Preparation of ZnO-TiO2 Composite Fine Particles Using the Ultrasonic Spray Pyrolysis Method and Their Characteristics on Ultraviolet Cutoff

ZnO-TiO2 composite fine particles were prepared by ultrasonic spray pyrolysis of TiO2 (anatase) particles suspended in Zn(NO3)2 aqueous solution. The morphology and the crystalline phases of fine particles were studied with varying nebulizing solution compositions, reactor temperature, and nitrogen carrier gas flow rate. The aggregate particles produced were spheres of ZnO (wurtzite structure) and TiO2 (anatase), whose diameters ranged from 0.36 to 0.5μm. These particles were hollow or solid aggregate particles consisting of ultrafine primary particles with diameters ranging from 10 to 100 nm. The crystallinity of prepared particles was improved by increasing the reactor temperature and lowering the flow rate of nitrogen. The largest crystallites were obtained at a solution concentration ratio of CZn(NO3)2/CTiO2 = 10:7. These composite particles showed a combined ultraviolet cutoff characteristic of ultraviolet light shielding in the wide range of wavelength ranging from 200 to 370 nm.