In Situ X. Ray Observation of the Phase Transitions from [alpha] to [gamma] and from [gamma] to Perovskite+Periclase in Mg2SiO4

• Published in: The review of high pressure science and technology Vol. 7; p. 119
• Main Authors: Kato, T, Kubo, T, Morishima, H, Ohtani, E, Suzuki, A, Yamazaki, D, Mibe, K, Kikegawa, T, Shimomura, O
• Format: Journal Article
• Language: English
• Published: Tokyo Japan Science and Technology Agency 01.01.1998
• ISSN: 0917-639X; 1348-1940

In situ X-ray observation has been made on Mg5SiO4 forsterite in the pressure ranges over 25-30 GPa and 1250°C using double stage multianvil system with sintered diamond anvil window and intense X-rays from synchrotm radiation. Forsterite (α-phase) transfomed into spinel (γ-phase) at 28 GPa and 800°C in the fist heating cycles of the two runs. Spinel transformed into the assemblage of perovskite and periclase in the second heating cycless at 26. 4 GPa and 1200°C and at 28. 5 GPa and 950°C. The results show that α-γ transition can proceed outside the stability field of spinel, and that the blocking temperature, above which the stable assmblage of perovskite and periclase can be formed, has a pressure dependence.