Olivine and Pyroxene Syntheses under High Temperature and High Pressure

Olivine (Mg2SiO4) and pyroxene (MgSiO3) single crystals were synthesized under high temperature (1 000~1 500 ℃) and high pressure (2~5 GPa) using the mixed powder of magnesium oxide (MgO) and silicon dioxide (SiO2) as starting materials. Results by TEM and XRD tests showed that the products increased with the temperature rising or the pressure decreasing. Meanwhile, phase transition relationship existed between Mg2SiO4 and MgSiO3 in this p-T ranges, and the mixed phase of Mg2SiO4-MgSiO3 would turn into the single phase of MgSiO3 at given pressure and temperature. The growth condition and character of Mg2SiO4 and MgSiO3 as well as phase transition relationship between Mg2SiO4 and MgSiO3 were discussed respectively.