Vv. Brazhkin et al., Mechanism of the formation of a diamond nanocomposite during transformations of C-60 fullerite at high pressure, JETP LETTER, 69(11), 1999, pp. 869-875
The results of an investigation of the transformation of C-60 fullerite to
diamond under pressure through intermediate three-dimensionally polymerized
and amorphous phases are reported. It is found that treatment of fullerite
C-60 at pressures 12-14 GPa and temperatures similar to 1400 degrees C pro
duces a nanocrystalline graphite-diamond composite with a concentration of
the diamond component exceeding 50%. At lower temperatures (700-1200 degree
s C) nanocomposites consisting of diamondlike (sp(3)) and graphitic (sp(2))
amorphous phases are formed. The nanocomposites obtained have extremely hi
gh mechanical characteristics: hardness comparable to that of best diamond
single crystals and fracture resistance two times greater than that of diam
ond. Mechanisms leading to the transformation of C-60 fullerite into diamon
d-based nanocomposites and the reasons for the high mechanical characterist
ics of these nanocomposites are discussed. (C) 1999 American Institute of P
hysics. [S0021-3640(99)01011-7].