Photoluminescent particle surfaces in mesoporous hosts

碱土金属氧化物（AEO）纳米晶体显示了迄今为止未被注意的潜在应用与吸附依赖的光学性能的无机荧光粉。为了将这些纳米级物体连接到我们的宏观世界，并保持其界面相关的光学性质，需要开发新的方法来固定纳米颗粒在介孔基质中。本项目的目标是使用新型金属蒸汽渗透技术以受控方式在惰性和化学反应性介孔涂层（SiO2，TiO 2，混合TiO 2/SiO2或MgO）内产生纳米级AEO颗粒（MgO，CaO，BaO，SrO）。研究了涂层性质、厚度、孔隙率、孔径分布和孔连通性对AEO颗粒沉积的影响，并由此研究了它们的光学性质。在一个中孔涂层内产生多个AEO颗粒浓度梯度将通过AE金属成核位点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，或通过用光刻或聚焦离子束技术图案化涂层。此外，多个涂覆步骤将允许结构具有孔隙率和化学组成的梯度，这也将用于产生AEO浓度梯度。在确定的涂层厚度的主机和空间可调浓度的各种AEO颗粒类型的基础上，我们设想复合材料，其中涂层内的一个选定区域的故意光激发可以产生基于能量转移过程的第二区域中的光致发光发射。作为一种替代合成方法，我们将采用硅烷在AEO颗粒表面上的受控吸附，并结合随后的氧化转化步骤，以生成致密的二氧化硅层，用于其化学保护。然后可以将相应的产物直接掺入蒸发诱导的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.