Phase equilibria of Ag–Sb–Te thermoelectric materials

Wu, Hsin‐Jay; Chen, Sinn Wen

doi:10.1016/j.actamat.2011.07.010

Cited by 33 publications

(20 citation statements)

References 43 publications

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“…These values are considered to be relatively low compared to those of intermetallic compounds and are comparable with those of pure metals [108]. This is, however, not surprising, considering the extremely small atomic misit between the ( 111 ) AgSbTe 2 and ( 0001 ) Sb p Te q crystallographic planes [100], which encourages formation of Sb 2 Te 3 or Sb 8 Te 3 precipitates in the form of long lamellae along these planes [28,29,57,58,[100][101][102][103]. These low values of interfacial free energy also initiate fast nucleation, thanks to low activation energy for nucleation, which is proportional to γ …”

Section: Formation Of Sb 2 Te 3 and Sb 8 Te 3 (R-3m) Phasesmentioning

confidence: 99%

“…This, however, is diicult to achieve. Hot-pressing at 540°C, that is, above Sb-solvus, expected to yield the desirable single δ-phase that does not contain Sb 2 Te 3 precipitates [101][102][103]. These Sb 2 Te 3 precipitates, indeed, were not observed in Series A samples; however, La-rich precipitates having stoichiometry close to LaTe 2 were observed [110].…”

Section: Microstructure and Implications On Thermoelectric Behaviormentioning

confidence: 99%

“…Endothermic peak at around 630-650 K is observed for La-free material, which is associated with Ag 2 Te + Sb 2 Te 3 → δ-AgSbTe 2 phase transition at 360°C [101][102][103]. La-doped material, however, does not exhibit this transition.…”

Section: Thermal Analysismentioning

confidence: 99%

“…It is also noteworthy that both values coincide at temperatures larger than 650 K, which can be associated with phase transition [58,[101][102][103]. Thorough discussion of thermal conductivity values measured for Series A and Series B materials and their relationship with microstructure appears elsewhere [58].…”

Section: Thermal Analysismentioning

confidence: 99%

“…Since it has limited solubility to Sb with relatively moderate slope of Sb-solvus, it is likely to decompose to δ+Sb 2 Te 3 phase mixture [28,29,[100][101][102][103], whereas Sb 2 Te 3 is equilibrium phase and may appear as diferent homologous forms [72,73,[104][105][106][107]. Precipitation of antimony-telluride second phase in δ-matrix is expected to afect TE performance due to contributions from both matrix and precipitate phases or variation of the average matrix composition.…”

Section: Formation Of Sb 2 Te 3 and Sb 8 Te 3 (R-3m) Phasesmentioning

confidence: 99%

See 4 more Smart Citations

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: Formation Of Sb 2 Te 3 and Sb 8 Te 3 (R-3m) Phasesmentioning

confidence: 99%

Section: Microstructure and Implications On Thermoelectric Behaviormentioning

confidence: 99%

Section: Thermal Analysismentioning

confidence: 99%

Section: Thermal Analysismentioning

confidence: 99%

Section: Formation Of Sb 2 Te 3 and Sb 8 Te 3 (R-3m) Phasesmentioning

confidence: 99%

See 3 more Smart Citations

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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Experimental Thermodynamic Study on the Ag‐Sb System at Elevated Temperatures

Aspiala¹,

Tesfaye²,

Taskinen³

2015

EPD Congress 2015

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Thermoelectric Materials

Owens‐Baird

Heinrich

Kovnir

2017

Encyclopedia of Inorganic and Bioinorganic Chemistry

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The field of thermoelectric materials has flourished over the last two decades. Significant successes achieved in the development of materials notwithstanding, novel and highly efficient materials are in steep demand due to a wide range of potential and current applications, ranging from wearable electronics to space missions. The main challenge in the improvement of the thermoelectric figure of merit ( zT ) is to optimize the intertwined intrinsic charge and thermal transport properties. High electrical conductivity and thermopower, along with low thermal conductivity, need to be achieved simultaneously to excel the thermoelectric efficiency. In this review, the thermoelectric concepts, basics of transport properties, and strategies for zT optimization are discussed in the first section. In the following sections, the predominate structure types associated with high‐performance bulk thermoelectric materials are discussed in detail: Bi 2 Te 3 , PbTe, TAGS/LAST systems, SnSe, Cu 2− x Se, chalcopyrites, tetrahedrites, clathrates, skutterudites, zinc antimonides, Yb 14 MnSb 11 , Heusler and half‐Heusler intermetallics. The basic crystal structures, the possibilities for doping and substitutions to adjust charge carrier concentration and thermal conductivity, baseline thermoelectric properties, and strategies for efficiency improvement are considered for each structure type. Examples of recent work highlighting these strategies are briefly presented.

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Phase equilibria of Ag–Sb–Te thermoelectric materials

Cited by 33 publications

References 43 publications

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

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

Experimental Thermodynamic Study on the Ag‐Sb System at Elevated Temperatures

Thermoelectric Materials

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