High-pressure neutron experiments on silica glass up to 17 GPa at J-PARC

Hattori, Takanori   ; Yagafarov, O.*; Katayama, Yoshinori; Chiba, Ayano*; Sano, Asami   ; Inamura, Yasuhiro  ; Otomo, Toshiya*; Funakoshi, Kenichi*; Abe, Jun*; Machida, Shinichi*

SiO glass consists of SiO tetrahedra which are mutually connected and forms the many-membered ring. Thus, the glass has large void in its structure, and therefore marked densification is expected under pressure. Actually, it is known that the density increases by 20% on compression to 8 GPa, accompanying the change in the intermediate range order. The density goes back to the original value by decompression, whereas the high-density state is recovered at ambient condition once the structure is relaxed by heating at high pressure. The mechanism has been investigated, but is still unknown. To reveal the mechanism, in situ high-pressure diffraction is indispensable. In this study, we collected data up to about 17 GPa by using 6-axis press below 10 GPa and Paris-Edinburgh press above 10 GPa. Thanks to incident slits and receiving collimator, no peaks from the materials surrounding sample were observed. In the talk, I will discuss differences between the densifications with and without structural relaxation.