【摘要】 通过对共沉淀方法制备的Zn(OH) 2 进行足够时间 (70min)的超声处理制备了具有网状结构的ZnO纳米团聚 (WLSZC)。采用高分辨率电子显微镜 (TEM)和光致发光 (PL)谱等方法对所制备的样品进行表征。在WSLZC的网状结构中 ,观察到了每一条边由一个单晶组成的多边形网状结构。PL测试表明 ,所有制备的样品都具有 4 6 9nm的发光峰。WSLZC的PL的强度比只有普通结构的纳米粉末ZnO要大 8～ 1 4倍。在所有超声处理的样品中都能观察到四重分裂的“施主 受主“跃迁峰。这个峰是由于超声处理时残留的非共轴应力和自旋相互作用的结果更多还原

【Abstract】 ZnO with various nano structures have tried to be prepared due to the special features of nano structured material. In this work, the web like structured ZnO clusters (WLSZC) have been prepared for the first time. The first step of this process is to prepare the colloidal Zn(OH) 2 by means of co preparation process. The second step (the key step to prepare WLSZC) is to treat the yield colloids using ultrasonic machine for 70 min. The third step is to sinter the as treated colloids in step 2 and obtain the WLSZC. The as prepared samples are characterized by the high resolution transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy. In WLSZC, we observe homogeneous polygons which consist of one single crystal particle at each side. In addition, the samples in this order demonstrate that with the decreasing of the ultrasonic treatment time, the size distribution decrease, the mean size increase, and less aggregation is found. The formation of WLSZC can be explained by the following reasons: the structural difference of as prepared samples can be attributed to the ultrasonic treatment and the duration of treatment. Colloid in de ioned water exposed to the ultrasonic standing wave (USW) is driven by an axial direct radiation force to concentrate at nodal. The longer the treatment time, the thinner the plane. Because the size of particles in the sample depends on the thickness of the plane, therefore the longer the treatment time, the smaller the particle size. The particles move toward and accumulate at preferred positions within the nodal plane and after enough treatment time a pre web like structured colloidal cluster is likely to form. The pre web like structure is presumably of more colloid in polygon side positions of WLSZC and less colloid in porous positions of WLSZC. From Sample B to Sample F, with less and less treatment time, the size distributions were narrower due to less and less accumulation. Unlike other worker’s results, the six samples evince just one very broad emission band with a peak at 469 nm and with fourfold splitting line. The PL intensity of Sample A is 8～14 times larger than those of other samples (B F). This phenomenon is due to the resonant effect of the polygonal pores (about 100 nm wide). In addition, the in plane movement of colloids was attributed to lateral variations within the nodal planes of ultrasonic sound giving rise to a lateral radiation force (perpendicular to the nodal plane) that probably produced internal stress along the direction perpendicular to the nodal plane in the colloid clusters, as well as probably remained in the samples along the direction perpendicular to the nodal plane. Due to combination of unaxial residual stress and spin exchange a fourfold spin splitting of donor acceptor transition is observed in the as prepared samples.The PL spectrum of the web like structured ZnO indicates that the web like structure would results in increasing PL intensity.更多还原