MOLECULAR-DYNAMICS SIMULATION OF ELEVATED-TEMPERATURE INTERFACIAL BEHAVIOR BETWEEN SILICA GLASS AND A MODEL CRYSTAL

Elevated temperature atomistic behavior was investigated using classic al molecular dynamics simulations of solid state interfaces. Initially , observations on a Lennard-Jones (LJ) crystal surface interfaced with an ideal vacuum were made. Assignment of temperatures associated with specific amounts of crystal surface disorder was possible. A temperat ure was observed at and above which disorder propagated through all pl anes of mobile atoms, making it possible to establish an approximate t ransition temperature for surface nucleated melting of the LJ crystal. Similar high temperature simulations were then performed on silica gl ass/LJ crystal interfaces at two system stress levels. No significant dependence of interface behavior on the stress states which were studi ed was observed. The presence of the glass surface resulted in a depre ssion of the temperature needed for the surface most planes of crystal atoms to roughen. This allowed LJ atoms to sample and occupy sites in the glass surface. Additional data presented shows this behavior was at least partly a function of the open structure inherent in glassy ox ide surfaces. (C) 1996 American Institute of Physics.