Simple band model for La1−xSrxCoO3: Evidence from electron spectroscopy

Kemp, J.P.; Beal, D.J.; Cox, P. A.

doi:10.1016/0022-4596(90)90112-b

Cited by 27 publications

(20 citation statements)

References 21 publications

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“…[11] and [12], the density of states at the Fermi level is calculated to be 1.1 (eV)\ per unit cell. This value is in good agreement with the values of 1.0, 1.3, and 1.5 (eV)\ obtained from the shift in the O-2p band toward the Fermi level with increasing Sr content measured using XPS by different authors (25)(26)(27). On the other hand, the screened impurity RBM would predict a constant Fermi level.…”

Section: Temperature Step Method: Partial Energy and Entropy Of Oxygensupporting

confidence: 90%

High-Temperature Coulometric Titration of La1−xSrxCoO3−δ: Evidence for the Effect of Electronic Band Structure on Nonstoichiometry Behavior

Lankhorst

Bouwmeester

Verweij

1997

Journal of Solid State Chemistry

132

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Section: Temperature Step Method: Partial Energy and Entropy Of Oxygensupporting

confidence: 90%

High-Temperature Coulometric Titration of La1−xSrxCoO3−δ: Evidence for the Effect of Electronic Band Structure on Nonstoichiometry Behavior

Lankhorst

Bouwmeester

Verweij

1997

Journal of Solid State Chemistry

132

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“…4͒. This is consistent with experimental facts in the sense that the observed 60 of La 1Ϫx Sr x CoO 3 show 32 that there is no rigid-band-like behavior in the VB spectrum as a result of the doping. Our calculated DOS curves also show significant changes introduced by the Sr substitution ͑Fig.…”

Section: A Electronic Structuresupporting

confidence: 90%

Electronic structure, phase stability, and magnetic properties ofLa1−xSrx
Ravindran
¹
,
Korzhavyi
²
,
Fjellvåg
³

et al. 1999
Phys. Rev. B

114

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In order to understand the role of hole doping on electronic structure, phase stability and magnetic properties of LaCoO 3 generalized-gradient-corrected, relativistic first-principles full-potential density functional calculations have been performed for La 1Ϫx Sr x CoO 3 as a function of x, using the supercell approach as well as the virtual crystal approximation ͑VCA͒. It has been shown that the rhombohedral distortion is stabilizing the nonmagnetic ͑i.e., diamagnetic or paramagnetic͒ ground state in LaCoO 3 . Spin-polarized calculation on the hypothetical cubic perovskite phase of LaCoO 3 shows that the ferromagnetic phase is lower in energy than the corresponding nonmagnetic phase. The analysis of the electronic structures show that a Peierls-Jahn-Teller-like instability arises in the ferromagnetic cubic phase and leads to the rhombohedral distortion in LaCoO 3 . The calculated magnetic moment for La 1Ϫx Sr x CoO 3 as a function of Sr substitution is found to be in very good agreement with recent neutron scattering measurements. We have successfully explained the hole-doping induced, nonmagnetic-to-ferromagnetic transition as well as the rhombohedral-to-cubic structural transition as a function of Sr substitution in La 1Ϫx Sr x CoO 3 . Due to the failure of the density functional theory to predict the semiconducting nature of LaCoO 3 , we are unable to explain the experimentally observed semiconductor-tometal transition in LaCoO 3 by Sr substitution. The origin of the ferromagnetism in La 1Ϫx Sr x CoO 3 has been explained through itinerant-band ferromagnetism.

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“…4 enable calculation of the density of states at the Fermi level equal to 1.1 eV 21 pro unit cell. The latter value is found to be in good agreement with the values of 1.0 and 1.3 eV 21 , which were derived from the shift in the O-2p band towards the Fermi level with increasing Sr content as measured using XPS [4,20]. Hence, it must be concluded that in compounds La 12x Sr x CoO 32d the downwards shift of the electron band as a result of screening expected in the screened impurity RBM must be small compared with the increase in Fermi level with increasing electron occupancy.…”

supporting

confidence: 86%

Use of the Rigid Band Formalism to Interpret the Relationship between O Chemical Potential and Electron Concentration inLa1−xSrx
Lankhorst
¹
,
Bouwmeester
²
,
Verweij
³

