Resarch On Structure And Phase Transition Of Cu-Ag Nanoalloy

Multicomponent metal nanoparticles are usually called nanoalloy. Compared with monocomponent nanoclusters, nanoalloy sxhibits complicate structures and properties. Furthermore, the thermodynamics and dynamics theory, based on bulk alloy, are inadequate for the alloy formation and phase stability of nanoparticles. The structure and property of nanoalloy are strongly determined by its composition, size and particle configuration. Therefore, it enables us to set up an ideal model for studying the electrical, optical, magnetical and chemical properties of nanoalloy. Cu/Ag nanoalloy has been proven to have extensive application in catalysis and optical field. It has became a major research emphasis home and abroad to study the mechanism of formation and phase transition of Cu/Ag nanoalloy through experiment or theoretical simulation.Molecular Dynamics simulation method has been adopted in simulations of formation and phase transition of Cu/Ag nanoalloy which with different composition or size. Formation and phase transition progress have been analysed through calculating the radical pair distribution function, potential energy curve and Lindeman parameter. Besides, semples of Cu/Ag nanoalloy has been prepared by magnetron sputtering beem deposition. With scanning transimission electon microscopy, the structure and element distribution can be characterized. The comprehensive comparison of simulation and experiment results offer an preliminary discuss on the formation and phase transition progress of nanoalloy, which set a theoretical foundation for controllable preparation and property of Cu/Ag nanoalloy.As analyzed in this work, core-shell structure with Ag shell and Cu core, multi-layer structure with Ag shell and random structure with Ag shell were observed in formation simulation. Structures of Cu/Ag nanoalloy are strongly influenced by the composition and size parameters:while there is fewer Ag, clusters tend to form core-shell structure; more Ag atoms or larger size will lead to multi-layer or random structure. Cu/Ag nanoalloy with core-shell structure exhibit excellent thermostability, however, thermostability of clusters with multi-layer or random structure is strongly depend on their composition.