Synthesis of Fe3O4/SiO2/Ag Hollow Composite Structure by Three-stage Synthesis and Properties explore

• Main Authors: Yu-Fang Huang, 黃鈺方
• Other Authors: Shih-Yun Chen
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/f4zqq4

碩士 === 國立臺灣科技大學 === 材料科學與工程系 === 107 === This study attempts to develop a simple, rapid and mass-produced three-stage process for the preparation of Fe3O4 hollow sphere composite structures. The prepared hollow composite structure was characterized by electron microscopy and electron energy loss spectroscopy to study the surface morphology and crystal structure of the samples obtained in each stage and to identify the phases of iron oxide. The experimental results show that the iron oxide hollow spheres prepared by the first stage spray lysis method have a size of 0.5 μm to 3 μm and an average shell thickness of about 20 nm. The prepared hollow spheres were reduced in an Ar/H2 atmosphere to successfully obtain a Fe3O4 structure having good ferromagnetic properties. The thickness of the SiO2 layer coated by the second stage sol-gel method is about 10 nm. The Ag particles grown in the third stage of the incipient wetness method have a size of about 10 to 30 nm and are uniformly distributed on the surface of the hollow sphere. However, the electron energy loss spectrum analysis indicates that the Fe3O4 hollow sphere is partially oxidized after the process of growing Ag particles, resulting in a decrease in the saturation magnetization. Finally, the surface-enhanced Raman spectroscopy properties of the hollow composite structure are discussed. Compared with the solid sphere composite structure in the literature, with R6G as the detector, the Raman spectral intensity of the hollow composite structure at 1650 cm-1 is more than an order of magnitude higher than that in the literature when the concentration of R6G is 10-8M. The reason for the enhancement is presumed to be related to the suspension characteristics provided by the hollow structure and the appropriate Ag particle size and spacing.