Structure and Properties of Transition Metal Oxychalcogenides and Oxypnictides

该项目属于EPSRC“物理科学”研究领域，也与“能源”主题相关。该项目将重点研究某些过渡金属氧硫族化合物和氧nictides的合成和表征。这些化合物是混合阴离子材料，倾向于形成层状结构并表现出许多理想的特性。例如，它们可以是超导体、半导体或离子导体。特别是，这些固体的磁性将被探测，以获得对任何存在的长范围磁有序的理解，并探索在给定温度范围内这种有序的性质。这些层状材料也有潜力用作锂离子电池的正极材料，因为它们可以进行锂- cu交换，然后再进行锂离子的脱嵌和嵌入。如果在化学上可行，成功制造的目标将作为电池电极进行测试，这显然与英国的研究战略一致。这部分工作将与法拉第研究所FutureCat项目合作。该项目将涉及新化合物的生产。这可以通过取代已知结构中的离子来实现，例如改变晶体位置上存在的过渡金属，这具有调整电子和磁性质的效果。当尝试一种特定的合成目标时，也可能产生新的材料，但相反形成了一种更有利的新产品；仔细检查结构数据将能够确定这一点，并将新化合物合成为纯相，开辟新的研究途径。将对新材料和现有材料进行深入的表征。结构，磁顺序和反应性的某些方面将特别关注。虽然可以通过计算来预测固体的行为，但只有当这些材料本身经过测试后，才能真正了解它们的性质。这些材料是用传统的陶瓷固态方法合成的，用杵和臼将反应物研磨在一起，然后在熔炉中将均匀的混合物加热到高温。由于反应物和产物对氧气和水分的敏感性，这种制备是在一个充满氩气的干燥箱中进行的，反应物混合物在真空下密封在硅管中，然后在炉中加热。结构确定是通过在室内和钻石光源（Harwell）的x射线衍射仪上收集的x射线粉末衍射数据的Rietveld细化来实现的。内部磁力计用于测量样品的磁化强度，通常从室温降至2 K。在中子源上进行的中子散射，如ISIS设施（Harwell）和ILL设施（法国格勒诺布尔），是探索这些化合物内磁有序的重要技术。牛津物理中选定的重要材料的晶体生长将使更广泛的物理性质和光谱测量得以实现，并在物理科学主题中实现新的性质。高压合成也可能是合适的，这将与位于Harwell校区的Element 6合作进行。

This project falls within the EPSRC 'Physical Sciences' research area and is also related to the 'Energy' theme. The project will focus on the synthesis and characterisation of certain transition metal oxychalcogenides and oxypnictides. These compounds are mixed-anion materials which tend to form layered structures and exhibit a number of desirable properties. For example, they can be superconductors, semiconductors or ionic conductors. In particular, the magnetic properties of these solids will be probed in order to gain an understanding of any long range magnetic ordering present and to explore the nature of this ordering over a given temperature range. These layered materials also have the potential to be used as cathode materials in Li-ion batteries due to the possibility of Li-Cu exchange and then deintercalation and intercalation of the Li ions. The targets that are successfully made will be tested as battery electrodes if this seems chemically viable, and this clearly aligns with the UK research strategy. This part of the work will be collaborative with the Faraday Institution FutureCat project. The project will involve the production of novel compounds. This can be achieved through the substitution of ions in known structures, such as changing the transition metal present on a crystallographic site, and this has the effect of tuning the electronic and magnetic properties. New materials may also arise when a particular synthetic target is attempted, but a more energetically favoured new product is formed instead; careful examination of structural data will enable this to be ascertained and the new compounds to be synthesised as pure phases, opening up new research avenues. The characterisation of both new and existing materials will be performed in depth. Structure, magnetic order and certain aspects of reactivity will be focussed on specifically. Although predictions about the behaviour of solids can be made computationally, it is only once these materials themselves have been tested that their properties are truly known. The materials are synthesised using the tradition ceramic solid state method of grinding reactants together using a pestle and mortar and then heating the homogeneous mixture to high temperatures in a furnace. Due to the likely oxygen and moisture sensitivity of both reactants and products, this preparation is carried out in an argon-filled dry box with the reactant mixture being sealed under vacuum in a silica tube before being heated in the furnace. Structure determination is achieved through Rietveld refinement of x-ray powder diffraction data collected on x-ray diffractometers in house and at the Diamond Light Source (Harwell). An in house magnetometer is used to measure the magnetisation of samples, generally from room temperature down to 2 K. Neutron scattering carried out at neutron sources, such as the ISIS Facility (Harwell) and the ILL Facility (Grenoble, France), is an essential technique for the exploration of magnetic ordering within these compounds. Crystal growth of selected important materials in Oxford Physics will enable a wider range of physical property and spectroscopic measurements to be performed, and new properties to be realised within the Physical Sciences theme. High pressure synthesis may also be appropriate and this will be carried out in collaboration with Element 6 located at the Harwell campus.