SYNTHESIS AND CHARACTERIZATION OF TRANSITION METAL OXIDES

Abstract

Owing to the large specific surface area and other superior properties over their bulk counterparts arising from quantum size effect, nanoscaled and nanostructured materials have attracted considerable research interest. Many novel nanoscale materials have been synthesized in the past 10 years. It is well known that the behaviors of nanomaterials strongly depend on the sizes, shape, dimensionality and morphologies, which are thus the key factors to their ultimate performance and applications. Therefore, it is of great interest to synthesize nanomaterials with a controlled structure and morphology. Manganese, cobalt and zinc oxides are important materials due to their wide applications in the area of catalysis, magnetic material and electrode material for batteries. These oxides were prepared by calcinations of their respective hydroxides under specific conditions. Manganese, Cobalt, and Zinc hydroxides in turn were prepared from liquid ammonia and their nitrate salts by the precipitation method. Their characterization was done using TGA/DTA, XRD, SEM and SQUID. TGA studies of manganese oxide (Mn203) suggested that it existed in hydrated form at low temperature and converted to anhydrous manganese oxide at around 650°C. While Cobalt and Zinc hydroxides existed in hydrated form at low temperatures and converted to anhydrous oxides at around 200°C and 150°C respectively. XRD studies suggested that their oxides have different Size with different form of oxides in different atmosphere. The particle size as calculated from the XRD data using the Sherrere Formula suggested that the particles were in nano-range. The Particle size, in different atmosphere, determined was in the range 16-76nm, 1-46nm and 23-43nm for the manganese oxides, cobalt oxides and zinc oxides, respectively. The results obtained from SEM and SQUID were also in good agreement with XRD results..