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The Structure and Thermoelectric Properties of Tungsten Bronze Ba6Ti2Nb8O30

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The Structure and Thermoelectric Properties of Tungsten Bronze Ba6Ti2Nb8O30. / Jiang, Dongting; Ekren, Dursun; Azough, Feridoon; Day, Sarah J.; Chen, Kan; Mahajan, Amit; Kepaptsoglou, Demie M.; Ramasse, Quentin M.; Reece, Michael J.; Freer, Robert.

In: Journal of Applied Physics, Vol. 126, No. 12, 27.09.2019.

Research output: Contribution to journalArticlepeer-review

Harvard

Jiang, D, Ekren, D, Azough, F, Day, SJ, Chen, K, Mahajan, A, Kepaptsoglou, DM, Ramasse, QM, Reece, MJ & Freer, R 2019, 'The Structure and Thermoelectric Properties of Tungsten Bronze Ba6Ti2Nb8O30', Journal of Applied Physics, vol. 126, no. 12. https://doi.org/10.1063/1.5119962

APA

Jiang, D., Ekren, D., Azough, F., Day, S. J., Chen, K., Mahajan, A., Kepaptsoglou, D. M., Ramasse, Q. M., Reece, M. J., & Freer, R. (2019). The Structure and Thermoelectric Properties of Tungsten Bronze Ba6Ti2Nb8O30. Journal of Applied Physics, 126(12). https://doi.org/10.1063/1.5119962

Vancouver

Jiang D, Ekren D, Azough F, Day SJ, Chen K, Mahajan A et al. The Structure and Thermoelectric Properties of Tungsten Bronze Ba6Ti2Nb8O30. Journal of Applied Physics. 2019 Sep 27;126(12). https://doi.org/10.1063/1.5119962

Author

Jiang, Dongting ; Ekren, Dursun ; Azough, Feridoon ; Day, Sarah J. ; Chen, Kan ; Mahajan, Amit ; Kepaptsoglou, Demie M. ; Ramasse, Quentin M. ; Reece, Michael J. ; Freer, Robert. / The Structure and Thermoelectric Properties of Tungsten Bronze Ba6Ti2Nb8O30. In: Journal of Applied Physics. 2019 ; Vol. 126, No. 12.

Bibtex - Download

@article{e86239a548484b1d9af4f90dcad0695b,
title = "The Structure and Thermoelectric Properties of Tungsten Bronze Ba6Ti2Nb8O30",
abstract = "Tungsten bronze structured materials have attracted attention as possible thermoelectrics because of their complex crystal structure. In this work, a new thermoelectric ceramic with tetragonal tungsten bronze (TB) structure, Ba6Ti2Nb8O30 (BTN) was prepared by the conventional mixed oxide (MO) route with some samples processed by Spark Plasma Sintering (SPS). Additions of MnO enabled fabrication of high density BTN ceramics at the low sintering temperature of 1580 K in air and by SPS. All samples were annealed in a reducing atmosphere after sintering. X-ray diffraction showed that Ba6Ti2Nb8O30 crystallises with tetragonal symmetry (P4bm space group). HAADF-EELS analysis confirmed the proposed crystal structure and provided exact elemental distributions in the lattice, showing higher concentrations of Ti in the 2b lattice sites compared to the 8d lattice sites. XPS showed the presence of two spin-orbit double peaks at 207.7eV in the reduced BTN samples, confirming the presence of Nb4+ ions. By the use of a sintering aid and optimisation of the processing parameters the ceramics achieved a high power factor of 280 μW/m∙K2 at 873 K. The BTN ceramics showed phonon glass type thermal conduction behaviour with low thermal conductivity of 1.7 to 1.65 W/m.K at 300 to 873 K. A thermoelectric figure of merit (ZT) of 0.14 was achieved at 873 K. This ZT value is comparable with results for many TB thermoelectrics. However, BTN has the advantage of much easier processing.",
keywords = "Tungsten bronze, Ba6Ti2Nb8O30, thermoelectric, thermal conductivity, HAADF",
author = "Dongting Jiang and Dursun Ekren and Feridoon Azough and Day, {Sarah J.} and Kan Chen and Amit Mahajan and Kepaptsoglou, {Demie M.} and Ramasse, {Quentin M.} and Reece, {Michael J.} and Robert Freer",
note = "{\textcopyright} 2019 Author(s).",
year = "2019",
month = sep,
day = "27",
doi = "10.1063/1.5119962",
language = "English",
volume = "126",
journal = "Journal of Applied Physics",
issn = "0021-8979",
publisher = "American Institute of Physics",
number = "12",

