Heat Transport in Novel 3D Patterned Nanostructures

点击翻译按钮获取中文摘要

Heat is something that all of us are familiar with - we use it to keep us warm and to cook our food. The flow of heat in materials is of fundamental technological importance and imposes constraints on how we design devices. Too little heat often means physical processes cannot activate. Too much heat and most technological systems eventually fail. In our homes, it is the flow of heat that is vital to our comfort, whilst optimising materials for our buildings to reduce heat loss is now of significant importance in tackling global warming and climate change. As such, it is perhaps surprising how little is understood about the flow of heat in materials. In particular, real materials often have complex three-dimensional geometries upon the microscopic scale with a range of interfacial regions. Perhaps the most critical aspect, how heat flows from one material to the next is also one of the aspects which is not well understood. Though studies have started to investigate how heat flows in such real materials and between materials, their success are limited by the lack of controlled model experimental systems that would allow different transport processes to be directly probed. There are several reasons for this. Firstly, when looking at the length scales which are comparable to the average distance heat carriers travel unperturbed, one needs to investigate nanoscale structures. The fabrication of controlled 3D geometries upon the nanoscale is incredibly challenging and to date has limited exploration. Secondly, for a detailed comparison with theory, one needs periodic systems, allowing relevant boundary conditions to be utilised. In this proposal, we will harness state-of-the-art nanofabrication in order to realise materials with controlled 3D geometry and structure. Our methodology, two-photon lithography, allows such 3D geometries to be written by design at a scale of 80nm which can then be translated into another material via electrodeposition. By varying the geometry, size and material, at the length scales of the heat carrier, known as the phonon, we will push our understanding of heat flow and the factors dominating it. We will directly probe the transport of electrons and heat through our unique structures upon the bulk scale and by harness scanning probe microscopy, at the nanoscale. This will provide an unparalleled insight into how nanoscale heat flow impacts bulk thermal properties, with relevant theory providing a foundation for the observations. Ultimately, this study has the potential to not only leap forward our understanding of heat transfer, but also to unlock new ways to control it, with the potential to make new devices, new forms of energy conversion and to develop new tools that help mankind control heat in our lives and our environment.