Formation, cationic site exchange and surface structure of mechanosynthesized EuCrO3 nanocrystalline particles

H. M. Widatallah, S. H. Al-Harthi, C. Johnson, Z. Klencsár, A. M. Gismelseed, E. A. Moore, A. D. Al-Rawas, C. I. Wynter, D. E. Brown

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26 Citations (Scopus)

Abstract

Nanocrystalline EuCrO3 particles (∼25 nm) have been prepared by pre-milling a 1 : 1 molar mixture of Eu2O3 and Cr 2O3 for 60 h followed by sintering at 700 °C (12 h). This temperature is ∼500-600 °C lower than those at which the material, in bulk form, is conventionally prepared. Rietveld analysis of the x-ray powder diffraction pattern of the EuCrO3 nanoparticles favours a structural model involving a slight degree of cationic exchange where ∼11% of the Eu3+ and Cr3+ ions exchange their normal dodecahedral A- and octahedral B-sites, respectively, in the perovskite-related structure. This cationic site exchange, which is unusual in a perovskite structure, has been well supported by the corresponding room-temperature 151Eu Mössbauer spectrum of the nanoparticles that in addition to displaying a distribution in the principal component of the EFG tensor (Vzz) at the usual A-sites of the 151Eu nuclei, also revealed the presence of a subcomponent with ∼11% area fraction and a considerably increased |V zz| value that was associated with Eu3+ ions at octahedral B-sites. X-ray photoelectron and Auger electron spectroscopic techniques reveal a complex surface structure where extremely thin layers of un-reacted Eu 2O3 and Cr2O3 cover most of the EuCrO3 nanoparticles' surfaces together with some traces of elemental Cr. The binding energies associated with Eu3+ 3d5/2, Eu3+ 4d3/2, Cr3+ 2p3/2 and O 2- 1s core-level electrons in EuCrO3 are estimated from the x-ray photoelectron data for the first time.

Original languageEnglish
Article number265403
JournalJournal of Physics D: Applied Physics
Volume44
Issue number26
DOIs
Publication statusPublished - Jul 6 2011

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Electronic, Optical and Magnetic Materials
  • Acoustics and Ultrasonics
  • Surfaces, Coatings and Films

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