Composition optimization of p-type AgSn m SbTe m +2 thermoelectric materials synthesized by mechanical alloying and spark plasma sintering

Xing, Zhi-Bo; Li, Zong‐Yue; Tan, Qing; Wei, Tian‐Ran; Wu, Chaofeng; Li, Jing‐Feng

doi:10.1016/j.jallcom.2014.06.176

Cited by 15 publications

(11 citation statements)

References 16 publications

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“…On the other hand, when more AgBiTe 2 is involved, the band gap of SnTe becomes smaller (see the discussion below), which would probably decrease the defect formation energy and increase the Sn vacancies, contributing to increased hole densities. A comparison of the hole concentrations of AgSn x BiTe x+2 and AgSn m SbTe m+2 , 16 Fig. 2(a), clearly shows that the former has much lower hole concentrations than the latter under the same x or m. This indicates that Bi is a more effective electron donor than Sb in SnTe and is consistent with previous ndings in other II-VI systems.…”

Section: Physical Characterizationsupporting

confidence: 85%

“…11 It was previously reported that by alloying a proper amount of AgSbTe 2 with SnTe, creating the quaternary system AgSn m SbTe m+2 , the hole concentration of SnTe can be reduced (not by Hall measurements) as evidenced by the variation of the Seebeck coefficient as a function of m. 8 The most recent study of this system by Xing et al, however, pointed towards an opposite direction that the hole concentration of SnTe increases with increasing AgSbTe 2 although curiously the Seebeck coefficient also increases in this process. 16 These results suggest that the introduction of AgSbTe 2 warrants additional investigations regarding its role in affecting the hole population of SnTe. Despite this, the presence of AgSbTe 2 in SnTe can greatly decrease the lattice thermal conductivity of SnTe by the nanostructure scattering of phonons 8,17,18 (the AgSn m SbTe m+2 system (TAST) is a nanostructured composite 17,18 ) similar to the AgPb m SbTe m+2 system (LAST).…”

Section: Introductionmentioning

confidence: 87%

“…The maximum power factor reaches $23 mW cm À1 K À2 around 750 K for the AgSn 15 BiTe 17 sample, which is comparable to that of the optimized AgSn m SbTe m+2 system. 8,16 However, lower electrical conductivities in AgSn x BiTe x+2 than in AgSn m SbTe m+2 suggest smaller electronic contributions to the respective total thermal conductivities.…”

Section: Electrical Propertiesmentioning

confidence: 99%

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SnTe–AgBiTe₂ as an efficient thermoelectric material with low thermal conductivity

et al. 2014

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SnTe is an intriguing alternative to its sister compound PbTe in thermoelectric energy conversion because of their electronic and structural similarity; however, it is challenging to optimize its thermoelectric performance to the level of PbTe because of the difficulties in decreasing its intrinsically large hole population and high thermal conductivity arising from the tin vacancies. We demonstrate here that by alloying some AgBiTe 2 in SnTe, thus forming AgSn x BiTe x+2 compositions the hole concentration can be duly decreased because of the high efficiency of Bi as an electron donor. The lattice thermal conductivity is also decreased due to the strong scattering of phonons (by point defect scattering as well as Ag-rich nanostructures) to achieve a value of $0.7 W m À1 K À1 at $750 K. As a result, a high thermoelectric figure ZT of merit of $1.1 at 775 K is achieved by chemical composition optimization (Â$15), making lead free SnTe-AgBiTe 2 a promising thermoelectric material.

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Section: Physical Characterizationsupporting

confidence: 85%

Section: Introductionmentioning

confidence: 87%

Section: Electrical Propertiesmentioning

confidence: 99%

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SnTe–AgBiTe₂ as an efficient thermoelectric material with low thermal conductivity

et al. 2014

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“…Considering the measured work function of SnTe as ∼5 eV and the reported value of work function of Te as ∼4.95 eV, , the dispersed SnTe/Te interfaces (typical energy barrier of ∼0.05 eV) may act like energy filtering centers in SnTe and contribute to more enhancement of the Seebeck coefficient. Such energy filtering of the charge carrier-induced enhancement of the Seebeck coefficient is earlier reported for Sn 1– x Sb x Te and AgSbTe 2 –SnTe alloys . Along with energy filtering, the other possibility of such an enhanced Seebeck coefficient could be the high carrier concentration in Te/SnTe samples, which suggests that in this sample, the Fermi level is deep below the valence band edge, and the heavy valence band also contributes to the Seebeck coefficient.…”

Section: Resultssupporting

confidence: 67%

“…Such energy filtering of the charge carrier-induced enhancement of the Seebeck coefficient is earlier reported for Sn 1−x Sb x Te 26 and AgSbTe 2 −SnTe alloys. 27 Along with energy filtering, the other possibility of such an enhanced Seebeck coefficient could be the high carrier concentration in Te/SnTe samples, which suggests that in this sample, the Fermi level is deep below the valence band edge, and the heavy valence band also contributes to the Seebeck coefficient. The systematic enhancement of the effective mass (m*) from 0.17m e (for SnTe) to 2.42m e (for Sn 0.7 Te) with the decrease of x in the Sn x Te sample supports the increasing contribution of the heavy valence band (details given in the Supporting Information S6).…”

Section: ■ Results and Discussionmentioning

confidence: 96%

Remarkable Improvement of Thermoelectric Figure-of-Merit in SnTe through In Situ-Created Te Nanoinclusions

Ahmad

Singh

Bhattacharya

et al. 2020

ACS Appl. Energy Mater.

