Shigeaki Ono

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The Earth's lower mantle is believed to be composed mainly of (Mg,Fe)SiO3 perovskite, with lesser amounts of (Mg,Fe)O and CaSiO3 (ref. 1). But it has not been possible to explain many unusual properties of the lowermost approximately 150 km of the mantle (the D" layer) with this mineralogy. Here, using ab initio simulations and high-pressure experiments, we(More)
Knittle, E. & Buffett, B. A.) 273–297 (American Geophysical Union, Washington DC, 1998). 14. Sidorin, I., Gurnis, M. & Helmberger, D. V. Evidence for a ubiquitous seismic discontinuity at the base of the mantle. Science 286, 1326–1331 (1999). 15. Lay, T., Williams, Q., Garnero, E. J., Kellogg, L. & Wysession, M. E. in The Core-Mantle Boundary Region (eds(More)
In situ observations of the perovskite–CaIrO3 phase transition in MgSiO3 and in pyrolitic compositions were carried out using a laser-heated diamond anvil cell interfaced with a synchrotron radiation source. For pure MgSiO3, the phase boundary between the orthorhombic Mg-perovskite and CaIrO3-type phases in the temperature range of 1300–3100 K was(More)
Post-aragonite phase of CaCO3, experimentally known to be stable above 40 GPa [S. Ono, T. Kikegawa, Y. Ohishi, J. Tsuchiya, Post-aragonite phase transformation in CaCO3 at 40 GPa, Am. Mineral. 90 (2005) 667–671], is believed to be a major carboncontaining mineral in the Earth’s mantle. Crystal structure of this mineral phase could not be solved using(More)
a Laboratory of Crystallography, Department of Materials ETH Zurich, HCI G 515, Wolfgang-Pauli-Str. 10, CH-8093 Zurich, Switzerland b Geology Department, Moscow State University, 119992 Moscow, Russia c Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima-cho, Yokosuka-shi, Kanagawa 237-0061, Japan(More)
Carbonates are important constituents of marine sediments and play a fundamental role in the recycling of carbon into the Earth's deep interior via subduction of oceanic crust and sediments. Study of the stability of carbonates under high pressure and temperature is thus important for modelling the carbon budget in the entire Earth system. Such studies,(More)
Using ab initio simulations and high-pressure experiments in a diamond anvil cell, we show that alumina (Al(2)O(3)) adopts the CaIrO(3)-type structure above 130 GPa. This finding substantially changes the picture of high-pressure behavior of alumina; in particular, we find that perovskite structure is never stable for Al(2)O(3) at zero Kelvin. The(More)
We have used a laser-heated diamond anvil cell to investigate the stability and compressibility of Cmcm CaIrO3-type (postperovskite structure) Al2O3 at pressures up to 200 GPa. A phase transformation from the Pbcn Rh2O3(II)-type to the CaIrO3-type structure was observed at 130 GPa, which is consistent with previous theoretical studies. The observed(More)
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. [1] Signatures of sulfur mass-independent fractionation (S-MIF) are observed(More)