Atomic Simulation of the Melting and Mechanical Behaviors of Silicon Nanowires

Abstract

Molecular dynamics simulations using a three-body potential show that the melting and mechanical behaviors of silicon nanowires are strongly dependent on their cross-section area. For the wire with a small cross-section area, rearrangements of surface atoms greatly affect thermal stability in a relatively low temperature regime. For these wires with a relatively large area, while some surface atoms adjust their positions, most of the interior atoms hold their tetrahedra packing patterns. At a high temperature, the accumulation of structural disorder can quickly extend into the entire wire, which resembles the melting of the bulk phase. By applying the uniaxial tensile, these silicon nanowires present the typical mechanical behavior of plastic materials. The atomic local stress in the necking region is apparently larger than that outside of the necking region. As the cross-section area becomes large, both the yield strength and tensile strength increase. With the increasing temperature, the elasticity decreases significantly.

Thermal Stability and Mechanical Properties of Hollow Si Nanowires from Atomic Modeling Combined with a Machine-Learning Prediction for Application as Li-Ion Battery Anodes

“…For SiHNW 1 , SiHNW 2 , and SiHNW 3a with the same inner radii, the yield strengths are 0.334, 0.987, and 2.140 GPa, respectively, and the tensile strengths are 0.401, 1.200, and 2.344 GPa, respectively. Compared with the solid Si nanowires having radii of 0.693, 0.859, and 1.034 nm from ref , the yield strength was reduced by 77.2, 71.3, and 45.6%, respectively, and the tensile strength was reduced by 75.6, 67.3, and 44.0%, respectively. For SiHNW 3b , compared with the solid Si nanowire having a radius of 1.034 nm and SiHNW 3a with the same inner radius, the yield strength is reduced by 70.4 and 45.7%, respectively, while the tensile strength is reduced by 62.7 and 33.5%.…”

“…While considering that these silicon hollow nanowires will mechanically respond to externally applied mechanical loads during performances, their mechanical properties need to be obtained in order to ensure the safety and reliability of these electrodes. The tensile test has been an effective approach to probe the mechanical properties of materials. − For the past few decades, a large number of experimental studies have investigated the mechanical properties of nanowires by tensile tests. However, since the experimental testing of the nanowires is significantly dependent on the experimental setup and operational procedures, this makes it very difficult to accurately apply external forces and measure stresses or strains at the atomic scale, and there exist large discrepancies among experimental observations.…”