Synthesis and structural analysis of C60-C70 two-component fullerene nanowhiskers

C60-C70 two-component fullerene nanowhiskers (C60-C70NWs) were synthesized by liquid-liquid interfacial precipitation (LLIP) using various ratios of C70 to C60 and then analyzed using a focused ion beam processing apparatus (FIB-SEM), scanning electron microscopy (SEM), Raman spectroscopy, ultraviolet-visible (UV-vis) spectroscopy, X-ray diffraction (XRD) and high-performance liquid chromatography (HPLC). Both C60 and C70 were saturated in the supernatant solutions with fullerene compositions in the mother solutions ranging from 12.4 mass% C70 to 73.4 mass% C70. C60-C70NWs contained a small amount of rhombohedral phase, indicating polymerization of C60. The solid solubility limit of C70 in the C60 matrix was found to be 13.7 mass%. In addition to fine C60-C70NWs, thick C60-C70 needle-like crystals were formed. The thick C60-C70 needle-like crystals were fractured using a molybdenum probe in the FIB. The fractured surfaces of the C60-C70 needle-like crystals showed modulated structures with chemical compositions characteristic of spinodal decomposition. The activation energy of diffusion was determined to be 37.1 kJ/mol.