| Autor: |
Jia, Muhua, Liu, Yungui, Jiang, Sheng, Wen, Wen, Zhai, Shuangmeng |
| Předmět: |
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| Zdroj: |
American Mineralogist; Nov2024, Vol. 109 Issue 11, p1973-1981, 9p |
| Abstrakt: |
In situ X-ray diffraction and Raman spectroscopy of a synthetic whitlockite, Ca9Mg(PO3OH) (PO4)6, have been conducted at high pressures or high temperatures. The results show that whitlockite is stable up to ~15 GPa at ambient temperature and undergoes a thermally induced dehydrogenation to merrillite above 973 K at ambient pressure. The obtained pressure-volume data were fitted using a third-order Birch-Murnaghan equation of state, yielding an isothermal bulk modulus of K0 = 79(4) GPa with a pressure derivative of K 0 ′ = 4.3(6). When K 0 ′ was fixed at 4, the refined isothermal bulk modulus was 81(1) GPa. The volumetric thermal expansion coefficient (αV) is 4.05(8) × 10-5 K−1, and the axial thermal expansion coefficients (αa and αc) are 1.07(5) × 10−5 K−1 and 1.91(6) × 10−5 K−1. Both compressibility and thermal expansion show an axial anisotropy. The effects of pressure and temperature on the Raman spectra of whitlockite have been quantitatively analyzed. The isothermal and isobaric mode Grüneisen parameters and the intrinsic anharmonic mode parameters of whitlockite were derived. Some amounts of OH−-bearing whitlockite may be preserved in meteorites if whitlockite undergoes a low-temperature process. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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