Investigation on Quick Fabrication of n-type Filled Skutterudites

doi:10.15541/jim20160136

Abstract

Abstract:

The cost-effective fabrication of CoSb₃-based filled skutterudites (SKD) thermoelectric materials is a bottleneck issue preventing their successful commercial application. In this study, we employed a simple and scalable process to simultaneously produce a rapid formation and consolidation of n-type filled skutterudites. This method, consisting of RF-induction melting, quenching and spark plasma sintering (SPS), required less than a half-hour, significantly shorter than conventional process of furnace melting (over 24 h), annealing (about one week) and SPS. The fabricated bulk SKD materials possessed homogeneous composition and structures with a good thermoelectric performance which are analogous to those materials fabricated according to a conventional process. The homogeneous microstructures and phase composition distribution which was a result of the simultaneously proceeded rapid reaction and densification of the grinding-destructed dendrite networks of the Sb/CoSb/CoSb₂ peritectic structure formed in the RF-induction melting and quenching. The good thermoelectric TE performance and the very low consumption of process time and energy would make this simple process a potential and practical method for industrial-level mass production of filled skutterudite thermoelectric materials.

Key words: filled skutterudites, melting-quenching/SPS, microstructure, thermoelectric performance

CLC Number:

TQ174

YAO Zheng, QIU Peng-Fei, LI Xiao-Ya, CHEN Li-Dong. Investigation on Quick Fabrication of n-type Filled Skutterudites[J]. Journal of Inorganic Materials, 2016, 31(12): 1375-1382.

Figures/Tables 8

Fig. 1(a) represents the Co-Sb binary phase diagram from Ref.[26]. Due to the presence of a Co-Sb peritectic reaction at a temperature of about 876℃, the CoSb3 skutterudite phase could not be directly formed after quenching. This was confirmed by investigating the XRD pattern of the quenched ingot which experienced a 300 s induction-melting at 1353 K (see Fig. 1(b)). The ingot consisted of a mixture of CoSb, CoSb2, Sb and YbSb2. No X-ray diffraction peaks belonging to the Skutterudite phase were detected. SEM and EDS analyses shown in Fig. 1(c) further proved the coexistence of CoSb, CoSb2, and Sb in the quenched ingot. Presence of these phases formed typical dendrite networks, in which CoSb primary phases encircled with CoSb2 peritectic phases were unevenly distributed in the Sb matrix. Under higher magnification (see Fig. 1(d)), some bar-shape areas with brighter contrast were also observed in the Sb matrix, which were identified as YbSb2 by EDS. Such microstructure features are identical to that observed in the ingots prepared using a traditional long-term (48 h) melting process reported in Ref.[27]. However, the melting duration in this study is greatly reduced to as short as 300 s, which is meaningful for future industrial-level mass production.

Fig. 1 (a) Co-Sb binary phase diagram from Ref. [26], (b) XRD patterns of the quenched sample, and (c, d) back scattering electron images of the quenched sample under different magnification

Fig. 2 XRD patterns for the melting-quenching/SPSed samples

Fig. 3 Back scattering electron images of the melting-quenching/ SPSed samples

Fig. 4 Yb filling fractions in the melting-quenching/SPSed samples

Fig. 5 Cross-section morphologies for the samples (a) 863 K-5 min, (b) 943 K-5 min and (c) TM, respectively, and (d) magnified image of (a), and (e, f) the EDS analyses on the two points (spectrum 115 and 116) shown in (d)

Fig. 6 Sketch of the reaction mechanism in the annealing process for the traditional melting-quenching/annealing method

Fig. 7 Temperature dependences of TE properties of the samples prepared by the melting-quenching/SPS method The data for the TM sample are also included for comparison

