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https://ptsldigital.ukm.my/jspui/handle/123456789/519454| Title: | Synthesis of metal oxide nanopowders by microwave assisted process and a thermal decomposition method |
| Authors: | Rashad Ahmed Hamid Al-Gaashani (P50316) |
| Supervisor: | Shahidan Bin Radiman, Professor Dr. |
| Keywords: | Metal oxide nanopowders Microwave assisted process Thermal decomposition method Metallic oxides |
| Issue Date: | 12-Dec-2012 |
| Description: | In this study, five nanostructured metal oxides (ZnO, MgO, CuO, SnO2 and α-Fe2O3) with various morphologies including nanoparticles, quantum dots (QDs), nanoflowers, nanoneedles, nanorods, nanoflakes, tetrapod nanostructures and others have been successfully synthesized as powders using two main methods, namely microwave-assisted method and thermal decomposition technique. The prepared samples of metal oxides have been characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV��vis spectroscopy. Effecst of the microwave power on the morphology and optical properties of ZnO nanostructures prepared using a microwave-assisted aqueous solution method has been investigated. The ZnO nanostructures were synthesized from zinc chloride and sodium hydroxide mixed aqueous solutions exposed for 5 minutes to microwave radiation at four different powers, namely 150, 450, 700 and 1000 W. The results showed that the power of microwave radiation influenced the shape and size of the synthesized nanostructures. It is also found that the average particle size of nanostructures decreased with decreasing microwave power. Herein, a comparative study between three different morphologies of as- prepared ZnO nanostructures, namely nanoparticles (NPs), nanoflowers (NFs) and nanorods (NRs) which involved structural, optical and XPS analyses has also been done. The possible growth mechanisms of ZnO nanostructures of different morphologies were proposed based on the interaction of microwaves with materials. In this work, two new simple methods for synthesizing Mg(OH)2 nanostructures, MgO nanoflakes and MgO/Mg(OH)2 nanocomposite were developed using a conventional microwave oven. The first method included the preparation of Mg(OH)2 by a simple reaction of magnesium powder with deionized water under microwave radiation. The second method involved the transformation of Mg(OH)2 to MgO nanoflakes and grass-like nanostructures by rapid microwave hybrid heating using a SiC-based composite susceptor. CuO, SnO2 and α-Fe2O3 nanostructuers with different morphologies have also been successfully prepared via a thermal decomposition method at different temperatures and times in air using one starting raw material for each oxide nanostructure. The methods used in this study are simple, green and effective in terms of cost and time. The optical property investigation exhibited that the biggest crystallite size of the prepared samples has the lowest energy band gap.,Ph.D |
| Pages: | 284 |
| Call Number: | TA418.9.N35.G334 2012 |
| Publisher: | UKM, Bangi |
| Appears in Collections: | Faculty of Science and Technology / Fakulti Sains dan Teknologi |
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