Size-Dependent Thermal Behaviors of 5-Fold Twinned Silver Nanowires: A Computational Study
HL Chen and SP Ju and SL Wang and CT Pan and CW Huang, JOURNAL OF PHYSICAL CHEMISTRY C, 120, 12840-12849 (2016).
The melting behaviors of silver nanowires (AgNWs) were investigated by molecular dynamics (MD) simulations using the 2nn-modified embedded-atom method potential (2nn-MEAM) during a temperature elevation process from 0 to 1500 K. Four AgNWs with diameters of 1.6, 2.4, 4.8, and 10 nm were considered, and these nanowire structures with 5-fold twinned boundaries were constructed according to the experimental observations. The melting point of bulk Ag predicted by the two-phase method is about 1280 K, which is very close to the experimental result of 1234 K, indicating the 2nn-MEAM potential can accurately reflect the thermal behavior of Ag material. For AgNWs, the melting points will significantly decrease from 1250 to 790 K as the AgNW diameters decrease from 10 to 1.6 nm. According to the variations of surface atom square displacement (SD) profiles at different temperatures, it is found that the premelting behaviors could be efficiently investigated for all S-fold twinned AgNWs before their melting temperatures. In addition, this phenomenon is very different from those of Ag single-crystal nanoparticles with diameters smaller than 8 nm, which melt at their melting temperatures without passing a surface premelting stage. The difference in thermal behaviors between the AgNWs and Ag single-crystal nanoparticles can be attributed to the twinned boundaries (TBs) within AgNWs.
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