Preparation of Nickel Ultrafine Particles
| Autor: | Szu-Han Wu, 吳思翰 |
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| Rok vydání: | 1999 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 87 In this thesis,the nickel ultrafine particles have been synthesized by microemulsion technology and polyol method. The composition, structure and magnetic properties of the nickel ultrafine particles obtained were analyzed and the influences of various preparation conditions on particle sizes were investigated. The preparation of nickel ultrafine particles by microemulsion technology was conducted in the n-hexanol/CTAB/water system at 73℃ with nickel chloride and hydrazine as the precursor and reducing agent, respectively. By the analyses of electron diffraction pattern and X-ray diffraction, the resultant particles were characterized to be the pure nickel crystalline with a face-centered cubic (f.c.c.) structure. It was found that the average size of nickel nanoparticles was larger at higher ratio of CTAB to nickel chloride. At a constant radio of CTAB to nickel chloride, the average size of nickel nanoparticles decreased of nickel chloride concentration or the increase of hydrazine concentration. The nickel ultrafine particles prepared in the microemulsions have an average diameters of 4~12 nm. The saturation magnetization was 20~65 emu/g, higher then those of ordinary nickel particles. The coercirity was 26~35 Oe, lower then those of ordinary nickel particles. The preparation of nickel ultrafine particles by polyol medod was conducted in the ethyene glycol solution at 25℃ with nickel chloride and hydrazine as the precursor and reducing agent respectively. By the analyses of electron diffraction pattern、X-ray diffraction、lattice image, and EDS, the resultant particles were characterized to be the pure nickel crystalline with a (f.c.c.) structure. The average size of nickel nanoparticles in crease with the increase of nickel chloride concentration, while decreased with the increase of hydrazine concentration. The nickel ultrafine particles prepared polyol method have an average diameters of 7~40 nm. The saturation magnetization was 3~5 emu/g, lower than those of ordinary nickel particles. The coercirity were 170~210 Oe. Such a high coercivity for nickel particles was obserred in the literature only at very low temperatures. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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