A comprehensive review on ultrasonic spray pyrolysis technique: Mechanism, main parameters and applications in condensed matter

Nanostructured materials have attracted much attention in recent decades. Nowadays, there are numerous nanomaterials with several applications. The ultrasonic spray pyrolysis method is a cost-effective and adaptable technique based on an aerosol process for synthesizing nanoparticles and depositing thin films. The technique is capable of synthesizing metal, oxide, and composite nanomaterials with precisely controllable morphologies and chemical compositions using metal salts in aqueous solvents. More importantly, it is popular, as evident from the growing number of studies being conducted on the technique. Here, we review studies conducted on basic principles and applications of the ultrasonic spray pyrolysis method and investigate effects due to its main parameters including the solution flow rate, the pyrolysis temperature, the distance between the nozzle and the substrate, the pyrolysis time, the carrier gas (oxygen/nitrogen) flow rate, and the precursor solution concentration on morphological properties of the prepared structures.