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1054-FF11-09

Fabrication and Characterization of Size- and Shape-Controlled C60 Nano/microcrystals by Solvent-Induced Reprecipitation Process (SIRP) Akito Masuhara1, Zhenquan Tan1, Hitoshi Kasai1,2, Hachiro Nakanishi1, and Hidetoshi Oikawa1 1 IMRAM, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai, 980-8577, Japan 2 PRESTO, 4-1-8 Honcho, Kawaguchi, 332-0012, Japan ABSTRACT We have first developed useful Solvent-Induced Reprecipitation Process, and have first succeeded in fabricating C60 nano/microcrystals with various shape and size, using m-xylene and 2-propanol as good and poor solvents, respectively. It was found that the resulting C60 nano/microcrystals had a hexagonal crystal structure, and that were a kind of crystal solvates in which the molar ratio of C60 to m-xylene was 3:2. C60 nano/microcrystals could be said to be important nano components of integrated devices in electronics. INTRODUCTION There are a lot of attentions of fullerene C60 molecule and bulk crystal, because of their great potential applications in many research fields such as physics, chemistry, and electronics [1-3]. Low-dimensional and well-defined C60 nano/microcrystals (N/MCs) are of much great interest, and a candidate for device applications. However, the convenient fabrication method has not still been established to prepare the C60 N/MCs. For example, Kasai et al. have prepared the fine C60 NCs with ca. 40 to 50 nm in size by the supercritical reprecipitation method, and their optical properties obviously depended on crystal size [4]. On the other hand, Miyazawa et al. have successfully fabricated C60 nanowhiskers by means of liquid-liquid interfacial precipitation method [5]. In addition, Nakanishi et al. reported that C60 nanocone prepared by self-assembly of chemically modified C60 molecules [6]. Despite of these investigations, it is still much difficult to control the size, shape, and monodispersity of C60 N/MCs, compare with inorganic M/NCs such as metals [7] and semiconductors [8]. It is well known that solvent molecules can be incorporated just like a guest molecule into the host C60 lattice to form crystal solvates, when C60 crystals grow in a solution [5, 6]. In the present article, we report C60 M/NCs having various morphologies can be easily prepared by the “Solvent-Induced Reprecipitation Process (SIRP)” [9], and will discuss the conditions of SIRP, morphology, and inner structure of C60 N/MCs. EXPERIMENT Fullerene C60 powder (> 99.9%), m- xylene (99%), and 2-propanol (99.5%) was purchased from Tokyo Kasei Co., Ltd. C60, and the solvents were used without further purification. C60 N/MCs were fabricated by the SIRP as follows [9]. A 200 µl of diluted m-xylene solution of C60, which concentration is ordinarily order of mM, was quickly injected into vigorously stirred 2-propanol (10 ml) as a poor medium. Afterwards, the dispersion liquid was left at room temperature for several hours to grow C60 N/MCs.

The resulting C60 N/MCs were filtrated onto Millipore filter, and then evaluated their crystal size and morphology by