Crystal structure and thermoelectric properties of Sr-Mo substituted CaMnO3

A combined experimental and computational study

D. Srivastava, Feridoon Azough, Robert Freer, E. Combe, R. Funahashi, D. M. Kepaptsoglou, Quentin Mathieu Ramasse, M. Molinari, Stephen R. Yeandel, Jakub D. Baran, Stephen C. Parker

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

A combination of experimental and computational techniques has been employed to study doping effects in perovskite CaMnO3. High quality Sr-Mo co-substituted CaMnO3 ceramics were prepared by the conventional mixed oxide route. Crystallographic data from X-ray and electron diffraction showed an orthorhombic to tetragonal symmetry change on increasing the Sr content, suggesting that Sr widens the transition temperature in CaMnO3 preventing phase transformation-cracking on cooling after sintering, enabling the fabrication of high density ceramics. Atomically resolved imaging and analysis showed a random distribution of Sr in the A-site of the perovskite structure and revealed a boundary structure of 90° rotational twin boundaries across {101}orthorhombic; the latter are predominant phonon scattering sources to lower the thermal conductivity as suggested by molecular dynamics calculations. The effect of doping on the thermoelectric properties was evaluated. Increasing Sr substitution reduces the Seebeck coefficient but the power factor remains high due to improved densification by Sr substitution. Mo doping generates additional charge carriers due to the presence of Mn3+ in the Mn4+ matrix, reducing electrical resistivity. The major impact of Sr on thermoelectric behaviour is the reduction of the thermal conductivity as shown experimentally and by modelling. Strontium containing ceramics showed thermoelectric figure of merit (ZT) values higher than 0.1 at temperatures above 850 K. Ca0.7Sr0.3Mn0.96Mo0.04O3 ceramics exhibit enhanced properties with S1000K = -180 μV K-1, ρ1000K = 5 × 10-5 Ωm, k1000K = 1.8 W m-1 K-1 and ZT ≈ 0.11 at 1000 K.

Original languageEnglish
Pages (from-to)12245-12259
Number of pages15
JournalJournal of Materials Chemistry C
Volume3
Issue number47
DOIs
Publication statusPublished - 30 Oct 2015
Externally publishedYes

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Crystal structure
Doping (additives)
Perovskite
Thermal conductivity
Substitution reactions
Strontium
Phonon scattering
Seebeck coefficient
Charge carriers
Densification
Electron diffraction
Oxides
Superconducting transition temperature
Molecular dynamics
Sintering
Phase transitions
Cooling
Imaging techniques
Fabrication
X ray diffraction

Cite this

Srivastava, D., Azough, F., Freer, R., Combe, E., Funahashi, R., Kepaptsoglou, D. M., ... Parker, S. C. (2015). Crystal structure and thermoelectric properties of Sr-Mo substituted CaMnO3: A combined experimental and computational study. Journal of Materials Chemistry C, 3(47), 12245-12259. https://doi.org/10.1039/c5tc02318a
Srivastava, D. ; Azough, Feridoon ; Freer, Robert ; Combe, E. ; Funahashi, R. ; Kepaptsoglou, D. M. ; Ramasse, Quentin Mathieu ; Molinari, M. ; Yeandel, Stephen R. ; Baran, Jakub D. ; Parker, Stephen C. / Crystal structure and thermoelectric properties of Sr-Mo substituted CaMnO3 : A combined experimental and computational study. In: Journal of Materials Chemistry C. 2015 ; Vol. 3, No. 47. pp. 12245-12259.
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Srivastava, D, Azough, F, Freer, R, Combe, E, Funahashi, R, Kepaptsoglou, DM, Ramasse, QM, Molinari, M, Yeandel, SR, Baran, JD & Parker, SC 2015, 'Crystal structure and thermoelectric properties of Sr-Mo substituted CaMnO3: A combined experimental and computational study', Journal of Materials Chemistry C, vol. 3, no. 47, pp. 12245-12259. https://doi.org/10.1039/c5tc02318a

Crystal structure and thermoelectric properties of Sr-Mo substituted CaMnO3 : A combined experimental and computational study. / Srivastava, D.; Azough, Feridoon; Freer, Robert; Combe, E.; Funahashi, R.; Kepaptsoglou, D. M.; Ramasse, Quentin Mathieu; Molinari, M.; Yeandel, Stephen R.; Baran, Jakub D.; Parker, Stephen C.

In: Journal of Materials Chemistry C, Vol. 3, No. 47, 30.10.2015, p. 12245-12259.

Research output: Contribution to journalArticle

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T1 - Crystal structure and thermoelectric properties of Sr-Mo substituted CaMnO3

T2 - A combined experimental and computational study

AU - Srivastava, D.

AU - Azough, Feridoon

AU - Freer, Robert

AU - Combe, E.

AU - Funahashi, R.

AU - Kepaptsoglou, D. M.

AU - Ramasse, Quentin Mathieu

AU - Molinari, M.

AU - Yeandel, Stephen R.

AU - Baran, Jakub D.

AU - Parker, Stephen C.

PY - 2015/10/30

Y1 - 2015/10/30

N2 - A combination of experimental and computational techniques has been employed to study doping effects in perovskite CaMnO3. High quality Sr-Mo co-substituted CaMnO3 ceramics were prepared by the conventional mixed oxide route. Crystallographic data from X-ray and electron diffraction showed an orthorhombic to tetragonal symmetry change on increasing the Sr content, suggesting that Sr widens the transition temperature in CaMnO3 preventing phase transformation-cracking on cooling after sintering, enabling the fabrication of high density ceramics. Atomically resolved imaging and analysis showed a random distribution of Sr in the A-site of the perovskite structure and revealed a boundary structure of 90° rotational twin boundaries across {101}orthorhombic; the latter are predominant phonon scattering sources to lower the thermal conductivity as suggested by molecular dynamics calculations. The effect of doping on the thermoelectric properties was evaluated. Increasing Sr substitution reduces the Seebeck coefficient but the power factor remains high due to improved densification by Sr substitution. Mo doping generates additional charge carriers due to the presence of Mn3+ in the Mn4+ matrix, reducing electrical resistivity. The major impact of Sr on thermoelectric behaviour is the reduction of the thermal conductivity as shown experimentally and by modelling. Strontium containing ceramics showed thermoelectric figure of merit (ZT) values higher than 0.1 at temperatures above 850 K. Ca0.7Sr0.3Mn0.96Mo0.04O3 ceramics exhibit enhanced properties with S1000K = -180 μV K-1, ρ1000K = 5 × 10-5 Ωm, k1000K = 1.8 W m-1 K-1 and ZT ≈ 0.11 at 1000 K.

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