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).