The impact of cerium content on oxygen stoichiometry, defect equilibrium, and thermodynamic quantities of Sr1−Ce FeO3−

Markov, A.A.; Nikitin, S.S.; Politov, B.V.; Шалаева, Е. В.; Tyutyunnik, А. P.; Леонидов, И. А.; Патракеев, М.В.

doi:10.1016/j.jallcom.2021.160051

Cited by 14 publications

(18 citation statements)

References 37 publications

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“…For as-prepared PrBa 1−x Sr x Fe 2 O 6−δ , the incommensurate satellites are barely distinguishable (Figure5c).Such incommensurate modulations are believed to be created by atomic displacement and/or an occupancy (composition) probability wave with wave vector q for some atomic sites in the lattice, and the modulated state can be intermediate before the formation of ordered superstructures with changes in the composition or temperature[31]. For a range of the A-sublattice-doped ferrites R x Sr 1−x FeO 3−δ (R is Y, Ce), which are known to be prone to the formation of ordered superstructures, similar incommensurate modulations have been observed in previous TEM studies[32][33][34][35]. The modulated states and ordered phases were found mainly in the reduced samples.…”

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confidence: 57%

Structural Features and Defect Equilibrium in Cubic PrBa1−xSrxFe2O6−δ

et al. 2022

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The structure, oxygen non-stoichiometry, and defect equilibrium in perovskite-type PrBa1−xSrxFe2O6−δ (x = 0, 0.25, 0.50) synthesized at 1350 °C were studied. For all compositions, X-ray diffraction testifies to the formation of a cubic structure (S.G. Pm3¯m), but an electron diffraction study reveals additional diffuse satellites around each Bragg spot, indicating the primary incommensurate modulation with wave vectors about ±0.43a*. The results were interpreted as a sign of the short-order in both A-cation and anion sublattices in the areas of a few nanometers in size, and of an intermediate state before the formation of an ordered superstructure. An increase in oxygen deficiency was found to promote the ordering, whereas partial substitution of barium by strontium caused the opposite effect. The oxygen content in oxides as a function of oxygen partial pressure and temperature was measured by coulometric titration, and the data were used for the modeling of defect equilibrium in oxides. The simulation results implied oxygen vacancy ordering in PrBa1−xSrxFe2O6−δ that is in agreement with the electron diffraction study. Besides oxidation and charge disproportionation reactions, the reactions of oxygen vacancy distribution between non-equivalent anion positions, and their trapping in clusters with Pr3+ ions were taken into account by the model. It was demonstrated that an increase in the strontium content in Pr0.5Ba0.5−xSrxFeO3−δ suppressed ordering of oxygen vacancies, increased the binding energy of oxygen ions in the oxides, and resulted in an increase in the concentration of p-type carriers.

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confidence: 57%

Structural Features and Defect Equilibrium in Cubic PrBa1−xSrxFe2O6−δ

et al. 2022

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“…A joint analysis of the expressions for equilibrium constants in combination with the equations taking into account the requirements of site conservation and electroneutrality gives the final model expression used for the approximation to the experimental data . Solid lines in Figure , representing the results of the approximation, prove the adequacy of the model and, thus, the reliability of the obtained thermodynamic parameters.…”

Section: Other Data Used In the Studymentioning

confidence: 83%

“…The oxygen content versus oxygen partial pressure in a gas phase was measured by coulometric titration. A description of the procedures related to material synthesis, its structural characterization, ceramics fabrication, and oxygen content measurement can be found in a previous paper …”

Section: Methodsmentioning

confidence: 99%

“…This section gives a brief overview of the previously obtained results necessary to carry out this study Figure shows the phase purity of Sr 1– x Ce x FeO 3–δ oxides.…”

Section: Other Data Used In the Studymentioning

confidence: 99%

“…In the prior work, the oxygen content in Sr 1– x Ce x FeO 3–δ was measured by coulometric titration in wide ranges of oxygen partial pressure and temperature. The obtained data were employed for thermodynamic modeling of the defect equilibrium and calculation of charge carrier concentrations . It was shown, in particular, that under moderately reducing conditions, the concentration of electrons localized on cerium ions exceeded that on iron ions.…”

Section: Introductionmentioning

confidence: 99%

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Impact of Cerium Content on Ion and Electron Transport in Sr_1–xCe_xFeO_3–δ

et al. 2021

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The electrical conductivity of perovskite-type Sr1–x Ce x FeO3–δ (x = 0.05, 0.10, and 0.15) was measured in the range of oxygen partial pressure from 10–19 to 0.5 atm at temperatures 750–950 °C. The results were analyzed using the concentration of iron and cerium ions in different oxidation states derived from the p O2 –T–δ diagrams of these compositions by thermodynamic analysis of defect equilibrium. Three models assuming different involvements of cerium and iron in electron transport in addition to hole and oxygen-ion conductivity were used for the simulation of electrical conductivity data. The best fit to the experimental data was obtained in the model, suggesting a minor contribution of electrons localized on cerium ions to conductivity via a separate network with low carrier mobility. The averaged mobility values for holes, electrons, and oxygen ions can be indicated for all compositions as 0.04, 5 × 10–3, and 1 × 10–5 cm2 V–1 s–1 with activation energies of 0.17, 0.5, and 0.7 eV, respectively. An increase in the cerium content in Sr1–x Ce x FeO3–δ from 0.05 to 0.15 was found to result in an almost 10-fold decrease in ion conductivity, which is attributed to a decrease in the mobility of oxygen ions, whereas it has an insignificant effect on hole and electron conductivity.

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