铂纳米晶在升温过程中结构演化与熔化特征的原子级模拟研究

An atomistic simulation of structural evolution and melting characteristics of Pt nanocrystal during continuous heating

采用分子动力学方法结合量子修正Sutton-Chen型多体力场,对由{100}面和{111}面构成的十四面体Pt纳米晶在升温过程中的热稳定性和熔化机制进行了计算机模拟研究,并引入统计半径和Lindemann指数来分析它的结构和形状演化过程.结果表明:该纳米晶在1500K时形状开始发生变化,并在1700K时转变为球形.铂纳米晶粒在1500K时开始出现表面预熔,在1650K时表面完全熔化并开始向内部传播,最终在1730K时整体熔化为液态粒子.表面预熔的出现对形状转变的发生是有利的.

Using molecular dynamics method with many-body potentials,we have studied the thermal stability and melting mechanism of platinum nanocrystal of truncated octahedron enclosed by {111} and {100} surfaces,and investigated its microstructure and shape by statistical radius and Lindemann index.The results show that the nanocrystal first shows shape changes at 1500K,then transforms to a spherical one at 1700K.The surface first shows the premelting behavior at 1500K,and the melt completely into liquid state.The melting process starts from the surface into the interior at this temperature,resulting in the complete melting of the nanocrystal at 1730K.The surface premelting is advantageous to shape transformation of octahedron-truncated nanocrystal.