Precipitation of Ag2Te in the thermoelectric material AgSbTe2

Sugar, Joshua D.; Medlin, Douglas L.

doi:10.1016/j.jallcom.2008.11.054

Cited by 99 publications

(83 citation statements)

References 30 publications

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“…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%

“…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%

See 1 more Smart Citation

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

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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“…Nevertheless, lamellar precipitations of Ag 2 Te are believed to play a crucial role in phonon scattering. 16,17 Dimensionless thermoelectric figure of merit ZT was calculated for obtained material (Eq. 1).…”

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confidence: 99%

Analysis of the Influence of Thermal Treatment on the Stability of Ag1−xSb1+xTe2+x and Se-Doped AgSbTe2

Wyżga

Wojciechowski

2015

Journal of Elec Materi

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In order to systematize the knowledge on thermodynamic stability and thermoelectric properties of AgSbTe 2 -based alloys, several experiments examining the influence of thermal treatment on their structural and thermoelectric properties were performed. Samples with a nominal composition of AgSbTe 2 and AgSbTe 1.98 Se 0.02 were prepared and then annealed in various temperature conditions. It was confirmed that Ag 1Àx Sb 1+x Te 2+x (b phase) is the only thermodynamically stable ternary compound in the Ag 2 Te-Sb 2 Te 3 pseudobinary system. It was also proved that thermal stability of b phase is limited-it slowly decomposes below 633 K. In contrast to some reports, it was also indicated that a small amount of Se does not lead to stabilisation of AgSbTe 2 crystal structure. Despite slow kinetics of the decomposition processes, thermoelectric properties of the material are notably affected by thermal treatment and amount of Ag 2 Te precipitations. Maximal ZT value of prepared materials varies from 0.65 at 575 K to 1.07 at 563 K.

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“…10). Several mechanisms have been suggested to explain the very low, glass-like κ lat , such as strong anharmonicity 12,17 , force-constants differences around Ag and Sb atoms 18 , and nanoprecipitates 13,14,[19][20][21][22] . However, the lack of direct microscopic measurements of the phonon scattering rates and mean-free-paths has hampered a detailed understanding.…”

Section: Introductionmentioning

confidence: 99%

“…However, further complexity arises as the δ-phase is observed slightly off stoichiometry in the pseudo-binary Ag 2 Te-Sb 2 Te 3 phase diagram 19,23,24 . In addition, it has remained a long-standing question whether the cations are ordered or disordered on their sublattice 12,[25][26][27][28] .…”

Section: Introductionmentioning

confidence: 99%

Phonon scattering rates and atomic ordering inAg1−xSb1+xTe2+x(
Ma
¹
,
Delaire
²
,
Specht
³

et al. 2014
Phys. Rev. B
15
0
12
0
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The phonon dispersions and scattering rates of the thermoelectric material Ag1−xSb1+xTe2+x (x = 0, 0.1, 0.2) were measured with inelastic neutron scattering, as function of both temperature T and off-stoichiometry x. In addition, detailed measurements of diffuse scattering were performed with both neutron and synchrotron x-ray diffraction. The results show that phonon scattering rates are large and weakly dependent on T or x, and the lattice thermal conductivity calculated from these scattering rates and group velocities is in good agreement with bulk transport measurements. We also find that the scattering rates and their temperature dependence cannot be accounted for with common models of phonon scattering by anharmonicity or point defects. The diffuse scattering measurements show a pervasive, complex signal, with several distinct components. In particular, broad superstructure reflections indicate a short-range ordering of the Ag and Sb cations on their sublattice. Single-crystal Bragg peak intensities also reveal large static atomic displacements, compatible with results from Rietveld refinement of neutron powder diffraction data. Our results indicate that a complex nanostructure, arising from multiple variants of nanoscale anisotropic superstructures of cations, and large atomic displacements, is likely responsible for the strong phonon scattering.

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Precipitation of Ag2Te in the thermoelectric material AgSbTe2

Cited by 99 publications

References 30 publications

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

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

Analysis of the Influence of Thermal Treatment on the Stability of Ag1−xSb1+xTe2+x and Se-Doped AgSbTe2

Phonon scattering rates and atomic ordering inAg1−xSb1+xTe2+x(
Ma
¹
,
Delaire
²
,
Specht
³

et al. 2014
Phys. Rev. B
15
0
12
0
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Precipitation of Ag2Te in the thermoelectric material AgSbTe2

Cited by 99 publications

References 30 publications

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

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

Analysis of the Influence of Thermal Treatment on the Stability of Ag1−xSb1+xTe2+x and Se-Doped AgSbTe2

Phonon scattering rates and atomic ordering inAg1−xSb1+xTe2+x(Ma1, Delaire2, Specht3 et al. 2014Phys. Rev. B150120View full textAdd to dashboardCite

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Phonon scattering rates and atomic ordering inAg1−xSb1+xTe2+x(
Ma
¹
,
Delaire
²
,
Specht
³

et al. 2014
Phys. Rev. B
15
0
12
0
View full text Add to dashboard Cite