1997 Fiscal Year Final Research Report Summary
Shock-induced Transition from C_<60> Fullerene to Amorphous Diamond and Exploring New Carbon Materials.
| Project/Area Number |
08454229
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
物質変換
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| Research Institution | University of Tsukuba (1997)
Tokyo Institute of Technology (1996) |
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Principal Investigator |
YAGI Hisako (平井 寿子) University of Tsukuba, Institute of Geoscience, assistant professor, 地球科学系, 講師 (60218758)
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| Co-Investigator(Kenkyū-buntansha) |
KONDO Ken-ichi Materials and Structure Laboratory, Tokyo Institute of Technology, , professor (50111670)
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| Project Period (FY) |
1996 – 1997
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| Keywords | C_<60> fullerene / nanocrystalline ceramics / diamond / shock compression / transparent / direct bonding / Iattice image / grain boundary |
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| Research Abstract |
Transparent "amorphous diamond", a new carbon material, has been synthesized from C_<60> fullerene by a shock compression and rapid quenching technique. This material is amorphous in the long-range order and diamond in short-range order, according to some diffractometric and spectroscopic analyzes. Because the material is comprised wholly of sp^3 carbon, and radial distribution function analysis has determined the arrangement of sp^3 tetrahedra as similar to that of crystalline diamond within the range of unit cell size, it has been labeled amorphous diamond rather than amorphous sp^3 carbon. Its unique transition process from C_<60> fullerene to amorphous diamond was tracked by using electron diffraction and electron energy loss spectroscopy to explore changes in structure and electronic state. The results of radial distribution function and of transition process obtained suggest that nanocrystalline diamond bulk material without sp^2 component can be fabricated if crystal growth is skillfully controlled by changing the shock condition and initial state of the starting material. In the present research, transparent and nanocrystalline diamond ceramics, consisting of a few nanometer-sized diamond crystallites that are unstable in themselves because of higher surface energy, were also fabricated by effectively using the potential of C_<60> fullerene to transform into diamond and the advantage of the shock compression and rapid quenching technique. The platelets were transparent and very hard, nearly comparable to type IIa diamond. Transmission electron microscopy and electron energy loss spectroscopy revealed that individual crystallites had combined directly or through a very thin and modified sp^3 carbon layr, which possibly stabilized the nanometer-sized crystallites. The size order and sp^3 configuration of the nanotexture caused the transparency and hardness of the present material.
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