Oxygen Diffusion in, and Thermal Expansionof, SrTiO&lt;sub&gt;3-δ&lt;/sub&gt;- and CaTiO&lt;sub&gt;3-δ&lt;/sub&gt;-Based Materials

Хартон, В.В.; Figueiredo, Filipe M.; Kovalevsky, Andrei V.; Viskup, A.P.; Naumovich, E.N.; Jurado, J. R.; Frade, J.R.

doi:10.4028/www.scientific.net/ddf.186-187.119

Cited by 30 publications

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“…The characterization of CaAl 0.5 Fe 0.5 O 2.5 ceramics included also scanning electron microscopy combined with energy dispersive spectroscopy (SEM/EDS), dilatometry, differential thermal and thermogravimetric analysis (DTA/TGA), and the measurements of total conductivity (four-probe DC) and steady-state oxygen permeability. The experimental procedures and equipment used for the characterization were reported elsewhere ( [6,[8][9][10][14][15][16] and references cited). All data on the oxygen permeation presented in this paper correspond to the membrane feed-side oxygen partial pressure (p 2 ) of 21 kPa (atmospheric air); the permeate-side oxygen pressure (p 1 ) varied from 0.8 to 20 kPa.…”

Section: Methodsmentioning

confidence: 99%

“…A high level of oxygen ionic conductivity is characteristic of perovskite-type ferrites derived from AFeO 3Àd , where A corresponds to the alkaline earth cations [1,[4][5][6]. However, these phases exhibit a number of specific disadvantages, including thermodynamic and/or dimensional instability under high oxygen chemical potential gradients, very high thermal expansion coefficients (TECs), and reactivity with carbon dioxide and water vapor.…”

Section: Introductionmentioning

confidence: 99%

“…These vacancies were assumed to significantly contribute to ionic transport, forming one-dimensional diffusion pathway for oxygen ion migration in the tetrahedral layers [12,13]. On the contrary, experimental data on partially ordered ferrites [6,11,14] suggest that oxygen-vacancy ordering leads to decreasing ionic conduction. Studying of the ionic transport in brownmillerite-type compounds may therefore provide a better understanding of oxygen diffusion processes in ferrite phases.…”

Section: Introductionmentioning

confidence: 99%

“…Studying of the ionic transport in brownmillerite-type compounds may therefore provide a better understanding of oxygen diffusion processes in ferrite phases. Continuing our research on Fecontaining mixed conductors [6,8,10,[14][15][16], the present work is focused on the determination of ionic conductivity of brownmillerite CaAl 0.5 Fe 0.5 O 2.5 and on the evaluation of structural factors affecting ion mobility in the brownmillerite lattice.…”

Section: Introductionmentioning

confidence: 99%

“…Stability of ferrite-based materials in CO 2 -and H 2 O-containing atmospheres may be improved by decreasing the A-site cation radius, e.g. by substitution of Sr with Ca, which also promotes brownmillerite formation [6].…”

Section: Introductionmentioning

confidence: 99%

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Oxygen ionic conduction in brownmillerite CaAl0.5Fe0.5O2.5+

Хартон

Marozau

Vyshatko

et al. 2003

Materials Research Bulletin

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The oxygen permeability of CaAl 0.5 Fe 0.5 O 2.5þd brownmillerite membranes at 1123-1273 K was found to be limited by the bulk ionic conduction, with an activation energy of 170 kJ/mol. The ion transference numbers in air are in the range 2 Â 10 À3 to 5 Â 10 À3 . The analysis of structural parameters showed that the ionic transport in the CaAl 0.5 Fe 0.5 O 2.5þd lattice is essentially along the c axis. The largest ion-migration channels are found in the perovskite-type layers formed by iron-oxygen octahedra, though diffusion in tetrahedral layers of the brownmillerite structure is also possible. Heating up to 700-800 K in air leads to losses of hyperstoichiometric oxygen, accompanied with a drastic expansion and, probably, partial disordering of the CaAl 0.5 Fe 0.5 O 2.5þd lattice. The average thermal expansion coefficients of CaAl 0.5 Fe 0.5 O 2.5þd ceramics in air are 16:7 Â 10 À6 and 12:6 Â 10 À6 K À1 at 370-850 and 930-1300 K, respectively.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Oxygen ionic conduction in brownmillerite CaAl0.5Fe0.5O2.5+

