Molecular dynamics simulation of neck growth in laser sintering of different-sized gold nanoparticles under different heating rates

The neck growth in the laser sintering of different-sized gold (100) nanoparticles under different heating rates is investigated using a molecular dynamics method. The numerical simulations are carried out for four pairs of two spherical nanoparticles under three different heating rates. For each pair, one nanoparticle has the same diameter of 4 nm and the other nanoparticle's diameter is varied, ranging from 4 nm to 20 nm. The results show that the solid state sintering automatically takes place by local potential at room temperature. The stable neck width increases as the size of the other nanoparticle increases. Once the limit stable neck width is reached, it no longer is affected by the nanoparticle size. For the subsequent laser heating to the same final temperature, a lower heating rate results in a larger stable neck width due to the longer sintering process. The neck growth mechanisms and rate under various sintering conditions are discussed.