Specific features of phase equilibriums in Ln–Ba–Fe–O systems

Volkova, N.E.; Urusova, A.S.; Gavrilova, L. Ya.; Bryuzgina, A. V.; Deryabina, K. M.; Mychinko, Mikhail; Lebedev, Oleg I.; Raveau, B.; Черепанов, В.А.

doi:10.1134/s1070363216080041

Cited by 14 publications

(20 citation statements)

References 19 publications

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“…The information concerning small‐sized rare earth‐ or yttrium‐based ferrites is limited, although undoped strontium ferrite and yttrium ferrite have been the objects of wide‐ranging studies as magnetic and membrane materials in the last few decades . The wide variety of specific features of phase formation in the related systems and significant differences in the phase diagrams of these systems require detailed study of each system, in particular Y 2 O 3 –SrO–Fe 2 O 3 .…”

Section: Introductionmentioning

confidence: 99%

Phase equilibria, structure, oxygen nonstoichiometry, and thermal expansion of oxides in the 1/2Y₂O₃–SrO–1/2Fe₂O₃ system

et al. 2018

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Phase equilibria in the 1/2Y 2 O 3 -SrO-1/2Fe 2 O 3 system were systematically studied at 1373 K in air. The homogeneity ranges and crystal structure of the solid solutions Sr 1−x Y x FeO 3−δ with 0.875 ≤ x ≤ 1 (sp. gr. Pnma) and 0.05 ≤ x ≤ 0.25 (sp. gr. Pm3 m) and Sr 3−z Y z Fe 2 O 7−δ with 0 ≤ z ≤ 0.25 (sp. gr. I4/mmm) were determined by X-ray diffraction analysis of quenched samples. The structural parameters of the single-phase oxides were refined by the Rietveld profile method. The isothermal-isobaric phase diagram for the 1/2Y 2 O 3 -SrO-1/2Fe 2 O 3 system at 1373 K in air is presented. The changes of oxygen content in the solid solutions Sr 1−x Y x FeO 3−δ (0.05 ≤ x ≤ 0.25) and Sr 3−z Y z Fe 2 O 7−δ with 0 ≤ z ≤ 0.25 vs temperature in air were determined by the thermogravimetric analysis. Oxygen content was also calculated from the iodometric titration results. The gradual substitution of strontium by yttrium in Sr 1−x Y x FeO 3−δ (0.05 ≤ x ≤ 0.25) leads to a decrease in the oxygen content and the mean oxidation state of iron. The average thermal expansion coefficients for Sr 1−x Y x FeO 3−δ (0.875 ≤ x ≤ 1 and 0.05 ≤ x ≤ 0.25) and Sr 3−z Y z Fe 2 O 7−δ (0 ≤ z ≤ 0.25) were calculated within the temperature range 298-1373 K in air. K E Y W O R D S crystal structure, oxygen content, phase diagram, solid solution, thermal expansion, total electric conductivity, X-ray diffraction

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Section: Introductionmentioning

confidence: 99%

Phase equilibria, structure, oxygen nonstoichiometry, and thermal expansion of oxides in the 1/2Y₂O₃–SrO–1/2Fe₂O₃ system

et al. 2018

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“…Thermal analysis was performed using a STA 409 PC instrument (Netzsch) within the temperature range 25‐1100°C in air. The absolute value of oxygen content at room temperature was determined by an iodometric titration method described elsewhere 27‐29 . The equivalence point was registered by an automatic titrator Akvilon ATP‐02 (St. Petersburg, Russia).…”

Section: Methodsmentioning

confidence: 99%

Phase equilibria and stability of intermediate phases in the Sm₂O₃–BaO–Fe₂O₃ system

et al. 2021

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Phase equilibria in the ½ Sm2O3–BaO–½ Fe2O3 system were systematically studied at 1100°C in air. Two individual compounds: Sm1.875Ba3.125Fe5O15‐δ and Ba3SmFe2O7.5+δ have been detected in the studied system at 1100°C in air. One more complex oxide with double perovskite structure SmBaFe2O5+w has been obtained under reduced oxygen partial pressure. Thermodynamic stability of SmBaFe2O5+w and its thermal stability in metastable state in air were determined. The subsolidus phase diagram for the ½ Sm2O3 – BaO – ½ Fe2O3 system at 1100°C in air has been constructed.

