In situ observations using interference contrast microscopy have carried out in an electrochemical deposition system of a ZnSO4 solution film. Concentration oscillation around a growing dendrite tip, which is illustrated by local contrast oscillation, has been found to correspond to sidebranching of the dendrite. A model concerning the competition between diffusion of cations and growth of dendrites has been used to explain this oscillation phenomenon. It appears that this concentration field oscillation in front of the dendrite tip plays an important role in sidebranching.

The dynamic behavior of the concentration field in crystallization is investigated by considering the coupling of the bulk concentration field and interfacial kinetics. It is shown that the concentration field may become unstable for perturbations with certain wavelength. When instability occurs, the physical environment in front of the growing interface will fluctuate and the interfacial growth mode will be affected accordingly. We suggest that our analysis can be used to interpret some spatial-temporal instabilities observed in crystallization.

In situ observations technique is evmloyed to study the freatctal growth in a thin isothermal aqueous-soulution film of Ba(NO3)2. The micromorphology and the growing process of the fractals have been investigated. The experimental findings provide direct evidence that the fractals are formed by random successive nucleation. A nucleation-limited-aggregation (NLA) model is proposed to describe the fractal growth in our system. A computer simuation using the NLA model is also presented.

We report here the electrodeposition of copper on an insulating glass substrate without introducing additives into the electrolyte and/or metallic clusters on the surface of the substrate. The deposit morphology, which varies from compact film to dense-branching patterns,can be achieved by changing the concentration and pHof the electrolyte, and the electric current in electrodeposition. The grain size of the electrodeposits is analysed for various growth conditions. We find that finer copper grains can be easily achieved at large electric current, high pH and low electrolyte concentration. We explain, using the theory of nucleation, why a metallic layer may develop horizontally over an insulating glass plate.