EAGER: Thermal pulsing enabled fast and reversible morphology control

University Of Tennessee Knoxville, Knoxville TN

Investigators

Abstract

CBET 1349507 PI: Kalyanaraman In 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.