New Materials from High Pressure and Beyond

新材料在电子、磁性和能源技术中的应用极大地推动了现代化学、物理学和材料科学的发展。高压方法对于材料合成和诱导新的电子态是重要的。该项目将探索令人兴奋的新材料，以及超越标准高压合成方法的材料发现新思路。在我们的高压材料合成中，化学反应在高达150，000个大气压的压力和高达1500 ℃的温度下进行。然后将样品冷却，然后减压至环境条件。在成功的案例中，发现具有新的化学组成或结构的新材料已经从高压和高温反应条件中“回收”。这是一个成功的发现致密，氧化物基，无机材料的策略，并将应用于几个特定的情况。磁铁矿是原始的磁性材料，在自旋电子器件等新技术中仍然具有根本的兴趣和实际重要性。我们最近解决了一个长期存在的问题（首次发现于1939年），关于磁铁矿的低温电子结构，我们发现了意想不到的“轨道分子”状态，其中电子分布在三个相邻的铁原子上。在这个项目中，我们将使用高压合成来恢复新的化学取代的类似物，这些类似物保留了磁铁矿的基本电子特征，以发现新的“轨道分子”状态或排列。钌还形成重要的磁性氧化物，如用于自旋电子和硅薄膜电子器件的铼酸锶。我们最近发现了一个新的钌氧化物家族，并将利用高压来探索其化学组成范围和电子和磁性。氮氧化物（氧化物-氮化物）材料在能源技术中非常重要，如分解水产生氢的光催化剂，以及WLED白光发射半导体器件的荧光粉。WLED器件是器件创新（GaN基蓝光LED的发现）和材料化学（氮化物磷光体的发现）如何在全球范围内实现真实的节能的一个很好的例子。我们将使用直接高压合成路线来生成新的氮氧化物，并通过合作探索其性能。材料的成功制备通常是高压合成的化学终点，但我们也将探索新的方法，其中合成的高压材料是化学研究的起点。这可以被描述为一种“硬-软”方法，通过“软”合成后改性减轻在“硬”高压和高温条件下制备的致密前体的不稳定性来产生新材料。最近的概念验证结果表明，“硬-软”化学可以在高压合成之外产生新的过渡金属氧化物。我们还将对回收材料的电子和磁性进行高压测量，以发现超出环境压力的电子特性，包括量子力学变化很重要的非常低的温度范围。

The discovery of new materials for electronic, magnetic and energy techmology applications motivates much of modern chemistry, physics and materials science. High pressure methods are important for materials synthesis and for inducing new electronic states. This project will explore exciting new materials and also new ideas for materials discovery that go beyond standard high pressure synthesis approaches. In our high pressure materials syntheses, a chemical reaction is carried out at pressures up to 150,000 atmospheres pressure and temperatures up to 1500C. Afterwards the sample is cooled and then decompressed to ambient conditions. In successful cases, a novel material with a new chemical composition or structure is found to have been 'recovered' from the high pressure and temperature reaction conditions. This is a successful discovery strategy for dense, oxide-based, inorganic materials and will be applied to several specific cases. Magnetite is the original magnetic material and remains of fundamental interest and of practical importance in new technologies such as spintronic devices. We have recently solved a long-running problem (first identified in 1939) concerning the low temperature electronic structure of magnetite and we discovered unexpected 'orbital molecule' states where electrons are spread over three adjacent iron atoms. In this project we will use high pressure synthesis to recover new chemically-substituted analogues that preserve the essential electronic features of magnetite, in order to discover new 'orbital molecule' states or arrangements. Ruthenium also forms important magnetic oxides such strontium ruthenate which is used in spintronic and silicon thin-film electronics devices. We have recently discovered a new familty of ruthenium oxides, and high pressure will be used to explore their chemical composition range and electronic and magnetic properties.Oxynitride (oxide-nitride) materials are important for energy technologies as photocatalyts that split water to generate hydrogen, and as phosphors for WLED white-light emitting semiconductor devices. WLED devices are an excellent example of how device innovation (discovery of GaN-based blue LEDs) and materials chemistry (discovery of nitride phosphors) have led to real energy savings on a global scale. We will use a direct high pressure synthesis route to generate new oxynitrides and explore their propeties through collaboration.The successful preparation of a material is usually the chemical end point for high pressure synthesis, but we will also explore new approaches where a synthesised high pressure material is the starting point for chemical investigations. This can be described as a 'hard-soft' method to generate novel materials by relieving the instability of a dense precursor made under 'hard' high pressure and temperature conditions through 'soft' post-synthesis modification. Recent proof-of-concept results have shown that 'hard-soft' chemistry can generate new transition metal oxides beyond high pressure synthesis. We will also perform high pressure measurements of electronic and magnetic properties of recovered materials to discover electronic properties beyond those at ambient pressure, including very low temperature regimes where quantum mechanical variations are important.