start-ver=1.4 cd-journal=joma no-vol=12 cd-vols= no-issue=1 article-no= start-page=4305 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2021 dt-pub=20210714 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Ultrafast olivine-ringwoodite transformation during shock compression en-subtitle= kn-subtitle= en-abstract= kn-abstract=Meteorites from interplanetary space often include high-pressure polymorphs of their constituent minerals, which provide records of past hypervelocity collisions. These collisions were expected to occur between kilometre-sized asteroids, generating transient high-pressure states lasting for several seconds to facilitate mineral transformations across the relevant phase boundaries. However, their mechanisms in such a short timescale were never experimentally evaluated and remained speculative. Here, we show a nanosecond transformation mechanism yielding ringwoodite, which is the most typical high-pressure mineral in meteorites. An olivine crystal was shock-compressed by a focused high-power laser pulse, and the transformation was time-resolved by femtosecond diffractometry using an X-ray free electron laser. Our results show the formation of ringwoodite through a faster, diffusionless process, suggesting that ringwoodite can form from collisions between much smaller bodies, such as metre to submetre-sized asteroids, at common relative velocities. Even nominally unshocked meteorites could therefore contain signatures of high-pressure states from past collisions. en-copyright= kn-copyright= en-aut-name=OkuchiTakuo en-aut-sei=Okuchi en-aut-mei=Takuo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=SetoYusuke en-aut-sei=Seto en-aut-mei=Yusuke kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=TomiokaNaotaka en-aut-sei=Tomioka en-aut-mei=Naotaka kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=MatsuokaTakeshi en-aut-sei=Matsuoka en-aut-mei=Takeshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=AlbertazziBruno en-aut-sei=Albertazzi en-aut-mei=Bruno kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=HartleyNicholas J. en-aut-sei=Hartley en-aut-mei=Nicholas J. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=InubushiYuichi en-aut-sei=Inubushi en-aut-mei=Yuichi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= en-aut-name=KatagiriKento en-aut-sei=Katagiri en-aut-mei=Kento kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=8 ORCID= en-aut-name=KodamaRyosuke en-aut-sei=Kodama en-aut-mei=Ryosuke kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=9 ORCID= en-aut-name=PikuzTatiana A. en-aut-sei=Pikuz en-aut-mei=Tatiana A. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=10 ORCID= en-aut-name=PurevjavNarangoo en-aut-sei=Purevjav en-aut-mei=Narangoo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=11 ORCID= en-aut-name=MiyanishiKohei en-aut-sei=Miyanishi en-aut-mei=Kohei kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=12 ORCID= en-aut-name=SatoTomoko en-aut-sei=Sato en-aut-mei=Tomoko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=13 ORCID= en-aut-name=SekineToshimori en-aut-sei=Sekine en-aut-mei=Toshimori kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=14 ORCID= en-aut-name=SuedaKeiichi en-aut-sei=Sueda en-aut-mei=Keiichi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=15 ORCID= en-aut-name=TanakaKazuo A. en-aut-sei=Tanaka en-aut-mei=Kazuo A. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=16 ORCID= en-aut-name=TangeYoshinori en-aut-sei=Tange en-aut-mei=Yoshinori kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=17 ORCID= en-aut-name=TogashiTadashi en-aut-sei=Togashi en-aut-mei=Tadashi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=18 ORCID= en-aut-name=UmedaYuhei en-aut-sei=Umeda en-aut-mei=Yuhei kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=19 ORCID= en-aut-name=YabuuchiToshinori en-aut-sei=Yabuuchi en-aut-mei=Toshinori kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=20 ORCID= en-aut-name=YabashiMakina en-aut-sei=Yabashi en-aut-mei=Makina kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=21 ORCID= en-aut-name=OzakiNorimasa en-aut-sei=Ozaki en-aut-mei=Norimasa kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=22 ORCID= affil-num=1 en-affil=Institute for Integrated Radiation and Nuclear Science, Kyoto University kn-affil= affil-num=2 en-affil=Graduate School of Science, Kobe University