Heat Transport in Novel 3D Patterned Nanostructures

热是我们都很熟悉的东西——我们用它来保暖和烹饪食物。材料中的热流具有基本的技术重要性，并对我们如何设计设备施加了限制。热量过少往往意味着物理过程无法启动。热量过高，大多数技术系统最终都会失灵。在我们的家中，热量的流动对我们的舒适度至关重要，而优化建筑材料以减少热量损失对于应对全球变暖和气候变化具有重要意义。因此，人们对物质中的热流知之甚少，这也许令人惊讶。特别是，真实的材料往往具有复杂的三维几何形状，在微观尺度上具有一系列的界面区域。热量如何从一种物质流向另一种物质，这也许是最关键的方面之一，也是人们尚未很好理解的一个方面。尽管研究已经开始调查热流在这些真实材料中以及材料之间是如何流动的，但由于缺乏可控制的模型实验系统，无法直接探测不同的传输过程，研究的成功受到了限制。这有几个原因。首先，当观察与热载体无扰动移动的平均距离相当的长度尺度时，需要研究纳米尺度的结构。在纳米尺度上制造受控制的三维几何形状具有难以置信的挑战性，迄今为止的探索有限。其次，为了与理论进行详细的比较，需要周期系统，允许使用相关的边界条件。在这个提议中，我们将利用最先进的纳米制造技术来实现具有受控3D几何和结构的材料。我们的方法，双光子光刻，允许这样的3D几何形状在80nm的尺度上设计，然后可以通过电沉积转化为另一种材料。在被称为声子的热载体的长度尺度上，通过改变其几何形状、大小和材料，我们将推动我们对热流及其主导因素的理解。我们将直接探测电子和热量的传输，通过我们独特的结构在体积尺度上，并利用扫描探针显微镜，在纳米尺度上。这将为纳米尺度热流如何影响体热性能提供无与伦比的见解，并为观测提供相关理论基础。最终，这项研究不仅有可能飞跃我们对传热的理解，而且有可能开启控制传热的新方法，有可能制造新的设备，新的能量转换形式，并开发新的工具，帮助人类在我们的生活和环境中控制热量。

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.