Investigation of DH isotope effect in guyanite using high-pressure neutron diffraction experiment

Sano, Asami   ; Hattori, Takanori   ; Funakoshi, Kenichi*; Abe, Jun*; Machida, Shinichi*

Guyanite is known to have large DH isotope effect on the unit cell volume. However the previous X-ray diffraction study has indicated that this volume difference merges at around 6 GPa. In order to explain the cause of this phenomenon from the crystallographic view, neutron diffraction experiment was conducte at BL11 in MLF, J-PARC. We observed the change in deuterium distribution from order to disorder at this pressure at 6 GPa. In the presentation, the relation between the change of hydrogen bond geometry and reduced partition function ratio will be discussed.