The effect of size and composition on structural transitions in monometallic nanoparticles

Abstract

Abstract. Predicting the morphological stability of nanoparticles is an essential step towards the accurate modelling of their chemophysical properties. Here we investigate solid-solid transitions in monometallic clusters of 0.5-2.0 nm diameter at finite temperatures and we report the complex dependence of the rearrangement mechanism on the nanoparticle's composition and size. The concerted Lipscomb's DiamondSquare-Diamond mechanisms which connects the decahedral or the cuboctahedral to the icosahedral basins, take place only below a material dependent critical size above which surface diffusion prevails and leads to low-symmetry and defected shapes still belonging to the initial basin.

The transformation of cuboctahedral to icosahedral nanoparticles: atomic structure and dynamics

“…In this respect, geometric descriptors such as average coordination numbers and related quantities, as used in metadynamics simulations by Baletto and coworkers are more generally applicable. 27,28 The advantage of the collective variable used here is that it allows to selectively drive only the cuboctahedral-to-icosahedral transition and gives very detailed insights into its atomic structure. Fig.…”

“…Barriers were found to be accessible at room temperature up to Ni 561 and Cu 561 , while higher barriers were found for Pd, Pt, Au and Ag. [27][28][29] Barreteau et al found energy barriers for Pd 147 and Rh 147 to be larger than 4 eV and larger than 10 eV for Pd 309 and Rh 309 using a tight binding approach. 30 This work is organized as follows.…”

Building machine learning force fields for nanoclusters

“…To probe whether results potentially yielding novel physical insights into the nanocluster behaviour can be obtained by using a M-FF, we finally investigate the kinetic behaviour of Ni 19 to explore the extent of shape fluctuations occurring in the nanocluster. [48][49][50][51][52] To do so, we carry out MD runs at 50 K-spaced temperatures comprising between 300 K and 1200 K. We perform four 480-ps long simulations for each temperature for each of the five morphologies considered in this work (380 simulations in total). The computational speedup factor associated with carrying out a M-FF rather than a BOMD simulation in these systems is ∼10 5 .…”

Melting of large Pt@MgO(1 0 0) icosahedra

“…This concerted and cooperative process can take place only at small sizes, before atomic surface diffusion mechanisms prevail. [24,22] On the other hand, only a few theoretical studies addressed how the geometrical distortion induced by the support epitaxy could affect the kinetic, energetic and thermodynamics of metallic nanoparticles. [18,25,26] Size and substrate interaction strength dependent structural transitions have been observed, while rearrangement towards equilibrium structures as predicted by Wullf-Kaishew method have been reported only in small systems and not in larger ones.…”