TY - JOUR
T1 - Nano-polycrystalline diamond synthesized from neutron-irradiated highly oriented pyrolytic graphite (HOPG)
AU - Terasawa, Mititaka
AU - Honda, Shin ichi
AU - Niwase, Keisuke
AU - Niibe, Masahito
AU - Hisakuni, Tomohiko
AU - Iwata, Tadao
AU - Higo, Yuji
AU - Shinmei, Toru
AU - Ohfuji, Hiroaki
AU - Irifune, Tetsuo
N1 - Funding Information:
This work (Research No. 2014-A28 ) was supported by the Joint Usage/Research Center PRIUS, Ehime University and by JSPS Grant-in Aid (No. 15K06440 ).
Publisher Copyright:
© 2018 Elsevier B.V.
PY - 2018/2
Y1 - 2018/2
N2 - 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.
AB - 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.
KW - Graphite
KW - High pressure and high temperature
KW - Irradiation induced defects
KW - Nano-polycrystalline diamond
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U2 - 10.1016/j.diamond.2018.01.001
DO - 10.1016/j.diamond.2018.01.001
M3 - Article
AN - SCOPUS:85041446086
VL - 82
SP - 132
EP - 136
JO - Diamond and Related Materials
JF - Diamond and Related Materials
SN - 0925-9635
ER -