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Title: Material properties of perovskites in the quasi-ternary system LaFeO3–LaCoO3–LaNiO3

We present an overview on the variation of electrical conductivity, oxygen permeation, oxygen surface exchange and thermal expansion coefficient as a function of the composition of perovskites in the quasi-ternary system LaFeO3–LaCoO3–LaNiO3. Powders of thirteen nominal perovskite compositions were synthesized under identical conditions by the Pechini method. The powder X-ray diffraction data of two series, namely La(Ni0.5Fe0.5)1-xCoxO3 and LaNi0.5- xFexCo0.5O3, are presented after the powders had been sintered at 1100 C for 6 h in air. The measurements revealed a rhombohedral structure for all compositions except LaNi0.5Fe0.5O3 for which 60% rhombohedral and 40% orthorhombic phase was found. Moreover, the maximum DC electrical conductivity value of the perovskites at 800 C was 1229 S cm-1 for the composition LaCoO3 and the minimum was 91 S cm-1 for the composition LaCo0.5Fe0.5O3. The oxygen permeation of samples with promising conductivities at 800 C was one order of magnitude lower than that of La0.6Sr0.4Co0.8Fe0.2O3 (LSCF). The highest value of 0.017 ml cm-2 min-1 at 950 C was obtained with LaNi0.5Co0.5O3. The coefficients of thermal expansion varied in the range of 13.2 x 10-6 K-1 and 21.9 x 10-6 K-1 for LaNi0.5Fe0.5O3 and LaCoO3, respectively. 57Fe M ssbauer spectroscopy was used as probe for themore » oxidation states, local environment and magnetic properties of iron ions as a function of chemical composition. Ultimately, the substitution had a great influence on the chemical properties of the materials.« less
 [1] ;  [2] ;  [1] ;  [1] ;  [1] ;  [3]
  1. Julich Research Centre (Germany)
  2. Central Electrochemical Research Inst., Tamil Nadu (India)
  3. Julich Research Centre (Germany); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
OSTI Identifier:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Journal of Solid State Chemistry
Additional Journal Information:
Journal Volume: 237; Journal Issue: C; Journal ID: ISSN 0022-4596
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
36 MATERIALS SCIENCE Perovskites; Electrical conductivity; Thermal expansion; Oxygen permeation; Mossbauer spectroscopy