Processing, microstructure and properties of LaCoO3-δ ceramics

• Published in: Journal of the European Ceramic Society 2001-11, Vol.21 (13), p.2301-2309
• Main Authors: KHARTON, V. V, FIGUEIREDO, F. M, KOVALEVSKY, A. V, VISKUP, A. P, NAUMOVICH, E. N, YAREMCHENKO, A. A, BASHMAKOV, I. A, MARQUES, F. M. B
• Format: Article
• Language: English
• Subjects: Applied sciences; Building materials. Ceramics. Glasses; Ceramic industries; Chemical industry and chemicals; Exact sciences and technology; Miscellaneous; Technical ceramics
• ISSN: 0955-2219; 1873-619X
• DOI: 10.1016/S0955-2219(01)00199-6

Dense lanthanum cobaltite ceramics with different microstructures were prepared using several procedures, including chemical and ceramic synthesis routes. XRD, SEM, dilatometry, total electrical conductivity and oxygen permeability measurements were used for their characterisation. Submicron size LaCoO3-delta powders obtained via a cellulose-precursor technique or a combustion synthesis process showed much higher sinterability and poor compactability with respect to the powder prepared by the standard ceramic procedure. The influence of the processing route on crystal lattice, electronic conductivity and thermal expansion of LaCoO3-delta ceramics was negligible. The preparation technique significantly affects the ceramic microstructure and the oxygen ionic conductivity. LaCoO3-delta membranes prepared via the standard ceramic technique, involving higher sintering temperatures, exhibit significantly higher oxygen permeation fluxes than ceramics prepared from organic precursors. This behaviour was attributed to the effect of grain-boundary resistivity to ionic transport, which decreases with increasing temperature and grain size, as commonly found for oxide solid electrolytes. 35 refs.