EAGER: Thermal pulsing enabled fast and reversible morphology control

CBET 1349507PI：Kalyanaraman在这项研究中，我们将调查对一项发现的理解，在这项发现中，纳米结构的尺寸和形态可以在非常短的纳秒时间内实现可逆变化。因此，由形貌直接控制的物理性质，如磁性、光学反射率、等离子激元共振颜色和电导率，也可以快速逆转。对这种效应的实验观察是，在快速热脉冲和静态磁场的特定组合下，纳米颗粒可以发生分解，然后通过加热重新形成。我们的假设是，材料的大小和或密度的快速变化是分裂的核心。我们设计了实验和模型来证实这些想法。实验将包括研究作为热脉冲、磁场和材料参数的函数的解体，而建模将用于预测纳米结构内温度变化的时空性质，从而估计导致解体的力。能够显示物理行为的可逆循环的材料和/或过程对于具有广泛社会经济影响的多种应用非常重要。例如，存储在我们的智能手机和计算机上的数据可以通过改变电子或磁性状态被多次读取、擦除和重写。然而，这种材料和工艺存在严重的局限性。例如，计算机逻辑由半导体材料主导。此外，不可能以足够快的方式逆转每个物理属性，从而实现更好的新应用。一个例子是太阳眼镜中的光致变色效应--虽然在那里很有用，但在电子应用中几乎没有什么用处，因为它非常慢。我们研究的影响将来自于展示这种基于可逆形态控制的逆转物理行为的新方法。由于它可以在纳秒内发生，我们展望了在动态热和电磁屏蔽、智能光学窗口、新型数据存储和存储、纳米级修复以及热量和温度测量方面的应用。

CBET 1349507PI: KalyanaramanIn this research we will investigate the understanding of a discovery in which a reversible change in the size and morphology of nanostructures can be achieved in very short nanosecond times. As a result, physical properties such as magnetism, optical reflectivity, plasmon resonance colors, and electrical conductivity, that are directed controlled by the morphology, can also be reversed rapidly. The experimental observation of this effect is that break-up of nanoparticles can occur under specific combinations of rapid thermal pulses and a static magnetic field, which can then be re-formed by thermal heating. Our hypothesis is that the rapid change in size and or density of the material is central to the break-up. We have designed experiments and modeling to confirm these ideas. Experiments will involve study of break-up as function of thermal pulsing, magnetic field, and materials parameters, while the modeling will be used to predict the spatio-temporal nature of temperature change within the nanostructures so as to estimate the forces leading to break-up.Materials and/or processes that can show reversible cycling of physical behavior are very important for a multitude of applications with wide ranging socio-economic impact. For example, the data stored on our smartphones and computers can be read, erased and rewritten multiple times through changes to the electronic or magnetic state. However, there is a severe limitation of such materials and processes. For instance computer logic is dominated by semiconductor materials. Also, it is not possible to reverse every physical property in a fast enough manner that would enable better new applications. One example is the photochromic effect found in sun glasses - although useful there, finds little use in electronic applications because it is extremely slow. The impact of our research will be from demonstrating this new approach to reverse physical behavior, based on reversible morphology control. Because it can happen in nanoseconds, we envision applications in dynamic heat and electromagnetic shielding, intelligent optical windows, novel data storage and memory, nanoscale repair, and measurement of heat and temperature.