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对于由分子组成的系统来说是一个重要的里程碑。需要大约该值的压力来破坏将分子结合在一起的强共价键，从而将分子系统转变为非分子系统。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，氢会变成金属，这种金属形式可能是木星磁场的原因。水和冰中的氢原子与氧原子分离并变得可移动，因此它们的导电方式类似于笔记本电脑和手机电池中的锂离子的导电方式。硫化氢形成一种金属化合物，仅在 -70°C 的温度下即可超导。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，氢键固体（如冰）的行为方式提供了对生化过程工作方式的深入了解，新型超导体为潜在的室温超导体提供了新途径，这将改变配电医学成像，并使“回到未来 II”悬浮滑板成为现实。然而，我们对百万大气压下的这些和其他重要富氢系统的理解受到以下事实的限制：最基本的信息——氢原子在晶体结构中的位置——目前尚不清楚。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，直到最近还仅限于低于 300,000 个大气压的压力，因此必须间接或通过计算模型获得有关氢原子位置的信息。在过去的七年里，我们一直在使用美国橡树岭国家实验室的 SNAP 仪器和散裂中子源来开发适合中子衍射研究的技术。我们现在已经达到了可以使用粉末和单晶衍射技术在超过一百万个大气压的压力下成功确定结构的阶段。该项目旨在使用所谓的金刚石砧室，其中样品被压缩在两颗大型宝石级钻石之间，以研究氢、冰和相关冰（半水合氨和氯化氢）以及高达百万个大气压的极高 Tc 超导体的结构 压力。