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“…The obtained results are in good agreement within the experimental error with the data measured earlier. 52,55 Using TGA data for Nd 1-x Ba x FeO 3-δ (x = 0.6 and 0.7) taken from our earlier works 52,55 and the absolute (3 -δ) values at room temperature from the present work, the mean oxidation state of iron ions was calculated (Figure 2). One can see that the average oxidation state of iron ions decreases with increasing temperature gradually approaching 3+ value due to…”

Section: Ndfeo 3 -Bafeo 3-δ Cross-sectionmentioning

confidence: 98%

“…necessary for the formation of quintuple structure, Ndenriched oxide (in regards to ideal Nd 2 Ba 3 Fe 5 O 15-δ composition) Nd 0.3 Ba 0.7 FeO 3-δ is completely disordered. 52,55 With the larger Pr no layered superstructure is formed but only disordered perovskites, no matter what Ln/Ba ratio was. 55,56 This results from the smaller size difference between Pr and Ba ions.…”

Section: Ndfeo 3 -Bafeo 3-δ Cross-sectionmentioning

confidence: 99%

“…52,55 With the larger Pr no layered superstructure is formed but only disordered perovskites, no matter what Ln/Ba ratio was. 55,56 This results from the smaller size difference between Pr and Ba ions. It was shown earlier that XRD could not detect the formation of a p × a p × 5a p superstructure due to nanoscale twinning of crystallites in orthogonal directions.…”

Section: Ndfeo 3 -Bafeo 3-δ Cross-sectionmentioning

confidence: 99%

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Phase equilibria in the Nd₂O₃–BaO–Fe₂O₃ system: Crystal structure, oxygen content, and properties of intermediate oxides

et al. 2022

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The phase equilibria in the ½Nd 2 O 3 -BaO-½Fe 2 O 3 system were systematically studied at 1373 K in air and presented in the form of a phase diagram. By X-ray diffraction (XRD) analysis of quenched samples, the homogeneity ranges and crystal structure were determined for the following intermediate oxides: Nd 1-x Ba x FeO 3-δ with 0.0 ≤ x ≤ 0.05 (space group (SG) Pnma) and with 0.6 ≤ x ≤ 0.7 (SG Pm-3m), Ba 6+y Nd 2-y Fe 4 O 15-δ with 0.0 ≤ y ≤ 0.4 (SG P6 3 mc), and Ba 1.1 Nd 1.9 Fe 2 O 7-δ (SG P4 2 /mnm). The structural parameters of single-phase oxides were refined by the Rietveld method. The changes in oxygen content for Nd 1-x Ba x FeO 3-δ (0.6 ≤ x ≤ 0.7), Ba 6 Nd 2 Fe 4 O 15-δ , and Ba 1.1 Nd 1.9 Fe 2 O 7-δ versus temperature in air were determined by thermogravimetric analysis. Gradual substitution of neodymium by barium in the Nd 1-x Ba x FeO 3-δ (0.6 ≤ x ≤ 0.7) oxides leads to a decrease of oxygen content. Partial ordering via formation of separate domains with a p × a p × 5a p superstructure in Nd 0.4 Ba 0.6 FeO 3-δ , which cannot be detected by XRD, noticeably influence its thermal expansion and electrical conductivity.

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Specific features of phase equilibriums in Ln–Ba–Fe–O systems

Cited by 14 publications

References 19 publications

Phase equilibria, structure, oxygen nonstoichiometry, and thermal expansion of oxides in the 1/2Y₂O₃–SrO–1/2Fe₂O₃ system

Phase equilibria, structure, oxygen nonstoichiometry, and thermal expansion of oxides in the 1/2Y₂O₃–SrO–1/2Fe₂O₃ system

Phase equilibria and stability of intermediate phases in the Sm₂O₃–BaO–Fe₂O₃ system

Phase equilibria in the Nd₂O₃–BaO–Fe₂O₃ system: Crystal structure, oxygen content, and properties of intermediate oxides

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Specific features of phase equilibriums in Ln–Ba–Fe–O systems

Cited by 14 publications

References 19 publications

Phase equilibria, structure, oxygen nonstoichiometry, and thermal expansion of oxides in the 1/2Y2O3–SrO–1/2Fe2O3 system

Phase equilibria, structure, oxygen nonstoichiometry, and thermal expansion of oxides in the 1/2Y2O3–SrO–1/2Fe2O3 system

Phase equilibria and stability of intermediate phases in the Sm2O3–BaO–Fe2O3 system

Phase equilibria in the Nd2O3–BaO–Fe2O3 system: Crystal structure, oxygen content, and properties of intermediate oxides

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Phase equilibria, structure, oxygen nonstoichiometry, and thermal expansion of oxides in the 1/2Y₂O₃–SrO–1/2Fe₂O₃ system

Phase equilibria, structure, oxygen nonstoichiometry, and thermal expansion of oxides in the 1/2Y₂O₃–SrO–1/2Fe₂O₃ system

Phase equilibria and stability of intermediate phases in the Sm₂O₃–BaO–Fe₂O₃ system

Phase equilibria in the Nd₂O₃–BaO–Fe₂O₃ system: Crystal structure, oxygen content, and properties of intermediate oxides