Abstract：Abstract：As a new type of thermoelectric material, CaB6 is rich in raw materials and environmentally friendly.In this paper, CaB6 bulk samples were successfully prepared by the in-situ reaction synthesis of spark plasma sintering using boron powder and calcium hydride powder as raw materials.First-principles calculation results showed that CaB6 exhibits metal transport characteristic.In the test temperature range of 373-773 K, the power factor showed an upward trend with increasing temperature, from 2.86 × 10-3 W/m-1K-2 to 3.6 × 10-3 W/m-1K-2.The thermal conductivity decreased from 11.63 W/m-1K-1 to 9.06 W/m-1K-1with the increasing temperature. Lattice thermal conductivity accounts for the majority of thermal conductivity.The trend of the lattice thermal conductivity with temperature is consistent with the theoretical calculation results.The CaB6 sample made at 1673K achieved the maximum ZT value when the test temperature was 773K, reaching 0.34.
[1]Takeda, Terui, Takahashi.Improvement of thermoelectric properties of alkaline-earth hexaborides.[J].Journal of Solid State Chemistry, 2006, :2823-2826
[2]Wu, Singh, R.E. Cohen. Electronic structure of calcium hexaboride within the weighted density approximation. Physical Review B, 2004:193105.
[3]H.Kino, F. Aryasetiawan, M. van. Schilfgaarde, et al. GW quasiparticle band structure of CaB6. Journal of Physics and Chemistry of Solids, 2002:1595-1597.
[4]J.Cao, Y. Zhu, Z. Q.Yang, et al. Origin of the magnetism in CaB6: a firstprinciples study.Phys. Rev. B 79, 2009:1-4.
[5]J.Matsushita, S. Komarneni. High temperature oxidation behavior of CaB6 sintered body. Journal of Materials Science, 1999:3043-3046.
[6]Liu, C.H., Conductivity transition of semiconducting boron carbide by doping. Materials Letters, 2001:308-312.
[7]K.Yagasaki, S. Notsu, Y. Shimoji, et al. Resistivity and thermopower of CaB6 single crystal. Physica B-Condensed Matter. 2003:1259-1260.
[8]C.James, V. victor, M. Scott. Effect of Current on Diffusivity in Metal Hexaborides: A Spark Plasma Sintering Study. ACS Appl. Mater. Interfaces. 9, 37357(2017)
[9]Z.H.Dou, T.A. Zhang, R.T. Niu, R. Pan. Preparation of CaB6 by combustion synthesis. J. Inorg. Mater, 2008:150-154.
[10]H.Xu, X.T.Wang, Z.F.Wang. Rapid preparation of CaB6 powders via induction heating from low-cost colemanite and petroleum coke. Ceramics International, 2018:14070-14075.
[11]K.Raghunath, C. Kalyan. Mater. Electrochemical energy storage characteristics of CaB6 . Materials Letters, 2016:118-121.
[12]M.Takeda, T. Fukuda, T. Miura. Thermoelectric Properties of Metal-Hexaborides. 21st International Conference on Thermoelectronics, 2002:173-176.
[13]Cathie L.Condron, Susan M. Kauzlarich, et al..Thermoelectric properties and microstructure of Mg3Sb2. Journal of Solid State Chemistry, 2006: 2252-2257.
[14]Qian?Zhang, ?Bolin?Liao, ?Yucheng?Lan, et al.High TE performance by resonant dopant In in SnTe Proceedings of the National. Academy of Sciences?Aug, 2013:13261-13266
[15]N.Tahara, M. Kakiage, I. Yanase, et al.Effect of Addition of Tartaric Acid on Synthesis of Boron Carbide Powder from Condensed Boric Acid-Glycerin Product.J. Alloy. Comp, 2013:58-64 .
[16]S.Q.Zheng, G.H.Min, Z. D. Zou, et al. Synthesis of calcium hexaboride powder via the reaction of calcium carbonate with boron carbide and carbon. Journal of the American Ceramic Society. 84, 2725(2001)
2020, Vol. 27 