Quenchable compressed graphite synthesized from neutron-irradiated highly oriented pyrolytic graphite in high pressure treatment at 1500 °c

Keisuke Niwase, Mititaka Terasawa, Shin Ichi Honda, Masahito Niibe, Tomohiko Hisakuni, Tadao Iwata, Yuji Higo, Takeshi Hirai, Toru Shinmei, Hiroaki Ohfuji, Tetsuo Irifune

Research output: Contribution to journalArticlepeer-review

Abstract

The super hard material of "compressed graphite" (CG) has been reported to be formed under compression of graphite at room temperature. However, it returns to graphite under decompression. Neutron-irradiated graphite, on the other hand, is a unique material for the synthesis of a new carbon phase, as reported by the formation of an amorphous diamond by shock compression. Here, we investigate the change of structure of highly oriented pyrolytic graphite (HOPG) irradiated with neutrons to a fluence of 1.4 × 1024 n/m2 under static pressure. The neutron-irradiated HOPG sample was compressed to 15 GPa at room temperature and then the temperature was increased up to 1500 °C. X-ray diffraction, high-resolution transmission electron microscopy on the recovered sample clearly showed the formation of a significant amount of quenchable-CG with ordinary graphite. Formation of hexagonal and cubic diamonds was also confirmed. The effect of irradiation-induced defects on the synthesis of quenchable-CG under high pressure and high temperature treatment was discussed.

Original languageEnglish
Article number5011209
JournalJournal of Applied Physics
Volume123
Issue number16
DOIs
Publication statusPublished - 2018 Apr 28
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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