Molecular dynamics simulation of the production of hollow silver nanoparticles under ultrafast laser irradiation
CC Jiang and YJ Mo and H Wang and RH Li and M Huang and SJ Jiang, COMPUTATIONAL MATERIALS SCIENCE, 196, 110545 (2021).
We used classical molecular dynamics with a two-temperature model to investigate the cavity-formation process of silver nanoparticles under ultrafast laser irradiation. We investigated two different scenarios. The first scenario involved a single silver nanoparticle and the second involved a silver nanosphere embedded in fused silica. For the former, simulation results indicated that the peak temperature and cooling time are two key factors affecting the formation of stable hollow nanostructures in silver nanoparticles. When the temperature was below 2000 K, there was no cavity formation in the particle. In contrast, when the temperature exceeded 3000 K, the silver nanoparticle exhibited an irregular structure, namely, that of a spherical shell with small perforations. The cooling time, which represents the duration for energy from a nanoparticle to dissipate into the surrounding matrix, is also crucial. The results revealed that a stable hollow nanostructure could only form when the cooling time was <180 ps. By analyzing the local pressure and root-mean-square displacement of the atoms, we observed that these two parameters were responsible for the formation of an inner cavity. In the second case, we demonstrated the dynamic transformation of a solid silver nanoparticle embedded in fused silica into a hollow nanostructure under ultrafast laser irradiation. The results from this case indicated the time range for dissipation of energy from a silver nanoparticle into the fused silica to be between 20 and 30 ps.
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