利用分子动力学的方法研究了Pb纳米线熔化温度的尺寸效应。研究表明,纳米线的熔化温度随着尺寸的减小而降低,纳米线的熔化过程从表面开始,并逐渐向中心趋近。纳米线在熔化过程中,温度也在逐渐升高,这不同于块体材料。Pb纳米线熔化温度的变化量与相同尺寸Pb纳米薄膜的变化量之比为2:1。另外,Pb纳米线的热力学稳定结构存在一个临界尺寸S(2nm〈S〈2.5nm),尺寸〈S,Pb纳米线的稳定结构是晶态,而〈S则为非晶态。
The size dependent melting temperature (M. T. ) of Pb nanowires is studied by molecular dynamics simulation method. It is found that the M.T. of Pb nanowires decrease with decreasing the size. The melting process starts from the surface, and then approaches to the center of the wires. It is shown that the M.T. increases during the melting process, which is different from the melting of bulk Pb. Furthermore, the M. T. variation ratio between Pb wires and films is 2: 1 in identical size. Furthermore, it is found that there exists a critical size S (2nm〈S〈2.5nm). The stable structure is crystal with size larger than S, and is amorphous with size smaller than S.