Structural, electrical and electrochemical properties of calcium-doped lanthanum nickelate

Structural, electrical and electrochemical properties of calcium-doped lanthanum nickelate

The present work focuses on the structural, thermo-mechanical and electrical properties of La2–xCaxNiO4 + δ with different calcium content (x=0–0.4) and the electrochemical performance of the electrodes on their base in contact with a Ce0.8Sm0.2O1.9 electrolyte. It was shown that the introduction of...

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Bibliographic Details
Published in:Solid state ionics Vol. 288; pp. 48 - 53
Main Authors: Kolchugin, A.А., Pikalova, E.Yu, Bogdanovich, N.M., Bronin, D.I., Pikalov, S.M., Plaksin, S.V., Ananyev, M.V., Eremin, V.A.
Format: Journal Article
Language:English
Published: Elsevier B.V 01-05-2016
Subjects:
Ca-doping
Calcium
Cathode
Diffusion rate
Direct current
Electrochemical analysis
Electrodes
Exchange
Lanthanum Nickelate
Oxygen
Oxygen Isotope Exchange
Polarization Resistance
SOFC
Surface chemistry
Lanthanum Nickelate
Oxygen Isotope Exchange
Ca-doping
Cathode
SOFC
Polarization Resistance
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Summary:The present work focuses on the structural, thermo-mechanical and electrical properties of La2–xCaxNiO4 + δ with different calcium content (x=0–0.4) and the electrochemical performance of the electrodes on their base in contact with a Ce0.8Sm0.2O1.9 electrolyte. It was shown that the introduction of even a small amount of calcium (x=0.1) stabilized the crystal structure in the tetragonal syngony across the whole temperature range 25–800°C. Dilatometric study of the compact samples in the entire concentration range of Ca showed no phase transitions up to 800°C. The total electrical conductivity, measured by a dc four-probe technique, increased with an increase in calcium content. However, electrochemical activity of the La2–xCaxNiO4 + δ – based electrodes, contrarily, drastically decreased. The polarization resistance Rη, derived from the impedance spectroscopy data, increased from 0.18Ω·cm2 (x=0) to 1.24Ω·cm2 (x=0.3) at 800°C. The coefficients of oxygen surface exchange (k⁎) and oxygen tracer diffusion (D⁎) calculated from the oxygen isotope exchange data for La2NiO4+δ were considerably higher than those for La1.7Ca0.3NiO4+δ (4.54∙10−7cm∙s−1 and 3.02·10−8cm2∙s−1 (x=0); 2.91∙10−8cm∙s−1 and 5.82·10−10cm2∙s−1 (x=0.3) at 800°C, respectively). It was found that for La1.7Ca0.3NiO4+δ the rate-determining stage of oxygen surface exchange is incorporation of oxygen, while for La2NiO4+δ it is oxygen dissociative adsorption. •La2-xCaxNiO4+δ was synthesized by the solid state reaction method•The electrical conductivity increases with an increase in Ca content•The electrochemical activity of La2-xCaxNiO4+δ-based cathodes decreases•Oxygen surface exchange and tracer diffusion coefficients decreases with Ca content•Lanthanum nickelate doped and undoped by Ca show different rate-determing stages
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ISSN:0167-2738
1872-7689
DOI:10.1016/j.ssi.2016.01.035