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

点击翻译按钮获取中文摘要

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.