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

Leonidov, Ilia A.; Markov, Alexey A.; Zavyalov, Mikhail A.; Merkulov, Oleg V.; Shalaeva, Elisaveta V.; Nikitin, Sergey S.; Tsipis, Ekaterina V.; Patrakeev, Mikhail V.

doi:10.3390/ma15134390

Open AccessArticle

Structural Features and Defect Equilibrium in Cubic PrBa_1−xSr_xFe₂O_6−δ

by

Ilia A. Leonidov

¹,

Alexey A. Markov

¹

,

Mikhail A. Zavyalov

¹,

Oleg V. Merkulov

^1,*

,

Elisaveta V. Shalaeva

¹,

Sergey S. Nikitin

²

,

Ekaterina V. Tsipis

² and

Mikhail V. Patrakeev

^1,2

¹

Institute of Solid State Chemistry, UB RAS, 620990 Ekaterinburg, Russia

²

Osipyan Institute of Solid State Physics RAS, Moscow District, 142432 Chernogolovka, Russia

^*

Author to whom correspondence should be addressed.

Materials 2022, 15(13), 4390; https://doi.org/10.3390/ma15134390

Submission received: 30 May 2022 / Revised: 18 June 2022 / Accepted: 19 June 2022 / Published: 21 June 2022

(This article belongs to the Special Issue Investigation of Optoelectronic Functional Crystals: Crystal Growth, Properties and Applications)

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Abstract

The structure, oxygen non-stoichiometry, and defect equilibrium in perovskite-type PrBa_1−xSr_xFe₂O_6−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.

P m \bar{3} m

), but an electron diffraction study reveals additional diffuse satellites around each Bragg spot, indicating the primary incommensurate modulation with wave vectors about ±0.43

a^{*}

. 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 PrBa_1−xSr_xFe₂O_6−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 Pr_0.5Ba_0.5−xSr_xFeO_3−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.

Keywords: perovskite; Sr-doped praseodymium-barium ferrite; incommensurate modulation; oxygen content; defect equilibrium; thermodynamics

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MDPI and ACS Style

Leonidov, I.A.; Markov, A.A.; Zavyalov, M.A.; Merkulov, O.V.; Shalaeva, E.V.; Nikitin, S.S.; Tsipis, E.V.; Patrakeev, M.V. Structural Features and Defect Equilibrium in Cubic PrBa_1−xSr_xFe₂O_6−δ. Materials 2022, 15, 4390. https://doi.org/10.3390/ma15134390

AMA Style

Leonidov IA, Markov AA, Zavyalov MA, Merkulov OV, Shalaeva EV, Nikitin SS, Tsipis EV, Patrakeev MV. Structural Features and Defect Equilibrium in Cubic PrBa_1−xSr_xFe₂O_6−δ. Materials. 2022; 15(13):4390. https://doi.org/10.3390/ma15134390

Chicago/Turabian Style

Leonidov, Ilia A., Alexey A. Markov, Mikhail A. Zavyalov, Oleg V. Merkulov, Elisaveta V. Shalaeva, Sergey S. Nikitin, Ekaterina V. Tsipis, and Mikhail V. Patrakeev. 2022. "Structural Features and Defect Equilibrium in Cubic PrBa_1−xSr_xFe₂O_6−δ" Materials 15, no. 13: 4390. https://doi.org/10.3390/ma15134390

APA Style

Leonidov, I. A., Markov, A. A., Zavyalov, M. A., Merkulov, O. V., Shalaeva, E. V., Nikitin, S. S., Tsipis, E. V., & Patrakeev, M. V. (2022). Structural Features and Defect Equilibrium in Cubic PrBa_1−xSr_xFe₂O_6−δ. Materials, 15(13), 4390. https://doi.org/10.3390/ma15134390

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Structural Features and Defect Equilibrium in Cubic PrBa_1−xSr_xFe₂O_6−δ

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