Studies of Phase Equilibrium in Mg2SiO4 up to Pressures Higher than 20 GPa
High pressure phase transformations of magnesium silicates have been studied extensively by many investigators relative to the composition of the Earth’s mantle. For example, for Mg2SiO4 Ringwood and Major  have reported the existence of the β phases. Suito  first succeeded in the synthesis of γ-Mg2SiO4 and studied the α-β phase boundary. Following this work, Ito et al.  clarified the detailed crystallographic data of the γ phase. With respect to successive transformation of γ-Mg2SiO4, Kumazawa et al.  and Ming and Bassett  have reported on its decomposition into the oxide mixture of stishovite plus MgO periclase. On the other hand, Liu [6,7] and Ito  have found that the post-spinel phase in Mg2SiO4 is actually the assemblage of MgSiO3 orthorhombic perovskite plus MgO periclase. Recently Suito  has reported some detailed stability relations among the α, β and γ phases in Mg2SiO4.
KeywordsPhase Boundary Transition Point Edge Length Pressure Medium Transition Curve
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