Nano-polycrystalline diamond synthesized from neutron-irradiated highly oriented pyrolytic graphite (HOPG)

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

Research output: Contribution to journalArticlepeer-review

Abstract

Highly oriented pyrolytic graphite (HOPG) is a unique source material for the synthesis of new types of diamond. It can transform to layered nano-polycrystalline diamond (NPD) under static high pressure and high temperature (HPHT) and to “amorphous diamond” by introducing structural defects by neutron irradiation followed by shock compression. Here, we investigated the structural change of the neutron-irradiated HOPG through a HPHT treatment at 2300 °C and 15 GPa by Raman, X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray absorption near edge structure (XANES) analyses. The recovered sample consists of randomly oriented nanodiamonds (50–100 nm), showing clearly a different microtexture from those of the layered NPD and “amorphous diamond” reported by the previous studies. This is likely as a result of competing effects of the introduction of irradiation-induced defects, which provided the preferential nucleation sites for cubic diamond, and their partial recovery upon annealing during the HPHT treatment. The present result suggests that NPDs with various crystalline structures can potentially be synthesized from neutron-irradiated HOPG by controlling the density and distribution of the defects introduced.

Original languageEnglish
Pages (from-to)132-136
Number of pages5
JournalDiamond and Related Materials
Volume82
DOIs
Publication statusPublished - 2018 Feb
Externally publishedYes

Keywords

  • Graphite
  • High pressure and high temperature
  • Irradiation induced defects
  • Nano-polycrystalline diamond

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Chemistry(all)
  • Mechanical Engineering
  • Materials Chemistry
  • Electrical and Electronic Engineering

Fingerprint Dive into the research topics of 'Nano-polycrystalline diamond synthesized from neutron-irradiated highly oriented pyrolytic graphite (HOPG)'. Together they form a unique fingerprint.

Cite this