Хартон

Marozau

Vyshatko

et al. 2003

Materials Research Bulletin

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Atomistic Study of a CaTiO₃‐Based Mixed Conductor: Defects, Nanoscale Clusters, and Oxide‐Ion Migration

Mather

Islam

Figueiredo

2007

Adv Funct Materials

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Mixed oxide‐ion and electronic conductivity can be exploited in dense ceramic membranes for controlled oxygen separation as a means of producing pure oxygen or integrating with catalytic oxidation. Atomistic simulation has been used to probe the energetics of defects, dopant‐vacancy association, nanoscale cluster formation, and oxide‐ion transport in mixed‐conducting CaTiO3. The most favorable energetics for trivalent dopant substitution on the Ti site are found for Mn3+ and Sc3+. Dopant‐vacancy association is predicted for pair clusters and neutral trimers. Low binding energies are found for Sc3+ in accordance with the high oxide‐ion conductivity of Sc‐doped CaTiO3. The preferred location for Fe4+ is in a hexacoordinated site, which supports experimental evidence that Fe4+ promotes the termination of defect chains and increases disorder. A higher oxide‐ion migration energy for a vacancy mechanism is predicted along a pathway adjacent to an Fe3+ ion rather than Fe4+ and Ti4+, consistent with the higher observed activation energies for ionic transport in reduced CaTi(Fe)O3–δ.

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Properties of CaTi1 ? xFexO3 ? ? Ceramic Membranes

et al. 2004

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CaCO 3 , TiO 2 and Fe 2 O 3 were mixed in the appropriate stoichiometric quantities and calcined at 1100 • C for 10 h. These powder mixtures were uniaxially pressed and sintered at temperatures ranging from 1350 to 1500 • C for 2 h in order to obtain dense disk-shaped samples with nominal CaTi 1−x Fe x O 3−δ (x = 0.05, 0.15, 0.20, 0.40 and 0.60) compositions. Dilatometry and in situ high temperature powder X-ray diffraction analysis showed a good agreement on the thermal expansion behaviour of these materials between room temperature and 1000 • C. The estimated linear thermal expansion coefficient is close to 13 × 10 −6 K −1 and is little affected by composition. No evidence for surface carbonation was detected in the infrared spectra collected on samples previously annealed in CO 2 atmospheres. The oxygen permeability measured at temperatures ranging from 750 to 1000 • C goes through a sharp maximum for x = 0.20. This result is interpreted by structural differences related to change from disordered to ordered oxygen vacancies. The overall performance of CaTi 0.80 Fe 0.20 O 3−δ is compared to other mixed conducting materials.

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Oxygen Diffusion in, and Thermal Expansionof, SrTiO<sub>3-δ</sub>- and CaTiO<sub>3-δ</sub>-Based Materials

Cited by 30 publications

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Oxygen ionic conduction in brownmillerite CaAl0.5Fe0.5O2.5+

Oxygen ionic conduction in brownmillerite CaAl0.5Fe0.5O2.5+

Atomistic Study of a CaTiO₃‐Based Mixed Conductor: Defects, Nanoscale Clusters, and Oxide‐Ion Migration

Properties of CaTi1 ? xFexO3 ? ? Ceramic Membranes

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Oxygen Diffusion in, and Thermal Expansionof, SrTiO<sub>3-δ</sub>- and CaTiO<sub>3-δ</sub>-Based Materials

Cited by 30 publications

References 0 publications

Oxygen ionic conduction in brownmillerite CaAl0.5Fe0.5O2.5+

Oxygen ionic conduction in brownmillerite CaAl0.5Fe0.5O2.5+

Atomistic Study of a CaTiO3‐Based Mixed Conductor: Defects, Nanoscale Clusters, and Oxide‐Ion Migration

Properties of CaTi1 ? xFexO3 ? ? Ceramic Membranes

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Atomistic Study of a CaTiO₃‐Based Mixed Conductor: Defects, Nanoscale Clusters, and Oxide‐Ion Migration