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標題: Study on synthesize and properties of nanosized cobalt particles
作者: 蔡蔚珍
Tsai, Wei-Chen
關鍵字: chemical reduction method;化學還原法;cobalt nano-particle;synthesize;magnetic;oxidation;奈米鈷粒子;合成;磁性;氧化
出版社: 化學工程學系
從以上實驗發現:PAA分子量愈大則有利於合成後鈷粒子分散液的穩定性; PVP分子量太大則不利於奈米粒子的合成;及合成反應溫度愈高則反應速率愈快,此造成反應時間短才不會使鈷粒子的粒徑變大。另外,經由雷射粒徑分析儀及HRTEM測量得知所合成的鈷粒子其最小平均粒徑為11.8nm,且由XRD分析結果顯示其結構為面心立方體。

The nano-materials that can yield outstanding brilliant performance have become the“Super Star” in materials science. They have prove to have decisive influence in information and photoelectric technology. Nano-materials with their alluring applications attract us to explore them in order to widen their uses and bring immense benefit to our life.
The magnetic nano-materials equip considerably extensive applications, including magnetic fluid, magnetic note, magnetic recording, magnetic light component, magnetic probe, magnetic refrigeration material, wave absorption material, cell separate, and wisdom mould medicine, etc. This thesis is to synthesize uniform cobalt nano-particles by chemical reduction method at the presence of metal ions, reduction agent, and water that serves as solvent. First, cobaltous chloride(CoCl2․6H2O), hyrazine hydrate(N2H5OH), and palladium chloride(PbCl2) were taken to serve as precursor, reduction agent, and nucleus agent, respectively, and charged surfactant of poly-vinyl pyrrolidone(PVP) was added to form cobalt nano-particles. Afterward, poly-acrylic acid(PAA) was used as the dispersant and terminator of reaction to reach stabilization and obtain cobalt nano-particle dispersion solution without other accompanied product.
The following phenomena were observed in this research. The higher molecular weight of PAA was the more stability of cobalt particles synthesis we obtained. However, PVP with higher molecular weight was unfavorable for the synthesis of nano-particles. In order to obtain the cobalt nano-particles with smaller size, the shorter reaction time was preferred. Therefore, higher reaction temperature was adopted to accelerate the synthesis. As a result, cobalt nano-particles with average diameter of 11.8nm, measured by laser particle diameter analyzer and high resolution transmission electron microscopy(HR-TEM), can be obtained. The nano-particles were characterized as face-centered cubic structure by using X-ray diffraction.
Zeta potential apparatus and superconducting quantum interference device magnetometry were also utilized to analyze the electric and magnetic force of cobalt nano-particles. It was found that the surface potential of colloid cobalt is in the solution decreased with the decreasing pH value. The saturation magnetization(Ms) value of cobalt nano with average size of 11.8 nm was about ±148emu/g. After cobalt oxidating process with higher temperature, nano cobalt was transformed to CoO from Co3O4 and lost their magnetic property.
The research result can be applied in the following exploitation:
(1) develop high performance of wave's absorption material with high performance.
(2) self-assemble nano cobalt as two-dimensional nano-structure to fabricate quantum disk.
Appears in Collections:化學工程學系所

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