Structure-Reactivity Relationships for Extended Solids: Tailored Design of Highly Functional Materials

氧化物基材料非常普遍，在技术的小型化中起着至关重要的作用，并为更高效率的设备开辟了道路。在过去十年中，可充电电池的性能有了显著提高，现在已成为各种设备（手机、电脑、汽车、医疗设备）的可靠部件。固体氧化物燃料电池（SOFC）是一种高效的二次电源，可以承受多种燃料，几乎不需要维护。大多数这些器件的核心是无机固态材料，需要对其各自的功能进行优化。对定制材料的需求是巨大的，这种材料既能提供可靠和高效的性能，又具有经济竞争力。本文对这些功能无机材料及其控制制备和加工进行了研究。不幸的是，迄今为止，人们对固态材料的化学反应性和形成知之甚少。事实上，一种功能材料的成功定向制备往往取决于合成化学家的经验和直觉。我们的目标化合物是用于能量转换的陶瓷，用于固体氧化物燃料电池（SOFC）技术的氧化物离子导体和用于可充电电池的新型层状锂导体。不幸的是，对于无机材料的合成几乎没有合理的设计策略。相同的材料组成可以产生具有不同性质的各种不同结构，传统上大多数金属氧化物都是在高温下直接制备的（T ~ 1000℃），而忽略了在较低温度下使用间接合成路线可以获得的结构和功能多样性。Bieringer的研究小组已经清楚地证明了大量的亚稳结构可以在较低的温度下获得。我们实时监测固体化学反应，并推导出反应途径，为扩展固体提供结构-反应性关系。在较低的温度下，我们遇到了各种各样的氧化物缺陷结构（氧化物缺陷结构负责氧化物离子的传导），它们具有作为固态电解质的潜在应用。在这个特别的提议中，我们的目标是进一步探索固态反应途径，试图建立可靠的结构-反应性关系，这将使功能固态材料的合理设计成为可能。本提案的第二部分涉及低温拓扑反应，我们在反应过程中只修改部分结构。我们使用金属氢化物作为固态还原剂。这使我们能够制备来自母体宿主结构的亚稳态产物，并且可以表现出不同寻常的氧化态和配位环境。一个具体的应用涉及层状氧化物结构中的同时还原（拓扑氧化离子去除）和阳离子嵌入。这些相可能是可调锂导体，用于可充电电池技术。拟议的研究项目将为学生提供独特的培训机会，并为毕业生在加拿大的可再生能源研究环境做好准备。

Oxide based materials are very common and have played vital roles in miniaturization of technologies and have opened up avenues for higher efficiency devices. The performance of rechargeable batteries have improved significantly during the last decade and are now reliable components in all types of devices (cell phones, computers, cars, medical devices). Solid Oxide Fuel Cells (SOFC) are highly efficient secondary power sources that can tolerate diverse fuels and require almost no maintenance. At the center of most of these devices are inorganic solid state materials that need to optimized for their respective functions. There is a tremendous need for tailored materials that can provide reliable and efficient performance while being economically competitive. This proposal is concerned with these functional inorganic materials and their controlled preparation and processing. Unfortunately to date the chemical reactivity and formation of solid state materials is only very poorly understood. In fact the successful targeted preparation of a functional material often depends on the experience and intuition of synthetic chemists. Our target compounds are ceramics with applications in energy conversion, oxide ion conductors for solid oxide fuel cell (SOFC) technology and novel layered lithium conductors for rechargeable batteries. Unfortunately almost no rational design strategies for the synthesis of inorganic materials are available. The same materials composition can result in a variety of different structures with different properties, traditionally most metal oxides are prepared directly at high temperatures (T > 1000°C) while ignoring the structural and thus functional diversity accessible at lower temperatures using indirect synthetic routs. The Bieringer research group has clearly demonstrated the large number of metastable structures that are accessible at lower temperatures. We monitor solid state chemical reactions in real time and derive reaction pathways which provide structure-reactivity relationships for extended solids. At lower temperatures we have encountered diverse oxide defect structures (oxide defect structures are responsible for oxide ion conduction) with potential applications as solid state electrolytes. In this particular proposal we aim at further exploring solid state reaction pathways in an attempt to establish reliable structure-reactivity relationships which will enable the rational design of functional solid state materials. The second component of this proposal deals with low temperature topotactic reactions where we only modify parts of a structure during the reaction. We are employing metal hydrides as solid state reductants. Those permit us to prepare metastable products derived from the parent host structures and can exhibit unusual oxidation states and coordination environments. A specific application is concerned with the simultaneous reduction (topotactic oxide ion removal) and cation intercalation in layered oxide structures. These phases are potentially tunable lithium conductors for rechargeable battery technology. The proposed research program will provide unique training opportunities for students and prepares graduates for the renewable energy research environment in Canada.