abstract
Phase relationships in the BaFe1-x-yZryNixO3-delta system were evaluated in the search for Ba-rich electrode materials with potential application in solid electrolyte cells for electrochemical NOx reduction. Co -sub-stitutions by zirconium and nickel into the iron sublattice of barium ferrite stabilize the cubic perovskite structure with a solid solution formation range limited to (x + y) &0.3. Characterization of BaFe(0.7)Zr(0.3-x)NixO(3-delta) (x = 0.10-0.20) perovskites included the determination of oxygen nonstoichiometry variations by TGA, measurements of electrical conductivity as a function of temperature and oxygen partial pressure, studies of thermal expansion, and assessment of chemical compatibility with selected solid electrolytes. BaFe0.7Zr0.3-xNixO3-delta perovskites exhibit substantial oxygen losses from the lattice above 350 degrees C, reaching Delta delta similar to 0.2 on heating to 1000 degrees C in air, with effects on electrical properties and thermochemical expansion. Electrical conductivity is p-type under oxidizing conditions, increases with Ni content, and reaches 3.5 S/cm at 400 degrees C. The perovskite phase is stable down to p(O-2) similar to 10(-17) at 900 degrees C. The average thermal expansion coefficients in air increase from (15-18)x 10(-6) K-1 at lower temperatures to similar to 30 x 10(-6)K(-1) above 400 degrees C. The optimum co-doping level was found to be x = y = 0.15 as this composition exhibits the best chemical compatibility with yttria-stabilized zirconia and BaZr0.85Y0.15O3-delta solid electrolytes. (c) 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
keywords
OXYGEN PERMEATION PROPERTIES; DOPED BARIUM ZIRCONATE; NITRIC-OXIDE; TRANSPORT-PROPERTIES; CATALYTIC DECOMPOSITION; CHEMICAL EXPANSION; NOX-STORAGE; CONDUCTIVITY; PERMEABILITY; REDUCTION
subject category
Chemistry; Materials Science; Metallurgy & Metallurgical Engineering
authors
Zakharchuk, K; Kovalevsky, A; Yaremchenko, A
our authors
Aleksey Yaremchenko
Principal Researcher
Andrei Kavaleuski
Principal Researcher
Kiryl Zakharchuk
PhD StudentProjects
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
acknowledgements
This work was developed within the scope of the PhD project of Kiryl Zakharchuk (grant SFRH/BD/138773/2018 funded by the FCT) and the project CICECO-Aveiro Institute of Materials (UIDB/50011/2020, UIDP/50011/2020 & LA/P/0006/2020) financed by national funds through the FCT/MCTES (PIDDAC).