Enhanced thermoelectric performance in Bi-doped p-type AgSbTe2 compounds

Mohanraman, Rajeshkumar; Sankar, Raman; Chou, F. C.; Lee, Chih‐Hao; Chen, Yang‐Yuan

doi:10.1063/1.4828478

Cited by 34 publications

(34 citation statements)

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“…ZT values of La-free and La-doped materials shown in Figure 12b correspond with those reported by Zhang et al [101], where the efects of La-doping are comparable to those of stoichiometric variations about AgSbTe 2 composition. Similar values are reported by Mohanraman et al [43] and Jovovic and Heremans [19] for Bi-doping, as well as, for Pb-doping [19]. Chen et al obtain similar ZT values for Ge-doping [111] and for Sn-doping [112], depending on concentration.…”

Section: Thermoelectrics For Power Generation -A Look At Trends In Thsupporting

confidence: 76%

“…These latice defects afect, of course, electronic properties, mainly electrical conductivity and Seebeck coeicient. Atempts to improve TE properties of AgSbTe 2 -based alloys by doping with diferent elements [19,25,[39][40][41][42][43][44][45][46][47] Notwithstanding the aforementioned successful experimental and computational atempts, a set of experimental routines, that is initiated and directed by predictions from irst principles for complete TE performance or any other computational procedure, is missing. …”

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confidence: 99%

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Silver-Antimony-Telluride: From First-Principles Calculations to Thermoelectric Applications

Amouyal¹

2016

Thermoelectrics for Power Generation - A Look at Trends in the Technology

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Silver-antimony-telluride (AgSbTe 2 ) based compounds have emerged as a promising class of materials for thermoelectric (TE) power generation at the mid-temperature range. This Chapter demonstrates utilization of irst-principles calculations for predicting TE properties of AgSbTe 2 -based compounds and experimental validations. Predictive calculations of the efects of La-doping on vibrational and electronic properties of AgSbTe 2 compounds are performed applying the density functional theory (DFT), and temperature-dependent TE transport coeicients are evaluated applying the Bolzmann transport theory (BTE). Experimentally, model ternary (AgSbTe 2 ) and quaternary (3 at. % La-AgSbTe 2 ) compounds were synthesized, for which TE transport coeicients were measured, indicating that thermal conductivity decreases due to La-alloying. The later also reduces electrical conductivity and increases Seebeck coeicients. All trends correspond with those predicted from irst-principles. Thermal stability issues are essential for TE device operation at service conditions, e.g. changes of matrix composition and second-phase precipitation, and are also addressed in this study on both computational and experimental aspects. It is shown that La-alloying afects TE igure-of-merit positively, e.g., improving from 0.35 up to 0.50 at 260 °C. We highlight the universal aspects of this approach that can be applied for other TE compounds. This enables us screening their performance prior to synthesis in laboratory.Keywords: silver-antimony-telluride, irst-principles calculations, thermoelectric transport properties, Bolzmann transport theory, latice dynamics, thermal stability IntroductionIt is of utmost technological importance to develop predictive tools that will provide us with information about design of materials' functional properties. In this context, density functional theory (DFT) irst-principle calculations ofer us such possibilities [1][2][3][4] Despite of relatively high ZT values of AgSbTe 2 phase, it is still challenging to increase them to the range of 2-3. Reaching at this limit will enable us employing this material for energy conversion at power levels >500 W [34]. Reduction in latice thermal conductivity is a conventional way to enhance TE performance and is achieved by either doping with solute elements [35] or formation of second phases to stimulate phonon scatering [36][37][38]. These latice defects afect, of course, electronic properties, mainly electrical conductivity and Seebeck coeicient. Atempts to improve TE properties of AgSbTe 2 -based alloys by doping with diferent elements [19,25,[39][40][41][42][43][44][45][46][47] Notwithstanding the aforementioned successful experimental and computational atempts, a set of experimental routines, that is initiated and directed by predictions from irst principles for complete TE performance or any other computational procedure, is missing. Thermoelectrics for Power Generation -A Look at Trends in the Technology 148A signiicant step in this direction is introduced by o...

