Progress in Ultrasonic Spray Pyrolysis for Condensed Matter Sciences Developed From Ultrasonic Nebulization Theories Since Michael Faraday

This review outlines, in great detail, the history of the phenomenon of ultrasonic nebulization of liquids since the discovery of such an effect by Michael Faraday and the explanation of the phenomenon by capillary wave mechanism and “cavitation” hypothesis. Capillary waves described by the Kelvin equation are confirmed by Lang's experiment and more theoretical models by Peskin & Raco and Jokanovic. Cavitation bubbles have been elaborated by the Rayleigh-Plesset equation as well as the correlation equations between predicted and experimentally measured droplet diameter. Correlation equations such as one by Rajan & Pandit and Avvaru et al. have been considered. Ultrasonic spray pyrolysis for materials processing and the theories that predict the final particle size distribution are introduced. The popularity of the technique is shown by the rising number of research groups in the world processing various materials by this method due to its cost-effectiveness, purity of its products, and controllability of particle size as well as final properties.