Concurrent La and A-Site Vacancy Doping Modulates the Thermoelectric Response to SrTiO3

Experimental and Computational Evidence

Feridoon Azough, Samuel S. Jackson, Dursun Ekren, Robert Freer, Marco Molinari, Stephen R. Yeandel, Pooja Panchmatia, Stephen C. Parker, David Hernandez Maldonado, Demie Kepaptsoglou, Quentin Mathieu Ramasse

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

To help understand the factors controlling the performance of one of the most promising n-type oxide thermoelectric SrTiO3, we need to explore structural control at the atomic level. In Sr1–xLa2x/3TiO3 ceramics (0.0 ≤ x ≤ 0.9), we determined that the thermal conductivity can be reduced and controlled through an interplay of La-substitution and A-site vacancies and the formation of a layered structure. The decrease in thermal conductivity with La and A-site vacancy substitution dominates the trend in the overall thermoelectric response. The maximum dimensionless figure of merit is 0.27 at 1070 K for composition x = 0.50 where half of the A-sites are occupied with La and vacancies. Atomic resolution Z-contrast imaging and atomic scale chemical analysis show that as the La content increases, A-site vacancies initially distribute randomly (x < 0.3), then cluster (x ≈ 0.5), and finally form layers (x = 0.9). The layering is accompanied by a structural phase transformation from cubic to orthorhombic and the formation of 90° rotational twins and antiphase boundaries, leading to the formation of localized supercells. The distribution of La and A-site vacancies contributes to a nonuniform distribution of atomic scale features. This combination induces temperature stable behavior in the material and reduces thermal conductivity, an important route to enhancement of the thermoelectric performance. A computational study confirmed that the thermal conductivity of SrTiO3 is lowered by the introduction of La and A-site vacancies as shown by the experiments. The modeling supports that a critical mass of A-site vacancies is needed to reduce thermal conductivity and that the arrangement of La, Sr, and A-site vacancies has a significant impact on thermal conductivity only at high La concentration.
Original languageEnglish
Pages (from-to)41988-42000
Number of pages13
JournalACS Applied Materials and Interfaces
Volume9
Issue number48
Early online date14 Nov 2017
DOIs
Publication statusPublished - 6 Dec 2017

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Vacancies
Doping (additives)
Thermal conductivity
Substitution reactions
strontium titanium oxide
Chemical analysis
Oxides
Phase transitions
Imaging techniques
Experiments

Cite this

Azough, Feridoon ; Jackson, Samuel S. ; Ekren, Dursun ; Freer, Robert ; Molinari, Marco ; Yeandel, Stephen R. ; Panchmatia, Pooja ; Parker, Stephen C. ; Maldonado, David Hernandez ; Kepaptsoglou, Demie ; Ramasse, Quentin Mathieu. / Concurrent La and A-Site Vacancy Doping Modulates the Thermoelectric Response to SrTiO3 : Experimental and Computational Evidence. In: ACS Applied Materials and Interfaces. 2017 ; Vol. 9, No. 48. pp. 41988-42000.
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abstract = "To help understand the factors controlling the performance of one of the most promising n-type oxide thermoelectric SrTiO3, we need to explore structural control at the atomic level. In Sr1–xLa2x/3TiO3 ceramics (0.0 ≤ x ≤ 0.9), we determined that the thermal conductivity can be reduced and controlled through an interplay of La-substitution and A-site vacancies and the formation of a layered structure. The decrease in thermal conductivity with La and A-site vacancy substitution dominates the trend in the overall thermoelectric response. The maximum dimensionless figure of merit is 0.27 at 1070 K for composition x = 0.50 where half of the A-sites are occupied with La and vacancies. Atomic resolution Z-contrast imaging and atomic scale chemical analysis show that as the La content increases, A-site vacancies initially distribute randomly (x < 0.3), then cluster (x ≈ 0.5), and finally form layers (x = 0.9). The layering is accompanied by a structural phase transformation from cubic to orthorhombic and the formation of 90° rotational twins and antiphase boundaries, leading to the formation of localized supercells. The distribution of La and A-site vacancies contributes to a nonuniform distribution of atomic scale features. This combination induces temperature stable behavior in the material and reduces thermal conductivity, an important route to enhancement of the thermoelectric performance. A computational study confirmed that the thermal conductivity of SrTiO3 is lowered by the introduction of La and A-site vacancies as shown by the experiments. The modeling supports that a critical mass of A-site vacancies is needed to reduce thermal conductivity and that the arrangement of La, Sr, and A-site vacancies has a significant impact on thermal conductivity only at high La concentration.",
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author = "Feridoon Azough and Jackson, {Samuel S.} and Dursun Ekren and Robert Freer and Marco Molinari and Yeandel, {Stephen R.} and Pooja Panchmatia and Parker, {Stephen C.} and Maldonado, {David Hernandez} and Demie Kepaptsoglou and Ramasse, {Quentin Mathieu}",
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Azough, F, Jackson, SS, Ekren, D, Freer, R, Molinari, M, Yeandel, SR, Panchmatia, P, Parker, SC, Maldonado, DH, Kepaptsoglou, D & Ramasse, QM 2017, 'Concurrent La and A-Site Vacancy Doping Modulates the Thermoelectric Response to SrTiO3: Experimental and Computational Evidence', ACS Applied Materials and Interfaces, vol. 9, no. 48, pp. 41988-42000. https://doi.org/10.1021/acsami.7b14231

