Supercooling, induction times and nucleation in flux growth: WO3 as a model solute

WO3 was chosen as a model solute in this investigation of nucleation by differential thermal analysis (DTA) and flux growth experiments. The compositions studied were:(1) 100 WO3−22 Na2C and (2) 100 WO3−44 NaFThe first composition supercooled 13 °C, the second 70°C when cooled at 20° per minute. Induction time experiments for WO3-NaF are interpreted as indicating that clusters of WO3 retain their identity even after heating to 480 °C above the liquidus, quickly reaching an equilibrium size at each soak temperature. Below the liquidus they increase in size but cannot form a stable nucleus until the critical supercooling of 35 °C is exceeded.