Band Degeneracy, Low Thermal Conductivity, and High Thermoelectric Figure of Merit in SnTe-CaTe Alloys

Rabih Al Rahal Al Orabi, Nicolas A. Mecholsky, Junphil Hwang, Woochul Kim, Jong Soo Rhyee, Daehyun Wee, Marco Fornari

Research output: Contribution to journalArticle

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Abstract

Pure lead-free SnTe has limited thermoelectric potentials because of the low Seebeck coefficients and the relatively large thermal conductivity. In this study, we provide experimental evidence and theoretical understanding that alloying SnTe with Ca greatly improves the transport properties leading to ZT of 1.35 at 873 K, the highest ZT value so far reported for singly doped SnTe materials. The introduction of Ca (0-9%) in SnTe induces multiple effects: (1) Ca replaces Sn and reduces the hole concentration due to Sn vacancies, (2) the energy gap increases, limiting the bipolar transport, (3) several bands with larger effective masses become active in transport, and (4) the lattice thermal conductivity is reduced by about 70% due to the contribution of concomitant scattering terms associated with the alloy disorder and the presence of nanoscale precipitates. An efficiency of ∼10% (for ΔT = 400 K) was predicted for high-temperature thermoelectric power generation using SnTe-based p- and n-type materials.

Original languageEnglish
Pages (from-to)376-384
Number of pages9
JournalChemistry of Materials
Volume28
Issue number1
DOIs
Publication statusPublished - 2016 Jan 12

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Thermal conductivity
Hole concentration
Seebeck coefficient
Thermoelectric power
Alloying
Transport properties
Vacancies
Power generation
Precipitates
Energy gap
Lead
Scattering
Temperature

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

Cite this

Al Rahal Al Orabi, Rabih ; Mecholsky, Nicolas A. ; Hwang, Junphil ; Kim, Woochul ; Rhyee, Jong Soo ; Wee, Daehyun ; Fornari, Marco. / Band Degeneracy, Low Thermal Conductivity, and High Thermoelectric Figure of Merit in SnTe-CaTe Alloys. In: Chemistry of Materials. 2016 ; Vol. 28, No. 1. pp. 376-384.
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abstract = "Pure lead-free SnTe has limited thermoelectric potentials because of the low Seebeck coefficients and the relatively large thermal conductivity. In this study, we provide experimental evidence and theoretical understanding that alloying SnTe with Ca greatly improves the transport properties leading to ZT of 1.35 at 873 K, the highest ZT value so far reported for singly doped SnTe materials. The introduction of Ca (0-9{\%}) in SnTe induces multiple effects: (1) Ca replaces Sn and reduces the hole concentration due to Sn vacancies, (2) the energy gap increases, limiting the bipolar transport, (3) several bands with larger effective masses become active in transport, and (4) the lattice thermal conductivity is reduced by about 70{\%} due to the contribution of concomitant scattering terms associated with the alloy disorder and the presence of nanoscale precipitates. An efficiency of ∼10{\%} (for ΔT = 400 K) was predicted for high-temperature thermoelectric power generation using SnTe-based p- and n-type materials.",
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Al Rahal Al Orabi, R, Mecholsky, NA, Hwang, J, Kim, W, Rhyee, JS, Wee, D & Fornari, M 2016, 'Band Degeneracy, Low Thermal Conductivity, and High Thermoelectric Figure of Merit in SnTe-CaTe Alloys', Chemistry of Materials, vol. 28, no. 1, pp. 376-384. https://doi.org/10.1021/acs.chemmater.5b04365

Band Degeneracy, Low Thermal Conductivity, and High Thermoelectric Figure of Merit in SnTe-CaTe Alloys. / Al Rahal Al Orabi, Rabih; Mecholsky, Nicolas A.; Hwang, Junphil; Kim, Woochul; Rhyee, Jong Soo; Wee, Daehyun; Fornari, Marco.

In: Chemistry of Materials, Vol. 28, No. 1, 12.01.2016, p. 376-384.

Research output: Contribution to journalArticle

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AU - Kim, Woochul

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AU - Fornari, Marco

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AB - Pure lead-free SnTe has limited thermoelectric potentials because of the low Seebeck coefficients and the relatively large thermal conductivity. In this study, we provide experimental evidence and theoretical understanding that alloying SnTe with Ca greatly improves the transport properties leading to ZT of 1.35 at 873 K, the highest ZT value so far reported for singly doped SnTe materials. The introduction of Ca (0-9%) in SnTe induces multiple effects: (1) Ca replaces Sn and reduces the hole concentration due to Sn vacancies, (2) the energy gap increases, limiting the bipolar transport, (3) several bands with larger effective masses become active in transport, and (4) the lattice thermal conductivity is reduced by about 70% due to the contribution of concomitant scattering terms associated with the alloy disorder and the presence of nanoscale precipitates. An efficiency of ∼10% (for ΔT = 400 K) was predicted for high-temperature thermoelectric power generation using SnTe-based p- and n-type materials.

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