The Relevance of Interactions in Nanoparticle Systems – Application to Particulate Thin Films

In the field of Particle Technology, processes cannot yet be designed from basic molecular understanding. Nanotechnology, however, begins to bridge this gap between molecules and particles and may thus open up new ways not only for the production and handling of particulate matter but also for the engineered design of advanced material properties. The visions and applications in nanoparticle technology cover a broad range, for instance quantum dots in information technology, refractory particles for advanced ceramics, highly active substances in pharmacy, catalysts or micro‐ and mesoporous adsorbents, to name only a few applications. Starting from the concept of product engineering, we investigate the basic preconditions for tailoring nanoparticulate properties, i.e. the control of the particle interactions. This concept is then applied to particulate thin film formation as an example of structure formation. The structure of dip‐coated samples, defined as the order of particles within the layer, was found to vary with the pH and the ion concentration adjusted in the sol bath. It was observed that the surface roughness scanned by an atomic force microscope increased with increasing electrolyte concentration. The structural evolution of the particulate network was studied by measuring the viscosity as a function of shear rate and solid concentration. Finally, the influence of coating structures on the transmission properties was determined. Especially in the case of LaCl₃ a strong dependence was observed. The results explicitly confirm a correlation between microscopic structure and macroscopic properties.     

Sr2 CeO4电荷迁移发光的光谱结构规律研究

利用高温固相反应法分别合成了不同物相形成机理的Sr2CeO4，Sr2CeO4：Ca^2 和Sr2CeO4：Ba^2 样品，并对其光谱特性进行了研究．结果发现，对于由SrO和CeO2直接反应生成的Sr2CeO4(Ⅰ)，激发主峰位于256nm左右；而对于SrCeO4和SrO反应生成的Sr2CeO4(Ⅱ)，激发主峰位于279nm左右．在Sr2CeO4(Ⅰ)中掺入Ca^2 ，其激发光谱随着Ca^2 离子浓度的增加逐渐接近于Sr2CeO4(Ⅱ)的激发光谱．激发主峰带应属于CeO6八面体终端Ce^4 -O^2-键的电荷迁移带．对于激发光谱中340nm左右的弱激发峰，其峰值波长不受形成机理及Ca^2 掺杂的影响，只是其强度随着激发主峰的红移而增加，它可能属于CeO6八面体平面上Ce^4 -O^2-键的电荷迁移带．形成机理及Ca^2 掺杂对发射光谱没有影响．Ca^2 在Sr2CeO4(Ⅱ)与Ba^2 在Sr2CeO4(Ⅰ)和(Ⅱ)中均难于替代Sr^2 的位置．