Non-congruence of high-temperature mechanical and structural behaviors of LaCoO3 based perovskites |
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| Affiliation: | 1. Division of Superconductivity and Magnetism, Faculty of Physics and Geoscience, University of Leipzig, D - 04103 Leipzig, Germany;2. Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India;3. Department of Physics, Dr. B. R. Ambedkar National Institute of Technology, Jalandhar 144011, India;4. Instituto de Fisica Gleb Wataghin, Universidade Estadual de Campinas (UNICAMP) Campinas, 13.083-859, SP, Brazil;5. Department of Physics, Federal University of Maranhão, São Luís 65080-805, Brazil;6. UGC-DAE Consortium for Scientific Research, Indore 452001, India;7. European Synchrotron Radiation Facility, BP 220, 38043 Grenoble Cedex, France;8. BCET, Gurdaspur, Punjab 143521, India;9. Centre for Materials Science & Engineering, National Institute of Technology, Hamirpur 177005, India |
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| Abstract: | This paper presents the mechanical behavior of LaCoO3 and La0.8Ca0.2CoO3 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 LaCoO3 in the 700–900 °C temperature range, leading to a significant increase in the measured Young’s modulus, whereas La0.8Ca0.2CoO3 exhibits softening from 100 °C to 1000 °C, as expected for most materials upon heating. Neutron diffraction, X-ray diffraction and micro-Raman spectroscopy are used 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 LaCoO3 as opposed to the softening behavior in La0.8Ca0.2CoO3 at high temperatures (above 500 °C). |
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| Keywords: | Lanthanum cobaltite Powder diffraction Raman spectroscopy Young’s modulus Temperature dependence Hysteresis |
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