First-principles thermodynamic modeling of lanthanum chromate perovskites

P. Dalach*, D. E. Ellis, A. Van De Walle

*Corresponding author for this work

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

Tendencies toward local atomic ordering in (A,A′)(B,B′)O 3-δ mixed composition perovskites are modeled to explore their influence on thermodynamic, transport, and electronic properties. In particular, dopants and defects within lanthanum chromate perovskites are studied under various simulated redox environments. (La 1-x,Sr x)(Cr 1-y,Fe y)O 3-δ (LSCF) and (La 1-x,Sr x)(Cr 1-y,Ru y)O 3-δ (LSCR) are modeled using a cluster expansion statistical thermodynamics method built upon a density functional theory database of structural energies. The cluster expansions are utilized in lattice Monte Carlo simulations to compute the ordering of Sr and Fe(Ru) dopant and oxygen vacancies (Vac). Reduction processes are modeled via the introduction of oxygen vacancies, effectively forcing excess electronic charge onto remaining atoms. LSCR shows increasingly extended Ru-Vac associates and short-range Ru-Ru and Ru-Vac interactions upon reduction; LSCF shows long-range Fe-Fe and Fe-Vac interaction ordering, inhibiting mobility. First principles density functional calculations suggest that Ru-Vac associates significantly decrease the activation energy of Ru-Cr swaps in reduced LSCR. These results are discussed in view of experimentally observed extrusion of metallic Ru from LSCR nanoparticles under reducing conditions at elevated temperature.

Original languageEnglish (US)
Article number014108
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume85
Issue number1
DOIs
StatePublished - Jan 17 2012

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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