NONEQUILIBRIUM MOLECULAR-DYNAMICS SIMULATION STUDY OF THE VISCOSITY OF GLASS-FORMING FLUORIDE MELTS

Nonequilibrium molecular dynamics simulation of viscosity was carried out on the glass forming fluoride melt of the ZrF4-BaF2-NaF system. The viscosity-temperature relationship near the liquidus temperature was obtained and the steep viscosity increase under cooling was simulated. Structural analysis of the simulated system revealed that F coordination in ZrFn polyhedra and their linkages changed with temperature and influenced the viscous flow phenomena. The formation of edge sharing between ZrF, polyhedra was the key factor in enlarging the viscous flow units and the cooperative motion between these polyhedra increased melt viscosity.