}

RIS (suitable for import to EndNote) - Download

TY - JOUR

T1 - The Structure and Thermoelectric Properties of Tungsten Bronze Ba6Ti2Nb8O30

AU - Jiang, Dongting

AU - Ekren, Dursun

AU - Azough, Feridoon

AU - Day, Sarah J.

AU - Chen, Kan

AU - Mahajan, Amit

AU - Kepaptsoglou, Demie M.

AU - Ramasse, Quentin M.

AU - Reece, Michael J.

AU - Freer, Robert

N1 - © 2019 Author(s).

PY - 2019/9/27

Y1 - 2019/9/27

N2 - Tungsten bronze structured materials have attracted attention as possible thermoelectrics because of their complex crystal structure. In this work, a new thermoelectric ceramic with tetragonal tungsten bronze (TB) structure, Ba6Ti2Nb8O30 (BTN) was prepared by the conventional mixed oxide (MO) route with some samples processed by Spark Plasma Sintering (SPS). Additions of MnO enabled fabrication of high density BTN ceramics at the low sintering temperature of 1580 K in air and by SPS. All samples were annealed in a reducing atmosphere after sintering. X-ray diffraction showed that Ba6Ti2Nb8O30 crystallises with tetragonal symmetry (P4bm space group). HAADF-EELS analysis confirmed the proposed crystal structure and provided exact elemental distributions in the lattice, showing higher concentrations of Ti in the 2b lattice sites compared to the 8d lattice sites. XPS showed the presence of two spin-orbit double peaks at 207.7eV in the reduced BTN samples, confirming the presence of Nb4+ ions. By the use of a sintering aid and optimisation of the processing parameters the ceramics achieved a high power factor of 280 μW/m∙K2 at 873 K. The BTN ceramics showed phonon glass type thermal conduction behaviour with low thermal conductivity of 1.7 to 1.65 W/m.K at 300 to 873 K. A thermoelectric figure of merit (ZT) of 0.14 was achieved at 873 K. This ZT value is comparable with results for many TB thermoelectrics. However, BTN has the advantage of much easier processing.

AB - Tungsten bronze structured materials have attracted attention as possible thermoelectrics because of their complex crystal structure. In this work, a new thermoelectric ceramic with tetragonal tungsten bronze (TB) structure, Ba6Ti2Nb8O30 (BTN) was prepared by the conventional mixed oxide (MO) route with some samples processed by Spark Plasma Sintering (SPS). Additions of MnO enabled fabrication of high density BTN ceramics at the low sintering temperature of 1580 K in air and by SPS. All samples were annealed in a reducing atmosphere after sintering. X-ray diffraction showed that Ba6Ti2Nb8O30 crystallises with tetragonal symmetry (P4bm space group). HAADF-EELS analysis confirmed the proposed crystal structure and provided exact elemental distributions in the lattice, showing higher concentrations of Ti in the 2b lattice sites compared to the 8d lattice sites. XPS showed the presence of two spin-orbit double peaks at 207.7eV in the reduced BTN samples, confirming the presence of Nb4+ ions. By the use of a sintering aid and optimisation of the processing parameters the ceramics achieved a high power factor of 280 μW/m∙K2 at 873 K. The BTN ceramics showed phonon glass type thermal conduction behaviour with low thermal conductivity of 1.7 to 1.65 W/m.K at 300 to 873 K. A thermoelectric figure of merit (ZT) of 0.14 was achieved at 873 K. This ZT value is comparable with results for many TB thermoelectrics. However, BTN has the advantage of much easier processing.

KW - Tungsten bronze, Ba6Ti2Nb8O30, thermoelectric, thermal conductivity, HAADF

U2 - 10.1063/1.5119962

DO - 10.1063/1.5119962

M3 - Article

VL - 126

JO - Journal of Applied Physics

JF - Journal of Applied Physics

SN - 0021-8979

IS - 12

ER -