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。现有的技术，如太阳能、风能和地热，已经得到了应用，并且正在努力提高它们的物理效益和成本效益。到目前为止，另一种尚未充分利用的可再生能源是“废热”。它的来源多种多样，从家用锅炉到大型发电厂，一个显著的例子是传统的内燃机，其中60%的能量以热量的形式损失掉了。设计一种由p-n结制成的半导体器件的可能性，当暴露在温度梯度下时，将输出电力，这是汽车行业提高燃油效率，降低碳足迹和最终用户成本的一个有吸引力的解决方案。这种被称为热电发电机的装置已经成功地用于航空航天应用，或者以其相反的形式作为珀尔帖冷却器，有助于解决能源三难困境的所有组成部分。该技术作为能源收割机广泛推广的主要障碍是原材料成本高和缺乏高温操作材料。本研究将探索由富土元素组成的新型无机氧化物，它们具有适合集成在高温热电发电机中的电学和热学性能。高效热电材料具有高导电性和低导热性，在标准的半导体图像中，它们是拮抗性质。专注于高温光谱，氧化物材料将显示设备可靠运行所需的化学稳定性。由于这些材料中的大多数都是电绝缘的，因此该概念是基于识别具有隐藏的电子晶格的结构模式，这些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，只有竞争的p型热电材料产生。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的可能性，并扩展我们对这种复杂化合物的理解。该项目的一个具体目标是制备由三聚体结构衍生的多晶和单晶层状氧化物，测量高温电导率和热功率，并使用化学掺杂来优化热电性能，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能和更复杂的现象，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.