Synthesis Of Fullerene Nano/micromaterials With Different Shapes And Investigation Of Their Physical Properties And HPHT Study For C₆₀ Nanotubes

Fullerenes, as one of the most important members of carbon family, constitute a new phase of carbon with distinctly different structural and electronic properties. Since the discovery of them, the fullerene has attracted much attention due to their unique chemical and physical properties. In the very resent, the synthesis and study of fullerene nanomaterials became the most focused research, and many interesting and novel properties of fullerene have been found. The development of synthetic methods for well-defined one-dimensional (1D) fullerene crystals has been considered a key prerequisite, and the fabrication of 1D fullerene crystals with different structures in the range of submicrometre and nanometer scale is still a challenge. In this work, using the method of mixing the fullerene solution, we have synthesized fullerene (C60,C70) nano/micro crystals with different shape. The shapes,composition and the structures were studied. We have also studied the mechanism of the fullerene crystals formation, the photoluminescence and field emission properties.Using m-xylene as shape controller, we have successfully synthesized C60 microtubes on silicon, glass and mental substrate by evaporating the C60 solution in the atmosphere of m-xylene. The outer diameter of C60 microtubes is ranging from 2 to 8 micrometer, and the shape is hexangular prism. The as-grown C60 microtubes is solvate with toluene and m-xylene, and the the molar ratio of the solvate component is 1:2:3 among toluene, m-xylene and C60, namely, the molar quantity of the C60 moleculars is the sum of the toluene and m-xylene. When heated in vaccum, we obtained the pure C60 microtubes. Through observing the images carefully, and some comparing experiments, we have given a mechanism of C60 microtubes that it is several nanorods assembled together to form a tubular structure. In this work, we have found an effective and simple way to obtain C60 microtubes.Through the control conditions of temperature and evaporating rate, we have fabricated C60 nanoflowers at low temperature. The C60 nanoflowers were assembled with many C60 nanorods contacted in the center. The diameter of C60 nanorods is ranging from several hundred nanometers to one micrometer, and the diameter is about 100 micrometers. Through evaporating the mixed C60 solution of toluene and m-xylene quickly, we can obtain C60 microtube arrays. After heated in vaccum, the C60 microtube arrays have a good field emission property.The C60 nanotubes were also fabricated. The outer and inner diameters of the C60 nanotubes were about 500nm and 200nm. We have treated the C60 nanotubes under (HTHP) condition。The C60 nanotubes with fcc structure translated into O phase under 1.5GPa, 300°C, and the C60 nanotubes containing solvent, which has the hcp structure, tanslated into dimmer structure. This result indicated that doping m-xylene into C60 nanotubes can prevent the C60 nanotubes from translating into O phase. The C60 nanotubes with fcc structure translated into O phase under 2.0GPa, 700K. However, the C60 bulk materials treated under the same condition had a mixed structure of O and T phase, in which the T phase mainly part. The result indicated that the C60 nanotubes need a higher temperature and pressure to translate into T phase due to the effect of small size.We have successfully doped m-xylene into C70 nanotubes in the synthesis process. The as-grown nanotubes were C70 solvates with m-xylene, which has a mixed phase of face-centered cubic and hexagonal close-packed system. The ratio of the length to the diameter of the nanotubes were controlled to 10-20, the Raman spectrum indicated that the C70 nanotubes consisted of monomeric C70 molecule. The doping of solvent has changed the symmetry of C70 molecule, which induced the strong PL intensity of C70 nanotubes, and one more peak was found which did not exist in the spectrum of bulk materials. With the help of the UV absorption, we considered the PL peaks were attributed to the radiative recombination polaron-exciton and the phonon replicas of it.