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Title: Single crystal growth and structural evolution across the 1st order valence transition in (Pr 1–yY y) 1–xCa xCoO 3-δ

Here, praseodymium-containing cobalt perovskites, such as (Pr 1-yY y) 1-xCa xCoO 3-δ, have been argued to undergo a first-order charge shift between Pr and hybridized Co-O orbitals that leads to a metal-insulator transition at a temperature, T VT. Magnetization and x-ray absorption spectroscopy measurements on single crystals of (Pr 0.85Y 0.15) 0.7Ca 0.3CoO 3-δ grown in an IR image furnace under 40-60 bar of oxygen confirm the presence of this valence transition. Single crystal x-ray synchrotron diffraction measurements are consistent with an isomorphic phase transition at T VT. No evidence of charge ordering was revealed by the single crystal diffraction. Dissimilar to analytical transmission electron microscopy measurements performed on a grain from a polycrystalline sample that revealed an oxygen vacancy order-disorder transition at T VT, the present single-crystal measurements did not evidence such a transition, likely reflecting a lower density of oxygen vacancies in the high-pO 2 grown single crystals.
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [1] ;  [1]
  1. Argonne National Lab. (ANL), Argonne, IL (United States)
  2. Univ. of Chicago, Argonne, IL (United States)
Publication Date:
Grant/Contract Number:
AC02-06CH11357
Type:
Published Article
Journal Name:
Journal of Solid State Chemistry
Additional Journal Information:
Journal Volume: 254; Journal Issue: C; Journal ID: ISSN 0022-4596
Publisher:
Elsevier
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22), Materials Sciences and Engineering Division; USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Scientific User Facilities Division; National Science Foundation (NSF)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; perovskite; cobaltite; valence transition; insulator-metal transition; isomorphic transition
OSTI Identifier:
1368593
Alternate Identifier(s):
OSTI ID: 1373417