Concurrent La and A-Site Vacancy Doping Modulates the Thermoelectric Response to SrTiO3 : Experimental and Computational Evidence. / Azough, Feridoon; Jackson, Samuel S.; Ekren, Dursun; Freer, Robert; Molinari, Marco; Yeandel, Stephen R.; Panchmatia, Pooja; Parker, Stephen C.; Maldonado, David Hernandez; Kepaptsoglou, Demie; Ramasse, Quentin Mathieu.

In: ACS Applied Materials and Interfaces, Vol. 9, No. 48, 06.12.2017, p. 41988-42000.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Concurrent La and A-Site Vacancy Doping Modulates the Thermoelectric Response to SrTiO3

T2 - Experimental and Computational Evidence

AU - Azough, Feridoon

AU - Jackson, Samuel S.

AU - Ekren, Dursun

AU - Freer, Robert

AU - Molinari, Marco

AU - Yeandel, Stephen R.

AU - Panchmatia, Pooja

AU - Parker, Stephen C.

AU - Maldonado, David Hernandez

AU - Kepaptsoglou, Demie

AU - Ramasse, Quentin Mathieu

PY - 2017/12/6

Y1 - 2017/12/6

N2 - To help understand the factors controlling the performance of one of the most promising n-type oxide thermoelectric SrTiO3, we need to explore structural control at the atomic level. In Sr1–xLa2x/3TiO3 ceramics (0.0 ≤ x ≤ 0.9), we determined that the thermal conductivity can be reduced and controlled through an interplay of La-substitution and A-site vacancies and the formation of a layered structure. The decrease in thermal conductivity with La and A-site vacancy substitution dominates the trend in the overall thermoelectric response. The maximum dimensionless figure of merit is 0.27 at 1070 K for composition x = 0.50 where half of the A-sites are occupied with La and vacancies. Atomic resolution Z-contrast imaging and atomic scale chemical analysis show that as the La content increases, A-site vacancies initially distribute randomly (x < 0.3), then cluster (x ≈ 0.5), and finally form layers (x = 0.9). The layering is accompanied by a structural phase transformation from cubic to orthorhombic and the formation of 90° rotational twins and antiphase boundaries, leading to the formation of localized supercells. The distribution of La and A-site vacancies contributes to a nonuniform distribution of atomic scale features. This combination induces temperature stable behavior in the material and reduces thermal conductivity, an important route to enhancement of the thermoelectric performance. A computational study confirmed that the thermal conductivity of SrTiO3 is lowered by the introduction of La and A-site vacancies as shown by the experiments. The modeling supports that a critical mass of A-site vacancies is needed to reduce thermal conductivity and that the arrangement of La, Sr, and A-site vacancies has a significant impact on thermal conductivity only at high La concentration.

AB - To help understand the factors controlling the performance of one of the most promising n-type oxide thermoelectric SrTiO3, we need to explore structural control at the atomic level. In Sr1–xLa2x/3TiO3 ceramics (0.0 ≤ x ≤ 0.9), we determined that the thermal conductivity can be reduced and controlled through an interplay of La-substitution and A-site vacancies and the formation of a layered structure. The decrease in thermal conductivity with La and A-site vacancy substitution dominates the trend in the overall thermoelectric response. The maximum dimensionless figure of merit is 0.27 at 1070 K for composition x = 0.50 where half of the A-sites are occupied with La and vacancies. Atomic resolution Z-contrast imaging and atomic scale chemical analysis show that as the La content increases, A-site vacancies initially distribute randomly (x < 0.3), then cluster (x ≈ 0.5), and finally form layers (x = 0.9). The layering is accompanied by a structural phase transformation from cubic to orthorhombic and the formation of 90° rotational twins and antiphase boundaries, leading to the formation of localized supercells. The distribution of La and A-site vacancies contributes to a nonuniform distribution of atomic scale features. This combination induces temperature stable behavior in the material and reduces thermal conductivity, an important route to enhancement of the thermoelectric performance. A computational study confirmed that the thermal conductivity of SrTiO3 is lowered by the introduction of La and A-site vacancies as shown by the experiments. The modeling supports that a critical mass of A-site vacancies is needed to reduce thermal conductivity and that the arrangement of La, Sr, and A-site vacancies has a significant impact on thermal conductivity only at high La concentration.

KW - Molecular dynamics

KW - Nanostructuring

KW - Perovskite

KW - Strontium titanate

KW - Thermal conductivity

KW - Vacancy-cation ordering

UR - http://pubs.acs.org/journal/aamick

U2 - 10.1021/acsami.7b14231

DO - 10.1021/acsami.7b14231

M3 - Article

VL - 9

SP - 41988

EP - 42000

JO - ACS applied materials & interfaces

JF - ACS applied materials & interfaces

SN - 1944-8244

IS - 48

ER -