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作 者:吴茂[1] 常玲玲[2] 崔亚男[1] 陈晓玮[1] 何新波[1] 曲选辉[1]
机构地区:[1]北京科技大学新材料技术研究院,北京100083 [2]北京控制工程研究所,北京100190
出 处:《北京科技大学学报》2014年第3期345-353,共9页Journal of University of Science and Technology Beijing
基 金:国家自然科学基金资助项目(51204016);高等学校博士学科点专项科研基金资助项目(20120006120011);中央高校基本科研业务费专项资金资助项目(FRF--TP--12--154A);国家博士后科学基金资助项目(11175020)
摘 要:采用分子动力学模拟方法研究了不同尺寸Au纳米颗粒在烧结过程中晶型转变及烧结颈长大机制.研究发现纳米颗粒的烧结颈生长主要分为两个阶段:初始烧结颈的快速形成阶段和烧结颈的稳定长大阶段.不同尺寸纳米颗粒烧结过程中烧结颈长大的主要机制不同:当颗粒尺寸为4 nm时,原子迁移主要受晶界(或位错)滑移、表面扩散和黏性流动控制;当尺寸在6nm左右时,原子迁移主要受晶界扩散、表面扩散和黏性流动控制;当颗粒尺寸为9 nm时,原子迁移主要受晶界扩散和表面扩散控制.烧结过程中Au颗粒的fcc结构会向无定形结构转变.此外,小尺寸的纳米颗粒在烧结过程中由于位错或晶界滑移、原子的黏性流动等因素会形成hcp结构.The sintering process of gold nanoparticles was investigated using molecular dynamics simulation, and the detailed crys-tal structure transformation and neck growth mechanisms were identified and analyzed for different particle sizes. It is found that the co-alescence of two nanoparticles experiences two stages, which are the initial rapid neck formation and stable neck growth. Simulation re-sults show that different particle sizes lead to different neck growth mechanisms. When the particle size is 4 nm, the major neck growth mechanisms are grain-boundary/dislocation slid, surface diffusion, and viscous flow. For the particles with the size of about 6 nm, the major neck growth mechanisms are grain-boundary diffusion, surface diffusion, and viscous flow. But when the particle size is 9 nm, the major neck growth mechanisms are grain-boundary diffusion and surface diffusion. During the sintering process, the fcc structure of the particles transforms to amorphous structure gradually. Besides, the hcp crystal structure forms in the small sized particles because of grain-boundary slid or viscous flow.
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