EAGER: Thermal pulsing enabled fast and reversible morphology control

CBET 1349507 PI：Kalyanaraman在这项研究中，我们将调查一个发现的理解，其中纳米结构的尺寸和形态的可逆变化可以在很短的纳秒时间内实现。结果，由形态直接控制的物理性质如磁性、光学反射率、等离子体共振颜色和电导率也可以快速逆转。这种效应的实验观察结果是，在快速热脉冲和静磁场的特定组合下，纳米颗粒可以发生破碎，然后可以通过热加热重新形成。我们的假设是，材料的尺寸和/或密度的快速变化是破碎的核心。我们设计了实验和建模来证实这些想法。实验将涉及作为热脉冲，磁场和材料参数的函数的分解的研究，而建模将用于预测纳米结构内的温度变化的时空性质，从而估计导致break-up的力。材料和/或过程，可以显示可逆的物理行为循环对于具有广泛的社会经济影响的许多应用是非常重要的。例如，存储在我们的智能手机和计算机上的数据可以通过电子或磁性状态的变化多次读取，擦除和重写。然而，这种材料和工艺存在严重的限制。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一个物理性质，从而实现更好的新应用。一个例子是太阳镜中发现的光致变色效应-尽管在那里很有用，但在电子应用中几乎没有用处，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。因为它可以在纳秒内发生，我们设想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中的应用。

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.