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Open AccessArticle

Suitability of Sm3+-Substituted SrTiO3 as Anode Materials for Solid Oxide Fuel Cells: A Correlation between Structural and Electrical Properties

1
Department of Physics, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005, India
2
Department of Chemical Engineering, Indian Institute of Technology, Kanpur 208016, India
3
Department of Physics, A.R.S.D. College, University of Delhi, Dhaula Kuan, New Delhi 110021, India
4
CNR-ICMATE, c/o DICCA-UNIGE, Via all’Opera Pia 15, 16145 Genova, Italy
5
DICCA-UNIGE, Via all’Opera Pia 15, 16145 Genova, Italy
*
Author to whom correspondence should be addressed.
Energies 2019, 12(21), 4042; https://doi.org/10.3390/en12214042
Received: 26 September 2019 / Revised: 21 October 2019 / Accepted: 22 October 2019 / Published: 24 October 2019
(This article belongs to the Special Issue Advanced Materials and Technologies for Fuel Cells)
Perovskite anodes, nowadays, are used in any solid oxide fuel cell (SOFC) instead of conventional nickel/yttria-stabilized zirconia (Ni/YSZ) anodes due to their better redox and electrochemical stability. A few compositions of samarium-substituted strontium titanate perovskite, SmxSr1−xTiO3−δ (x = 0.00, 0.05, 0.10, 0.15, and 0.20), were synthesized via the citrate-nitrate auto-combustion route. The XRD patterns of these compositions confirm that the solid solubility limit of Sm in SrTiO3 is x < 0.15. The X-ray Rietveld refinement for all samples indicated the perovskite cubic structure with a P m 3 ¯ m space group at room temperature. The EDX mapping of the field emission scanning electron microscope (FESEM) micrographs of all compositions depicted a lower oxygen content in the specimens respect to the nominal value. This lower oxygen content in the samples were also confirmed via XPS study. The grain sizes of SmxSr1−xTiO3 samples were found to increase up to x = 0.10 and it decreases for the composition with x > 0.10. The AC conductivity spectra were fitted by Jonscher’s power law in the temperature range of 500–700 °C and scaled with the help of the Ghosh and Summerfield scaling model taking νH and σdc T as the scaling parameters. The scaling behaviour of the samples showed that the conduction mechanism depends on temperature at higher frequencies. Further, a study of the conduction mechanism unveiled that small polaron hopping occurred with the formation of electrons. The electrical conductivity, in the H2 atmosphere, of the Sm0.10Sr0.90TiO3 sample was found to be 2.7 × 10−1 S∙cm−1 at 650 °C, which is the highest among the other compositions. Hence, the composition Sm0.10Sr0.90TiO3 can be considered as a promising material for the application as the anode in SOFCs. View Full-Text
Keywords: solid oxide fuel cells (SOFCs); ionic conductivity; Raman spectroscopy; powder X-ray diffraction solid oxide fuel cells (SOFCs); ionic conductivity; Raman spectroscopy; powder X-ray diffraction
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Singh, S.; Pandey, R.; Presto, S.; Carpanese, M.P.; Barbucci, A.; Viviani, M.; Singh, P. Suitability of Sm3+-Substituted SrTiO3 as Anode Materials for Solid Oxide Fuel Cells: A Correlation between Structural and Electrical Properties. Energies 2019, 12, 4042.

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