Ferroelastic Behavior of LaCoO3-Based Ceramics |
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| Authors: | Kjersti Kleveland Nina Orlovskaya Tor Grande Anne Marie Mardal Moe Mari-Ann Einarsrud Kristin Breder George Gogotsi |
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| Affiliation: | Department of Chemistry, Norwegian University of Science and Technology, N–7491 Trondheim, Norway;Oak Ridge National Laboratory, Oak Ridge, Tennessee 3731–6069;Institute for Problems of Strength, National Academy of Sciences of Ukraine, Kiev, Ukraine |
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| Abstract: | LaCoO3 and La0.8Ca0.2CoO3 ceramics show a nonelastic stress–strain behavior during four-point bending experiments where hysteresis loops are observed during loading–unloading cycles. Permanent strain is stored in the material after unloading, and a mechanism related to ferroelastic domain switching in the rhombohedral perovskite is proposed. Domain switching in the materials has been confirmed using X-ray diffractometry. Fracture toughnesses of La0.8Ca0.2CoO3 measured using single-edge notched beam and single-edge V-notched beam methods coincide and are equal to 2.2 MPa·m1/2 at room temperature and decrease to ～1 MPa·m1/2 at temperatures >300°C. A decrease in fracture toughness is consistent with ferroelastic behavior, because the rhombohedral distortion decreases with increasing temperature. |
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| Keywords: | ferroelastic materials cobalt/cobalt compounds stress strain |
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