Tailoring the structural, thermal and transport properties of Pr2NiO4+δ through Ca-doping strategy

Materials with a layered Ruddlesden–Popper structure having high oxygen mobility are promising for SOFC cathodes and oxygen separation membranes. This work aims at studying structural and transport features of Pr2-xCaxNiO4+δ (x = 0–0.6) oxides synthesized by a modified co-precipitation method and si...

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Bibliographic Details
Published in:Solid state ionics 2019-05, Vol.333, p.30-37
Main Authors: Sadykov, V.A., Pikalova, E.Yu, Vinokurov, Z.S., Shmakov, A.N., Eremeev, N.F., Sadovskaya, E.M., Lyagaeva, J.G., Medvedev, D.A., Belyaev, V.D.
Format: Article
Language:English
Subjects:
Calcium
Conductivity
Doping
Electrodes
in situ synchrotron XRD
Ion currents
Ionic conductivity
Mechanical properties
Oxygen
Phase transitions
Pr2-xCaxNiO4
Solid oxide fuel cells
Synchrotron radiation
Thermal expansion coefficient
Thermomechanical properties
Transport properties
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Summary:Materials with a layered Ruddlesden–Popper structure having high oxygen mobility are promising for SOFC cathodes and oxygen separation membranes. This work aims at studying structural and transport features of Pr2-xCaxNiO4+δ (x = 0–0.6) oxides synthesized by a modified co-precipitation method and sintered at 1250 °C. The samples were characterized by in situ XRD using synchrotron radiation, TGA, oxygen heteroexchange with C18O2 and dc four-probe method. The phase transitions Fmmm ↔ I4/mmm were observed for all samples caused both by the temperature increase and oxygen loss. The electronic conductivity increases with Ca doping, while ionic conductivity varies in a complex manner remaining rather high (~10−3–10−1 S/cm), thus ensuring high values of ambipolar conductivity attractive for the practical application. The best ambipolar conductivity values at high temperatures were demonstrated for the undoped sample as well as for those with a low (x = 0.1) or high (x = 0.3; 0.5) dopant content. The relationships between structural, thermomechanical and transport properties are discussed. •Structure evolution of Pr2-xCaxNiO4 depending on temperature and media was studied.•Fmmm – I4/mmm phase transition was revealed for some samples.•Intermediate thermal expansion coefficient values were demonstrated.•Electrical conductivity tends to increase with Ca content.•Despite of non-monotonous variation with Ca content, ionic conductivity remains rather high.
ISSN:0167-2738
1872-7689
DOI:10.1016/j.ssi.2019.01.014