Phase diagram and thermodynamics of the La2O3–Ga2O3 system revisited

Zinkevich, M.; Geupel, S.; Aldinger, Fritz; Durygin, Andriy; Saxena, Surendra K.; Yang, Mei; Liu, Zhe

doi:10.1016/j.jpcs.2006.03.012

Cited by 28 publications

(16 citation statements)

References 24 publications

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“…The considerable error might be explained by experimental difficulties to reach equilibrium at the low investigation temperatures, and/ or by significant deviations between the thermodynamic standard data used for the calculation of the enthalpy of formation from the elements [29] and assessed values. [8][9][10] Anyway the model parameters were fitted to the experimental data, [30] whereas the calculated standard enthalpy of formation from the elements [29] was rejected, bearing in mind the high degree of uncertainty of the resulting description. The perovskite phase: the calculated heat capacities of LaCrO 3 are compared with experiments from the literature in Fig.…”

Section: Lanthanum Chromatesmentioning

confidence: 99%

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Thermodynamic Assessment of the La-Cr-O System

Povoden

Chen

Grundy³

et al. 2008

J. Phase Equilib. Diffus.

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The La-Cr and the La-Cr-O systems are assessed using the Calphad approach. The calculated La-Cr phase diagram as well as LaO 1.5 -CrO 1.5 phase diagrams in pure oxygen, air, and under reducing conditions are presented. Phase equilibria of the La-Cr-O system are calculated at 1273 K as a function of oxygen partial pressure. In the La-Cr system reported solubility of lanthanum in bcc chromium is considered in the modeling. In the La-Cr-O system the Gibbs energy functions of La 2 CrO 6 , La 2 (CrO 4 ) 3 , and perovskite-structured LaCrO 3 are presented, and oxygen solubilities in bcc and fcc metals are modeled. Emphasis is placed on a detailed description of the perovskite phase: the orthorhombic to rhombohedral transformation and the contribution to the Gibbs energy due to a magnetic order-disorder transition are considered in the model. The following standard data of stoichiometric perovskite are calculated: D f;oxides H 298K ðLaCrO 3 Þ = À 73:7 kJ mol À1 , and S 298 K ðLaCrO 3 Þ = 109:2 J mol À1 K À1 . The Gibbs energy of formation from the oxides, D f;oxides GðLaCrO 3 Þ = À 72:403 À 0:0034T (kJ mol 21 ) (1273-2673 K) is calculated. The decomposition of the perovskite phase by the reaction LaCrO 3 ! 1 2 La 2 O 3 + Cr + 3 4 O 2 ðgÞ " is calculated as a function of temperature and oxygen partial pressure: at 1273 K the oxygen partial pressure of the decomposition, p O 2 ðdecompÞ = 10 À20:97 Pa. Cation nonstoichiometry of La 1-x CrO 3 perovskite is described using the compound energy formalism (CEF), and the model is submitted to a defect chemistry analysis. The liquid phase is modeled using the two-sublattice model for ionic liquids.

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Section: Lanthanum Chromatesmentioning

confidence: 99%

“…The assessment of the La-Cr-O system using the Calphad approach is based on the recently reassessed La-O [8] and Cr-O subsystems. [9] The lattice stabilities of elements are adopted from Dinsdale.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic Assessment of the La-Cr-O System

Povoden

Chen

Grundy³

et al. 2008

J. Phase Equilib. Diffus.

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“…No quaternary phases or solid solutions were found in the Sr-Mn-Cr-O oxide system. 16 Previous assessments of the La-O, Cr-O, La-Cr-O, and Cr-Mn-O oxide databases are adopted from Povoden et al, [17][18][19][20][21] with some modifications denoted in the supplement file to this paper, LSCM_v1.0.tcm (ThermoCalc macrofile), and the La-Sr-Mn-O oxide database is taken from Grundy et al, [22][23][24][25][26][27] also with the following slight modification: Grundy et al 23,24 allowed Mn 31 on the A-site of LSM to reproduce experimental oxygen nonstoichiometries under low oxygen partial pressures. Due to large differences between the ionic radii of La 31 and Mn 31 and possible coordination numbers (1.5 Å for 12-fold coordinated La 31 , 0.785 Å for at maximum 6-fold coordinated Mn 31 ), 28 we omit Mn 31 on the A-site.…”

