Modeling the Phase Stability of Janus, Core鈥揝hell, and Alloyed Ag鈥揅u and Ag鈥揂u Nanoparticles

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• 作者：Hongcheng Peng ; Weihong Qi ; Siqi Li ; Wenhai Ji
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：January 29, 2015
• 年：2015
• 卷：119
• 期：4
• 页码：2186-2195
• 全文大小：599K
• ISSN：1932-7455

文摘

On the basis of the Gibbs free energy (GFE) model of Janus, core鈥搒hell, and alloyed structures of Ag鈥揅u and Ag鈥揂u nanoparticles, the structural stability and size-composition phase diagram are obtained. For phase segregated structure, small size and low temperature are more beneficial at fixed composition. If the temperature is fixed, the segregated phase is favored at small size and low composition. The lowest critical size to phase segregation is 6 nm for Ag鈥揅u NPs and 4.5 nm for Ag鈥揂u NPs at 400 K and Ag atom fraction of approximately 50%, and raising the temperature reduces the critical size. For Ag鈥揅u phase diagram, it is found that the core size is dominated by the transformation between Janus and core鈥搒hell structure. When the core is sufficient large, the Ag鈥揅u NPs will keep the core鈥搒hell structure. As the core size gets smaller, the core location will be moved from center to off-center until it forms quasi-Janus or Janus NPs. However, for the Ag鈥揂u phase diagram, there is no Janus structure at large scale of composition.