Abstract
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.
Highlights
It has been reported that some organic crystals suddenly crack, break, or jump when they are heated from room temperature
We observed that single crystal nanofibers of coronene on a substrate jumped over a centimeter-scale distance at an initial velocity of up to ~ 20 m/s, which is a few orders of magnitude faster than that of reported thermosalient crystals
The theoretical investigation revealed that the abrupt force generated by the phase transition together with the nanoscale dimensions and elastic properties create a dynamical instability in the nanofibers and this instability leads to the motion
Summary
It has been reported that some organic crystals suddenly crack, break, or jump when they are heated from room temperature. These measurements showed that the crystal motions are related to temperature-induced structural phase transitions between polymorphs of the crystals. We observed that single crystal nanofibers of coronene on a substrate jumped over a centimeter-scale distance at an initial velocity of up to ~ 20 m/s, which is a few orders of magnitude faster than that of reported thermosalient crystals.
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