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Title: Microdomain Formation, Oxidation, and Cation Ordering in LaCa 2Fe 3O 8+y

The compound LaCa 2Fe 3O 8+y, also known as the Grenier phase, is known to undergo an order-disorder transformation (ODT) at high temperatures. Oxidation has been observed when the compound is cooled in air after the ODT. In this study, we have synthesized the Grenier compound in air using traditional solid state reactions and investigated the structure and composition before and after the ODT. Thermal analysis showed that the material undergoes an order-disorder transformation in both oxygen and argon atmospheres with dynamic, temperature dependent, oxidation upon cooling. Results from scanning transmission electron microscopy (STEM) suggest that the Grenier phase has preferential segregation of Ca and La on the two crystallographic A-sites before the ODT, but a random distribution above the ODT temperature. Furthermore, STEM images suggest the possibility that oxygen excess may exist in La-rich regions within microdomains rather than at microdomain boundaries.
 [1] ;  [2] ;  [3]
  1. Boise State Univ., ID (United States). Dept. of Materials Science and Engineering
  2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Fundamental and Computational Sciences Directorate
  3. Boise State Univ., ID (United States). Dept. of Materials Science and Engineering; Center for Advanced Energy Studies, Idaho Falls, ID (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 0002-7820; 47296
Grant/Contract Number:
Published Article
Journal Name:
Journal of the American Ceramic Society
Additional Journal Information:
Journal Volume: 98; Journal Issue: 7; Journal ID: ISSN 0002-7820
American Ceramic Society
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org:
Country of Publication:
United States
36 MATERIALS SCIENCE; Chemical Imaging; LCF material system; Environmental Molecular Sciences Laboratory
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1221482; OSTI ID: 1295969