Layered transition metal oxychalcogenides: structures, electronic properties and chemistry

氧化物是一类重要的固态材料，具有广泛的性质，是理解电子在固体中的基本行为方式的关键，也是许多重要技术的核心。该提案旨在研究一类不太为人所知的固态化合物：氧硫化物，它含有氧化物和硫化物离子，通常采用层状结构，具有明确的富氧化物部分与富硫化物部分共生。对电子和离子在每一层中的行为方式以及两种层之间相互作用的研究有望产生一系列与氧化物互补的性质，并可能产生可应用于新技术的化合物。近年来在PI小组中发现的新硫氧化合物将使用一系列实验技术进行测量，如中子粉末衍射、原位x射线粉末衍射、磁强计和电导率测量。固态核磁共振（NMR）光谱学也将成为该计划的重要组成部分，并将与纽约州立大学石溪分校的克莱尔·格雷教授小组合作进行。所有这些测量的结果将相互关联，在这些材料上进行的理论计算，以及在其他相关材料上报告的结果。目的是回答有关材料电子特性的基本问题，并研究这些化合物中锂离子和铜离子的迁移率。这些化合物将与类似的氧化物和硫化物进行比较。该计划的合成部分将扩展PI小组在材料合成方面可用的合成技术范围，包括电化学方法，这将对某些产品的成分提供更好的控制。这些研究将特别关注于理解固体中从绝缘状态到导电状态的转变，以及这种电子变化与化合物晶体结构变化的相关性。离子迁移率将与材料的行为相关，这些材料在可充电锂离子电池技术中是重要的电极和可能的电解质。此外，离子迁移率将与电子和结构变化相关联。PI团队在合成、结构表征和物理性质测量方面拥有专业知识，而Grey教授团队在固态核磁共振光谱方面处于世界领先地位，这是该项目的重要组成部分。两组之间的关系将通过为培训目的定期交换人员和交换意见而得到加强。

Oxides are an important class of solid state material with a wide range of properties which are key to understanding the fundamental way in which electrons behave in solids, and which are central to many important technologies. This proposal aims to investigate a less well known class of solid state compound: the oxysulfides, which contain both oxide and sulfide ions and which often adopt layered structures with well-defined oxide-rich portions intergrown with sulfide-rich portions. The investigation of the way in which electrons and ions behave in each layer and the interaction between the two types of layer is expected to yield a range of properties complementary to those of the oxides and may yield compounds with application in new technologies.New oxysulfide compounds identified in recent years in the PI's group will be measured using a range of experimental techniques such as neutron powder diffraction, in-situ X-ray powder diffraction, magnetometry and electrical conductivity measurements. Solid state nuclear magnetic resonance (NMR) spectroscopy will also form an important part of the programme and will be carried out in collaboration with the group of Prof. Clare Grey at SUNY Stony Brook. The results of all these measurements will be correlated with each other, with theoretical calculations carried out on these materials, and with results reported on other, related materials. The aims are to answer fundamental questions about the electronic properties of the materials and to investigate the mobilities of lithium, and copper ions in these compounds. The compounds will be compared with analogous oxides and sulfides. The synthetic part of the programme will extend the range of synthetic techniques available in the PI's group for the synthesis of materials to include electrochemical methods which will offer greater compositional control over some of the products These investigations will specifically focus on understanding the transition from the insulating state to the conducting state in solids and the correlation of such electronic changes with changes in the crystal structure of the compounds. The ionic mobilities will be correlated with the behaviour of materials which are important as electrodes and possible electrolytes in rechargeable lithium ion battery technologies. Furthermore the ionic mobilities will be correlated with the electronic and structural changes.The collaboration between the PI's group, which has expertise in synthesis, structural characterisation and physical property measurements, and Prof. Grey's group, which is world-leading in solid state NMR spectroscopy is an important component of the project. The relationship between the two groups will be strengthened by regular exchange of personnel for training purposes and the exchange of ideas.