金属团簇在单晶表面的稳定性和扩散行为的Monte Carlo研究

采用MonteCarlo方法,研究了正二十面体结构的Cu、Ni、Pd和Pt等金属团簇在Pd(001)表面的稳定性和扩散行为.研究表明,载体对负载型金属团簇的稳定性和扩散性质有明显的影响.由于载体表面和金属团簇的振动偶合,金属团簇结构变化的温度要低于自由团簇的结构转化温度.负载型金属团簇的稳定性不仅取决于团簇内部原子之间的相互作用而且取决于团簇与载体之间的相互作用.对金属团簇扩散的研究表明,金属团簇的扩散常数与单金属原子的扩散常数相差不大,通过比较金属团簇的结构变化温度和扩散常数发现,团簇的稳定性和扩散行为有密切的联系.

Diffusion and Stability of Metal Clusters Supported on Pd(001) Surface

The stability and diffusion behaviors of 1.3 MPa Pt, Pd, Ni and Cu clusters supported on Pd(001) ~surface were studied by the Monte Carlo method. The support surface can strongly influence the stability and diffusion behaviors of the supported clusters. The structure transition temperatures of the supported clusters are much lower than the melting temperatures of their corresponding free clusters due to the vibration coupling between the support and the clusters. The stability of the supported clusters depends on not only the strength of metal-support interaction but also the strength of the metal-metal interaction. The diffusion constants of supported 1.3 MPa clusters are similar to those of corresponding metal atoms. Combining the diffusion parameters with the critical temperature of the supported clusters, the thermal stability is closely related to the diffusion behaviors of the metal clusters.