Molecular dynamics simulations of the melting process of Pb nanofilms

Abstract

Metallic nanofilms have attracted plenty of research interests because of their important applications in integrated circuits and thermoelectric conversion technology. However, there has not been much research discussing the thermodynamic properties of nanometal films with thickness less than 5 nanometers. To fill this research gap, this article investigates the melting behavior of Pb nanofilms through molecular dynamic simulations. The results show that most nanofilms experience a turning point in their potential energy during melting, followed by a sharp decrease due to the collapse of their previous two-dimensional structure. The melting temperature of nanofilms is found to decrease with decreasing thickness, following the trend predicted by the Safaei model, except for nanofilms with 1-3 atomic layers, which exhibit an abnormally high melting point. It is suggested that this anomaly is due to the reconstruction of nanofilms into a more stable structure, possibly the {111} plane. This study can inspire research on the thermal stability and structural evolution of nanometal films and aid in their future design and preparation.