Growth kinetics of CdS in germanium oxide glassy matrix

In the present work we revisit the size data of CdS microcrystals previously collected in the glassy matrix of Germanium oxide. The CdS clusters analyzed using electron microscopy images have shown a wurtzite structure. The mean average radius, dispersion and volume evaluated from the histograms showed good agreement for t1/3, t2/3 and t laws, respectively. We observed that the amount of microcrystals remains constant throughout the heat treatment process, as well as that the radii distribution has a lower limit and increases with heat treatment. The distribution of radii follows a distribution similar to the Lifshitz–Slyozov–Wagner distribution limited in the origin. Discussions led to the conclusion that the growth of CdS is a process that occurs after the fluctuating nucleation and coalescence phases. We then analyze the growth process, assuming that the evaporation is overcome by the precipitation rate, stabilizing all clusters with respect to dissolution back into the matrix. The problem was simplified neglecting anisotropy and the assuming a spherical shape for clusters and particles. The low interface tension was described in terms of an empirical potential barrier in the surface of the cluster. The growth dynamics developed considering that the number of clusters remains constant, and that the minimum size of these clusters grow with time, as the first order approximation showed a good agreement with the t law.

Histogram of size distribution in samples annealed at 823 K and 923 K. Dots are the Lifshitz–Slyozov distribution, and solid lines are the modified Lifshitz–Slyozov distribution.Figure optionsDownload as PowerPoint slideHighlights
► CdS microcrystals in glassy matrix of Germanium oxide.
► Mean average radius, dispersion, volume agrees with t1/3, t2/3 and t laws.
► Results fits Lifshitz–Slyozov–Wagner distribution modified to limit in origin.
► Growth process analyzed with evaporation overcome by precipitation rate.
► First order approximation showed a good agreement with the t law.