Optical in situ diagnostics of droplets, nanoparticles and aggregates in spray-flame synthesis

喷雾火焰合成中液滴、纳米颗粒和聚集体的光学原位诊断

• 批准号: 375857474
• 负责人: Professor Dr.-Ing. Stefan Will
• 金额: --
• 依托单位: Lehrstuhl für Technische Thermodynamik (LTT)
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/375857474?language=en
• 关键词: Optical; situ; diagnostics; droplets; nanoparticles

The product properties of nanoparticles from spray flame synthesis (SFS) do not only depend on their chemical composition but also to a large extent on their particle morphology. Within the project advanced laser optical methods are employed to investigate particle growth and aggregation and correlates particle properties with the boundary conditions of the synthesis (precursor type, concentration, solvent, volume flow). It can thus make a significant contribution to process understanding. In the first phase of the project, the method of Wide-Angle Light Scattering (WALS) approach was enhanced to measure droplet sizes in the spray flame. In this project phase, evaluation routines will be further improved allowing for a more accurate and faster determination. The WALS method is also used for in situ measurement of the characteristics of nanoparticles and aggregates (radius of gyration, fractal dimension) in an extended range of the flame. For selected material systems (especially iron oxide) these investigations are complemented by the use of time-resolved Laser-Induced Incandescence (TiRe-LII) for the measurement of primary particle size, allowing for the determination of key properties essential for the process chain. The combined measurement techniques are also used to investigate various questions which have come into the focus of interest especially due to the work of the groups in the SPP. On the one hand, these concern the formation of a preferred route of particle formation (directly from droplets or from the gas phase) depending on the composition of the solvent. On the other hand, the effect of pulsations observed in the process on the particle properties is investigated. For this purpose, time-resolved flame luminescence is combined and correlated with WALS measurements, which are performed in single shot mode.In addition to the exchange with the central project regarding material systems, process conditions and data, a cooperation with several experimentally working groups of the SPP is carried out to directly provide mutually complementary data. Furthermore, collaboration with groups working in the field of numerical simulation have been agreed upon and first mutually interesting and accessible material systems have been defined. On the one hand, the data of this project serve for the direct validation of the simulation, on the other hand the numerical projects provide further information, e.g. on the form of a particle size distribution, to enable a model-based and thus improved evaluation of the WALS data.

喷雾火焰合成纳米粒子的产物性质不仅取决于其化学组成，而且在很大程度上还取决于其粒子的形态。在该项目中，使用了先进的激光光学方法来研究颗粒的生长和聚集，并将颗粒的性质与合成的边界条件(前体类型、浓度、溶剂、体积流量)相关联。因此，它可以对流程理解做出重大贡献。在该项目的第一阶段，改进了广角光散射(WALS)方法，以测量喷雾火焰中的液滴尺寸。在本项目阶段，评价程序将进一步改进，以便更准确和更快地确定。WALS方法还被用来在更大的火焰范围内原位测量纳米颗粒和聚集体的特征(旋转半径、分维)。对于选定的材料系统(特别是氧化铁)，这些研究得到了使用时间分辨激光诱导白炽灯(TIRE-LII)测量初级颗粒尺寸的补充，从而能够确定工艺链所必需的关键特性。综合测量技术还被用来调查已经成为关注焦点的各种问题，特别是由于最高人民检察院各小组的工作。一方面，这些问题涉及到根据溶剂的组成(直接从液滴或从气相)形成粒子的首选路线的形成。另一方面，研究了过程中观察到的脉动对颗粒性质的影响。为此，时间分辨火焰发光与WALS测量相结合，并以单次激发模式进行关联。除了与中央项目就材料系统、工艺条件和数据进行交换外，还与SPP的几个实验工作组合作，直接提供相互补充的数据。此外，与在数值模拟领域工作的团体的合作已经达成一致，并首先确定了相互感兴趣和可访问的材料系统。一方面，该项目的数据用于直接验证模拟，另一方面，数值项目提供进一步的信息，例如关于颗粒尺寸分布的形式，以实现基于模型的WALS数据的改进评估。