Abstract
Particle size of ceramic powders precipitated in an ultrasonic-driven solution is discussed. Cavities in a homogeneous solution offer heterogeneous nucleation sites since they are simply gas/liquid interface and also the vaporization of solvent into them causes a local supersaturation around them. Higher intensity of ultrasound means a larger number of cavities, while its frequency is related to the bubble size and the threshold of cavitation. In a case of magnetite precipitation via oxidation of Fe(OH)2 in solution, another dominant factor on the particle size is the ultrasonic enhancement of dissolution. There exists an optinum intensity of ultrasound to increase the particle size of magnetite where the number of cavities and the dissolution effect are balanced.
