X-ray powder diffraction meets the thermosalient effect – The jumping crystals

The thermosalient effect is a rare property of certain materials for actuation by elastic deformation and/or by a ballistic event. We present a remarkable jumping crystal, giving  direct evidence for the driving force behind its impressive crystal motility, as studied by X-ray powder diffraction (XRPD). The system switches between five structures that are related by four phase transitions including a thermosalient transition. The mechanical effect is driven by an extraordinary thermal expansion, with coefficients that are among the highest values reported for molecular solids thus far.