PbTe-based thermoelectric nanocomposites with reduced thermal conductivity by SiC nanodispersion

Abstract

For further thermoelectric performance enhancement by the nanocomposite effect, a small amount (<2 vol. %) of 30 nm SiC particles were added into a compositionally optimized AgPb m SbTe mþ2 thermoelectric alloy fabricated by mechanical alloying and spark plasma sintering. Although the energy filtering effect is not available in the present composite due to the mismatched interface between SiC and the matrix, a small amount of SiC dispersions were revealed to be effective to reduce the thermal conductivity via enhancing phonon scattering. A high figure of merit up to 1.54 at 723 K was obtained in the AgPb m SbTe mþ2 matrix composite containing 1 vol. % SiC nanoparticles. V C 2014 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4869220] Thermoelectric materials have drawn increasing attention because of their potential in energy harvesting and electronic cooling device applications. 1-3 The efficiency of thermoelectric conversion depends on the dimensionless figure of merit, ZT, defined as ZT ¼ a 2 (qj) À1 T, where a is the Seebeck coefficient (also called as thermopower), T is the absolute temperature, q is the electrical resistivity, and j is the thermal conductivity, 4 respectively. It is not easy to independently control these parameters to improve the ZT value because of the coupling relationship among a, q, and j. In last ten years, nanostructuring in the form of quantum well, 5 superlattice, 6 nanodot, 7,8 as well as nanostructured bulk composites 9,10 have shed new light on the improvement of thermoelectric materials, where they can significantly reduce thermal conductivity without affecting electrical properties, even improvement in some cases. Enhanced thermoelectric performance in many materials with ZT > 1 or ZT % 1 has been reported, such as Bi 2 Te 3 , 11,12 PbTe/PbS, 13-15 and oxide compounds. 16 Especially, in PbTe-based AgPb m SbTe mþ2 (LAST, lead-antimony-silver-tellurium) compounds, a high ZT value up to 1.7 at 700 K was achieved by Hsu et al. in 2004. 17 Previous studies 9,17,18 indicated that the endotaxial nanostructure is very effective in enhancing ZT value of LAST alloys, such as the phase-segregation with the presence of embedded nanodots (appear to be rich in Ag and Sb) in the PbTe matrix, which are believed to play an important role in scattering phonons without influencing electron transport meanwhile. However, one may worry about the stability of such a nanostructure when used for a long time at high temperatures. Alternatively, intentionally mixing inert nanoparticles into a thermoelectric matrix should be an easier approach to create composites, which should have more difficulty to grow or coalesce than the in situ precipitates formed by annealing. In fact, it is demonstrated that mixing SiC nanoparticles into the BiSbTe matrix can effectively enhance its thermoelectric and mechanical properties. 19,20 In this work, we explored the effect of incorporating nano-SiC particles in the LAST matrix on the TE properties. The atoms of Si and C are much lighter than those of Pb and Te as t...

Thermoelectric Transport in Nanocomposites

“…Other materials such as manganese silicide based NCs [100] and magnesium silicide based NCs [101,102,103], polycrystalline SnSe embedded with PbTe nanoinclusions [104], Skutterudites CoSb 3 compounds [105] and Yb x Co 4 Sb 12 alloy [106] based NCs, n -type half-Heuslers alloy Hf 0.75 Zr 0.25 NiSn 0.99 Sb 0.01 based NCs [107], p -type half-Heuslers alloy Zr 0.5 Hf 0.5 CoSb 0.8 Sn 0.2 based NCs [108] and Zr 0.25 Hf 0.25 NiSn based NCs [109], BiCuSeO-based NCs [110] and InGaAs alloy embedded with ErAs nanoparticles [111,112] are also studied. Furthermore, some non-TE materials like carbon nanotube [113], C 60 [114,115], graphene [116,117], SiC [118] and platinum nanocrystals [119] are used as nanoconstituents to embed into Bi 2 Te 3 and Sb 2 Te 3 based materials to enhance ZT .…”

Synthesis and Thermoelectric Properties of Copper Sulfides via Solution Phase Methods and Spark Plasma Sintering

“…The energy crisis and environmental problems have promoted the swift development of TE materials in the past few decades [1][2][3][4]. Compared to the mainstream tellurium-based TE materials [5][6][7][8], nanostructured metal chalcogenides with low cost, low toxicity, and abundant elements exhibit interesting physical properties [9,10]. Therefore, nanostructured metal chalcogenides TE materials such as Cu-Se [11][12][13] and Cu-S materials [14][15][16][17] have received more attention.…”

Enhanced thermoelectric performance of chalcogenide Cu 2 CdSnSe 4 by ex-situ homogeneous nanoinclusions

“…Furthermore, this value is nearly comparable to that in classical p-type thermoelectric materials, such as fully filled skutterudites and commercial Bi 2 Te 3 -based materials. Meanwhile, M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT matrices, SiC nanodispersions in PbTe-based thermoelectric nanocomposites [20], hierarchical nanostructured β-Zn 4 Sb 3 -Cu 3 SbSe 4 [21], or β-Zn 4 Sb 3 alloy bulk embedded with (Bi 2 Te 3 ) 0.2 (Sb 2 Te 3 ) 0.8 [22]. Provided the phonon mean-free path is reduced by enhanced phonon boundary scattering to a greater degree than any reduction in the mean-free path of charge carriers, significantly reduced thermal conductivities without negatively affecting electrical properties (even improving in some cases) could be obtained, leading to a net effect of an improvement in the figure of merit.…”