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Title: Chemically induced expansion of La2NiO4+ δ-based materials
Authors: Kharton, VV
Kovalevsky, AV
Avdeev, M
Tsipis, EV
Patrakeev, MV
Yaremchenko, AA
Naumovich, EN
Frade, JR
Keywords: Oxides
Thermal gravimetric analysis
Thermal expansion
Issue Date: 21-Mar-2007
Publisher: American Chemical Society
Citation: Kharton, V. V., Kovalevsky, A. V., Avdeev, M., Tsipis, E. V., Patrakeev, M. V., Yaremchenko, A. A., Naumovich, E. N., & Frade, J. R. (2007). Chemically induced expansion of La2NiO4+ δ-based materials. Chemistry of Materials 19, 8, 2027–2033. doi:10.1021/cm070096x
Abstract: The equilibrium chemical strains induced by the oxygen hyperstoichiometry variations in mixed-conducting La2Ni1-xMxO4+δ (M = Fe, Co, Cu; x = 0−0.2) with K2NiF4-type structure, were studied by controlled-atmosphere dilatometry at 923−1223 K in the oxygen partial pressure range 5 × 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 (εC) is less than 0.02%. The ratio between these values and the corresponding nonstoichiometry increment varies from −3 × 10-3 to 6 × 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) × 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 K2NiF4-type lattice, namely the opposing variations of the unit-cell parameters on changing oxygen stoichiometry. © 2007, American Chemical Society
ISSN: 1520-5002
Appears in Collections:Journal Articles

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