Preparation and mechanism of Fe3O4/Au core/shell super-paramagnetic microspheres |
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Authors: | Yali Cui Daodao Hu Yu Fang and Jianbiao Ma |
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Institution: | (1) Department of Chemistry, Shaanxi Normal University, 710062 Xi’an, China;(2) National Key Laboratory on Adsorption and Separation of Functional Polymers, Nankai University, 300072 Tianjin, China |
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Abstract: | In the presence of Fe3O4 nano-particles, a new type of super-paramagnetic Fe3O4/Au microspheres with core/shell structures was prepared by reduction of Au3+ with hydroxylamine. The formation mechanism of the core/shell microspheres was studied in some detail. It was shown that
the formation of the complex microspheres can be divided into two periods, that is, surface reaction-controlled process and
diffusion-controlled process. The relative time lasted by either process depends upon the amount of Fe3O4 added and the initial concentration of Au3+. XPS analysis revealed that along with increasing in coating amount, the strength of the characteristic peaks of Au increased,
and the Auger peaks of Fe weakened and even disappeared. Size distribution analysis showed that the core/shell microspheres
are of an average diameter of 180 nm, a little bit larger than those before coating. |
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Keywords: | Fe3O4 gold super-paramagnetic microspheres core/shell structure |
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