Renewal: Simple Molecular Systems at Ultrahigh Pressures

非技术描述：压力不仅是日常生活许多方面所熟悉的简单参数，而且是一种有效的工具，可用于创造在普通条件下无法获得的奇异材料。在许多情况下，当日常物质在实验室中承受极端压力时，例如在地球核心的压力或 200 万倍大气压下，就可以合成全新的材料。一个例子是新发现的含有大量氢的材料中的超导性——无电阻导电的能力。事实上，这些材料已被证明在室温下或可能高于室温下具有超导性。该项目从根本上研究这些材料和相关材料，其目标是制造可用于现代技术的室温超导体。更广泛地说，这项在高压下对这些材料和相关材料的研究预计将为化学和物理学、材料科学和工程、行星科学和天体物理学等广泛的科学领域提供信息。这些发现还可能导致氢储存和分离机制的改进，从而影响未来的能源需求。国家用户设施开发的技术可供科学界使用。拟议项目的一个重要组成部分是下一代研究人员的教育和培训，特别是来自许多在科学和技术学科中代表性不足的群体的研究人员，例如伊利诺伊大学芝加哥分校，这是一个为少数族裔服务的机构。技术说明：该项目支持研究简单元素和分子系统在 300 GPa (3 Mbar) 以上压力下的基本相互作用。采用全套最先进的实验和理论技术来研究所选材料的结构和输运特性，重点关注表现出极高温度超导性和其他奇异物理特性的低原子序数 (Z) 材料。理论和计算方法用于预测高压下的稳定成分和结构，并采用先进的高压-温度 P-T 方法来原位合成和表征这些材料。这项工作的重点是氢主导材料，例如超氢化物，我们的小组已证明它们在兆巴压力下，在室温附近（甚至可能高于室温）时表现出非常高的 Tc 超导性。理论和计算用于解释结果并指导后续的合成和表征。这种经过验证的理论-实验联合“材料设计”方法导致了我们之前的发现，它被应用于解决新问题，包括扩大所探索的压力-温度-磁场的成分范围和极端条件，以及理解潜在的传输机制，包括这些低Z系统预期的量子效应。全方位的相关实验和理论技术，包括新的建模和模拟方法，都应用于这些材料的研究。特别是，国家用户设施的新兴能力被应用于通过新的综合方法探测材料的结构、电子和传输特性。这项工作有可能增进我们对极端条件下物质的理解，从而改善我们对控制材料行为的基本相互作用的认识，并导致创造出用于实际应用的新的有用材料。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical Description: Pressure is not only simple parameter familiar in many aspects of everyday life, but it is also an effective tool that can be used to create exotic materials not accessible under ordinary conditions. In many cases, altogether new materials can be synthesized when everyday substance are subjected to extreme pressures in the laboratory, for example at the kinds of pressure found in the core of Earth, or 2 million times atmospheric pressure. An example is superconductivity – the ability to conduct electricity without resistance – in newly discovered materials that contain a great deal of hydrogen. Indeed, these materials have been shown to superconduct at, and possibly above, room temperature. This project investigates these and related materials, both fundamentally and with the goal of making room-temperature superconductors that could be used in modern technology. More broadly, this study of these and related materials at high pressure is expected to inform a broad range of scientific fields, from chemistry and physics, to materials science and engineering, to planetary science and astrophysics. The findings could also lead to improved mechanisms of hydrogen storage and separation that could impact future energy needs. The techniques developed at national user facilities are made available to the scientific community. An important component of the proposed project is the education and training of the next generation of researchers, particularly those from many groups that are underrepresented in scientific and technical disciplines, for example at the University of Illinois Chicago, which is a Minority-Serving Institution. Technical Description:This project supports the study of fundamental interactions in simple elemental and molecular systems to pressures above 300 GPa (3 Mbar). A full range of state-of-the-art experimental and theoretical techniques are used to investigate the structural and transport properties of selected materials, with a focus on low-atomic number (Z) materials that exhibit very high-temperature superconductivity and other exotic physical properties. Theoretical and computational methods are used to predict stable compositions and structures at high pressures, and advanced high pressure-temperature P-T methods are employed to synthesize and characterize these materials in-situ. The focus of this work is hydrogen-dominant materials, such as superhydrides, that our group has shown to exhibit very high Tc superconductivity in the vicinity of, and possibly above, room temperature, at megabar pressures. Theory and computation are used to interpret the results and guide subsequent synthesis and characterization. This proven joint theoretical-experimental ‘materials by design’ approach that led to our previous discoveries are applied to address new questions that include expanding the range of compositions and extreme conditions of pressure-temperature-magnetic field explored and understanding underlying transport mechanisms, including quantum effects expected for these low-Z systems. The full range of relevant experimental and theoretical techniques, including new modeling and simulation methods, are brought to bear on the study of these materials. In particular, new and emerging capabilities at national user facilities are applied to probe the structural, electronic, and transport properties of materials with new integrated approaches. The work has the potential to advance our understanding of matter at extreme conditions, and thereby improve our picture of the fundamental interactions that govern the behavior of materials, as well as lead to the creation of new useful materials for practical applications.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.