◆Earth, Planetary and Materials Sciences

Geodynamics Research Center (GRC) is an international research institute where researchers conduct leading-edge studies on materials and states of the Earth's deep interior in order to reveal dynamics and evolution of the Earth and planets, based on advanced high-pressure experiments and numerical simulations. We investigate various issues of the Earth and planetary sciences, chemical composition of the Earth's lower mantle, materials and structures of the Earth's core, Earth's deep water, internal structure of solar planets and exoplanets and dynamics of the planetary interior, and expand our techniques and knowledge to a field of material sciences for synthesizing novel useful materials such as the world-hardest material "HIME-Diamond".

The radius of the Earth is about 6,400 km, but only 10 km depth is achieved by drillings. The Earth's deep interior is an unreachable place where pressure and temperature at the center are estimated to be respectively 360 GPa and 5000 K or higher. Thus, high-pressure and temperature experiments and numerical simulations are essential tools to study dynamics and composition under such extreme conditions. Developments of the techiniques at GRC lead to an innovative area of high-pressure materials sciences; syntheses of newly novel materials which are obtainable only by high pressure experiments.

◆PRIUS: Premier Research Institute for Ultrahigh-pressure Sciences

GRC operates PRIUS from 2013 which is one of the "Joint Usage / Research Centers" in Japan authorized by the Ministry of Education, Culture, Sports, Science and Technology. Missions of PRIUS, as an international education and research hub, are to conduct Earth and planetary science and material science research by using the high-pressure techniques with the objective of creating new fields of science thorough the international collaborations and interdisciplinary networks of researchers.
  ◆High-pressure and temperature experiments

GRC conducts experiments under conditions of ultra high pressure and high temperature experiments of the Earth's and planetary deep interiors by using two types of high-pressure generationg appaturs: Munti-anvil high-pressure apparatus and Diamond anvil cell apparatua. GRC is equipped with several types of Multi-anvil apparatus, including the world-largest class one of 6000-ton press, BOTCHAN.

◆Phase transitions of minerals

A “phase transition” is characterized by the change of configuration of a toms in mineral by the effect of pressure. Diamond is a high pressure form of graphite, whose phase transition occurs at 5 GPa (150 km depth). Measurements of the conditions where the phase transitions occur and changes of the physical properties of minerals (density, sound velocity, chemical properties etc) accompanying the phase transition bring fruitful information for understandings of the Earth's deep structure and materials.

◆Numeral simulations

Ab initio computations: Theoretical and computational investigation on the
ultrahigh-pressure behaviors of materials in the Earth and planets are conducted by using computer simulations based on quantum mechanics.

Fluid mechanics computation: Numerical simulations based on the fluid and continuum mechanics are conducted to reveal the convective motions in the mantle and core of the Earth and terrestrial planets for the understandings of the dynamics and evolution processes of the planets. Large scale computations using realistic parameters of the Earth, phase transitions, viscosity and compression behaviors under high pressure, are performed for 3-D spherical-geometry simulations.
  ◆What is HIME-Diamond?

HIME-Diamond synthesized in GRC is the hardest diamond and likely the hardest material in the world. Unlike normal diamond made of a single
crystal, HIME-Diamond consists of closely-packed nanometer-sized diamonds (~10 nanometers = one hundred-thousandth millimeters). Thus the HIME-Diamond is also called "Nano-polycrystalline diamond (NPD)".

◆Toward higher pressure generations

Experiments under higher pressure are of importance to investigate the interiors of the Earth and planets. The harder the compression material is, the higher the pressure we can reach and thus HIME-Diamond plays a
major role in future development of experiments at ultrahigh pressure. The high transparency of HIME-Diamond enables high-pressure experiments using optical in-situ observations and synchrotron radiations.

◆Novel polycrystalline materials and gems

GRC conducts syntheses of novel polycrystalline materials by applying techniques learned from making of HIME-Diamond. Nano-polycrystalline
stishovite (NPS) made from silica (SiO2) is one of the novel materials synthesized by GRC. NPS shows excellent physical properties having both hardness and toughness. Garnets (one of the main constituents within the Earth) with a variety of chemical compositions can be synthesized as nano-polycrystalline materials.