title: Shock compression response of forsterite above 250 GPa.
abstract: Forsterite (Mg2SiO4) is one of the major planetary materials, and its behavior under extreme conditions is important to understand the interior structure of large planets, such as super-Earths, and large-scale planetary impact events. Previous shock compression measurements of forsterite indicate that it may melt below 200 GPa, but these measurements did not go beyond 200 GPa. We report the shock response of forsterite above ~250 GPa, obtained using the laser shock wave technique. We simultaneously measured the Hugoniot and temperature of shocked forsterite and interpreted the results to suggest the following: (i) incongruent crystallization of MgO at 271 to 285 GPa, (ii) phase transition of MgO at 285 to 344 GPa, and (iii) remelting above ~470 to 500 GPa. These exothermic and endothermic reactions are seen to occur under extreme conditions of pressure and temperature. They indicate complex structural and chemical changes in the system MgO-SiO2 at extreme pressures and temperatures and will affect the way we understand the interior processes of large rocky planets as well as material transformation by impacts in the formation of planetary systems.
authors: Department of Earth and Planetary Systems Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.
authors: Toshimori
authors: T
authors: Sekine
authors: Graduate School of Engineering, Osaka University, Suita 565-0871, Japan.; Photon Pioneers Center, Osaka University, Suita 565-0871, Japan.
authors: Norimasa
authors: N
authors: Ozaki
authors: Graduate School of Engineering, Osaka University, Suita 565-0871, Japan.
authors: Kohei
authors: K
authors: Miyanishi
authors: Graduate School of Engineering, Osaka University, Suita 565-0871, Japan.
authors: Yuto
authors: Y
authors: Asaumi
authors: Geodynamics Research Center, Ehime University, Matsuyama 790-8577, Japan.
authors: Tomoaki
authors: T
authors: Kimura
authors: Graduate School of Engineering, Osaka University, Suita 565-0871, Japan.
authors: Bruno
authors: B
authors: Albertazzi
authors: Graduate School of Engineering, Osaka University, Suita 565-0871, Japan.
authors: Yuya
authors: Y
authors: Sato
authors: Institute of Laser Engineering, Osaka University, Suita 565-0871, Japan.
authors: Youichi
authors: Y
authors: Sakawa
authors: Institute of Laser Engineering, Osaka University, Suita 565-0871, Japan.
authors: Takayoshi
authors: T
authors: Sano
authors: Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-856, Japan.
authors: Seiji
authors: 0000-0001-6076-3614
authors: S
authors: Sugita
authors: Planetary Exploration Research Center, Chiba Institute of Technology, Narashino 275-0016, Japan.
authors: Takafumi
authors: T
authors: Matsui
authors: Graduate School of Engineering, Osaka University, Suita 565-0871, Japan.; Photon Pioneers Center, Osaka University, Suita 565-0871, Japan.
authors: Ryosuke
authors: R
authors: Kodama
mesh_terms: D007834:Lasers; D044367:Phase Transition; D055585:Physical Phenomena; D011312:Pressure; D017655:Silicon Compounds
chemical_list: D017655:Silicon Compounds; C503823:forsterite
keywords: Forsterite; Hugoniot; MgO; incongruent crystallization; large rocky planets; laser shock compression; phase equilibria; phase transition; planetary impacts