ISSP - The institute for Solid State Physics

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Yamamuro Group
Professor
YAMAMURO,
Osamu

Research Associate
AKIBA,
Hiroshi

To The Group's Homepage Japanese Only

We are studying chemical physics of complex condensed matters, especially glasses and supercooled liquids, water and related materials, ionic liquids, and nanoparticles of hydrogen storage metals. Glass transition is a mysterious phenomenon in which liquids solidify without structural change. This is one of big and long-standing issues in physics. Water, which is the most familiar material for us, exhibits various unique phenomena caused by hydrogen bonds. Ionic liquids have nanometer-size domains and hierarchical dynamics generated by competing electrostatic and van der Waals interactions. Hydrogen atoms in metal nanoparticles give rise to unusual structure and dynamics caused by the surface effects and resultant distorted potential energy surfaces. These substances are investigated by neutron scattering, x-ray diffraction, heat capacity, and dielectric measurements. Our aim is to find simple (?) rules involved in complex systems from the three different points of view, i.e., structure, dynamics, and thermodynamic.

X-ray diffraction patterns of the vapor-deposited glass (red curve) and crystal (blue curve) of CO2. The pair-distribution function analyses revealed that the nearest-neighbor configuration of CO2 molecules is as shown in the figure for both glassy and crystalline states.
Arrhenius plots of bulk and nanoparticles of palladium hydrides. These relaxation times were determined by the QENS experiments with 4 spectrometers. The Q dependence of the relaxation clarified that τ1, τ2 and τ3 correspond to the H atomic diffusion at the O-sites while τ4 at the T-sites.

Research Subjects

  1. Dynamics of disordered condensed systems, such as glass transitions and boson peaks
  2. Structure and dynamics of water and related materials such as hydrated porous crystals
  3. Thermal and dynamical properties of ionic liquids
  4. Structural and dynamical properties of nanoparticles of hydrogen storage metals