Megabar Neutron Diffraction for Hydrogen, Ices and Superconductor Research MENHIR

用于氢、冰和超导体研究的兆巴中子衍射 MENHIR

• 批准号: EP/Y020987/1
• 负责人: John Loveday
• 金额: $ 95.46万
• 依托单位: University of Edinburgh
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FY020987%2F1
• 关键词: Megabar; Neutron; Diffraction; Hydrogen; Ices

The pressure of around one million atmospheres is an important milestone for systems composed of molecules. Pressures around this value are required to break the strong covalent bonds which hold molecules together and hence transform molecular systems into non-molecular systems. This change from molecular to non-molecular leads to profound changes in properties. Hydrogen has been reported to become a metal and this metallic form may be the cause of Jupiter's magnetic field. The hydrogen atoms in water and ice detach from the oxygen atoms and become mobile so that they conduct electricity in a way similar to the way that lithium ions in the batteries of laptops and phones conduct. Hydrogen sulphide forms a metallic compound which superconducts at a temperature of only -70 C. A study of these and similar phenomena yields information that is of both fundamental and technological importance. For example, the behaviour of hydrogen atoms provides stringent tests for our understanding of quantum behaviour, the way hydrogen-bonded solids like ice behave provides insight into the way biochemical processes work, and novel superconductors offer new routes to a potential room temperature superconductor which would transform power distribution medical imaging and could make a 'Back To The Future II' hoverboard a reality. However, our understanding of these and other important hydrogen-rich systems at million atmosphere pressures is limited by the fact that the most fundamental information -- the position of the hydrogen atoms in the crystal structures -- is currently not known. The reason for this lack of information is that neutron diffraction which is the only technique able to measure hydrogen atom positions directly was until recently restricted to pressures below 300,000 atmospheres and so information on the positions of the hydrogen atoms had to be obtained indirectly or from computational modelling. For the past seven years we have been developing the use of suitable technology for neutron diffraction studies using the SNAP instrument and the Spallation Neutron Source at Oak Ridge National Laboratory in the United States. We have now reached the stage where structures can be successfully determined at pressures in excess of one million atmospheres using both powder and single crystal diffraction techniques.This project aims to use a so called diamond anvil cell where the sample is compressed between two large gem quality diamonds to study the structures of hydrogen, ice and related ices (ammonia hemihydrate and hydrogen chloride), and very high Tc superconductors up to million atmosphere pressures.

大约一百万个大气压的压力是由分子组成的系统的一个重要里程碑。这个值附近的压力需要打破将分子保持在一起的强共价键，从而将分子系统转化为非分子系统。这种从分子到非分子的变化导致了性质的深刻变化。据报道，氢变成了金属，这种金属形式可能是木星磁场的原因。水和冰中的氢原子从氧原子中分离出来，变得移动的，因此它们的导电方式与笔记本电脑和手机电池中的锂离子的导电方式相似。硫化氢形成一种金属化合物，它在零下70摄氏度的温度下就能超导。对这些现象和类似现象的研究产生了具有基础和技术重要性的信息。例如，氢原子的行为为我们理解量子行为提供了严格的测试，像冰这样的氢键固体的行为方式提供了对生化过程工作方式的洞察，新型超导体为潜在的室温超导体提供了新的途径，这将改变配电医学成像，并可能使“回到未来II”悬浮板成为现实。然而，我们对这些和其他重要的富氢系统在百万大气压下的理解是有限的，因为最基本的信息-氢原子在晶体结构中的位置-目前还不知道。缺乏信息的原因是中子衍射是唯一能够直接测量氢原子位置的技术，直到最近才被限制在30万个大气压以下的压力下，因此关于氢原子位置的信息必须间接或从计算模型中获得。在过去的七年里，我们一直在开发使用合适的技术，中子衍射研究使用SNAP仪器和Sputron中子源在橡树岭国家实验室在美国。我们现在已经达到了这样一个阶段，即利用粉末和单晶衍射技术可以在超过一百万个大气压的压力下成功地确定结构。本项目旨在使用所谓的金刚石压砧，将样品压缩在两个大宝石级金刚石之间，以研究氢、冰和相关冰的结构（半水合氨和氯化氢），以及高达百万大气压的极高Tc超导体。