Chemically induced expansion of La(2)NiO(4+delta)-based materials
authors Kharton, VV; Kovalevsky, AV; Avdeev, M; Tsipis, EV; Patrakeev, MV; Yaremchenko, AA; Naumovich, EN; Frade, JR
nationality International
journal CHEMISTRY OF MATERIALS
keywords OXYGEN-ION CONDUCTORS; FORMER SOVIET-UNION; THERMAL-EXPANSION; TRANSPORT-PROPERTIES; CERAMICS; OXIDES; DIFFRACTION; BEHAVIOR; METHANE; ELECTROCHEMISTRY
abstract The equilibrium chemical strains induced by the oxygen hyperstoichiometry variations in mixed-conducting La(2)Ni(1-x)M(x)O(4+delta) (M = Fe, Co, Cu; x = 0-0.2) with K(2)NiF(4)-type structure, were studied by controlled-atmosphere dilatometry at 923-1223 K in the oxygen partial pressure range 5 x 10(-4) to 0.7 atm. In combination with the oxygen content measured by coulometric titration and thermogravimetry, the results reveal a very low chemical expansivity, favorable for high-temperature electrochemical applications. Under oxidizing conditions, the isothermal expansion relative to atmospheric oxygen pressure (epsilon(C)) is less than 0.02%. The ratio between these values and the corresponding nonstoichiometry increment varies from -3 x 10(-3) to 6 x 10(-3), which is much lower compared to most permeable mixed conductors derived from perovskite-like cobaltites and ferrites. Consequently, the chemical contribution to apparent thermal expansion coefficients at a fixed oxygen pressure, (13.7-15.1) x 10(-6) K(-1), does not exceed 5%. The high-temperature X-ray diffraction studies showed that this behavior results from strongly anisotropic expansion of the K(2)NiF(4)-type lattice, namely the opposing variations of the unit-cell parameters on changing oxygen stoichiometry.
publisher AMER CHEMICAL SOC
issn 0897-4756
year published 2007
volume 19
issue 8
beginning page 2027
ending page 2033
digital object identifier (doi) 10.1021/cm070096x
web of science category Chemistry, Physical; Materials Science, Multidisciplinary
subject category Chemistry; Materials Science
unique article identifier WOS:000245549500023
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journal impact factor 9.567
5 year journal impact factor 10.102
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