Phase equilibrium and electrical conductivity of SrCo0.8Fe0.2O3−δ

Grunbaum, Nicolás; Mogni, L.; Prado, F.; Caneiro, A.

doi:10.1016/j.jssc.2004.03.026

Cited by 81 publications

(85 citation statements)

References 26 publications

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“…At 9 GPa all features of the XANES spectrum are similar to those of the spectra at 13 GPa. Such hysteresis suggests the occurrence of a mixture of phases with close compositions and related structures 27 . The hysteresis results in this case from the non-negligible elastic strain energy of coherent or semi-coherent interfaces that must be taken into account to describe the to- involve several coupled Mn atoms 28 .…”

Section: Ab Initio Xanes Calculationsmentioning

confidence: 99%

Stability of Jahn-Teller distortion inLaMnO3under pressure: An x-ray absorption study

et al. 2007

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The local environment of manganese atoms in LaMnO3 under pressure up to 15.3 GPa has been studied by x-ray absorption spectroscopy. For pressures below 8 GPa, no change is detected within the MnO6 octahedra. Above this pressure a continuous reduction of the long Mn-O distance takes place, however the octahedral distortion persists over the whole pressure range. At 15.3 GPa the average Jahn-Teller splitting of the distances is reduced by about one third, indicating that a total removal of the local Jahn-Teller distortion would occur only for pressures around 30 GPa, where metallization is reported to take place. A hysteresis in the long distance reduction is observed down to ambient pressure, suggesting the coexistence of MnO6 distorted and undistorted units. The physics underlining the remarkable properties of the manganite LaMnO 3 and its doped alloys is rich and complex. The actual path followed by a given system towards ferromagnetism and/or metallization, through chemical substitution, thermal treatment or pressure involves modifications of a delicate balance between delocalization and carriers trapping not yet completely understood. In the ground state LaMnO 3 is an antiferromagnetic semiconductor crystallizing in an orthorhombic variant of the cubic perovskite structure space group P bnm. The MnO 6 octahedra are distorted due to the Jahn-Teller (JT ) effect of the Mn) and the M n − O distances are split into 4 short bonds and 2 long bonds. In the basal ab plane long and short M n − O bonds alternates. The apical and basal short bonds have different length, however this additional distortion is not resolved by local probes such as real space high resolution diffraction and x-ray absorption spectroscopy. The local radial distribution actually seen by these probes corresponds then to the JT splitting, with 4 oxygensat short distances (M n − O) s ≈ 1.94Å and 2 oxygens at the long distance (M n − O) l ≈ 2.15Å. LaMnO 3 undergoes a transition at T * ≈ 710-750 K from the JT distorted orthorhombic phase O to a high temperature nearly cubic O' phase 1 . The transition is accompanied by abrupt changes in the electrical resistivity and Weiss constant 2 . The cell distortion is nearly removed and the orbital ordering disappears in the O' phase, but the JT distortion of MnO 6 octahedra persists at the local scale 3,4,5 . The transition then happens as an order-disorder transition, in agreement with the thermodynamic calculations 6 . More recently Qiu and co-workers 7 reported on neutron powder diffraction measurements showing that the JT distortion of MnO 6 octahedra is maintained also in the high temperature rhomboedral phase (T ≥ 1010 K) and suggested the presence of ordered clusters with strong antiferrodistorsive coupling.New insights for the role of the JT distortion can be obtained by the exploration of its pressure dependence. In LaMnO 3 , the application of an external hydrostatic pressure produces a reduction of the lattice distortions and an enhancement of the carrier mobility 8,9 . The M n − O − M n angle -ti...

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Section: Ab Initio Xanes Calculationsmentioning

confidence: 99%

Stability of Jahn-Teller distortion inLaMnO3under pressure: An x-ray absorption study

et al. 2007

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“…The oxygen nonstoichiometry and phase stability of SrCo 1−x Fe x O 3−δ have been studied by a number of groups [42−46], focusing on the composition SrCo 0.8 Fe 0.2 O 3−δ . Liu et al [43] studied the temperature range of 823 − 1263 K and PO 2 = 0.015 − 1 bar using TG and XRD, while Grunbaum et al [44] …”

Section: Srco 1−x Fe X O 3−δmentioning

confidence: 99%

Thermodynamic modeling of the Sr–Co–Fe–O system

et al. 2016

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This paper reviews and assesses phase equilibria and thermodynamic properties of phases in the Sr-Co-Fe-O system, with a focus on oxides, especially the SrCo 1−x Fe x O 3−δ perovskite. In our work, the SrCo 1−x Fe x O 3−δ perovskite was modeled with a three-sublattice model, where the three sublattices correspond to the A, B and oxygen sites in an ABO 3 perovskite, respectively. A number of other important ternary oxide phases in Sr-Co-O and Sr-Co-Fe-O were also considered. Available thermodynamic and phase diagram data were carefully assessed. A thermodynamic description of Sr-Co-O was derived using the CALPHAD approach and was further extrapolated to that of Sr-Co-Fe-O. The thermodynamic database of Sr-Co-Fe-O established in this work allows for calculating phase diagrams, thermodynamic properties, cation distribution and defect chemistry properties, and therefore enables material composition optimization for various applications, including solid oxide fuel cells and oxygen membranes.

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“…Due to the high oxygen permeability of SrCo 0.8 Fe 0.2 O 3)d membrane, its phase structure and stability in reducing environments were extensively investigated [7,9,35,36]. For SrCo 0.8 Fe 0.2 O 3)d membrane material, the perovskite phase is thermodynamically stable only at higher oxygen partial pressure (>0.1 atm) and high temperatures (>790°C) [17].…”

Section: Development Of Miec Membrane Materialsmentioning

confidence: 99%

Development and Application of Oxygen Permeable Membrane in Selective Oxidation of Light Alkanes

et al. 2005

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In this paper, oxygen permeable membrane used in membrane reactor for selective oxidation of alkanes will be discussed in detail. The recent developments for the membrane materials will be presented, and the strategy for the selection of the membrane materials will be outlined. The main applications of oxygen permeable membrane in selective oxidation of light alkanes will be summarized, which includes partial oxidation of methane (POM) to syngas and partial oxidation of heptane (POH) to produce H 2 , oxidative coupling of methane (OCM) to C 2 , oxidative dehydrogenation of ethane (ODE) to ethylene and oxidative dehydrogenation of propane (ODP) to propylene. Achievements for the membrane material developments and selective oxidation of light alkanes in membrane reactor in our group are highlighted.

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Phase equilibrium and electrical conductivity of SrCo0.8Fe0.2O3−δ

Cited by 81 publications

References 26 publications

Stability of Jahn-Teller distortion inLaMnO3under pressure: An x-ray absorption study

Stability of Jahn-Teller distortion inLaMnO3under pressure: An x-ray absorption study

Thermodynamic modeling of the Sr–Co–Fe–O system

Development and Application of Oxygen Permeable Membrane in Selective Oxidation of Light Alkanes

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