Abstract
The stable phase of Mg2GeO4 is spinel type (γ-phase) at room temperature and it converts to olivine type (α-phase) at temperature above 810°C and melts at 1855°C in air. In the present study, the phase equilibrium among a-, 7'- and the melt were empirically determined in the region of temperature and pressure up to 2200°C and 5 GPa. The dependency of the melting temperature on the pressu re is linear and given by d Tm/dP =30°C. GPa-1. The triple point, where α-, γ-phases and the melt coexist, locates at 1950°C and 3.5 GPa. The phase boundary between α-and γ-phases is a curve concave downwards as illustrated in Fig.3.
