大型放射光施設 SPring-8

Speaker : Yanbin Wang

Language : 英語

Affiliation : The University of Chicago (Beamline Scientist,13 BMD @APS)

Title : High pressure synchrotron experiments on structure and properties of silicate melts

Abstract:
In this presentation, we present recent results on structural evolution of silicate and carbonate melts at high pressures, along with measurements of density, elasticity, and viscosity, to help understand structural influences on melt properties. High-pressure structure studies on glasses and melts were conducted using large-volume high-pressure devices at GSECARS and HPCAT sectors of the Advanced Photon Source. Structures of jadeite (Jd; polymerized) and diopside (Di; depolymerized) melts exhibit distinct responses to pressure. In Jd melt, T-O (T denotes tetrahedrally coordinated Al and Si) bond length, T-T bond distance, and T-O-T bond angle all display rapid and non-linear decrease with increasing pressure to ~3 GPa. In Di melt, these parameters vary linearly with pressure and change very little. Molecular dynamics calculations were employed to examine details of structural evolution in the two types of liquids. A model was established which links structural evolution to changes in melt density and viscosity, with pressure [1]. On the other hand, carbonate melts are characterized by the planar CO₃ trigonal formation under upper mantle pressures, as opposed to SiO₄ tetrahedra in silicate melts. Recent studies using high-speed falling-sphere viscometry how that carbonate melts tend to have extremely low viscosities [2], as the CO₃ units have no unpaired orbitals available for covalent bonding and hence do not polymerize. Implications for the dynamics of melt migration in the deep earth will be discussed.
[1] Wang, Y., et al. (2014) Nature Comm., 5, 3241, doi: 10.1038/ncomms4241.
[2] Kono, Y., et al. (2014), Nature Comm., 5, 5091, doi: 10.1038/ncomms6091.

Speaker : Tony Yu

Language : 英語

Affiliation : The University of Chicago (Beamline Scientist,13 BMD @APS)

Title : An overview of GSECARS LVP program

Abstract:
The development of synchrotron-based large-volume high pressure (LVP) techniques for studying earth-related materials under extreme pressure and temperature (PT) conditions has been an ongoing effort at the GeoSoilEnviroCARS (GSECARS) of the Advanced Photon Source (APS). Over the years, these developmental efforts have enabled us to conduct coordinated studies on earth materials in both the solid and liquid states under high PT conditions. In this presentation we will show, with the following examples, how state-of-the-art techniques were used in our recent scientific studies: (1) high PT ultrasonic velocity measurements, (2) rheological properties of earth materials at high pressure and temperature, using the deformation DIA (D-DIA), (3) acoustic emission recording coupled with D-DIA for monitoring ductile vs. brittle behavior and reaction progress in rock deformation studies, (4) high pressure 3D imaging of composite materials using the high-pressure x-ray tomographic microscope (HPXTM), and (5) structure studies of non-crystalline materials using a Paris-Edinburgh Press (PEP) combined with a multi-channel collimator (MCC). These techniques have the potential to provide the community with a complete suite of tools for structure, density, elasticity and viscosity measurements of earth materials.

担当者 : 肥後 祐司 (Yuji Higo)
Mail : higo@spring8.or.jp
PHS : 3721