一维纳米材料辐照损伤效应研究

With the development of high energy heavy ion accelerators in the world, the energy of ions supplied by accelerator is becoming more and more higher, which promotes the fundamental research works on defects production in solids、damage mechanisms. Many great progress assoiciated with strong electronic excitation effect have been made and a lot of new phenomena and effects that can not be explained well using the classical damage model are found. Up to now, the strong electronic excitation effect on insulator, semi-conductor, conductor, super-conductor and non-crystal alloy are investigated with swift heavy ions from C to U ions and lots of valuable experimental data have been obtained. Howerer, the basic mechanim of strong electronic excitation is still not clear. The strong electronic excitation effect of swift heavy ion on solid materials will be acted as an starting point of our project. Combining the advanced nano-material producing technology, the one-dimensional nano-materials (Au、Ti and InSb) with different diameter will be irradiated by the heavy ions with GeV energy supplied by the accelerator in Lanzhou. The influence of irradiation damage on one-dimensional manterial's structure and physical properties will be studied by adopting three irradiating models: "free standing model"、"lying model" and "binding model" . We will focurs our attention on the swift heavy ion modification of one-dimensional nano-material, to explore the basic physical process of how electron excitation lead to atom displacement, to clarify the influence of samll size effect on that physcial process and to enhance the understanding of micro-mechanism in electron stopping power.

随着国际上高能重离子加速器的不断发展，可提供的离子能量越来越高，促进了离子在固体中缺陷产生、损伤机制等基础研究，使得强电子激发效应研究取得了一系列突破，发现了许多新的无法用经典损伤模型解释的新现象和新效应。到目前，尽管人们已经研究了从C到U的各种快重离子在绝缘体、半导体、导体、超导体和非晶合金中强电子激发效应，获得了一大批非常有价值基于宏观材料的实验结果，但是仍然不完全清楚强电子激发效应的基本机制。本项目拟以一维纳米材料的快重离子强电子激发效应为出发点，结合先进的纳米材料制备工艺，利用加速器提供的GeV能量的离子辐照不同直径的纳米线(Au、Ti和InSb)，利用"站立式"、"平躺式"和"捆绑式"三种辐照方式研究辐照损伤对一维纳米材料结构和物理性质的影响，试图从一维纳米材料入手，探索电子激发转化为原子位移的基本物理过程，明确材料的小尺寸效应对上述物理过程的影响，推进对电子能损效应微观机制认识

随着国际上高能重离子加速器的不断发展，可以提供的离子能量越来越高，这些都促进了快重离子在固体中缺陷产生、损伤机制等基础研究，也使得强电子激发效应研究取得了一系列突破，发现了经典损伤模型无法解释的新现象和新效应。当前重离子强电子激发效应的研究对象虽然涉及半导体、金属、合金等众多材料，但它们绝大部分以块体材料为主，研究对象尺寸都在mm甚至cm量级。该项目以一维纳米材料为研究对象，通过利用加速器加速的重离子辐照不同直径的金纳米线和半导体纳米线，发现重离子不仅可以引起纳米线表面形貌的变化（凸起、火山口等的形成）和内部结构的变化（形成层错四面体），而且还发现重离子在不同直径的纳米线上引起的溅射效应不同，直径越小，引起的溅射效应越明显。这些研究结果对于分析高能重离子与纳米材料相互作用机理具有重要的推动作用，可以帮助人们进一步认识重离子辐照过程中电子能损引起的材料表面和内部结构的变化。