置,Ga填充上限约为0.22,当Ga的名义组成x≤0.25时,样品的电导率、室温载流子浓度Np随Ga含量的增加而增加,Seebeck系数随Ga含量的增加而减小.室温下霍尔测试表明,每一个Ga授予框架0.9个电子,比Ga的氧化价态Ga3+小得多.由于Ga离子半径相对较小,致使Ga填充方钴矿化合物的热导率κ及晶格热导率κL较其他元素填充的方钴矿化合物低.当x=0.22时对应的样品在300 K时的热导率和晶格热导率分别为3.05 Wm-1.K-1和2.86 Wm-1.K-1.在600 K下Ga0.22Co4.0Sb12.0样品晶格热导率达到最小,为1.83 Wm-1.K-1,最大热电优值Z,在560 K处达1.31×10-3K-1.
GaxCo4Sb12 skutterudites with different content of Ga were prepared by melt-anneal combined with spark plasma sintering (SPS), and the effect of different Ga content on the thermoelectric properties was studied. The Rietveld structure analysis shows that Ga occupies the hole 2a The upper limit of Ga filling is about 0.22. When the nominal composition of Ga is less than or equal to 0.25, the conductivity and the carrier concentration at room temperature Np increase with the increase of Ga content, and the Seebeck coefficient decreases with the increase of Ga content. Lower Hall tests show that each Ga confers 0.9 electrons to the framework, which is much smaller than the oxidation state Ga3 + of Ga. Due to the relatively small Ga ion radius, the thermal conductivity κ and the lattice heat of the Ga-filled skutterudite compound The conductivity κ L was lower than that of the other compounds.When x = 0.22, the thermal conductivity and the lattice thermal conductivity of the corresponding samples at 300 K were 3.05 Wm-1.K-1 and 2.86 Wm- 1.K-1. At 600 K, the lattice thermal conductivity of Ga0.22Co4.0Sb12.0 sample reaches the minimum value of 1.83 Wm-1.K-1, the maximum thermoelectric figure of merit Z is 1.31 × 10 at 560 K -3K-1.