Improved thermoelectric performance of hot pressed nanostructured n-type SiGe bulk alloys

Basu, Ranita; Bhattacharya, Shovit; Bhatt, Ranu; Roy, Mainak; Ahmad, Sajid; Singh, Ajay; Navaneethan, M.; Hayakawa, Y.; Aswal, D. K.; Gupta, S. K.

doi:10.1039/c3ta14259k

Cited by 169 publications

(127 citation statements)

References 36 publications

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“…3,8 A very promising field of application are thermoelectric generators, that attracted a lot of attention in the last years. The dimensionless figure of merit ZT = (S 2 σ/k)T could continuously be increased up to 1.84, reported in 2014 by Basu et al 9 for a Ge 80 Si 20 alloy. Z is the thermoelectric figure of merit, S the Seebeck coefficient, σ the electrical conductivity and T the absolute temperature.…”

Section: Introductionmentioning

confidence: 62%

“…This composition, around the minimum in the thermal conductivity k, is optimal for maximizing the figure of merit. Furthermore, a nanoparticulate approach can enhance S 2 σ and also decrease k. [9][10][11] The synthesis routines for Ge x Si 1−x particles and layers are manifold. One example for a liquid phase process is described by Barry et al 2 who use hydrogen silsesquioxane and soluble germanium diiodide complexes to synthesize Si x Ge 1−x NCs.…”

Section: Introductionmentioning

confidence: 99%

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Germanium-silicon alloy and core–shell nanocrystals by gas phase synthesis

et al. 2015

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Section: Introductionmentioning

confidence: 62%

Section: Introductionmentioning

confidence: 99%

Germanium-silicon alloy and core–shell nanocrystals by gas phase synthesis

et al. 2015

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“…[17][18][19][20][21] Apart from the improvement of electronic properties, these strategies are also helpful to impede the propagation of thermal phonons by enhancing interface phonon scattering together with creating local structural disorder to increase the frequency of phonon scattering processes as well. Based on these strategies many materials such as Bi 2 Te 3 , [22][23][24][25][26] LAST, 27 TAGS, 28 PbTe 29, 30 SiGe 31,32 b-phase hexagonal structure (space group P 3m1; no. 164) which is under our investigation, consists of two inequivalent Mg sites, denoted as Mg(I) and Mg(II) which are covalent and ionic in nature respectively.…”

Section: Introductionmentioning

confidence: 99%

Graphene boosts thermoelectric performance of a Zintl phase compound

et al. 2015

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The concept of nanocomposites derived by incorporating a second minor phase in bulk thermoelectric materials has established itself as an effective paradigm for optimizing high thermoelectric performance.In this work, this paradigm is for the first time extended to bulk Zintl phase Mg 3 Sb 2 and its isoelectronically Bi-doped derivative Mg 3 Sb 1.8 Bi 0.2 system. Herein, we report the synthesis, microstructural details, electronic structure and thermoelectric properties of (Mg 3 Sb 2 , Mg 3 Sb 1.8 Bi 0.2 )/ graphene nanosheet (GNS) nanocomposites with different mass ratios. Field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) investigation reveals that Mg 3 Sb 2 nanoparticles are homogenously anchored on the surface of GNS. We demonstrate that Mg 3 Sb 2 -based materials incorporated with a small content of graphene outperform optimally, resulting in potential ptype thermoelectric materials. The present nanocomposite additive of GNS deriving such a novel nanocomposite of (Mg 3 Sb 2 , Mg 3 Sb 1.8 Bi 0.2 )/GNS, enhances the electrical conductivity significantly, thereby resulting in a substantially large increase in the power factor. The enhanced electrical conductivity of these nanocomposites is attributed to the increase in the carrier concentration and high carrier mobility owing to the ultra high mobility of graphene. X-ray photoelectron spectroscopy (XPS) core level spectra confirm weak bonding between GNS and Mg 3 Sb 2 . Increase in carrier concentration is reflected in XPS valence band spectra and change in spectral weight near valence band maxima is indicative of increased electrical conductivity in the nanocomposite material. The thermal conductivity of these nanocomposites is noted to be reduced at high temperature. These favorable conditions lead to enhanced thermoelectric figure-of-merit (ZT) z 0.71 at 773 K for Mg 3 Sb 2 /GNS and a ZT z 1.35 at 773 K for Mg 3 Sb 1.8 Bi 0.2 /GNS nanocomposites with the mass ratio of 80 : 1 which are $170% and $125% higher values compared to bare Mg 3 Sb 2 and bare Mg 3 Sb 1.8 Bi 0.2 respectively. We strongly believe that the present novel strategy of fabricating such a nanocomposite of a Zintl compound by utilizing GNS as a nanocomposite additive, may provide an emerging path for improving thermoelectric properties of various Zintl phase compounds.

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“…Basu et al [33] reported a very large value of ZT for Si80Ge20 that was prepared by a hot-press sintering technique. There is the suggestion that the material is nanostructured.…”

Section: Application To Silicon-germaniummentioning

confidence: 99%

“…In Figure 5, we show the variation of ZT with temperature from Basu's data and from our calculations. [33]. The bottom curve is a calculation based on the assumption that n is proportional to T and the middle curve is for n proportional to T 2 .…”

Section: Application To Silicon-germaniummentioning

confidence: 99%

Extrapolation of Transport Properties and Figure of Merit of a Thermoelectric Material

Goldsmid

Sharp

2015

Energies

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Abstract:The accurate determination of the thermoelectric properties of a material becomes increasingly difficult as the temperature rises. However, it is the properties at elevated temperatures that are important if thermoelectric generator efficiency is to be improved. It is shown that the dimensionless figure of merit, ZT, might be expected to rise with temperature for a given material provided that minority carrier conduction can be avoided. It is, of course, also necessary that the material should remain stable over the whole operating range. We show that the prediction of high temperature properties in the extrinsic region is possible if the temperature dependence of carrier mobility and lattice thermal conductivity are known. Also, we show how the undesirable effects arising from mixed or intrinsic conduction can be calculated from the energy gap and the relative mobilities of the electrons and the positive holes. The processes involved are discussed in general terms and are illustrated for different systems. These comprise the bismuth telluride alloys, silicon-germanium alloys, magnesium-silicon-tin and higher manganese silicide.

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Improved thermoelectric performance of hot pressed nanostructured n-type SiGe bulk alloys

Cited by 169 publications

References 36 publications

Germanium-silicon alloy and core–shell nanocrystals by gas phase synthesis

Germanium-silicon alloy and core–shell nanocrystals by gas phase synthesis

Graphene boosts thermoelectric performance of a Zintl phase compound

Extrapolation of Transport Properties and Figure of Merit of a Thermoelectric Material

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