Single crystal X-ray diffraction study of MgSiO3 perovskite from 77 to 400 K |
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| Authors: | Nancy L Ross Robert M Hazen |
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| Institution: | 1. Geophysical Laboratory, Carnegie Institution of Washington, 2801 Upton St., NW, 20008, Washington, DC, USA
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| Abstract: | Single crystal X-ray diffraction study of MgSiO3 perovskite has been completed from 77 to 400 K. The thermal expansion coefficient between 298 and 381 K is 2.2(8) × 10-5 K-1. Above 400 K, the single crystal becomes so multiply twinned that the cell parameters can no longer be determined.From 77 to 298 K, MgSiO3 perovskite has an average thermal expansion coefficient of 1.45(9) × 10-5 K-1, which is consistent with theoretical models and perovskite systematics. The thermal expansion is anisotropic; the a axis shows the most expansion in this temperature range ( a = 8.4(9) × 10-6 K-1) followed by c(c = 5.9(5) × 10-6 K-1) and then by b, which shows no significant change in this temperature range. In addition, the distortion (i.e., the tilting of the SiO6] octahedra) decreases with increasing temperature. We conclude that the behavior of MgSiO3 perovskite with temperature mirrors its behavior under compression. |
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