On thermal and vibrational properties of LaGaO3 single crystals |
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| Authors: | Nina Orlovskaya Mykola Lugovy Cassandra Carpenter Siddhartha Pathak David Steinmetz Edgar Lara-Curzio Christine Klemenz Miladin Radovic |
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| Affiliation: | 1. Department of Mechanical, Materials, and Aerospace Engineering, University of Central Florida, Orlando, FL 32816, USA;2. Department of Materials Science and Engineering, Drexel University, Philadelphia, PA, USA;3. Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA;4. Advanced Materials Processing and Analysis Center, University of Central Florida, Orlando, FL 32816, USA;5. Department of Mechanical Engineering, Texas A&M University, College Station, TX 77843, USA |
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| Abstract: | The thermal expansion and vibrational properties of [1 0 0] and [0 0 1] LaGaO3 single crystals have been studied by thermal mechanical analysis and micro-Raman spectroscopy. A first-order orthorhombic to rhombohedral phase transition has been confirmed by both techniques, as well as by in situ heating using optical microscopy. The appearance of a metastable intermediate phase, tentatively assigned as monoclinic, has been detected both by optical microscopy and Raman spectroscopy upon heating of the [1 0 0] and [0 0 1] LaGaO3 single crystals. Not only temperature, but the stress-induced orthorhombic to rhombohedral phase transition has also been detected by Raman mapping of the residual impression made by Vickers indentation. The position map of bands belonging to the lower-temperature/pressure orthorhombic and the higher-temperature/pressure rhombohedral phase show that the rhombohedral phase is located inside the impression, where the applied indentation stresses are the highest, whereas no rhombohedral phase is detected outside the impression, where the surface has not been altered by contact stresses. |
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