抄録
Particle shape is one of the most important characteristics in determining the physical and chemical properties. Crystallization adding impurities in crystal growth processes is a method of changing crystal shape. The shape change of crystals occurs, when the growth speed of a specific crystal face becomes slow. However, the mechanism of crystal habit is complicated due to many controlling parameters, such as supersaturation, concentration and a kind of impurities, etc. It needs to solve the mechanism for the control of the crystal shape. Sodium chloride, which is a typical ionic compound, has been selected in this study. It is considered that there are two cases determined by supersaturation in the crystal growth. One case is attachment of adatoms or admoleculars, and the other case is attachment of clusters. For an industrial application, the influence of clusters on the crystal growth was examined by experiments and cluster dynamics simulations.
In the experiment, the technique of differential scanning calorimetory (DSC) was used for measuring the cluster size with changing kinds of habit modifiers. It turned out that the cluster size changes with differences from the habit modifiers. Cluster size of sodium chloride with manganese ions was bigger than that with copper ions. Furthermore, a LCR meter was used for obtaining informations of cluster motions. The mobility of clusters was evaluated by measuring electric conductivity. It was also investigated by molecular dynamics (MD) simulation about the formation and the movement of clusters.
