Modeling the Phase Stability of Janus, Core–Shell, and Alloyed Ag–Cu and Ag–Au Nanoparticles
Modeling the Phase Stability of Janus, Core–Shell, and Alloyed Ag–Cu and Ag–Au Nanoparticles
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DOI：
10.1021/jp510725a
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发表时间：
2015-01
影响因子：
3.7
通讯作者：
Hongcheng Peng;W. Qi;Siqi Li;Wenhai Ji
中科院分区：
文献类型：
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作者：
Hongcheng Peng;W. Qi;Siqi Li;Wenhai Ji
基于Ag-Cu和Ag-Au纳米粒子的Janus、核壳结构和合金结构的Gibbs自由能（GFE）模型，得到了它们的结构稳定性和尺寸-组成相图。对于相分离结构，在固定成分条件下，尺寸小、温度低更有利。在温度一定的情况下，小尺寸和低成分有利于分离相的形成。在400 K和银原子分数约为50%时，Ag - cu NPs的最低相偏析临界尺寸为6 nm， Ag - au NPs的最低相偏析临界尺寸为4.5 nm。对于Ag-Cu相图，发现核尺寸主要由Janus结构和核壳结构之间的转变所决定。当核足够大时，Ag-Cu NPs将保持核壳结构。随着核心尺寸变小，核心位置将从中心向偏离中心移动，直到形成准Janus或Janus NPs。然而，对于Ag-Au相图来说，在1点处不存在Janus结构。
On the basis of the Gibbs free energy (GFE) model of Janus, core–shell, and alloyed structures of Ag–Cu and Ag–Au 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–Cu NPs and 4.5 nm for Ag–Au NPs at 400 K and Ag atom fraction of approximately 50%, and raising the temperature reduces the critical size. For Ag–Cu phase diagram, it is found that the core size is dominated by the transformation between Janus and core–shell structure. When the core is sufficient large, the Ag–Cu NPs will keep the core–shell 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–Au phase diagram, there is no Janus structure at l...