Skip to main content Accessibility help

Hardness and deformation microstructures of nano-polycrystalline diamonds synthesized from various carbons under high pressure and high temperature

  • H. Sumiya (a1) and T. Irifune (a2)


Mechanical properties of high-purity nano-polycrystalline diamonds synthesized by direct conversion from graphite and various non-graphitic carbons under static high pressures and high temperatures were investigated by microindentation testing with a Knoop indenter and observation of microstructures around the indentations. Results of indentation hardness tests using a superhard synthetic diamond Knoop indenter showed that the polycrystalline diamond synthesized from graphite at ⩾15 GPa and 2300–2500 °C (consisting of fine grains 10–30 nm in size and layered crystals) has very high Knoop hardness (Hk ⩾ 110 GPa), whereas the hardness of polycrystalline diamonds synthesized from non-graphitic carbons at ⩾15 GPa and below 2000 °C (consisting only of single-nano grains 5–10 nm in size) are significantly lower (Hk = 70 to 90 GPa). Microstructure observations beneath the indentations of these nano-polycrystalline diamonds suggest that the existence of a lamellar structure and the bonding strength of the grain boundary play important roles in controlling the hardness of the polycrystalline diamond.


Corresponding author

a)Address all correspondence to this author. e-mail:


Hide All
1Irifune, T., Kurio, A., Sakamoto, S., Inoue, T.Sumiya, H.: Ultrahard polycrystalline diamond from graphite. Nature 421, 599 2003
2Sumiya, H., Irifune, T., Kurio, A., Sakamoto, S.Inoue, T.: Microstructure features of polycrystalline diamond synthesized directly from graphite under static high pressure. J. Mater. Sci. 39, 445 2004
3Sumiya, H.Irifune, T.: Indentation hardness of nano-polycrystalline diamond prepared from graphite by direct conversion. Diamond Relat. Mater. 13, 1771 2004
4Naka, S., Horii, K., Takeda, Y.Hanawa, T.: Direct conversion of graphite to diamond under static pressure. Nature 259, 38 1976
5Onodera, A., Higashi, K.Irie, Y.: Crystallization of amorphous carbon at high static pressure and high temperature. J. Mater. Sci. 23, 422 1988
6Yusa, H., Takemura, K., Matsui, Y., Morishima, H., Watanabe, K., Yamawaki, H.Aoki, K.: Direct transformation of graphite to cubic diamond observed in a laser-heated diamond anvil cell. Appl. Phys. Lett. 72, 1843 1998
7Yusa, H.: Nanocrystalline diamond directly transformed from carbon nanotubes under high pressure. Diamond Relat. Mater. 11, 87 2002
8Dubrovinskaia, N., Dubrovinsky, L., Langenhorst, F., Jacobsen, S.Liebske, C.: Nanocrystalline diamond synthesized from C60. Diamond Relat. Mater. 14, 16 2005
9Sumiya, H., Yusa, H., Inoue, T., Ofuji, H.Irifune, T.: Conditions and mechanism of formation nano-polycrystalline diamonds directly from graphite and non-graphitic carbon at high-pressure and high-temperature. J. High Press. Res. 26, 63 2006
10Kawai, N.Endo, S.: The generation of ultra hydrostatic pressure by a split sphere apparatus. Rev. Sci. Instrum. 41, 1178 1970
11Irifune, T.Sumiya, H.: Nature of polycrystalline diamond synthesized by direct conversion of graphite using Kawai-type multianvil apparatus. New Diamond Frontier Carbon Technol. 14, 313 2004
12Sumiya, H.: Super-hard diamond indenter prepared from high-purity synthetic diamond crystal. Rev. Sci. Instrum. 76, 026112 2005
13Sumiya, H., Toda, N.Satoh, S.: Mechanical properties of synthetic type IIa diamond crystal. Diamond Relat. Mater. 6, 1841 1997
14Sumiya, H., Yamaguch, K.Ogata, S.: Deformation microstructure of high-quality synthetic diamond crystal subjected to Knoop indentation. Appl. Phys. Lett. 88, 161904 2006
15Dubrovinskaia, N., Dubrovinsky, L., Crichton, W., Langenhorst, F.Richter, A.: Aggregated diamond nanorods, the densest and least compressible form of carbon. Appl. Phys. Lett. 87, 083106 2005
16Dubrovinskaia, N., Dub, S.Dubrovinsky, L.: Super wear resistance of aggregated diamond nanorods. Nano Lett. 6, 824 2006
17Veprek, S.: Nanostructured superhard materials in Handbook of Ceramic Hard Materials edited by R. Riedel, Wiley-VCH Vch Verlagsgesellschaft Mbh 2000 104
18Yip, S.: The strongest size. Nature 391, 532 1998


Related content

Powered by UNSILO

Hardness and deformation microstructures of nano-polycrystalline diamonds synthesized from various carbons under high pressure and high temperature

  • H. Sumiya (a1) and T. Irifune (a2)


Altmetric attention score

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed.