Heterogeneous crystal nucleation of supercooled lithium disilicate melt in glassy carbon containers

Repetitive-scanning calorimetry (RS-DSC) was used to study the heterogeneous crystal nucleation of supercooled lithium disilicate melt in glassy carbon containers. Due to the poor wetting, the liquid formed a nearly spherical droplet in each of the 300 runs. Lithium disilicate (LS2) crystals grew at the surface of the droplet. Raman mapping revealed carbon particles in the center of the crystals presumably seeding the crystallization of LS2. Heterogeneous crystal nucleation rates of LS2 were determined by the statistical method from the mean waiting time (isothermal RS-DSC) and the mean supercooling (isochronal RS-DSC). The maximum nucleation rate of LS2 was two orders of magnitude larger and at approximately 270 K deeper supercooling than previously reported for treating lithium disilicate melt in noble metal containers.