Crystallization and freezing processes assisted by power ultrasound

Power ultrasound may be used to control crystal properties in solutions and melts. The first part of this chapter concerns the thermodynamics and kinetics of crystallization. The second part reviews several studies dealing with ultrasound-assisted crystallization or freezing processes. The influence of operating conditions (dissipated acoustic power or intensity, frequency, duration, ultrasonic device) on the properties of crystals and the process rate is discussed. The third part investigates elementary mechanisms (temperature, pressure, diffusive and chemical effects) underlying the sonocrystallization process according to the literature as well as on the ground of our own results. A special paragraph is devoted to ice crystallization in supercooled aqueous solutions.