Kayoko Hotta

GC-MS analysis of the solvents contained in C60 nanowhiskers

The solvent molecules contained in C60NWs affect not only the shape but also the crystal structure of C60NWs. The solvents contained in C60NWs were found to be toluene and IPA by the GC-MS analysis. The most abundant solvent was toluene and the quantity of residual toluene in the as-prepared C60NWs was about 7 mass%. The quantity of impurity solvents is reported for the as-prepared, air-dried, vacuum-dried and heat-treated C60NWs.

Molecular dynamics and structural phase transition in C60 nanowhiskers

Nanowhiskers of C60 (C60 NWs) have been formed by a liquid-liquid interfacial precipitation method which uses an interface of the concentrated toluene solution of C60/2-propanol. In order to study the motion of C60 molecules in nanowhiskers, we have performed measurements of low-temperature X-ray diffraction, magnetic susceptibility, specific heat and 13C-NMR for C60 NWs. The temperature dependence of lattice constant for C60 NWs is in good agreement with that for pristine C60 powder, which demonstrates the large discontinuity at Tc ~ 265 K caused by the structural phase transition. However, the temperature dependence of magnetic susceptibility for C60 NWs exhibits a faint anomaly at Tc. The temperature dependence of specific heat for C60 NWs shows two small anomalies at 232 K and 254 K. High resolution 13C-NMR measurements of the C60 NWs indicate that both of toluene and 2-propanol molecules interact with the C60 NW molecules in the suspension and the precipitate states obtained from the LLIP method. The broader linewidth of 13C-NMR in the dried C60 NWs compared with that in the pristine C60 powder indicates that the slower molecular reorientation in the dried C60 NWs compared with that in the pristine C60 powder. Since a rapid rotation of C60 molecules could be directly detected by 13C-NMR, polymer formation between C60 molecules is unlikely in C60 NWs at room temperature.

Growth mechanism of vertically aligned fullerene micro tubes prepared by the liquid-liquid interfacial precipitation method

C60-based materials such as FNWs and FNTs are new candidates for organic electronics and solar cells. Recently, a method to produce vertically-aligned fullerene microtube crystals (VFMTs) has been established. The VFMTs are exepected to be used as field emission devices, solar cells, fuel cells, and so forth. To realize such attractive applications, structures and arrangements of VFMTs should be controlled. In oder to know the growth mechanism of VFMTs, Scanning electron microscopy (SEM) observations were performed for several injection periods of VFMTs. In the initial stage of synthesis (IPA injection time of 60 min), vertically aligned thin non-tubular fullerene microwhiskers (VFMWs) formed on AAO substrates. The outer and inner diameter of VFMWs became increased with increasing the injected amount of IPA. And also the size of tube holes became larger. The tubular structures appeared at an injection time of around 90 min. At an injection time of 120 min, vertically aligned FMTs with hexagonal cross sections and holes were obtained and their diameter and structure did not change up to the final stage of injection time of 3 00 min.

Growth Control and Properties of Fullerene Nanofibers

Fullerene nanofibers are the fine needle-like crystals composed of fullerene molecules and can be synthesized in a solution at ambient temperature and atmosphere. The growth control of the fullerene nanofibers are necessary in order to apply them for practical uses. We have developed a method to synthesize short fullerene nanowhiskers with a uniform length suitable for the electrodes in solar cells and fuel cells. This paper reports the synthesis of C60 nanofibers, including their properties and application.Copyright