Evolution of three-shell onion-like and core-shell structures in(AgCo)_(201) bimetallic clusters  

作　　者：王强 李国建 李东刚 吕逍 赫冀成 

机构地区：[1]Key Laboratory of Electromagnetic Processing of Materials(Ministry of Education),Northeastern University

出　　处：《Chinese Physics B》2009年第5期1843-1849,共7页中国物理B（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant No 50374027);the program for New Century Excellent Talents in University(Grant No NCET-06-0289);the 111 project of China(Grant No B07015)

摘　　要：This paper studies the structural evolution of （AgCo）201 clusters with different Co concentrations under various temperature conditions by using molecular dynamics with the embedded atom method. The most stable position for Co atoms in the cluster is the subsurface layer at low temperature （lower than 200 K for the Ag200Col cluster）. The position changes to the core layer with the increase of temperature, but there is an energy barrier in the middle layer. This makes the Ag-Co cluster form an Ag Co-Ag three-shell onion-like configuration. When the temperature is high enough [higher than 800 K for （AgCo）2m clusters with 50% Co], Co atoms can obtain enough energy to overcome the energy barrier and the cluster forms an Ag-Co core-shell configuration. Amorphization for the onion-like and core-shell clusters is induced by the large lattice misfit at Ag-Co interfaces. The structural evolution in the Ag-Co cluster is related to the release of excess energy.This paper studies the structural evolution of （AgCo）201 clusters with different Co concentrations under various temperature conditions by using molecular dynamics with the embedded atom method. The most stable position for Co atoms in the cluster is the subsurface layer at low temperature （lower than 200 K for the Ag200Col cluster）. The position changes to the core layer with the increase of temperature, but there is an energy barrier in the middle layer. This makes the Ag-Co cluster form an Ag Co-Ag three-shell onion-like configuration. When the temperature is high enough [higher than 800 K for （AgCo）2m clusters with 50% Co], Co atoms can obtain enough energy to overcome the energy barrier and the cluster forms an Ag-Co core-shell configuration. Amorphization for the onion-like and core-shell clusters is induced by the large lattice misfit at Ag-Co interfaces. The structural evolution in the Ag-Co cluster is related to the release of excess energy.

关 键 词：bimetallic cluster STRUCTURE molecular dynamics 

分 类 号：O561[理学—原子与分子物理]