“…The obtained ZT is as high as the highest reported values, as shown in Fig. 6, even though the report had shown very low density, from which low κ
ph was obtained, and no experimental value of the specific heat capacity 16, 19 . It is noteworthy that the enhanced ZT value was achieved with high density (over 97%), which means AgSbTe 2 has a range of possible applications.Figure 6Comparison of the ZT values:Data 1~9 are from ref.…”
Section: Resultsmentioning
confidence: 58%
“…The red dashed lines in all four panels are the corresponding data from ref. 19., while that in ( c ) is the total thermal conductivity from ref. 19.
…”
Section: Resultsmentioning
confidence: 99%
“…Also, some papers have reported good TE properties in the non-stoichiometric compositions formed by controlling the secondary phase, such as nanoscaled Ag 2 Te and Sb 2 Te 3
17, 18 . Others have tried to not only reduce the lattice thermal conductivity but also adjust the carrier concentrations using dopants such as Na, Se, and Mn in AgSbTe 2
19–21 ; by suppressing the formation of impurity phases, they enhanced the TE properties. It is clear from the research mentioned that large-scale precipitates have a deleterious impact on TE properties, whereas the formation of nanoscale dispersion enhances these properties.…”
We report the enhanced thermoelectric properties of Ce-doped AgSbTe2 (AgSb1−xCexTe2) compounds. As the Ce contents increased, the proportion of heterophase Ag2Te in the AgSbTe2 gradually decreased, along with the size of the crystals. The electrical resistivity and Seebeck coefficient were dramatically affected by Ce doping and the lattice thermal conductivity was reduced. The presence of nanostructured Ag2Te heterophases resulted in a greatly enhanced dimensionless figure of merit, ZT of 1.5 at 673 K. These findings highlight the importance of the heterophase and doping control, which determines both electrical and thermal properties.
“…The obtained ZT is as high as the highest reported values, as shown in Fig. 6, even though the report had shown very low density, from which low κ
ph was obtained, and no experimental value of the specific heat capacity 16, 19 . It is noteworthy that the enhanced ZT value was achieved with high density (over 97%), which means AgSbTe 2 has a range of possible applications.Figure 6Comparison of the ZT values:Data 1~9 are from ref.…”
Section: Resultsmentioning
confidence: 58%
“…The red dashed lines in all four panels are the corresponding data from ref. 19., while that in ( c ) is the total thermal conductivity from ref. 19.
…”
Section: Resultsmentioning
confidence: 99%
“…Also, some papers have reported good TE properties in the non-stoichiometric compositions formed by controlling the secondary phase, such as nanoscaled Ag 2 Te and Sb 2 Te 3
17, 18 . Others have tried to not only reduce the lattice thermal conductivity but also adjust the carrier concentrations using dopants such as Na, Se, and Mn in AgSbTe 2
19–21 ; by suppressing the formation of impurity phases, they enhanced the TE properties. It is clear from the research mentioned that large-scale precipitates have a deleterious impact on TE properties, whereas the formation of nanoscale dispersion enhances these properties.…”
We report the enhanced thermoelectric properties of Ce-doped AgSbTe2 (AgSb1−xCexTe2) compounds. As the Ce contents increased, the proportion of heterophase Ag2Te in the AgSbTe2 gradually decreased, along with the size of the crystals. The electrical resistivity and Seebeck coefficient were dramatically affected by Ce doping and the lattice thermal conductivity was reduced. The presence of nanostructured Ag2Te heterophases resulted in a greatly enhanced dimensionless figure of merit, ZT of 1.5 at 673 K. These findings highlight the importance of the heterophase and doping control, which determines both electrical and thermal properties.
“…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.
…”
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...
“…Phase-change memory (PCM) based on chalcogenide compounds has been considered to be the most promising candidate for next-generation nonvolatile data storage techniques such as digital versatile disk-random access memory (DVD-RAM), due to its excellent physical performance [1][2][3][4][5][6]. Currently, Ge 2 Sb 2 Te 5 (GST) films are the best chalcogenide material for PCM and have received sustained attention [7][8][9][10][11].…”
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