【摘要】 对弹性应变起源的理解对于晶体材料或非晶材料来说都非常重要.然而人们对非晶变形的认知远远落后于对晶体的认知.本文采用在透射电镜中实施非晶氧化硅纳米线的原位单轴弹性拉伸,获得一系列拉伸过程中的电子衍射谱,通过计算它们的径向分布函数,结合逆蒙塔卡罗方法实现结构的重构,从中提取出原子尺度的结构变化信息.结果显示,氧化硅非晶纳米线的弹性应变主要来源于键长的弹性伸长和键角分布的变化,并且后者的贡献更大.本工作将对我们正确理解非晶材料的高强度提供非常重要的帮助.更多还原

【Abstract】 An understanding of the origin of elastic strain is extremely important for both crystalline materials and amorphous materials. Owing to the lack of a long range order in their structure, it is arduous to dynamically study the elastic mechanism of amorphous materials experimentally at atomic scale compared with their crystalline counterparts. Here, the elastic deformation mechanism of amorphous silica nanowires(NWs) has been studied for the first time via in situ elastic tensile tests in a transmission electron microscope. Radial distribution functions(RDFs) calculated from the corresponding selected area electron diffraction patterns(SAEDPs) at different strains were used to reconstruct a structural model based on the reverse Monte-Carlo(RMC) method. The result interestingly indicates that the elastic strain of silica glass NWs can be mainly attributed to the elastic elongation of the bond length accompanied by a change in the bond angle distribution. This work is useful for understanding the high strength of amorphous materials.更多还原