Molecular dynamics study of neck growth in laser sintering of hollow silver nanoparticles with different heating rates

Engineered hollow nanoparticles have exhibited their potential in nanotechnology applications, but so far the investigation of the deformation mechanisms for these hollow particles during the sintering process has rarely been reported. Hence, a comparative study of both solid and hollow spherical silver nanoparticles with different sizes under different heating rates of laser sintering is conducted systematically in this paper, based on molecular dynamics simulations. An interesting phenomenon is observed where the temperature for fast neck growth shows an inverse trend in all the hollow nanoparticle pairs at an ultrahigh heating rate, which is quite different from that known in the solid particle cases. This finding implies that besides the size and heating rate, the nanoparticle geometry could also play an important role in the sintering process. At a low heating rate, the plastic deformation combined with structural reconfigurations induced by the lattice sliding in the hollow shells is found to be an important mechanism during the heating process. At an ultrahigh heating rate, the transition from fcc crystal directly to disordered structure from both outside and inside surfaces becomes more dominant than the structural reconfiguration with lattice defects, which is facilitated by the introduction of the inner free surfaces in hollow nanoparticles. The entire hollow particle pairs thus show an obvious tendency to coalesce and melt at a lower temperature level than with a low heating rate.