Preparation and Characterization of Magnetic Metal Oxide Nanoparticles

• Main Authors: Wei, Ming-Fen, 魏明芬
• Other Authors: 吉凱明
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/73002723696524946815

碩士 === 國立中正大學 === 化學研究所 === 90 === Abstract The main focus of this thesis is to prepare metal oxide nanoparticles by decomposition of organometallic precursors. We made choice of Fe(acac)3, Co(acac)2, Mn(acac)2 as organometallic precursors. The precursor together with different surfactants, like TOPO, CTAB and oleic acid were dissolved in organic solvent. The reflux of the solution is then proceeded. We successfully obtained γ-Fe2O3, CoO and Mn3O4 metal oxide nanoparticles. In structural analysis, we observed the shape and the size of nanoparticles by transmission electron microscopy (TEM). We used energy dispersive spectroscopy (EDS), electron diffractometer (ED), X-ray powder diffractometer (XRD) and electron spectroscopy for chemical analysis (ESCA), to identify composition of nanoparticles. In our study, we confirmed these products are metal oxide nanoparticles. Besides, we used superconducting quantum interference device magnetometer (SQUID), to measure magnetic character of iron-oxide nanoparticles and cobalt-oxide nanoparticles. We discovered from the experiment result, the size of nanoparticles was varied with the time of reflux, the concentration of surfactant and precursor. We proved that nanoparticles enlarged with prolonging the time of reflux. In addition, we suitably increased the concentration of surfactant or precursor, these nanoparticles grew into bigger and more stable state. By control of the reaction time and the concentration, we confined the particle size in a range of 3.79±0.94 nm to 13.48±2.44 nm for γ-Fe2O3 nanoparticles. Using atomic absorption spectroscopy (AAS), we detected average percentage of Fe2O3 inside powder was 55.43 %. In magnetic study, we proved the g-Fe2O3 nanoparticles were small enough so that they exhibited superparamagnetic phenomenon. We found saturation magnetization to be 79 emu/g for γ-Fe2O3 nanoparticles (7.16±1.27 nm) at 300 K. The CoO nanoparticles with diameter of 3 ~ 5 nm exhibited superparamagnetic phenomenon. Consequently, we successfully fabricated polyhedron g-Fe2O3, CoO and Mn3O4 nanoparticles. Beside, g-Fe2O3 nanoparticles exhibited ferrimagnetism and CoO nanoparticles exhibited superparamagnetism.