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SnTe exhibits very low Seebeck coefficient along with high electrical–thermal conductivities owing to very high hole concentration that results from intrinsic Sn vacancies. All these unfavorable thermoelectric parameters restrict pristine SnTe from becoming an outstanding thermoelectric material. In this work, we demonstrate the improvement in figure-of-merit of SnTe through in situ creation of Te nanoinclusions in the SnTe matrix. We have intentionally added excess Te in stoichiometric Sn/Te (1:1) for the synthesis of SnTe. During solidification of SnTe from the melt, the excess Te in the liquid state gets expelled to the grain boundaries. On further cooling, when Te starts to solidify, it exerts strain in the already solidified SnTe grains and creates extensive structural defects including dislocations, twin boundaries, and subgrain boundaries that scatter phonons of midwavelength. The point defect due to intrinsic Sn vacancies and SnTe/Te grain boundaries respectively scatters phonons of low and high wavelengths. Effective scattering of the entire spectrum of phonons through the hierarchical defects gives rise to an ultralow lattice thermal conductivity of 0.5 W m–1 K–1 that is close to the theoretical minimum limit. The contribution from the heavy hole valence band in transport along with energy filtering of charge carriers at the SnTe/Te interface results in improvement of the Seebeck coefficient near room temperature. The cumulative effect of improved Seebeck coefficient and suppressed thermal conductivity gives rise to a high figure-of-merit (ZT) value of ∼1.5 at 750 K and an average ZT of ∼0.48 for the Sn0.9Te sample.

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ChemInform Abstract: Composition Optimization of P‐Type AgSn_mSbTe_m+2 Thermoelectric Materials Synthesized by Mechanical Alloying and Spark Plasma Sintering.

Xing

Tan

et al. 2014

ChemInform

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Synthesized by Mechanical Alloying and Spark Plasma Sintering. -AgSn mSbTem+2 (m = 2, 4, 10, 18) thermoelectric materials are prepared by mechanical alloying of the elements in a planetary ball mill followed by spark plasma sintering (50 MPa, 749 K, 5 min). The samples are characterized by XRD, SEM, and thermoelectric measurements. Both the electrical and thermal conductivities increase with increasing m, but the Seebeck coefficient shows a maximum at m = 4, resulting in an optimal composition with a relatively high thermoelectric figure of merit of up to 0.8 at 723 K. The title system holds great promise as an alternative p-type, lead-free, thermoelectric material. -(XING, Z.-B.; LI, Z.-Y.; TAN, Q.; WEI, T.-R.; WU, C.-F.; LI*, J.-F.; J. Alloys Compd. 615 (2014) 451-455, http://dx.

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Composition optimization of p-type AgSn m SbTe m +2 thermoelectric materials synthesized by mechanical alloying and spark plasma sintering

Cited by 15 publications

References 16 publications

SnTe–AgBiTe₂ as an efficient thermoelectric material with low thermal conductivity

SnTe–AgBiTe₂ as an efficient thermoelectric material with low thermal conductivity

Remarkable Improvement of Thermoelectric Figure-of-Merit in SnTe through In Situ-Created Te Nanoinclusions

ChemInform Abstract: Composition Optimization of P‐Type AgSn_mSbTe_m+2 Thermoelectric Materials Synthesized by Mechanical Alloying and Spark Plasma Sintering.

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Composition optimization of p-type AgSn m SbTe m +2 thermoelectric materials synthesized by mechanical alloying and spark plasma sintering

Cited by 15 publications

References 16 publications

SnTe–AgBiTe2 as an efficient thermoelectric material with low thermal conductivity

SnTe–AgBiTe2 as an efficient thermoelectric material with low thermal conductivity

Remarkable Improvement of Thermoelectric Figure-of-Merit in SnTe through In Situ-Created Te Nanoinclusions

ChemInform Abstract: Composition Optimization of P‐Type AgSnmSbTem+2 Thermoelectric Materials Synthesized by Mechanical Alloying and Spark Plasma Sintering.

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SnTe–AgBiTe₂ as an efficient thermoelectric material with low thermal conductivity

SnTe–AgBiTe₂ as an efficient thermoelectric material with low thermal conductivity

ChemInform Abstract: Composition Optimization of P‐Type AgSn_mSbTe_m+2 Thermoelectric Materials Synthesized by Mechanical Alloying and Spark Plasma Sintering.