Material properties of perovskites in the quasi-ternary system LaFeO{sub 3}–LaCoO{sub 3}–LaNiO{sub 3}
- Central Electrochemical Research Institute, Karaikudi 630 006, Tamil Nadu (India)
- Forschungszentrum Jülich GmbH, Institute of Energy and Climate Research, Materials Synthesis and Processing (IEK-1), D-52425 Jülich (Germany)
- Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science JCNS and Peter Grünberg Institute PGI, JARA-FIT, D-52425 Jülich Germany (Germany)
An overview is presented on the variation of electrical conductivity, oxygen permeation, and thermal expansion coefficient as a function of the composition of perovskites in the quasi-ternary system LaFeO{sub 3}–LaCoO{sub 3}–LaNiO{sub 3}. 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(Ni{sub 0.5}Fe{sub 0.5}){sub 1−x}Co{sub x}O{sub 3} and LaNi{sub 0.5-x}Fe{sub x}Co{sub 0.5}O{sub 3}, 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 LaNi{sub 0.5}Fe{sub 0.5}O{sub 3} for which 60% rhombohedral and 40% orthorhombic phase was found. The maximum DC electrical conductivity value of the perovskites at 800 °C was 1229 S cm{sup −1} for the composition LaCoO{sub 3} and the minimum was 91 S cm{sup −1} for the composition LaCo{sub 0.5}Fe{sub 0.5}O{sub 3}. The oxygen permeation of samples with promising conductivities at 800 °C was one order of magnitude lower than that of La{sub 0.6}Sr{sub 0.4}Co{sub 0.8}Fe{sub 0.2}O{sub 3} (LSCF). The highest value of 0.017 ml cm{sup −2} min{sup −1} at 950 °C was obtained with LaNi{sub 0.5}Co{sub 0.5}O{sub 3}. The coefficients of thermal expansion varied in the range of 13.2×10{sup −6} K{sup −1} and 21.9×10{sup −6} K{sup −1} for LaNi{sub 0.5}Fe{sub 0.5}O{sub 3} and LaCoO{sub 3}, respectively. {sup 57}Fe Mössbauer spectroscopy was used as probe for the oxidation states, local environment and magnetic properties of iron ions as a function of chemical composition. The substitution had a great influence on the chemical properties of the materials. - Graphical abstract: Compositional dependence of isothermal electrical conductivity at 800 °C and thermal expansion coefficient in the series La(Fe{sub 0.5}Ni{sub 0.5}){sub (1−x)}Co{sub x}O{sub 3} and LaNi{sub 0.5−x}Fe{sub x}Co{sub 0.5}O{sub 3}.
- OSTI ID:
- 22584070
- Journal Information:
- Journal of Solid State Chemistry, Vol. 237; Other Information: Copyright (c) 2016 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
Similar Records
Crystal structure, microstructure and reducibility of LaNi{sub x}Co{sub 1-x}O{sub 3} and LaFe{sub x}Co{sub 1-x}O{sub 3} Perovskites (0<x<=0.5)
Electrical conductivity and seebeck coefficient of nonstoichiometric La sub 1 minus x Sr sub x CoO sub 3 minus. delta