Takazawa Ken, Inoue Jun-Ichi, Mitsuishi Kazutaka, Yoshida Yukihiro, Kishida Hideo, Tinnemans Paul, Engelkamp Hans, Christianen Peter C M
Center for Green Research on Energy and Environmental Materials, National Institute for Materials Science, Tsukuba, Ibaraki, 305-0003, Japan.
MANA, National Institute for Materials Science, Tsukuba, Ibaraki, 305-0044, Japan.
Sci Rep. 2021 Feb 4;11(1):3175. doi: 10.1038/s41598-021-82703-5.
For decades, it has been reported that some organic crystals suddenly crack, break, or jump when they are heated from room temperature. Recently, such crystals have been intensively studied both in fundamental science and for high-speed mechanical device applications. According to these studies, the sudden crystal motions have been attributed to structural phase transitions induced by heating. Stress created by the phase transition is released through the sudden and rapid motion of the crystals. Here we report that single crystal nanofibers of coronene exhibit a new type of ultrafast motion when they are cooled from room temperature and subsequently heated to room temperature. The nanofibers make centimeter-scale jumps accompanied by surprisingly unique behaviors such as sharp bending and wriggling. We found that the motions are caused by a significantly fast structural phase transition between two polymorphs of coronene. A theoretical investigation revealed that the sudden force generated by the phase transition together with the nanoscale dimensions and elastic properties create dynamical instability in the nanofibers that results in the motions. Our finding demonstrates the novel mechanism that leads to ultrafast, large deformation of organic crystals.
几十年来，一直有报道称，一些有机晶体在从室温加热时会突然破裂、折断或跳动。最近，这类晶体在基础科学和高速机械设备应用方面都受到了深入研究。根据这些研究，晶体的突然运动归因于加热引起的结构相变。相变产生的应力通过晶体的突然快速运动得以释放。在此我们报告，蒄单晶纳米纤维在从室温冷却随后又加热至室温时会呈现出一种新型的超快运动。这些纳米纤维会进行厘米级的跳动，并伴随着诸如急剧弯曲和扭动等令人惊讶的独特行为。我们发现，这些运动是由蒄的两种多晶型物之间显著快速的结构相变引起的。一项理论研究表明，相变产生的突然力连同纳米尺度的尺寸和弹性特性在纳米纤维中产生了动力学不稳定性，从而导致了这些运动。我们的发现展示了导致有机晶体超快、大变形的新机制。
