Uniaxial compression of silicon nanoparticles: An atomistic study on the shape and size effects

Abstract

Molecular dynamics simulations were carried out to investigate the mechanical properties of silicon nanoparticles during uniaxial compression by a flat-punch indenter. We considered a large set of systems, with dimensions in the range 10 nm to 50 nm, and various shapes like cubic (perfect and blunt), spherical, truncated spherical, and Wulff-shaped, as well as two compression orientations and two temperatures. Thorough analyses of the simulations first revealed that the relation between nanoparticle size and strength, usually termed as 'smaller is stronger', is critically dependent on the nanoparticle shape, at least for the investigated size range. For instance, a significant and size-dependent strength decrease is determined for facetted Wulff-like nanoparticles, but not for cubic or spherical systems for compression along <100>. We also found that the nanoparticle shape greatly influences plasticity. Several original plasticity mechanisms are obtained, among which the nucleation of half-loop V-shaped dislocation contained in two different {111} planes, dislocations gliding in unusual {110} planes, or the nucleation of partial dislocations in shuffle {111} planes. Our investigations suggest that plasticity properties are mainly governed by the localization of shear stress build up during elastic loading, and the geometry of surfaces in contact with indenters, these two characteristics being intimately related to the nanoparticle shape.

Ductile deformation of core-shell Si-SiC nanoparticles controlled by shell thickness

“…Note that it is now well documented that the plastic deformation along 100 of silicon nanospheres is critically dependent on the choice of the interatomic potential in molecular dynamics simulations. For instance, with the Tersoff potential [34], a βtin phase transformation is observed, whereas Stillinger-Weber potentials result in the nucleation of perfect 1/2 110 dislocations [14,25,35]. To gain further insights, we performed additional calculations using the Erhart-Albe SiC potential [36] as an alternative to EDIP.…”

“…Uniaxial compression is achieved by using two moving virtual planar indenters, defined by a quadratic repulsive force field as implemented in LAMMPS [21]. Infinitely hard indenters are set using a force field parameter equal to 1000 eV Å −3 [14,22]. These indenters are initially located on each side of the nanoparticle, and move towards each other at a constant velocity of 0.1 Å/ps during compression tests, with a 100 orientation relatively to the silicon lattice.…”

“…On the one hand, silicon is a model for covalent materials, and its bulk plasticity properties are reasonably known [9]. Furthermore, we have at our disposal an abundant information on the mechanical properties of silicon nanoparticles [10][11][12][13][14]. On the other hand, Si-SiC composites are promising materials for sensors in bionanotechnology [15], because of the excellent biocompatibility and functionalization capability of silicon carbide, while silicon remains the base material in current electronic devices.…”

Mechanical Properties of Amorphous Silicon Nanoparticles

“…Finally, maybe the most interesting aspect is that many plasticity mechanisms have been identified in SiNP, among which amorphization [13], dislocation nucleation and propagation [14,15,16,17], and phase change [14,16,18,19,20]. Furthermore, not only the size but also the SiNP shape is shown to influence mechanical properties [21].…”

Heat Transfer in Cadmium Telluride-Water Nanofluid over a Vertical Cone under the Effects of Magnetic Field inside Porous Medium

“…They found an augmentation in Nusselt number due to the increment in thermal radiation and Rayleigh number, whereas a reverse trend was found by increasing the Hartmann number. Some interesting experimental and theoretical work on nanoparticle shape effects can be found in References [25][26][27][28][29][30][31].…”