Ordered States in Oxides

氧化物的有序态

基本信息

批准号：
EP/F02083X/1
负责人：
J Attfield
金额：
$ 17.15万
依托单位：
University of Edinburgh
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2008
资助国家：
英国
起止时间：
2008 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FF02083X%2F1
关键词：
Ordered States Oxides

项目摘要

The electronic properties of transition metal oxides continue to drive many fields, from fundamental condensed matter physics and solid state chemistry to materials science and engineering applications. High temperature superconductivity (HTSC) in copper oxides and colossal magnetoresistances (CMR) in manganite perovskites are two particularly important phenomena that have led to many other perovskite oxides being widely studied for their electronic properties.Knowledge of structure is always important for understanding materials properties. Transition metal oxide structures are often based on simple high symmetry structures e.g. perovskite, spinel, but the above orderings lower symmetry leading to slight lattice distortions and superstructures. It has become clear that much subtle but important information can be gained from high resolution powder diffraction studies. Powder diffraction is needed partly because many of these materials are difficult to crystallise, but more fundamentally, the distortions lead to severe (micro)twinning in crystals that makes conventional single crystal structure determinations difficult (e.g. in the case of Fe3O4).Powder diffraction is a simple technique but remains one of the most popular in the synchrotron X-ray and neutron user communities. A variety of instruments are now available at ISIS, ILL, ESRF and (in the future) Diamond. These are applied to many problems in chemistry, physics, materials science, engineering and geosciences. To make the best use of available facilities, as well as providing a broad training in leading powder diffraction techniques, this project will study several materials using a range of instruments.The structures and magnetic order in high pressure Cr, Ru and Bi-based perovskites will be investigated. These materials will be synthesised using a recently commissioned Walker press. The complex superstructures associated with charge, spin and orbital order in RBaMn2O6 manganites will also be studied. Charge ordering in magnetite (Fe3O4) is a classic and long running problem. We aim to improve on a previous structural model through further high resolution powder diffraction study, and analysing data from heavily twinned microcrystals. Further aspects of the student training will be through attending workshops in Grenoble (HERCULES) and ISIS, and by 3 month visits to each centre.

过渡金属氧化物的电子特性继续推动许多领域，从基本的凝结物理和固态化学到材料科学和工程应用。铜氧化物中的高温超导性（HTSC）和锰矿钙钛矿中的巨大磁路（CMR）是两个特别重要的现象，这些现象已导致许多其他钙钛矿氧化物广泛研究了其电子特性。过渡金属氧化物结构通常基于简单的高对称结构，例如钙钛矿，尖晶石，但上述订购较低的对称性导致小晶格扭曲和上层建筑。很明显，从高分辨率粉末衍射研究中可以获得很多微妙但重要的信息。 Powder diffraction is needed partly because many of these materials are difficult to crystallise, but more fundamentally, the distortions lead to severe (micro)twinning in crystals that makes conventional single crystal structure determinations difficult (e.g. in the case of Fe3O4).Powder diffraction is a simple technique but remains one of the most popular in the synchrotron X-ray and neutron user communities.现在可以在ISIS，ILL，ESRF和（将来）Diamond上提供各种乐器。这些应用于化学，物理，材料科学，工程和地球科学方面的许多问题。为了充分利用可用的设施，并在领先的粉末衍射技术方面提供了广泛的培训，该项目将使用一系列仪器研究多种材料。将研究高压CR，RU和BI-BAI-BAI-BAID PEROVSKITES中的结构和磁性。这些材料将使用最近委托的Walker Press合成。还将研究与电荷，旋转和轨道顺序相关的复杂的上层建筑，并研究RBAMN2O6锰矿中的复杂上层建筑。磁铁矿（FE3O4）中的充电订购是一个经典且长期运行的问题。我们旨在通过进一步的高分辨率粉末衍射研究来改善先前的结构模型，并分析来自重度微晶的数据。学生培训的进一步方面将是通过参加格勒诺布尔（Hercules）和ISIS的研讨会，以及对每个中心进行3个月的访问。