NEW CRYSTAL STRUCTURES OF 2D AND 3D
POLYMERIZED C60
FULLERITES
L.A. Chernozatonskii1,
EG. Gal'pern 2, I.V.
Stankevich2,
Ya.K.Shimkus1
1 Institute of
Biochemical Physics, Moscow 117334, Russian Federation
2 Institute of
Organoelement Compounds, 117813 Moscow, Russian Federation
Keywords: Fullerenes, High
pressure, Crystal structures, Polymers
Fullerenes C60 under high pressure
310 GPa and temperatures ~1000 K are transformed into multiphase
superhard structures [1-3].
In order to explain experiments [1-3] we have
considered some new 2D and 3D structures, which we constructed
using MM2 method of molecular mechanics. The following
structures, defined on the base of geometric parameters of the
inner oligomer C60 fragments containing from 4 to 32
sp3-like C atoms (2+2 or 4+4 cycloadditions of fullerenes) are
presented:
- 2D structures of barrel-like C60
[4] polymerized in a layer which explain chain structures
with intermolecular distances in line (0.63-0.72 nm) and
between lines (0.77-0.81 nm) [2];
- 2D structures of octahedral-like
fullerenes polymerized in a layer which may be formed in
fullerite under nonhydrostatic pressure.
- 3D polymerized C60 barrelene
structures, one of which (orthorombic cell: a,b,c
=0.72,0.63,1.98 nm) may be explained hard compound with
2.6 g/cm3 density [2];
- three structures of 3D polymerized
fullerenes which geometry parameter's well agree with
V.Blank team experimental data [1,3];
- 3D polymerized octahedral-like fullerite
with based center cubic unit cell (a=0.9 nm, r >>
3.4 g/cm3) and 32 sp3-like carbon atoms in C60
fragment, this cell includes fourfold "gluing"
together C20 polyhedrons (places between C60
cages) forming pseudo-FCC lattice (a'=0.63 nm) and maybe
explaining characterized picks in X-ray diffraction from
superhard C60 compounds [1-3].
This work was supported by the Russian
Basic Research Fund (Grant 96-02-18445-a) and the Russian
Programe "Fullerene and Atomic Clusters".
- V.D. Blank, et al. Phys. Lett. A 205
(1995) 208-211
- V.A. Davidov, et al. JETP Letters
38 (1996) 467-271
- V.D. Blank et al. Appl.Phys.A 64
(1997) 208-247
- L.A. Chernozatonskii, Phys.Lett. A
160 (1991) 392-296