Cristin-resultat-ID: 1148862
Sist endret: 12. februar 2015, 22:54
NVI-rapporteringsår: 2014
Resultat
Vitenskapelig artikkel
2014

Oxygen nonstoichiometry in (Ca2CoO3)0.62(CoO2): a combined experimental and computational study

Bidragsytere:
  • Matthias Schrade
  • Simone Casolo
  • Paul J. Graham
  • Clemens Ulrich
  • Sean Li
  • Ole Martin Løvvik
  • mfl.

Tidsskrift

Journal of Physical Chemistry C
ISSN 1932-7447
e-ISSN 1932-7455
NVI-nivå 1

Om resultatet

Vitenskapelig artikkel
Publiseringsår: 2014
Publisert online: 2014
Trykket: 2014
Volum: 118
Hefte: 33
Sider: 18899 - 18907
Open Access

Importkilder

Scopus-ID: 2-s2.0-84906536565

Beskrivelse Beskrivelse

Tittel

Oxygen nonstoichiometry in (Ca2CoO3)0.62(CoO2): a combined experimental and computational study

Sammendrag

The oxygen nonstoichiometry in the misfit calcium cobaltite (Ca2CoO3)0.62(CoO2) has been studied experimentally and by density functional theory (DFT) calculations. The standard oxidation enthalpy ΔH0Ox of oxygen deficient (Ca2CoO3)0.62(CoO2) was measured directly using simultaneous thermogravimetry and differential scanning calorimetry. ΔH0Ox was found to be in agreement with the prediction from a previously published defect chemical model based on purely thermogravimetrical analysis. A series of samples with different oxygen vacancy concentration was prepared by annealing in air, followed by rapid quenching. Room-temperature Raman spectroscopy showed a sharp mode at 700 cm–1 decreasing in intensity with increasing vacancy concentration. We discuss this observation as evidence for oxygen vacancies being preferably formed within the central layer of the Ca2CoO3 subsystem. DFT calculations demonstrated that the calculated electronic structure is sensitive to the chosen model of the crystal structure. Still, for all investigated models, the standard formation enthalpy of oxygen vacancies within the Ca2CoO3 moiety was much lower than that for a site within the CoO2 layer, in agreement with the presented experimental data.

Bidragsytere

Matthias Schrade

  • Tilknyttet:
    Forfatter
    ved Senter for materialvitenskap og nanoteknologi ved Universitetet i Oslo
  • Tilknyttet:
    Forfatter
    ved Fysisk institutt ved Universitetet i Oslo

Simone Casolo

  • Tilknyttet:
    Forfatter
    ved Università degli Studi di Milano

Paul J. Graham

  • Tilknyttet:
    Forfatter
    ved University of New South Wales

Clemens Ulrich

  • Tilknyttet:
    Forfatter
    ved University of New South Wales

Sean Li

  • Tilknyttet:
    Forfatter
    ved University of New South Wales
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