Material Response to Dense Electronic Excitations: Nonlinear Defect Dynamics and Phase Transformations

非技术描述：材料对高能带电粒子能量耗散的响应对于缺陷工程、离子束修改、离子束处理、离子束分析、地质年龄测定、空间探索、高能加速器和核应用非常重要。当带电粒子穿透固体时，它的能量被转移到原子核和电子，导致固体中复杂的能量耗散过程，这些过程在时间和空间上是耦合的。转移到电子的能量导致高度局域的、密集的电子激发，这种激发往往超过了强脉冲激光产生的激发。这些耦合过程将材料带到极端的、往往是瞬时的状态，在那里形成了独特的缺陷、新颖的纳米结构和材料相，并且可以诱导竞争性的自我修复。该项目的目标是实现对材料响应的这些耦合现象的批判性理解，并确定新的途径来控制缺陷、纳米结构和相的形成，用于先进的电光系统，用于定制材料的功能和性能，以及用于先进能源技术的更好的材料设计。该项目提供了一套独特的综合教育、研究、培训和推广活动，以教育本科生和研究生进行新一类工程材料的基础研究，从STEM领域代表性不足的群体中招收学生，并为学术界、国家实验室和行业的下一代劳动力提供先进光电和能源技术方面的培训。技术描述：该项目应用实验方法，在电子和原子水平上理解、模拟和最终控制陶瓷材料对高能带电粒子极端能量耗散的非平衡动态响应，以指导材料发现和定制材料功能和性能。所研究的ABO3模型钙钛矿材料具有不同的成键特征，对电子缺陷和晶格缺陷有很强的发光特征，对电子和核能量损失的响应也有明显的不同。在一系列条件下，实验研究了这些模型钙钛矿结构对单离子和多离子事件的响应，以改变在未损伤的单晶和含有不同损伤程度的单晶中转移到电子和原子的能量分配。这些研究旨在利用原位离子束分析和光谱分析技术，以及先进的显微镜和X射线衍射方法，分别和同时探测从低温到高温辐照下的高电子激发密度和电子和原子过程的耦合。这项研究提供了对具有极端能量耗散的复杂电子和原子关联的革命性新理解，使得能够形成独特的缺陷态，设计和发现具有先进技术的新功能的材料，并为下一代高能加速器、空间环境和核应用开发自修复和耐辐射材料。该项目提供了一套独特的教育、研究和培训活动，涉及最先进的离子束能力、材料表征技术和缺陷物理，以及书面和口头沟通技能，为学生为技术工作做准备。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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: The response of materials to energy dissipation from energetic charged particles is important for defect engineering, ion-beam modification, ion-beam processing, ion-beam analysis, geologic age dating, space exploration, high-energy accelerators and nuclear applications. As a charged particle penetrates a solid, its energy is transferred to atomic nuclei and to electrons leading to complex energy dissipation processes in the solid that are coupled in time and space. The energy transferred to electrons results in highly-local, dense electronic excitations that often exceed those produced by intense pulsed lasers. These coupled processes bring materials to extreme and often transient regimes where unique defects, novel nanostructures, and material phases are formed, and where competitive self-healing can be induced. The goal of this project is to achieve critical understanding on these coupled phenomena on the response of materials and to identify new pathways to control the formation of defects, nanostructures and phases for advanced electro-optical systems, for tailoring materials functionality and performance, and for the design of better materials for advanced energy technologies. This project provides a unique set of integrated education, research, training and outreach activities to educate both undergraduate and graduate students in fundamental research on a new class of engineering materials, recruits students from under-represented groups in STEM areas, and provides training for the next-generation workforce in advanced electro-optical and energy technologies across academia, national laboratories and industry. Technical Description: This project applies experimental approaches to understand, model and ultimately control the far-from-equilibrium dynamic response of ceramic materials to extreme energy dissipation from energetic charged-particles at the level of electrons and atoms in order to guide materials discovery and tailor materials functionality and performance. The model ABO3 perovskites to be studied exhibit different bonding character, strong luminescence signatures for electronic and lattice defects, and distinctly different response to electronic and nuclear energy loss. The response of these model perovskite structures to single and multiple ion events is experimentally investigated over a range of conditions to vary the partitioning of energy transfer to electrons and atoms in both undamaged single crystals and in single crystals containing different pre-existing levels of damage. The investigations are designed to both separately and simultaneously probe high electronic excitation densities and the coupling of electronic and atomic processes under irradiation from cryogenic to elevated temperatures using in situ ion-beam analysis and optical spectroscopy techniques, as well as advanced microscopy and x-ray diffraction methods. This research provides transformative new understanding of the complex electronic and atomic correlations with extreme energy dissipation that enables the formation of unique defect states, the design and discovery of materials with novel functionalities for advanced technologies, and the development of self-healing and radiation tolerant materials for next generation high-energy accelerators, space environments and nuclear applications. This project provides a unique set of education, research and training activities on state-of-the-art ion-beam capabilities, materials characterization techniques and defect physics, as well as written and oral communication skills, that prepare students for the technological workforce.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.