| Summary: | 碩士 === 國立交通大學 === 應用化學系所 === 94 === Abstract
This thesis mainly deals with the synthesis and characterizations of magnetic nanoparticles (NPs) and their alloys and composites. First of all, the surfactant-capped Co NPs with 10 nm in diameter was prepared by using Co2(CO)8 as a precursor, followed by thermal decomposition at 280℃. The influence of various surfactants on the formation of Co NPs has also investigated. The Co NPs were found to be superparamagnetic, but they show weak ferromagnetism at a small applied magnetic field.
Secondly, we have attempted to couple CdSe quantum dots (QDs) to magnetic Co NPs to form a bifunctional magnetic/luminescence nanocomposite of Co@CdSe. The average diameter of Core-shell Co@CdSe NPs is about 12 nm ( the core diameter is about 10 nm and the shell thickness is 1nm ). The reaction time and temperature used in the preparation on were found to change the emission wavelength. We have also discussed the influence of one-pot and two-pot chemical syntheses on the formation of Co NPs. The luminescence and spectroscopy of Co@CdSe were characterized by using photoluminescence (PL) and UV-Visible spectroscopy and the major results are presented.
Thirdly, we report the investigation results of an organometallic synthetic route for preparing superparamagnetic Sm2Co17 NPs. The oleic acid and oleylamine capped-Sm2Co17 NPs were found to have average size 7.35 nm. At room temperature, the Sm2Co17 NPs were observed superparamagnetic, but weak ferromagnetism at low temperature.
Transmission electron microscopy (TEM), electron diffraction (ED), and energy disperse spectrometry (EDS) have been used to characterize the size distribution, identify the phases, and determine the compositions of the NPs. Temperature-and field-dependent magnetization measurements were performed by using a superconducting quantum interference device (SQUID) magnetometer to confirm the superparamagnetism and investigate magnetic hysteresis.
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