High-Pressure Structural Controls Group

The high-pressure synthesis method using a belt-type appatus with a large volume enables the synthesis of various functional crystals unique to ultra high-pressure synthesis. 2-dimensional high-purity hBN crystals have been provided as insulating films for research on graphene-related materials, contributing to many international collaborative studies. We are also conducting research to determine the structure and synthesis conditions of high-pressure phases by in-situ observation under high pressure using synchrotron radiation X-ray.

The quality of hBN crystal substrates significantly impacts the carrier transport properties of graphene devices fabricated on them. Our collaborative research with the University of Manchester has achieved a mobility exceeding 10 million cm²/V·sec at low temperatures in FY2025[ 1 ]. Precise determinations of the bulk modulus and thermal expansion coefficient were performed for the rare earth high-coordinated boride RB₄ with Shastry-Sutherland Lattices (SSL) using synchrotron X-ray diffraction experiments. Structural anisotropy is more pronounced at low temperatures than under high pressure, suggesting it results from magnetic interactions within the SSL lattice[ 2 ].