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Section: Thermoelectrics For Power Generation -A Look At Trends In Thsupporting

confidence: 76%

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confidence: 99%

Silver-Antimony-Telluride: From First-Principles Calculations to Thermoelectric Applications

Amouyal¹

2016

Thermoelectrics for Power Generation - A Look at Trends in the Technology

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“…10 Additionally, several high values of zT(>1) have been obtained in AgSbTe 2 -type materials by doping it with In Ref. 11,Bi,12 and by alloying it with AgSbSe 2 . 13 Attempts to dope n-type are not expected to be useful, because the conduction band is unfavorable to obtaining a high zT.…”

Section: Introductionmentioning

confidence: 99%

Off-stoichiometric silver antimony telluride: An experimental study of transport properties with intrinsic and extrinsic doping

2015

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AgSbTe2 is a thermoelectric semiconductor with an intrinsically low thermal conductivity and a valence band structure that is favorable to obtaining a high thermoelectric figure of merit zT. It also has a very small energy gap Eg ∼ 7.6 ± 3 meV. As this gap is less than the thermal excitation energy at room temperature, near-intrinsic AgSbTe2 is a two carrier system having both holes (concentration p) and electrons (n). Good thermoelectric performance requires heavy p-type doping (p > > n). This can be achieved with native defects or with extrinsic doping, e.g. with transition metal element. The use of defect doping is complicated by the fact that many of the ternary Ag-Sb-Te and pseudo-binary Sb2Te3-Ag2Te phase diagrams are contradictory. This paper determines the compositional region most favorable to creating a single phase material. Through a combination of intrinsic and extrinsic doping, values of zT > 1 are achieved, though not on single-phased material. Additionally, we show that thermal conductivity is not affected by defects, further demonstrating that the low lattice thermal conductivity of I-V-VI2 materials is due to an intrinsic mechanism, insensitive to changes in defect structure.

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“…24,25 In this paper, Sb 3+ was substituted with Sn 2+ in ptype Ag(Sb 1−x Sn x )Te 2 systems to optimize the charge-carrier concentration and simultaneously reduce lattice thermal conductivity by enhancing phonon scattering through the naturally formed fine dispersion of Ag 2 Te nanoprecipitates in the matrix. When x = 0.03, the sample exhibited the highest ZT value of 1.1 at 600 K; therefore, Ag(Sb 0.97 Sn 0.03 )Te 2 can be used as a p-type TE material.…”

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confidence: 99%

“…The synthesis procedures detailed in our previous report 24 were used to obtain highly dense crystalline ingots with a dark silvery metallic shine as shown in Fig. 1(a).…”

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confidence: 99%

Influence of nanoscale Ag2Te precipitates on the thermoelectric properties of the Sn doped P-type AgSbTe2 compound

et al. 2014

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We report a maximal figure of merit (ZT) value of 1.1 at 600 K was obtained for the sample of which x = 0.03, representing an enhancement greater than 20% compared with a pristine AgSbTe2 sample. This favorable thermoelectric performance originated from the optimal Sn2+ substitution for Sb3+ in AgSbTe2, which not only increased electrical conductivity but also led to a substantial reduction in thermal conductivity that was likely caused by an enhanced phonon-scattering mechanism through the combined effects of lattice defects and the presence of Ag2Te nanoprecipitates dispersed in the matrix.

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Enhanced thermoelectric performance in Bi-doped p-type AgSbTe2 compounds

Cited by 34 publications

References 35 publications

Silver-Antimony-Telluride: From First-Principles Calculations to Thermoelectric Applications

Silver-Antimony-Telluride: From First-Principles Calculations to Thermoelectric Applications

Off-stoichiometric silver antimony telluride: An experimental study of transport properties with intrinsic and extrinsic doping

Influence of nanoscale Ag2Te precipitates on the thermoelectric properties of the Sn doped P-type AgSbTe2 compound

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