Magnetism, Electronic Properties and Ferroelectricity in Heavy Metal Pyrochlores

元素周期表中过渡系列的金属，如铁、锰和镍，它们的化合物中通常有不成对的电子，这导致了它们一些最有趣的特性，如颜色、磁性和导电性。过渡金属系列中的重金属包括铂、钨，这些元素的氧化物表现出类似的有用性质。该项目的目的是制备这些重过渡金属的氧化物——过渡金属与钙或镉等第二金属结合——并研究它们的电子和磁性能。一种结构类型，或金属和氧化物离子的排列，将被研究，即焦绿石结构，也被称为这种名称的自然存在的矿物。对这些重金属过渡金属的焦绿石结构类型的研究很少，但已知的一些特性显示出一些迷人的特性，例如在低温下的超导性（对电子流动的零电阻）以及当材料加热或冷却时在绝缘行为和高导电性之间的转变。一旦材料被合成（使用各种技术，包括在高压下的反应——复制自然界中发现的反应条件），他们将在结构和物理性质方面进行研究。通过这项工作，我们打算全面了解组成（例如哪种重金属类型），结构（金属和氧化物离子在焦绿石结构中的确切排列）和物理性质之间的关系。有了这些信息，我们将了解如何生产在电子、传感器和数据存储系统中具有潜在有用应用的新材料。

Metals from the transition series in the Periodic Table - such as iron, manganese and nickel often have unpaired electrons in their compounds and this leads some of their most interesting properties such as colour, magnetism and electrical conductivity. Heavy metals from the transition metal series include platinum, tungsten and the oxides of these elements show similar useful properties. The aim of this project is to prepare oxides of these heavy transition metals - where the transition metal is in combination with a second metals such as calcium or cadmium - and study their electronic and magnetic properties. One structure type, or arrangement of the metal and oxide ions, will be studied namely the pyrochlore structure which is also known for a naturally occuring mineral of this name. The pyrochlore structure type has been poorly studied for these heavy transition metals but where known shows some fascinating properties such as superconductivity (zero resistance to the flow of electrons)at low temperature and transitions between insulating behaviour and high electrical conductivity when the materials is heated or cooled. Once materials have been synthesised (using a variety of techniques including reactions under high pressures - replicating reaction conditions found in nature) they will be studied in terms of their structures and physical properties. Through this work we intend to develop a complete understanding of how composition (e.g. which heavy metal type), structure (the exact arrangement of the metal and oxide ions in the pyrochlore structure)and physical properties are related. With this information we will be understand how to produce new materials with potential useful applications in electronic, sensor and data storage systems.