Jump to main content
Jump to site search
PLANNED MAINTENANCE Close the message box

Scheduled maintenance work on Wednesday 27th March 2019 from 11:00 AM to 1:00 PM (GMT).

During this time our website performance may be temporarily affected. We apologise for any inconvenience this might cause and thank you for your patience.

Issue 18, 2016
Previous Article Next Article

Kinetic trapping through coalescence and the formation of patterned Ag–Cu nanoparticles

Author affiliations


In recent years, due to its inherent flexibility, magnetron-sputtering has been widely used to synthesise bi-metallic nanoparticles (NPs) via subsequent inert-gas cooling and gas-phase condensation of the sputtered atomic vapour. Utilising two separate sputter targets allows for good control over composition. Simultaneously, it involves fast kinetics and non-equilibrium processes, which can trap the nascent NPs into metastable configurations. In this study, we observed such configurations in immiscible, bi-metallic Ag–Cu NPs by scanning transmission electron microscopy (S/TEM) and electron energy-loss spectroscopy (EELS), and noticed a marked difference in the shape of NPs belonging to Ag- and Cu-rich samples. We explained the formation of Janus or Ag@Cu core/shell metastable structures on the grounds of in-flight mixed NP coalescence. We utilised molecular dynamics (MD) and Monte Carlo (MC) computer simulations to demonstrate that such configurations cannot occur as a result of nanoalloy segregation. Instead, sintering at relatively low temperatures can give rise to metastable structures, which eventually can be stabilised by subsequent quenching. Furthermore, we compared the heteroepitaxial diffusivities along various surfaces of both Ag and Cu NPs, and emphasised the differences between the sintering mechanisms of Ag- and Cu-rich NP compositions: small Cu NPs deform as coherent objects on large Ag NPs, whereas small Ag NPs dissolve into large Cu NPs, with their atoms diffusing along specific directions. Taking advantage of this observation, we propose controlled NP coalescence as a method to engineer mixed NPs of a unique, patterned core@partial-shell structure, which we refer to as a “glass-float” (ukidama) structure.

Graphical abstract: Kinetic trapping through coalescence and the formation of patterned Ag–Cu nanoparticles

Back to tab navigation

Supplementary files

Publication details

The article was received on 22 Nov 2015, accepted on 05 Apr 2016 and first published on 08 Apr 2016

Article type: Paper
DOI: 10.1039/C5NR08256K
Author version
Download author version (PDF)
Citation: Nanoscale, 2016,8, 9780-9790

  •   Request permissions

    Kinetic trapping through coalescence and the formation of patterned Ag–Cu nanoparticles

    P. Grammatikopoulos, J. Kioseoglou, A. Galea, J. Vernieres, M. Benelmekki, R. E. Diaz and M. Sowwan, Nanoscale, 2016, 8, 9780
    DOI: 10.1039/C5NR08256K

Search articles by author