Layered Oxides Thermoelectrics for High Temperature Waste heat Recovery

能源需求不断增长，我们的社会面临着寻找对环境影响最小的可持续能源的挑战。已经部署了太阳能、风能和地热等现有技术，目前正在努力提高其实际效益和成本效益。另一种迄今为止尚未充分利用的可再生能源来源是“废”热。它来自各种来源，从家用锅炉到大型发电厂，一个突出的例子是传统的内燃机，其中60%的能量以热量的形式损失。设计由p-n结制成的半导体器件的可能性，当暴露于温度梯度时，该半导体器件将输出电力，这对于汽车工业来说是一种有吸引力的解决方案，以提高燃料效率，降低碳足迹和最终用户成本。这种装置，称为热电发电机已成功地用于航空航天应用或在其匡威的形式作为珀尔帖冷却器，有助于所有组件的能量三元悖论。该技术作为能量收集器的广泛传播的主要障碍是高原材料成本和缺乏高温操作的材料。本研究将研究由地球丰富的元素组成的新型无机氧化物，其具有适合于集成在高温热电发电机中的电和热特性。高效热电材料具有高电导率和低热导率，这在标准半导体图片中是对立的性质。专注于高温光谱，氧化物材料将显示器件可靠运行所需的化学稳定性。由于这些材料中的大多数是电绝缘的，因此该概念基于识别具有隐藏的电子晶格的结构图案，该电子晶格可以充当导电通道。类似的概念已经成功地应用于层状氧化物，其中仅生产具有竞争力的p型热电材料。该项目旨在探索利用电子、热和磁晶格之间的强相关性来规避这类材料中遇到的限制并扩展我们对这种复杂化合物的理解的可能性。该项目的一个具体目标是制备来自三金红石结构的多晶和单晶层状氧化物，测量高温电导率和热功率，并使用化学掺杂优化热电性能以获得p型和n型化合物。所提出的化合物的层状结构有利于奇异的磁性和更复杂的现象，如能斯特-埃廷豪森效应和自旋塞贝克效应将被研究。

Energy demand is growing and our society faces a challenge to find sustainable sources with minimal environmental impact. Existing technologies such as solar, wind and geothermal have been deployed and effort to improve their physical and cost effectiveness is ongoing. Another source of renewable energy available which has not been harvested to its full potential so far is "waste" heat. It arises from a variety of sources, from household boiler to large scale power plant, and a striking example is the conventional combustion engine in which 60 % of the energy produced is lost in the form of heat. The possibility to design a semiconductor device made of p-n junctions which when exposed to a temperature gradient will output electrical power is an attractive solution for the automotive industry to improve fuel efficiency, lower the carbon foot print and end-user costs. This device, called a thermoelectric generator has been successfully used for aero-spatial application or in its converse form as Peltier cooler, contributes to all component of the energy trilemma. The major barrier for a widespread dissemination of this technology as energy harvester is the high raw material costs and a lack of material for high temperature operation.This research will investigate new classes of inorganic oxide composed of earth abundant elements presenting electrical and thermal properties suitable for integration in a high temperature thermoelectric generator. Efficient thermoelectric materials possess high electrical conductivity and low thermal conductivity which, in a standard semiconductor picture, are antagonistic properties. Focusing on the high temperature spectrum, oxides materials will display the chemical stability required for the device to function reliably. Since the majority of these materials are electrically insulating, the concept is based on identifying structure patterns that have hidden electronic lattice which could act as conducting channel. Similar concept has been successfully applied on layered oxides where only competitive p-type thermoelectric materials where produced. The project aims to explore the possibility to use the strong correlation between electronic, thermal and magnetic lattice to circumvent the limitations encountered in this class of materials and expand our understanding of this complex compounds.A specific objective of the project is to prepare poly- and single crystalline layered oxides derived from the trirutile structure, measure the high temperature conductivity and thermopower and optimise the thermoelectric property using chemical doping to obtain both p and n type compounds. The layered structures of the proposed compounds are conducive to exotic magnetic properties and more complex phenomena such as Nernst-Ettinghausen effect and spin Seebeck effect will be investigated.