Vv. Kharton et al., Mixed electronic and ionic conductivity of LaCo(M)O-3 (M = Ga, Cr, Fe or Ni) IV. Effect of preparation method on oxygen transport in LaCoO3-delta, SOL ST ION, 138(1-2), 2000, pp. 135-148
Measurements of oxygen permeation through dense LaCoO3-delta membranes prep
ared by different routes (standard ceramic or from organic precursors) show
ed a considerable role of processing conditions and microstructure on perme
ation fluxes. The higher permeability observed in ceramics produced by the
ceramic route was attributed to a lower grain-boundary resistance to oxygen
transport. Experimental data were also compared with results of numerical
modeling of oxygen transport in LaCoO3-delta based on isotopic diffusion da
ta in single crystals. Ionic conduction in ceramics with smaller grain size
is lower than in single crystals, suggesting a significant grain boundary
resistance. In contrast, oxygen permeability of LaCoO3-delta prepared by th
e standard ceramic synthesis route, involving higher sintering temperatures
is higher than expected. This suggests easy diffusion along grain boundari
es. The influence of the ceramic microstructure on total electrical conduct
ivity and thermal expansion of lanthanum cobaltite ceramics was found negli
gible. (C) 2000 Elsevier Science B.V. All rights reserved.