Magnetism, Electronic Properties and Ferroelectricity in Heavy Metal Pyrochlores

元素周期表中过渡系列的金属-如铁，锰和镍在其化合物中通常具有未成对电子，这导致了它们的一些最有趣的性质，如颜色，磁性和导电性。来自过渡金属系列的重金属包括铂、钨，并且这些元素的氧化物显示出类似的有用性质。该项目的目的是制备这些重过渡金属的氧化物-其中过渡金属与钙或镉等第二种金属结合-并研究其电子和磁性。一种结构类型，或金属和氧化物离子的排列，将被研究，即烧绿石结构，这也是已知的自然发生的矿物的这个名字。烧绿石结构类型对于这些重过渡金属的研究很少，但是已知的烧绿石显示出一些迷人的特性，例如低温下的超导性（对电子流动的零电阻）以及当材料被加热或冷却时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），它们将被研究其结构和物理特性。通过这项工作，我们打算发展一个完整的了解如何组成（例如，重金属类型），结构（烧绿石结构中的金属和氧化物离子的确切排列）和物理性质是相关的。通过这些信息，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.