初始温度和冷却速率对金属团簇凝固行为的影响

Effects of initial temperature and cooling rate on freezing behaviors of metallic clusters

用分子动力学结合嵌入原子势研究了含有531个原子的Co531,Cu531和Ni531团簇从不同初始温度以不同冷却速率凝固到200K时的凝固行为.结果表明初始温度和冷却速率对团簇的凝固点有很大影响.初始温度越高,冷却速率越小,团簇的凝固点越高.凝固条件的改变会对三种团簇的凝固结构产生不同的影响.Cu531和Ni531团簇尽管在不同条件下的凝固点不同,但凝固结构都是二十面体.而Co531从高温以低冷却速率凝固时会形成与其块体相同的hcp结构,其他条件下的凝固成二十面体结构.

The effects of initial temperature and cooling rate on the freezing behaviors of clusters Co531, Cu531, and Ni531 are studied by the molecular dynamics with a general embedded atom method. The results show that their freezing points are obviously influenced by initial temperature and cooling rate. Higher initial temperature or smaller cooling rate results in a higher freezing point. The variations of freezing structures for all clusters with the change of freezing condition are different. The icosahedron is formed for Cu531 and Ni531 in spite of their different freezing points. The HCP structure similar to the Co bulk is formed for Co531 under higher initial temperature and smaller cooling rate, the icosahedron is formed for other conditions.