Photoluminescent particle surfaces in mesoporous hosts

碱土氧化物(AEO)纳米晶作为具有吸附相关光学性质的无机荧光粉显示出了迄今未被注意到的潜在应用。为了在保持与界面相关的光学性质的情况下将这些纳米物体连接到我们的宏观世界，需要开发新的方法来将纳米粒子固定在介孔基质中。本项目的目标是利用新的金属蒸气渗透技术，在惰性和化学反应的介孔涂层(二氧化硅、二氧化钛、混合二氧化钛或氧化镁)中以可控的方式制备纳米AEO颗粒(MgO、CaO、BaO、SRO)。研究了涂层性能、厚度、孔隙率、孔径分布和孔连通性对AEO粒子沉积的影响，从而研究了AEO粒子的光学性质。在一个介孔涂层内产生多个AEO颗粒浓度梯度将通过对AE金属成核位的空间控制功能化来实现，例如通过利用具有可变热稳定性的表面基团，或者通过利用光刻或聚焦离子束技术对涂层进行图案化。此外，多个涂覆步骤将允许具有孔隙率和化学成分梯度的结构，这也将用于产生AEO浓度梯度。根据定义的涂层厚度和各种AEO粒子类型的空间可调浓度，我们设想了一种复合材料，其中涂层内一个选定区域的故意光激发可以基于能量转移过程在第二个区域产生光致发光。作为另一种合成方法，我们将利用硅烷在AEO颗粒表面的受控吸附结合后续的氧化转化步骤来生成致密的二氧化硅层，以用于化学保护。然后，相应的产物可以直接并入蒸发诱导自组装过程中，以形成介孔涂层。

Alkaline earth oxide (AEO) nanocrystals show a so far unnoticed potential for applications as inorganic phosphors with adsorption-dependent optical properties. To connect these nanoscopic objects to our macroscopic world under preservation of their interface-related optical properties, new approaches for nanoparticle immobilization inside mesoporous host matrices need to be developed. The goal of the present project is to create nanoscale AEO particles (MgO, CaO, BaO, SrO) in a controlled way inside inert as well as chemically reactive mesoporous coatings (SiO2, TiO2, mixed TiO2/SiO2 or MgO) using novel metal vapour infiltration techniques. The influence of the coating properties thickness, porosity, pore size distribution and pore connectivity on the deposition of AEO particle and consequently their optical properties will be investigated. The generation of multiple AEO particle concentration gradients within one mesoporous coating will be achieved by spatially controlled functionalization of sites for AE metal nucleation, e.g. by utilizing surface groups with variable thermal stabilities, or by patterning of the coating with lithographic or focused ion beam techniques. In addition, multiple coating steps will allow for structures with gradients in porosity and chemical composition, which will also be employed for the generation of AEO concentration gradients. On the basis of defined coating thicknesses of the host and spatially adjustable concentrations of various AEO particle types we envision composites where the deliberate photoexitation of one selected area inside the coating can produce photoluminescence emission in the second region based on energy transfer processes. As an alternative synthetic approach, we will employ the controlled adsorption of silanes onto AEO particle surfaces in combination with subsequent oxidative conversion steps to generate dense silica layers for their chemical protection. Respective products can then be directly incorporated into the evaporation-induced self-assembly process for the formation of the mesoporous coatings.