Synthesis of Superhard and Ultrahard Materials by 3D-polymerization of C₆₀, C₇₀ Fullerenes Under High Pressure (15 GPa) and Temperatures up to 1820 K

Abstract

Solid fullerenes C60 and C70 have been treated at high pressure of 15 GPa and high temperatures of 520 - 1820 K for a time of exposure of 60 s and a quenching rate of 300 K s−1 using a toroid-type apparatus. X-ray diffraction and Raman spectra confirm the realization of 3D-polymerized phases in these solids at 15 GPa. The pressure/temperature maps of synthesis of metastable carbon phases on the basis of C60 and C70 have thus been extended to 15 GPa. The longitudinal and shear sound wave velocities were measured by acoustic microscopy techniques. A maximum sound wave velocity of (21±1)×105 m s−1 was observed in the sample synthesized from C60 at T = 1170 K. The elastic constants were calculated using experimental data. The acoustic microscopy images of experimental samples have been investigated.

Characteristics of local atomic configurations in ball‐milled fullerenes

“…It should be noted that thermodynamic conditions (short‐time pulse pressure and temperature: τ ∼ 10 –8 s, ΔP ∼ 5 GPa, ΔT ∼ 1000 K) occurring in the material in a shock contact point due to the collision of the grinding balls in the planetary mill are similar to those used in Refs. . They are reasonable for a polymerization of pristine fullerenes as well as for the appearance of diamond‐like components in the obtained amorphous carbon .…”

“…Preliminary studies with Raman and IR‐spectroscopy have shown the presence of dimers in the structure of the milled material that will be reported in the future. The polymerization of pristine fullerenes was observed not only after ball‐milling but also at high temperature and pressure . It should be noted that thermodynamic conditions (short‐time pulse pressure and temperature: τ ∼ 10 –8 s, ΔP ∼ 5 GPa, ΔT ∼ 1000 K) occurring in the material in a shock contact point due to the collision of the grinding balls in the planetary mill are similar to those used in Refs.…”

Detection of organic compounds in impact glasses formed by the collision of an extraterrestrial material with the Libyan Desert (Africa) and Tasmania (Australia)

“…In other superficial dark inclusions, Raman spectra showing only a band centred at 1572m cm -1 was found, suggesting the presence of a high ordered fullerene-type compound. According to literature, that band could correspond to the crystalline 3Dpolymeric C60 structure after high-pressure/high-temperature treatment at 15 GPa and 670 K [35]. Moreover, some Raman spectroscopic studies on the so-called onion-like fullerene spherical nanostructures have also identified a Raman band at 1572 cm -1 when a high degree of structural perfection of the graphitic network is attained (subjecting nanodiamonds to temperatures in the range 1800-1900 K) [36,37].…”

Applications of High-Tc Superconductivity

“…High-pressure -high-temperature treatment of C 60 and C 70 fullerenes leads to polymerization and transformation into new metastable carbon structures (Blank et al, 1998(Blank et al, , 2006. Among various polymeric forms, the 3D-polymeric ones are the hardest Fig.…”

“…Interacting with diamond, Nb and Mo metals form carbides bonding diamond crystallites into a united compact material having relatively high critical temperatures of the transition to the superconducting state. The alternative route is the sintering of superconductor powders with superhard fulleritesnew carbon materials produced from C 60 and C 70 fullerenes (Blank et al, 1998(Blank et al, , 2006. Under high pressure and temperature treatment soft C 60 and C 70 powders transform into fullerene polymers and other carbon structures with various hardness including superhard and even superior to diamond.…”