Ding Yuanhua, Li Chengyi, Guo Rong
School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002, PR China.
Ultrason Sonochem. 2010 Jan;17(1):46-54. doi: 10.1016/j.ultsonch.2009.02.011. Epub 2009 Mar 6.
Pomponlike La(2)(MoO(4))(3) microstructures assembled with single-crystalline nanoflakes have been facilely fabricated via a surfactant-assisted ultrasound route for the first time. Various synthesis conditions were examined, such as the surfactant concentration, the molecular structure of surfactants, and the pH value. The obtained pomponlike microstructures were characterized by X-ray diffraction (XRD), (field-emission) scanning electron microscopy [(FE)SEM], transmission electron microscopy (TEM), and nitrogen adsorption/desorption isotherms. It has been revealed that a minimum concentration of sodium dodecylsulfate (SDS) was required for the formation of pomponlike La(2)(MoO(4))(3) microstructures. When the SDS concentration is above 0.02 mol L(-1), the pomponlike microstructures become more perfect, and the size is also increased with the increasing SDS concentration. Under the same sonication, similar pomponlike microstructures were obtained when a cationic surfactant, cetyltrimethyl ammonium bromide (CTAB), was used instead of the anionic surfactant SDS, indicating that the hydrophobic alkyl chains are an important factor for the formation of the pomponlike La(2)(MoO(4))(3) microstructures. It is also found that the pomponlike La(2)(MoO(4))(3) microstructures can only be obtained within an optimal pH range of 8.0-9.0 under sonication. Based on TEM, Fourier transform infrared spectroscopy (FT-IR) and solubilization experiment, a formation mechanism of pomponlike La(2)(MoO(4))(3) microstructures was proposed, in which the collaborative action of surfactants and sonication plays a key role. Furthermore, the porosity of the pomponlike La(2)(MoO(4))(3) microstructures were discussed.
首次通过表面活性剂辅助超声法轻松制备了由单晶纳米片组装而成的绒球状La₂(MoO₄)₃微结构。研究了各种合成条件，如表面活性剂浓度、表面活性剂的分子结构和pH值。通过X射线衍射（XRD）、（场发射）扫描电子显微镜[（FE）SEM]、透射电子显微镜（TEM）和氮吸附/解吸等温线对所得绒球状微结构进行了表征。结果表明，形成绒球状La₂(MoO₄)₃微结构需要最低浓度的十二烷基硫酸钠（SDS）。当SDS浓度高于0.02 mol L⁻¹时，绒球状微结构变得更加完美，并且尺寸也随着SDS浓度的增加而增大。在相同的超声处理下，当使用阳离子表面活性剂十六烷基三甲基溴化铵（CTAB）代替阴离子表面活性剂SDS时，获得了类似的绒球状微结构，这表明疏水烷基链是形成绒球状La₂(MoO₄)₃微结构的重要因素。还发现，在超声处理下，仅在8.0 - 9.0的最佳pH范围内才能获得绒球状La₂(MoO₄)₃微结构。基于TEM、傅里叶变换红外光谱（FT - IR）和增溶实验，提出了绒球状La₂(MoO₄)₃微结构的形成机制，其中表面活性剂和超声处理的协同作用起关键作用。此外，还讨论了绒球状La₂(MoO₄)₃微结构的孔隙率。
