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Thermodynamics and behavior of γ-Mg2SiO4at high pressure: Implications for Mg2SiO4phase equilibrium

✍ Scribed by A. Chopelas; R. Boehler; T. Ko

Publisher
Springer-Verlag
Year
1994
Tongue
English
Weight
914 KB
Volume
21
Category
Article
ISSN
0342-1791

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✦ Synopsis

Raman spectra of )J-Mg2SiO4 taken to 200 kbar were used to calculate entropy and heat capacity at various P-Tconditions. These new thermodynamic data on ~-MgSiO4, similar data on MgSiO 3 perovskite (pv), previous data on fl-MgSiO 4 and MgO (row), and previous volumetric data of all phases were used to calculate the phase boundaries in the Mg2SiO 4 phase diagram. Our resulting slope for the fl ---> 7 transition (50__ 4 bar K -1) is in excellent agreement with recent multi-anvil studies. The slopes for the fl ~ pv + MgO and 7 ~ pv + MgO are -7 _+ 3 and -25 _+ 4 bar K-1, respectively, and are consistent with our CO 2 laser heated diamond anvil studies. These slopes result in a fl-7-MgO + pv triple point at approximately 229 kbar and 2260 K for the iron free system.

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