Thermochemistry of La{sub 0.7}Sr{sub 0.3}Mn{sub 1-x}Fe{sub x}O{sub 3} solid solutions (0<x<1)

Journal Article · Mon Aug 15 00:00:00 EDT 2011 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2011.05.039· OSTI ID:21580228

Kemik, Nihan ^[1]; Takamura, Yayoi ^[1]; Navrotsky, Alexandra ^[1]

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1. Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616 (United States)

The structure, the energetics and the internal redox reactions of La{sub 0.7}Sr{sub 0.3}Fe{sub x}Mn{sub 1-x}O{sub 3} have been studied in the complete solid solution range 0.0<x<1.0. High temperature oxide melt drop solution calorimetry was performed to determine the enthalpies of formation from binary oxides and the enthalpy of mixing. There is a noticeable change in the energetics of the solid solution near x=0.7, which is due to the growing concentration of Fe{sup 4+} at higher Fe/(Fe+Mn) ratio. The balance between different valences of the transition metals, Mn and Fe, is the main factor in determining the energetics of the La{sub 0.70}Sr{sub 0.30}Fe{sub x}Mn{sub 1-x}O{sub 3} solid solution. - Graphical abstract: Enthalpy of mixing ({Delta}H{sub mix}) of La{sub 0.7}Sr{sub 0.3}Mn{sub 1-x}Fe{sub x}O{sub 3-{gamma}} solid solution at room temperature as a function of Fe/(Fe+Mn) ratio, x. Linear fits for the two regions at low and high x are shown as solid lines. The inset shows the content of Mn{sup 3+}, Mn{sup 4+}, Fe{sup 3+} and Fe{sup 4+} as a function of x based on the work by Jonker. The redox reactions between different valence states of Fe and Mn dominate the energetic behavior of the solid solution. Highlights: > Investigated the structure, the energetics and the internal redox reactions of La{sub 0.7}Sr{sub 0.3}Mn{sub 1-x}Fe{sub x}O{sub 3}. > Determined the formation and mixing enthalpy by high temperature oxide melt solution calorimetry. > Symmetry of the perovskite, transition metal valence and energetics are interdependent. > Thermochemical data shows convincing evidence of the interplay between the Mn{sup 4+} and the Fe{sup 4+} ions. > Balance between different valences of Mn and Fe dominates the energetics of La{sub 0.7}Sr{sub 0.3}Fe{sub x}Mn{sub 1-x}O{sub 3}.

• OSTI ID: 21580228
• Journal Information: Journal of Solid State Chemistry, Vol. 184, Issue 8; Other Information: DOI: 10.1016/j.jssc.2011.05.039; PII: S0022-4596(11)00288-X; Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
FORMATION HEAT
IRON IONS
MANGANESE IONS
MIXING HEAT
OXIDES
PEROVSKITE
REDOX REACTIONS
SOLID SOLUTIONS
SOLIDS
TEMPERATURE RANGE 0400-1000 K
THERMODYNAMICS
TRANSITION ELEMENTS
CHALCOGENIDES
CHARGED PARTICLES
CHEMICAL REACTIONS
DISPERSIONS
ELEMENTS
ENTHALPY
HOMOGENEOUS MIXTURES
IONS
METALS
MINERALS
MIXTURES
OXIDE MINERALS
OXYGEN COMPOUNDS
PEROVSKITES
PHYSICAL PROPERTIES
REACTION HEAT
SOLUTIONS
TEMPERATURE RANGE
THERMODYNAMIC PROPERTIES