The application of ultrasound radiation to the synthesis of nanocrystalline metal oxide in a non-aqueous solvent

Highly crystalline metal oxide nanoparticles of TiO2, WO3, and V2O5 were synthesized in just a few minutes by reacting transition metal chloride with benzyl alcohol using ultrasonic irradiation under argon atmosphere in a non-aqueous solvent. The sonochemical process was conducted at a relatively low temperature, 363 K. A unique crystallization process of these nanoparticles has been observed and characterized by powder X-ray diffraction (PXRD), high resolution scanning electron microscopy (HRSEM), and BET. The particles' size and shape measured from HRSEM reveal quasi zero-dimensional, spherical TiO2 particles in the range of 3-7 nm. The V2O5 Particles have a quasi one-dimensional ellipsoidal morphology, with lengths in the range of 150-200 nm and widths varying between 40 and 60 nm. The WO3 particles were obtained as quasi two-dimensional platelets with square shapes having facets ranging from 30 to 50 nm. The thickness of these platelets was between 2 and 7 nm. The mechanism of the reactions leading to these three metal oxide nanoparticles in a non-aqueous system is substantiated by Nuclear Magnetic Resonance (NMR), and Electron Spin Resonance (ESR). (C) 2009 Elsevier B.V. All rights reserved.