铂纳米粒子热稳定性的原子级模拟研究

Thermal stability of platinum nanoparticle: an atomistic simulation study

本文采用分子动力学结合嵌入原子多体势,模拟了铂纳米粒子在升温过程中的热稳定性和熔化机制,并利用共近邻分析方法分析了它的微结构演化过程.模拟的结果表明:铂纳米粒子的熔点明显低于体材料的熔点;由于表面层原子的结合力较弱,在升温过程中表面会首先出现预熔;纳米粒子的熔化是从表面层开始的,并随着温度的升高,熔化的表面层会逐渐向内部扩展,最终导致纳米粒子整体转变为液态结构;当温度低于表面预熔温度时,纳米粒子保持良好的晶态结构.

Using molecular dynamics method with many-body potentials,we have studied the thermal stability and melting process of platinum nanoparticle, and investigated its microstructure by common neighbor analysis methods. The results show that the melting point of Pt nanoparticle is much lower than that of bulk counterpart. Due to the weak strength of interatomic forces, the surface first appears the premelting behavior. The melting process of Pt nanoparticle starts from the surface into the interior. Finally , it becomes a disordered liquid when the temperature reaches the melting point. Pt nanoparticle can preserve its crystalline structure below the premelting temperature of surface.