| Summary: | 碩士 === 國立清華大學 === 材料科學工程學系 === 89 === Surface modification is an important technology for applications of nanomaterials. Because the high surface energy is a unique property of nanoparticles, one of the key nanotechnologies is to realize and control the surface properties of nanomaterials. With modification, nanoparticles can be better dispersed and agglomeration is reduced. They may be converted to be more useful and powerful materials. Nanomaterials find many new applications in chemical, biological, and physical fields.
In this study, surface modification was made by a chemical method to cover a layer of protective agent ( stearic acid or polyethylene glycol )on the particle surface. Four kinds of starting materials, Ag and Ni microcrystalline powders, and Pd70Ag30 and Si nanoparticles, were studied. The sintering properties of normal and modified particles were investigated, and the light emission characteristics of normal and modified Si particles were also compared.
According to the FTIR spectra, the modification process was efficient to coat a layer of stearic acid (SA) on the powder surface. From the thermogravimetric analysis, the oxidation of powders after surface modification was reduced. The sintering curves showed that the protective agents could effectively suppress the sintering. The sintering behaviors of modified powders were different from those of normal powders, because the surface energy was decreased and the powder surface was protected by the agents. The photolumescence (PL) spectrum of modified Si nanoparticles was changed since the protective agent had modified the surface states, thus altering the light emission characteristics.
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