1996
Phys. Rev. Lett.
94
9
56
0
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The equilibrium oxygen chemical potential of mixed oxygen ion and electron conducting perovskites La 12x Sr x CoO 32d was measured as a function of d and x by high temperature oxygen coulometric titration. An almost linear decrease in the chemical potential is observed with increasing net electron concentration. The observed behavior is interpreted to reflect the corresponding change in the Fermi level upon gradually filling up states in a broad electron band with electrons induced by vacancy formation and Sr doping. Assuming a rigid band formalism, an apparent density of states at the Fermi level was calculated, the value of which is in good agreement with that obtained from XPS.[ S0031-9007(96) PACS numbers: 71.20. Eh, 61.72.Ji, 66.30.Fq Many of the 3d transition metal perovskite-type oxides are characterized by increased lattice oxygen vacancy formation at high temperatures, which results in substantial departure from oxygen stoichiometry. Vacancy formation is accompanied by a proportional change in the average valency of either the transition metal or oxygen ions. The relatively high vacancy mobility in conjunction with the metalliclike electronic conductivity causes these materials to be permeable for oxygen gas [1], which is of interest for various applications. In addition, many of the 3d transition metal perovskites are studied for special electronic and magnetic transitions which may occur either as a function of temperature or composition [2][3][4]. In the ZSA theory [5], the electronic structure of these oxides is interpreted in terms of the competition between charge disproportionation of the Mott Hubbart type,L, where d n denotes the n-electron 3d state of the transition metal and L denotes a hole in the wide anion valence band. Although charge disproportionation was not observed in LaCoO 3 by XAS [3], Sarma et al. [4] state that for this material the influence of both types of charge fluctuation is of the same order of magnitude, leading to a very mixed character of the ground state. Charge disproportionation was used to model oxygen nonstoichiometry [6] and Seebeck data [7] of La 12x Sr x CoO 32d . In both cases, however, the best fit implied the simultaneous presence of unrealistically high concentrations of Co 21 and Co 41 . In Sr-doped LaCoO 3 , significant spectral intensities at the Fermi energy have been observed by Sarma et al.[4] using UPS and bremsstrahlung isochromat spectroscopy. They concluded that electron hole states, created by substitution of La 31 by Sr 21 , overlap the top of the wide oxygen 2p band giving rise to a mixed-valency metallic compound. Furthermore, conductivity and Seebeck measurements [7] at high temperatures also indicate metalliclike properties for Sr-doped LaCoO 3 . These observations favor the interpretation in terms of itinerant electron behavior in these solids.The aim of this study is, on the one hand, to improve existing oxygen nonstoichiometry models for the compounds La 12x Sr x CoO 32d by incorporating the delocalized nature of the conduction electron...

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Simple band model for La1−xSrxCoO3: Evidence from electron spectroscopy

Cited by 27 publications

References 21 publications

High-Temperature Coulometric Titration of La1−xSrxCoO3−δ: Evidence for the Effect of Electronic Band Structure on Nonstoichiometry Behavior

High-Temperature Coulometric Titration of La1−xSrxCoO3−δ: Evidence for the Effect of Electronic Band Structure on Nonstoichiometry Behavior

Electronic structure, phase stability, and magnetic properties ofLa1−xSrx
Ravindran
¹
,
Korzhavyi
²
,
Fjellvåg
³

et al. 1999
Phys. Rev. B

Use of the Rigid Band Formalism to Interpret the Relationship between O Chemical Potential and Electron Concentration inLa1−xSrx
Lankhorst
¹
,
Bouwmeester
²
,
Verweij
³

1996
Phys. Rev. Lett.
94
9
56
0
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Simple band model for La1−xSrxCoO3: Evidence from electron spectroscopy

Cited by 27 publications

References 21 publications

High-Temperature Coulometric Titration of La1−xSrxCoO3−δ: Evidence for the Effect of Electronic Band Structure on Nonstoichiometry Behavior

High-Temperature Coulometric Titration of La1−xSrxCoO3−δ: Evidence for the Effect of Electronic Band Structure on Nonstoichiometry Behavior

Electronic structure, phase stability, and magnetic properties ofLa1−xSrxRavindran1, Korzhavyi2, Fjellvåg3 et al. 1999Phys. Rev. B

Use of the Rigid Band Formalism to Interpret the Relationship between O Chemical Potential and Electron Concentration inLa1−xSrxLankhorst1, Bouwmeester2, Verweij3 1996Phys. Rev. Lett.949560View full textAdd to dashboardCite

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Electronic structure, phase stability, and magnetic properties ofLa1−xSrx
Ravindran
¹
,
Korzhavyi
²
,
Fjellvåg
³

et al. 1999
Phys. Rev. B

Use of the Rigid Band Formalism to Interpret the Relationship between O Chemical Potential and Electron Concentration inLa1−xSrx
Lankhorst
¹
,
Bouwmeester
²
,
Verweij
³

1996
Phys. Rev. Lett.
94
9
56
0
View full text Add to dashboard Cite