New York University Abu Dhabi, PO Box 129188, Abu Dhabi, United Arab Emirates.
University of Naples Federico II, Department of Chemical Sciences, Via Cintia, I-80126, Naples, Italy.
Sci Rep. 2016 Jul 12;6:29610. doi: 10.1038/srep29610.
The ability of thermosalient solids, organic analogues of inorganic martensites, to move by rapid mechanical reconfiguration or ballistic event remains visually appealing and potentially useful, yet mechanistically elusive phenomenon. Here, with a material that undergoes both thermosalient and non-thermosalient phase transitions, we demonstrate that the thermosalient effect is preceded by anomalous thermal expansion of the unit cell. The crystal explosion occurs as sudden release of the latent strain accumulated during the anisotropic, exceedingly strong expansion of the unit cell with αa = 225.9 × 10(-6) K(-1), αb = 238.8 × 10(-6) K(-1) and αc = -290.0 × 10(-6) K(-1), the latter being the largest negative thermal expansivity observed for an organic compound thus far. The results point out to the occurence of the thermosalient effect in phase transitions as means to identify new molecular materials with strong positive and/or negative thermal expansion which prior to this work could only be discovered serendipitously.
热致伸缩固体（无机马氏体的有机类似物）通过快速机械重构或弹道事件移动的能力仍然具有视觉吸引力和潜在的有用性，但在机械上却难以捉摸。在这里，我们使用一种经历热致伸缩和非热致伸缩相变的材料，证明了热致伸缩效应之前是单元晶格的异常热膨胀。晶体爆炸是由于在各向异性、异常强烈的单元晶格膨胀过程中积累的潜在应变的突然释放而发生的，单元晶格的各向异性膨胀系数为 αa = 225.9 × 10(-6) K(-1)、αb = 238.8 × 10(-6) K(-1) 和 αc = -290.0 × 10(-6) K(-1)，后者是迄今为止观察到的有机化合物中最大的负热膨胀系数。这些结果表明，在相变中出现热致伸缩效应是识别具有强正和/或负热膨胀的新型分子材料的一种手段，在此之前，这些材料只能偶然发现。