References 29

[1]	TRITT T M.Holey and unholey semiconductors.Science, 1999, 283(5403): 804-805.
[2]	SNYDER GERALD JEFFREY, ERIC S TOBERER.Complex thermoelectric materials.Nature Materials, 2008, 7: 105-114.
[3]	LIU HUI-LI, SHI XUN, XU FANG-FANG,et al. Copper ion liquid-like thermoelectric . Nature Materials, 2012, 11(5): 422-425.
[4]	JUNG DO-YOUNG, KUROSAKI KEN, KIM CHANG-EUN,et al. Thermal expansion and melting temperature of the half-Heusler compounds: MNiSn (M=Ti, Zr, Hf) . Journal of Alloys and Compounds, 2010, 489(2): 328-331.
[5]	HE YING, LU PING, SHI XUN,et al. Ultrahigh thermoelectric performance in mosaic crystals . Advanced Materials, 2015, 27(24): 3639-3644.
[6]	HE YING, DAY TRISTAN, ZHANG TIAN-SONG,et al. High thermoelectric performance in non-toxic earth-abundant copper sulfide . Advanced Materials, 2014, 26(23): 3974-3978.
[7]	SHI XUN, YANG JIONG, SALVADOR JAMES R,et al. Multiple-filled skutterudites: high thermoelectric figure of merit through separately optimizing electrical and thermal transports . Journal of the American Chemical Society, 2011, 133(20): 7837-7846.
[8]	ROGL G, GRYTSIV A, ROGL P,et al. n-type skutterudites (R,Ba,Yb)(y)Co4Sb12 (R = Sr, La, Mm, DD, SrMm, SrDD) approaching ZT approximate to 2.0 . Acta Materialia, 2014, 63: 30-43.
[9]	LIU WEI-SHU, JIE QING, KIM HEE SEOK,et al. Current progress and future challenges in thermoelectric power generation: from materials to devices. Acta Materialia, 2015, 87: 357-376.
[10]	YANG JI-HUI, STABLER FRANCIS R.Automotive applications of thermoelectric materials.Journal of Electronic Materials, 2009, 38(7): 1245-1251.
[11]	ZHANG QI-HAO, HUANG XIANG-YANG, BAI SHENG- QIANG,et al. Thermoelectric devices for power generation: recent progress and future challenges. Advanced Engineering Materials, 2016, 18(2): 194-213.
[12]	TANG YUN-SHAN, BAI SHENG-QIANG, REN DU-DI,et al. Interface structure and electrical property of Yb0.3Co4Sb12 Mo-Cu element prepared by welding using Ag-Cu-Zn solder. Journal of Inorganic Materials, 2015, 30(3): 256.
[13]	RECKNAGEL C, REINFRIED N, HOHN P,et al. Application of spark plasma sintering to the fabrication of binary and ternary skutterudites. Science and Technology of Advanced Materials, 2007, 8(5): 357-363.
[14]	SHI X, KONG H, LI C P,et al. Low thermal conductivity and high thermoelectric figure of merit in n-type BaxYbyCo4Sb12 double-filled skutterudites. Applied Physics Letters, 2008, 92(18): 182101.
[15]	SU XIAN-LI, LI HAN, WANG GUO-YU,et al. Structure and transport properties of double-doped CoSb2.75Ge0.25-xTex(x= 0.125-0.20) with in situ nanostructure . Chemistry of Materials, 2011, 23(11): 2948-2955.
[16]	WU TING, BAI SHENG-QIANG, SHI XUN,et al. Enhanced thermoelectric properties of BaxEuyCo4Sb12 with very high filling fraction. Journal of Inorganic Materials, 2013, 28(2): 224-228.
[17]	YANG JUN-YOU, CHEN YUE-HUA, ZHU WEN,et al. Effect of La filling on thermoelectric properties of LaxCo3.6Ni0.4Sb12-filled skutterudite prepared by MA-HP method. Journal of Solid State Chemistry, 2006, 179(1): 212-216.
[18]	LIU WEI-SHU, ZHANG BO-PING, LI JING-FENG,et al. Enhanced thermoelectric properties in CoSb3-xTex alloys prepared by mechanical alloying and spark plasma sintering. Journal of Applied Physics, 2007, 102(10): 103717.
[19]	BISWAS KRISHNENDU, MUIR SEAN, SUBRAMANIAN M A.Rapid microwave synthesis of indium filled skutterudites: an energy efficient route to high performance thermoelectric materials.Materials Research Bulletin, 2011, 46(12): 2288-2290.
[20]	ZHANG JIAN-JUN, XU BO, WANG LI-MIN,et al.High-pressure synthesis of phonon-glass electron-crystal featured thermoelectric LixCo4Sb12. Acta Materialia, 2012, 60(3): 1246-1251.
[21]	LIANG TAO, SU XIAN-LI, YAN YONG-GAo,et al. Ultra-fast synthesis and thermoelectric properties of Te doped skutterudites. Journal of Materials Chemistry A, 2014, 2(42): 17914-17918.
[22]	LI HAN, TANG XIN-FENG, ZHANG QING-JIE,et al. Rapid preparation method of bulk nanostructured Yb0.3Co4Sb12+ycompounds and their improved thermoelectric performance . Applied Physics Letters, 2008, 93(25): 252109.
[23]	LI HAN, TANG XIN-FENG, ZHANG QING-JIe,et al. High performance InxCeyCo4Sb12 thermoelectric materials with in situ forming nanostructured InSb phase. Applied Physics Letters, 2009, 94(10): 102114.
[24]	YU JIAN, ZHAO WEN-YU, ZHOU HONG-YU,et al. Rapid preparation and thermoelectric properties of Ba and In double-filled p-type skutterudite bulk materials. Scripta Materialia, 2013, 68(8): 643-646.
[25]	ZHAO X Y, SHI X, CHEN L D,et al. Synthesis and thermoelectric properties of Sr-filled skutterudite SryCo4Sb12. Journal of Applied Physics, 2006, 99(5): 053711 .
[26]	HANNINGER G, IPSER H, TERZIEFF P,et al. The Co-Sb phase- diagram and some properties of NiAs-type Co1+/-xSb. Journal of the Less-Common Metals, 1990, 166(1): 103-114.
[27]	YAO ZHENG, LI XIAO-YA, TANG YUN-SHAN,et al. Genomic effects of the quenching process on the microstructure and thermoelectric properties of Yb0.3Co4Sb12. Journal of Electronic Materials, 2014, 44(6): 1890-1895.
[28]	ZHAO XUE-YIN, SHI XUN, CHEN LI-DONG,et al. Synthesis of YbyCo4Sb12/Yb2O3 composites and their thermoelectric properties. Applied Physics Letters, 2006, 89(9): 092121.
[29]	ZHOU H.Preparation and Thermoelectric Properties of Nonequilibrium-structure Filled Skutterudite Based Thermoelectric Materials. Wuhan University of Technology, 2011: 41.