Using different composition melts in Li_2O-Nb_2O_5 system, their density, surace tension and viscosity were measured. The results showed that the density and surface tension varied linearly as a function of temperature and composition. We found a nonlinear increase in viscosity at the congruent and stoichiometric melt compositions when the temperature approached to the liquidus curves. In contrast, the melt close to the eutectic compositions showed a linear change in viscosity with temperature down to the solidification temperatures.
