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lcc830306银虫 (小有名气)
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Cerium oxide (CeO2) nanoparticles were prepared sonochemically,by using cerium nitrate and azodicarbonamide as starting materials,and ethylenediamine or tetraalkylammonium hydroxide as additives. The additives have a strong effect on the particle size and particle size distribution. CeO2 nanoparticles with small particle size and narrow particle size distribution are obtained with the addition of additives; while highly agglomerated CeO2 nanoparticles are obtained in the absence of additives. Monodispersed CeO2 nanoparticles with a mean particle size of ca. 3.3 nm are obtained when tetramethylammonium hydroxide (TMAOH) is used as the additive and the molar ratio of cerium nitrate/azodicarbonamine/TMAOH is 1/1/1. Blue shifts of the absorption peak and the absorption edges of the products are observed in the UV-Vis absorption spectra as a result of the quantum size effect. The samples have been characterized using powder XRD, TEM, DLS, and absorption spectra. |
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lz3333
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3楼2010-05-03 22:05:56
【答案】应助回帖
| 二氧化铈的纳米颗粒是通过声化学反应制备的，即通过以硝酸铈和偶氮甲酰胺作为起始原料，乙二胺或胺类氢氧化物作为添加剂制得的。添加剂对颗粒的大小及大小分布影响很大。通过添加剂的添加，可获得具有较小颗粒和较窄的颗粒大小分布的氧化铈纳米颗粒；同时添加剂的添加会避免氧化铈纳米颗粒的高度团聚。当以四甲基氢氧化铵（即TMAOH）作为添加剂，并且硝酸铈：偶氮二碳胺：TMAOH的摩尔比为1:1:1时，可得到单分散的氧化铈纳米颗粒，其平均颗粒大小在3.3nm左右。利用量子尺寸效应机制，我们通过紫外可见吸收光谱观察了产物的吸收峰和吸收边的蓝移现象。样品还通过粉末X射线衍射、透射电子显微镜、动态光散射和吸收光谱进行了表征。 |
2楼2010-05-03 22:05:07
