This title appears in the Scientific Report : 2016 

Material properties of perovskites in the quasi-ternary system LaFeO$_{3}$–LaCoO$_{3}$–LaNiO$_{3}
Tietz, F. (Corresponding author)
Arul Raj, I. / Ma, Q. / Baumann, S. / Mahmoud, A. / Hermann, Raphael
Streumethoden; JCNS-2
Werkstoffsynthese und Herstellungsverfahren; IEK-1
Streumethoden; PGI-4
Journal of solid state chemistry, 237 (2016) S. 183 - 191
Orlando, Fla. Academic Press 2016
Journal Article
Jülich Centre for Neutron Research (JCNS)
Materials and Processes for Energy and Transport Technologies
Quantum Condensed Matter: Magnetism, Superconductivity
Controlling Collective States
Controlling Collective States
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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 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. 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 13.2×10−6 K−1 and 21.9×10−6 K−1 for LaNi0.5Fe0.5O3 and LaCoO3, respectively. 57Fe 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.