Section: Assessment Of Oxide Subsystemsmentioning

confidence: 99%

Thermodynamic modeling of La₂O₃–SrO–Mn₂O₃–Cr₂O₃for solid oxide fuel cell applications

et al. 2012

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“…The assessment of the La-Fe-O system is based on the recently reassessed La-O [41] and the Fe-O subsystems. [42] The two-sublattice ionic liquid model (Fe 2+ ,Fe 3+ ) p (O 2À ,Va qÀ ) q is adopted from Taylor and Dinsdale [43] for the liquid description in the Fe-O system.…”

Section: Thermodynamic Modeling and Optimizationmentioning

confidence: 99%

“…Higher oxidation states are unlikely to exist in the liquid at normal oxygen partial pressures. Two different models for the Fe-O liquid have been presented: (Fe 2+ ,Fe 3+ ) p (O 2À ,Va qÀ ) q was used by Taylor and Dinsdale, [43] whereas Selleby and Sundman [42] proposed the description (Fe 2+ ) p (FeO 3 [41] Dinsdale, [44] Selleby and Sundman, [42] and Taylor and Dinsdale. [43] G liq Fe 3þ :Va qÀ is obtained by the reciprocal reaction:…”

Section: Perovskite Phasementioning

confidence: 99%

Thermodynamic Assessment of the La-Fe-O System

Povoden-Karadeniz

Grundy²,

Chen

et al. 2009

J. Phase Equilib. Diffus.

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The La-Fe and the La-Fe-O systems are assessed using the Calphad approach, and the Gibbs energy functions of ternary oxides are presented. Oxygen and mutual La and Fe solubilities in body-centered cubic (bcc) and face-centered cubic (fcc) structured metallic phases are considered in the modeling. Oxygen nonstoichiometry of perovskite-structured La 1±x Fe 1±y O 32d is modeled using the compound energy formalism (CEF), and the model is submitted to a defect chemistry analysis. The contribution to the Gibbs energy of LaFeO 3 due to a magnetic orderdisorder transition is included in the model description. Lanthanum-doped hexaferrite, LaFe 12 O 19 , is modeled as a stoichiometric phase. D f,elements°H298 K (LaFe 12 O 19 ) = 25745 kJ/mol,°S 298 K (LaFe 12 O 19 ) = 683 J/mol AE K, and D f,oxides°G (LaFe 12 O 19 ) = 4634 2 37.071T (J/mol) from 1073 to 1723 K are calculated. The liquid phase is modeled using the two-sublattice model for ionic liquids. The calculated La-Fe phase diagram, LaO 1.5 -FeO x phase diagrams at different oxygen partial pressures, and phase equilibria of the La-Fe-O system at 873, 1073, and 1273 K as a function of oxygen partial pressures are presented.

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Phase diagram and thermodynamics of the La2O3–Ga2O3 system revisited

Cited by 28 publications

References 24 publications

Thermodynamic Assessment of the La-Cr-O System

Thermodynamic Assessment of the La-Cr-O System

Thermodynamic modeling of La₂O₃–SrO–Mn₂O₃–Cr₂O₃for solid oxide fuel cell applications

Thermodynamic Assessment of the La-Fe-O System

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Phase diagram and thermodynamics of the La2O3–Ga2O3 system revisited

Cited by 28 publications

References 24 publications

Thermodynamic Assessment of the La-Cr-O System

Thermodynamic Assessment of the La-Cr-O System

Thermodynamic modeling of La2O3–SrO–Mn2O3–Cr2O3for solid oxide fuel cell applications

Thermodynamic Assessment of the La-Fe-O System

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Thermodynamic modeling of La₂O₃–SrO–Mn₂O₃–Cr₂O₃for solid oxide fuel cell applications