Thermodynamic assessment of the lanthanum-oxygen system

Grundy, A. Nicholas; Hallstedt, Bengt; Gauckler, Ludwig J.

doi:10.1361/105497101770338950

Cited by 65 publications

(56 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The DFT formation energies of La 2 O 3 and Y 2 O 3 are À16.98 and À17.85 eV, respectively (À17.70 [15] and À18.79 eV, [16] experimentally). The deformation energy is approximately 3.3 eV for La 2 O 3 , calculated as the energy difference of this oxide in the space groups P3m1 and Pm3m with a perovskite lattice constant of 3.97 .…”

mentioning

confidence: 99%

Trends in Stability of Perovskite Oxides

et al. 2010

View full text Add to dashboard Cite

Perovskite oxides with general formula AMO 3 have a large variety of applications as dielectrics and piezoelectrics, [1] ferroelectrics [2] and/or ferromagnetic materials, [3] among others. Rare earth and alkaline earth metal perovskites are useful as catalysts for hydrogen generation, [4] as oxidation catalysts for hydrocarbons, [5] and as effective and inexpensive electrocatalysts for state-of-the-art fuel cells, [6] mainly due to the possibility of tuning their mixed ionic-electronic conductivity through substitution of A and M and subsequent formation of oxygen vacancies. Despite the general interest in perovskites, so far there have been no ab initio studies devoted to their formation energies, and the trends in stability are unknown.Among the available theoretical techniques to investigate perovskites, DFT is an appealing candidate, since it has proved useful for understanding metals and alloys at the atomic scale.[7] Nevertheless, the well-known shortcoming of DFT in describing strongly correlated systems has prevented its use for the estimation of properties such as band gaps and electron localization-delocalization of oxides, and there are numerous corrections. [8] Despite these limitations, Figure 1 a shows the experimental formation energies from elements and O 2 of 20 perovskites at 298 K and the corresponding standard DFT energies using the RPBE-GGA [9] exchange-correlation functional. The simulations are able to reproduce trends in the formation energies, and the calculated energies are shifted by about 0.75 eV compared to experiments. The A component is Y, La, Ca, Sr, or Ba, while M is a 3d metal from Ti to Cu. However, it is possible to combine the formation energies of these compounds with those of their sesquioxides (A 2 O 3 and M 2 O 3 ), rutile dioxides (MO 2 ), monoxides (AO and MO), and O 2 to reproduce the energetics of several reactions (Figure 1 b-d). The reactions are shown in the Supporting Information. The excellent correspondence between experiments and theory shows that DFT very accurately captures the mixing energies between oxides. The chemical reaction depicted in Figure 1 a and the way of representing its Gibbs energy, are given by Equations (1) and (2).In terms of trends the agreement is beyond the expected accuracy of DFT in general, but the shift is about 0.75 eV. We note that imitations in O 2 description by DFT are well known and some alternatives have been proposed, obtaining remarkable agreements with experiments. [8c,10] We obtain the total DFT energy of O 2 indirectly from the tabulated Gibbs energy of formation of water and from the DFT energies of H 2

show abstract

mentioning

confidence: 99%

Trends in Stability of Perovskite Oxides

et al. 2010

View full text Add to dashboard Cite

show abstract

“…In the La-Sr-Mn-Cr-O oxide system, complete solid solubility of Mn and Cr is reported for La 1Àx Sr x Mn 1Ày Cr y O 3Àd perovskite. 17 Plint et al 48 concluded from the similarity between x-ray absorbtion spectra of Cr K of LaCrO 3 and La 1Àx Sr x Mn 0.5 Cr 0.5 O 3Àd with x 5 0.2, 0.25, and 0.3 at 1173 K-edges that Cr 41 were absent in the latter. …”

Section: B La-sr-cr-oxidementioning

confidence: 99%

“…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%

“…46 Complete solid solution between the LaMnO 3 and the LaCrO 3 perovskites was affirmed. 17 d of LaMn 0.9 Cr 0.1 O 3Àd was measured using thermogravimetry. In the La-Sr-Mn-Cr-O oxide system, complete solid solubility of Mn and Cr is reported for La 1Àx Sr x Mn 1Ày Cr y O 3Àd perovskite.…”

Section: B La-sr-cr-oxidementioning

confidence: 99%

“…Strategies of liquid modeling are discussed in detail in the assessments of binary subsystems. 17,19,50 The experimental liquidus course indicates strong deviation from ideal mixing, which requires a complex model description. In addition to end-member ionic species, in the current liquid description of SrO-Cr 2 41 .…”

Section: A Parameterization Of Thermodynamic Parameters Of the Sr-crmentioning

confidence: 99%

See 2 more Smart Citations

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

et al. 2012

View full text Add to dashboard Cite

show abstract

Trends in Stability of Perovskite Oxides

et al. 2010

View full text Add to dashboard Cite

Perovskite oxides with general formula AMO 3 have a large variety of applications as dielectrics and piezoelectrics, [1] ferroelectrics [2] and/or ferromagnetic materials, [3] among others. Rare earth and alkaline earth metal perovskites are useful as catalysts for hydrogen generation, [4] as oxidation catalysts for hydrocarbons, [5] and as effective and inexpensive electrocatalysts for state-of-the-art fuel cells, [6] mainly due to the possibility of tuning their mixed ionic-electronic conductivity through substitution of A and M and subsequent formation of oxygen vacancies. Despite the general interest in perovskites, so far there have been no ab initio studies devoted to their formation energies, and the trends in stability are unknown.Among the available theoretical techniques to investigate perovskites, DFT is an appealing candidate, since it has proved useful for understanding metals and alloys at the atomic scale. [7] Nevertheless, the well-known shortcoming of DFT in describing strongly correlated systems has prevented its use for the estimation of properties such as band gaps and electron localization-delocalization of oxides, and there are numerous corrections. [8] Despite these limitations, Figure 1 a shows the experimental formation energies from elements and O 2 of 20 perovskites at 298 K and the corresponding standard DFT energies using the RPBE-GGA [9] exchange-correlation functional. The simulations are able to reproduce trends in the formation energies, and the calculated energies are shifted by about 0.75 eV compared to experiments. The A component is Y, La, Ca, Sr, or Ba, while M is a 3d metal from Ti to Cu. However, it is possible to combine the formation energies of these compounds with those of their sesquioxides (A 2 O 3 and M 2 O 3 ), rutile dioxides (MO 2 ), monoxides (AO and MO), and O 2 to reproduce the energetics of several reactions (Figure 1 b-d). The reactions are shown in the Supporting Information. The excellent correspondence between experiments and theory shows that DFT very accurately captures the mixing energies between oxides. The chemical reaction depicted in Figure 1 a and the way of representing its Gibbs energy, are given by Equations (1) and (2).

show abstract

Thermodynamic assessment of the lanthanum-oxygen system

Cited by 65 publications

References 32 publications

Trends in Stability of Perovskite Oxides

Trends in Stability of Perovskite Oxides

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

Trends in Stability of Perovskite Oxides

Contact Info

Product

Resources

About

Thermodynamic assessment of the lanthanum-oxygen system

Cited by 65 publications

References 32 publications

Trends in Stability of Perovskite Oxides

Trends in Stability of Perovskite Oxides

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

Trends in Stability of Perovskite Oxides

Contact Info

Product

Resources

About

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