kn-affil= affil-num=3 en-affil=Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC) kn-affil= affil-num=4 en-affil=Institute for Open and Transdisciplinary Research Initiatives, Osaka University kn-affil= affil-num=5 en-affil=Graduate School of Engineering, Osaka University kn-affil= affil-num=6 en-affil=Graduate School of Engineering, Osaka University kn-affil= affil-num=7 en-affil=Japan Synchrotron Radiation Research Institute, kn-affil= affil-num=8 en-affil=Graduate School of Engineering, Osaka University kn-affil= affil-num=9 en-affil=Graduate School of Engineering, Osaka University kn-affil= affil-num=10 en-affil=Graduate School of Engineering, Osaka University kn-affil= affil-num=11 en-affil=Institute for Planetary Materials, Okayama University kn-affil= affil-num=12 en-affil=RIKEN SPring-8 Center kn-affil= affil-num=13 en-affil=Graduate School of Science, Hiroshima University kn-affil= affil-num=14 en-affil=Graduate School of Engineering, Osaka University kn-affil= affil-num=15 en-affil=RIKEN SPring-8 Center kn-affil= affil-num=16 en-affil=Graduate School of Engineering, Osaka University kn-affil= affil-num=17 en-affil=Japan Synchrotron Radiation Research Institute kn-affil= affil-num=18 en-affil=Japan Synchrotron Radiation Research Institute kn-affil= affil-num=19 en-affil=Institute for Integrated Radiation and Nuclear Science, Kyoto University kn-affil= affil-num=20 en-affil=Japan Synchrotron Radiation Research Institute kn-affil= affil-num=21 en-affil=Japan Synchrotron Radiation Research Institute kn-affil= affil-num=22 en-affil=Graduate School of Engineering, Osaka University kn-affil= END start-ver=1.4 cd-journal=joma no-vol=7 cd-vols= no-issue=3 article-no= start-page=370 end-page=374 dt-received= dt-revised= dt-accepted= dt-pub-year=2020 dt-pub=202005 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Strong hydrogen bonding in a dense hydrous magnesium silicate discovered by neutron Laue diffraction en-subtitle= kn-subtitle= en-abstract= kn-abstract=A large amount of hydrogen circulates inside the Earth, which affects the long-term evolution of the planet. The majority of this hydrogen is stored in deep Earth within the crystal structures of dense minerals that are thermodynamically stable at high pressures and temperatures. To understand the reason for their stability under such extreme conditions, the chemical bonding geometry and cation exchange mechanism for including hydrogen were analyzed in a representative structure of such minerals (i.e. phase E of dense hydrous magnesium silicate) by using time-of-flight single-crystal neutron Laue diffraction. Phase E has a layered structure belonging to the space group R (3) over barm and a very large hydrogen capacity (up to 18% H2O weight fraction). It is stable at pressures of 13-18 GPa and temperatures of up to at least 1573 K. Deuterated high-quality crystals with the chemical formula Mg2.28Si1.32D2.15O6 were synthesized under the relevant high-pressure and high-temperature conditions. The nuclear density distribution obtained by neutron diffraction indicated that the O-D dipoles were directed towards neighboring O2- ions to form strong interlayer hydrogen bonds. This bonding plays a crucial role in stabilizing hydrogen within the mineral structure under such high-pressure and high-temperature conditions. It is considered that cation exchange occurs among Mg2+, D+ and Si4+ within this structure, making the hydrogen capacity flexible. en-copyright= kn-copyright= en-aut-name=PurevjavNarangoo en-aut-sei=Purevjav en-aut-mei=Narangoo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=OkuchiTakuo en-aut-sei=Okuchi en-aut-mei=Takuo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=HoffmanChristina en-aut-sei=Hoffman en-aut-mei=Christina kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= affil-num=1 en-affil=Institute for Planetary Materials, Okayama University kn-affil= affil-num=2 en-affil=Institute for Planetary Materials, Okayama University kn-affil= affil-num=3 en-affil=Neutron Scattering Division, Neutron Sciences Directorate, Oak Ridge National Laboratory kn-affil= en-keyword=hydrogen bonding kn-keyword=hydrogen bonding en-keyword=Earth's deep mantle kn-keyword=Earth's deep mantle en-keyword=dense hydrous magnesium silicates kn-keyword=dense hydrous magnesium silicates en-keyword=neutron diffraction kn-keyword=neutron diffraction END