Molecular dynamics investigation of gold nanoparticle coalescence under realistic gas-phase synthesis conditions

• Published in: Journal of aerosol science 2024-06, Vol.179, p.106356, Article 106356
• Main Authors: Grammatikopoulos, P., Toulkeridou, E.
• Format: Article
• Language: English
• Subjects: Flame aerosol synthesis; Gas-phase synthesis; Inert-gas condensation; Molecular dynamics; Nanoparticle coalescence
• ISSN: 0021-8502; 1879-1964
• DOI: 10.1016/j.jaerosci.2024.106356

Dependence of nanoparticle (NP) coalescence on various physical parameters (e.g., temperature, number of NPs, NP size, orientation, crystallinity, shape, or composition, etc.) is a very active field of investigation. However, most computational studies on NP coalescence to date are performed in vacuum, with only a handful of studies taking gas pressure into account and even fewer doing a systematic analysis. This is due to two reasons: first, many computational studies complement inert-gas condensation experiments, which typically happen at high vacuum. Second, a simulation set-up in vacuum is simpler and computationally less costly. Here we utilised classical molecular dynamics for a rigorous investigation of the effect (or lack of) of gas pressure, as well as of other parameters (namely temperature, angular momenta, and inert-gas species), on the early stages of coalescence between two metallic NPs. Our approach is relevant for both inert-gas condensation in high vacuum and aerosol synthesis in standard atmospheric conditions. Multiple linear regression analysis confirmed temperature as the key factor determining the degree of coalescence; relative angular momenta direction was revealed as yet another important contributor, whereas the effect of pressure was deemed insignificant for early coalescence stages. To shed light onto the sintering process we elaborate on interesting atomistic mechanisms. We aspire that our study may indicate potential strategies for both gas-phase synthesis methods. [Display omitted] •Utilisation of the most sophisticated scheme for inert-gas cooling to date.•Simulation of the most realistic gas-phase synthesis conditions, incorporating both inert-gas condensation and aerosol synthesis.•Investigation of many parameters potentially affecting nanoparticle coalescence, including pressure, relative angular momenta, inert-gas atomic weight, etc.•Utilisation of multiple linear regression analysis to establish statistically significant correlations.•Elaboration of atomistic mechanisms (including new ones).