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Title: Non-congruence of high-temperature mechanical and structural behaviors of LaCoO 3 based perovskites

Our paper presents the mechanical behavior of LaCoO 3 and La 0.8Ca 0.2CoO3 ceramics under four-point bending in which the two cobaltites are subjected to a low stress of ~8 MPa at temperatures ranging from room temperature to 1000 °C. Unexpected stiffening is observed in pure LaCoO 3 in the 700–900 °C temperature range, leading to a significant increase in the measured Young’s modulus, whereas La 0.8Ca 0.2CoO 3 exhibits softening from 100 °C to 1000 °C, as expected for most materials upon heating. we use neutron diffraction, X-ray diffraction and micro-Raman spectroscopy to study the crystal structure of the two materials in the RT–1000 °C temperature range. Despite a detailed study, there is no conclusive evidence to explain the stiffening behavior observed in pure LaCoO 3 as opposed to the softening behavior in La 0.8Ca 0.2CoO 3 at high temperatures (above 500 °C).
Authors:
 [1] ;  [1] ;  [1] ;  [2] ;  [1] ;  [1] ;  [3] ;  [1] ;  [4] ;  [5] ;  [6] ;  [7] ;  [7]
  1. Univ. of Central Florida, Orlando, FL (United States). Dept. of Mechanical and Aerospace Engineering
  2. (ORNL), Oak Ridge, TN (United States). Chemical Engineering Materials Division
  3. (Ukraine)
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Engineering Materials Division
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Quantum Condensed Matter Division
  6. Univ. of London (United Kingdom). School of Engineering and Materials Science
  7. Swiss Federal Laboratories for Materials Science and Technology, Duebendorf (Switzerland)
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Journal of the European Ceramic Society
Additional Journal Information:
Journal Volume: 37; Journal Issue: 4; Journal ID: ISSN 0955-2219
Publisher:
Elsevier
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Lanthanum cobaltite; Powder diffraction; Raman spectroscopy; Young’s modulus; Temperature dependence; Hysteresis
OSTI Identifier:
1341565
Alternate Identifier(s):
OSTI ID: 1460428