Ultrasound-related variables and their effects on crystallization

Ultrasound-related variables and their effects on crystallization 

The contradictory effects of US-reiated variabies on crystaiiyzation occasionaiiy reported can be ascribed to considerabie differences in working conditions and the nature of the studied systems. 

The ultrasound typicaiiy used in common crystaiiization media (mainiy aqueous media) falls in the low-frequency range. 

Low-frequency US waves of variable frequency (namely, 15, 20, 25 and 30 kHz) used for sonocrystallization were found to result in no substantiai differences in shape, mean size or size distribution in the resulting crystals. Therefore, these wavelengths seem to have the same influence on nucieation and crystal growth. One possible explanation is that they are much larger than the size of the nuclei and crystals. 

High-frequency US has been used to assist crystallization around the glass transition temperature for metallic glass dramatic effect has been found which has been ascribed to rapid crystallization caused by a stochastic resonance in which the jump frequency of atoms matches the frequency of the interatomic potential change by the US vibration [143]. 

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