High Pressure Synthesis of All Transition Metal Oxide Perovskites and Related Materials

寻找具有优异性能的新型电子材料和磁性材料是现代化学、物理和材料科学发展的动力。超导铜酸盐和磁阻锰酸盐的重大发现，加上对多铁性材料、燃料电池和电池中的混合导体以及W（白光）LED荧光粉等光电子学的新兴趣，引起了全世界对金属氧化物相关材料的兴趣。该项目以钙钛矿为中心，钙钛矿是一类广泛的材料，其结构基于矿物CaTiO3的ABX3排列。钙钛矿的不可阻挡的兴起是由其巨大的化学和结构灵活性以及其杰出的物理和化学性质所驱动的，这些性质通常是其领域中最好的，例如铁电性BaTiO3， YBa2Cu3O7高tc超导体，自旋电子学的（La,Sr）MnO3和Sr2FeMoO6 CMR（巨磁电阻），多铁性BiFeO3，混合导体如掺杂LaCrO3用于燃料电池，分子钙钛矿如（CH3NH3）PbI3用于光伏器件。其中许多在钙钛矿b位含有过渡金属（TM）。该项目将以最近的发展为基础，探索“全过渡金属”（ATM）氧化物钙钛矿，其中TM占据ABO3钙钛矿结构中的所有A和B位点。过去几年的概念验证实验表明，这种材料可以在高压条件下合成，并且一些材料具有基于TM阳离子排序的有用和有趣的电子特性，例如从负磁阻到大正磁阻的新颖开关。该项目将探索一系列新的ATM和相关的富tm氧化物钙钛矿的化学品种和电子和磁性能。压力是材料勘探中的一个重要变量。我们在两级压机中达到了22 GPa，提供了一个适当的压力范围来稳定ATM氧化物钙钛矿。

The search for new electronic and magnetic materials with outstanding properties motivates much of modern chemistry, physics and materials science. The major discoveries of superconducting cuprates and magnetoresistive manganites, plus renewed interests in multiferroics, mixed conductors in fuel cells and batteries, and optoelectronics such as W(hite light)LED phosphors have given rise to worldwide interest in metal oxide-related materials. This project is centred on perovskites, which are a broad class of materials with structures based on the ABX3 arrangement of the mineral CaTiO3. The inexorable rise of perovskites has been driven by their enormous chemical and structural flexibility and by their outstanding physical and chemical properties, which are often the best in their field, e.g. ferroelectric BaTiO3, YBa2Cu3O7 high-Tc superconductor, (La,Sr)MnO3 and Sr2FeMoO6 CMR (colossal magnetoresistance) for spintronics, multiferroic BiFeO3, mixed conductors such as doped LaCrO3 for fuel cells, molecular perovskites like (CH3NH3)PbI3 for photovoltaic devices. Many of these contain Transition Metals (TM) at the perovskite B-sites.This project will build on recent developments to explore 'All Transition Metal' (ATM) oxide perovskites where TM's occupy all of the A and B sites in the ABO3 perovskite structure. Proof of concept experiments in the last few years have shown that such materials can be synthesised using high pressure conditions, and some have useful and interesting electronic properties based on TM cation ordering, e.g. a novel switch from negative to large positive magnetoresistances. This project will explore the chemical variety and electronic and magnetic properties of a range of new ATM and related TM-rich oxide perovskites using high pressure synthesis. Pressure is an important variable in materials exploration. We have achieved up to 22 GPa in our two stage press providing an appropriate pressure range to stabilise the ATM oxide perovskites.