The fullerite superhard material.
Fullerite is the solid material harder than diamond. Fullerite is a molecular crystal formed by the molecules of fullerene C60 and C60.
Fullerite is a molecular crystal, the products are bulk polymerization, spherical carbon molecules, fullerenes C60 and C70.
Not found in nature, obtained by artificial means.
As a rule, is obtained from fullerenes fullerenes at a pressure of more than 90 000 atmospheres and temperatures above 300 °C. In the presence of catalysts fullerite synthesized at a low pressure of 8 GPA and room temperature.
Fullerite fully preserves the rigid structure of fullerenes, which are interconnected polymerization durable diamond-like bonds.
This leads to spatial frames having extremely high rigidity and hardness.
Under normal conditions (300 K) of the fullerene molecule form a face-centered cubic crystal lattice of fullerite. At temperatures below 260 K there is a change in the crystal structure of fullerite, it becomes a simple cubic crystal lattice.
At temperatures above 260 K the molecules of fullerenes in a fullerite rotate. This is due to the small forces of interaction between molecules in the crystal of C60 fullerite and very high symmetry. Speed, of course, depends on the temperature, and at a temperature of 300 K is equal to approximately 1012 Hz. At low temperatures less than 260 K the rotation of fullerene molecules in the crystal fullerite is terminated.
The unit cell of the crystal lattice of fullerite under normal conditions (300 K) contains 8 tetrahedral and 4 octahedral voids, each of which is surrounded by 4 and 6 molecules of C60. The dimensions of the octahedral voids are of 0.42 nm, the tetrahedral — 0,22 nm.
– chemical resistance,
– the presence of relatively large intermolecular interstices. These voids can be filled with a small molecules including atoms of metals,
– thermally stable. Is stable in inert atmosphere up to temperatures of the order of 926,85 OS (1200 K).
|Name of the parameter:||Value:|
|The fullerite density*, g/cm3||1,7|
* For comparison: the density of graphite is 2.3 g/cm3, of a diamond is 3.5 g/cm3.