Abstract Nobel metal particles of designed morphology have found many ingenious applications in fields such as catalysis, plasmonics, metamaterials, etc. A thorough investigation of influential factors that determine the particle morphology is desirable. Micron-sized Ag particles prepared by physical vapor deposition usually result from two-step growth: condensation from dense vapor followed by continual growth of the sessile particles landing on substrate. The primary particle-substrate contact may be the decisive factor in determining the particle morphology which in turn needs be precisely characterized. Here we report investigation on the growth process of five-fold twinned Ag particles towards targeted morphology by using scanning electron microscopic imaging at variable incidence angles, in conjunction with 3D modelling, so as to reveal the particle–substrate contact profile and to infer the growth mechanism. Five-fold twinned Ag particles were obtained at large yield on SiO2/Si(1 0 0), MgO(1 0 0) and LaAlO3(1 0 0) substrates. Results show that fivefold twinned Ag particles on SiO2/Si(1 0 0) substrate are usually fully developed, demonstrating higher symmetries ( I h or D 5 h ) and acute contact angles, while on MgO(1 0 0) and LaAlO3(1 0 0) substrates the particles are usually heavily truncated with a contact characterized by also some obtuse angles. Difference in morphology occurs in the secondary growth stage where Ag atom migration along the particle-substrate interface may or may not be allowed. A set of parameters including contacting facet/contact angles and the height-edge length ratio are proposed for the morphology description of the five-fold twinned particles on support. Our work has resolved the influential factors in determining the morphology of large metal particles from physical vapor deposition where continual growth of sessile particles landing on substrate plays a pivotal role. By manipulating the particle-substrate contact and the secondary growth stage, five-fold twinned metal particles with designed morphology can be prepared for specific applications.

中文翻译：

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用于生长机制探索的粒子形态全景图：来自蒸汽冷凝的微米级五重孪晶银粒子的案例研究

摘要 设计形态的诺贝尔金属粒子在催化、等离子体、超材料等领域有许多巧妙的应用，需要对决定粒子形态的影响因素进行彻底研究。通过物理气相沉积制备的微米级 Ag 颗粒通常由两步生长产生：密集蒸汽冷凝，然后降落在基板上的固着颗粒不断生长。初级粒子与基材的接触可能是决定粒子形态的决定性因素，而粒子形态又需要精确表征。在这里，我们通过使用可变入射角的扫描电子显微成像结合 3D 建模，报告了对五重孪晶 Ag 颗粒向目标形态的生长过程的研究，以揭示颗粒 - 基材的接触轮廓并推断生长机制。在 SiO2/Si(1 0 0)、MgO(1 0 0) 和 LaAlO3(1 0 0) 衬底上以高产率获得了五重孪晶 Ag 颗粒。结果表明，SiO2/Si(1 0 0) 衬底上的五重孪晶 Ag 颗粒通常完全发育，表现出更高的对称性 (I h 或 D 5 h ) 和锐角接触角，而在 MgO(1 0 0) 和 LaAlO3(1 0 0) 基板 颗粒通常被严重截断，接触特征也有一些钝角。形态差异发生在二次生长阶段，其中可能允许或不允许 Ag 原子沿粒子 - 基材界面迁移。提出了一组参数，包括接触面/接触角和高度 - 边缘长度比，用于载体上五重孪晶颗粒的形态描述。我们的工作解决了从物理气相沉积中确定大金属颗粒形态的影响因素，其中落在基板上的固着颗粒的持续生长起着关键作用。通过操纵颗粒-基材接触和二次生长阶段，可以为特定应用制备具有设计形态的五重孪晶金属颗粒。