Crystallization kinetics of glassy materials: the ultimate kinetic complexity?

Four examples of complex crystallization kinetics changing with fundamental experimental conditions (temperature, heating rate) were introduced—formation of tetragonal ZrO2 in vanadium-doped zirconia catalyst, crystal growth in Y3Al5O12 (YAG) glass microspheres, multi-phase crystallization in (GeTe4)50(GaTe3)50 chalcogenide glass for far-infrared optics and formation of crystallites in selenium glass. In each case, a unique solution employing either mathematic or kinetic deconvolution was utilized to obtain full description of the crystal growth kinetics and its dependence on temperature/heating rate. The article discusses merits and flaws of each approach together with the general advantages and disadvantages of the mathematic and kinetic deconvolution procedures. In conclusion, the kinetic deconvolution can be used as an exploratory tool; suitability of the method for full kinetic description of the process is conditioned by relative constancy of apparent activation energy across the explored range of experimental conditions and by describability of the experimental data within a framework of some standard kinetic model. On the other hand, mathematic deconvolution is not limited by the above-listed conditions and cannot properly account for potential mutual dependences occurring between the particular sub-processes.