High-pressure neutron diffraction experiment at SNAP, SNS

Sano, Asami   ; Hattori, Takanori   ; Utsumi, Wataru; Komatsu, Kazuki*; Kagi, Hiroyuki*; Nagai, Takaya*

-AlOOH, distorted rutile type oxyhydroxide, is an important hydrous mineral in the deep earth that has the ability to transport hydrogen into the lower mantle. Theoretical studies have pointed out that hydrogen would locate at the center between two oxygen atoms at high pressure, which is so called symmetrization of the hydrogen bond. To investigate the pressure response of strong hydrogen bond -AlOOH, we conduct neutron diffraction experiment at SNAP in SNS. Neutron diffraction patterns of -AlOOH was measured on SNAP to 7 GPa. The intensity of the peak that is only observed in the space group P2nm become weak at high pressure suggesting the transition to H-disordered or symmetric hydrogen bond model with Pnnm.