Energy-efficient syntheses of intermetallic compounds using a microwave-assisted polyol process. Elucidation of the reaction process towards the development of adapted reaction conditions for the production of tailor-made nanostructured materials.

多元醇工艺是一种资源高效的生产金属微粒和纳米颗粒的方法。在此过程中，金属盐溶解在多元醇中，然后在低于T = 300℃的温度下还原金属阳离子，多元醇作为溶剂和还原剂以及影响颗粒形状和大小的表面活性剂。通常可以防止颗粒的烧结和聚集。除了诸如银、金或铂等元素金属外，还可以得到二元和多元金属间化合物的纳米颗粒。与传统的熔融或烧结工艺相比，反应温度相对较低，也可以导致动力学控制的结晶和亚稳相，这是传统合成路线难以或无法达到的。当用微波辐射对反应物混合物进行快速加热时，多元醇反应通常进行得很有效，并产生具有确定粒度和形态的均匀产物。尽管多元醇工艺有30多年的历史，有大量的实验研究和理论考虑，但对氧化还原机制知之甚少。因此，在本项目中，重点是通过体外和原位技术阐明多元醇还原的反应机制。反应机制的知识对于开发新的三元金属间相的合成途径至关重要，这将在第二个工作包中进行研究。

The polyol process is a resource-efficient method for the production of metallic micro- and nanoparticles. In this process, metal salts are dissolved in a polyalcohol and the metal cations are subsequently reduced at temperatures below T = 300 ° C. The polyol serves as solvent and reducing agent as well as surfactant which can influence the particle shape and size. Sintering and aggregation of the particles can often be prevented. In addition to elemental metals such as, e.g. silver, gold or platinum, nanoparticles of binary and multinary intermetallic compounds are also obtained. The reaction temperatures which are comparatively low compared to traditional melting or sintering processes can also lead to kinetically controlled crystallizations and to metastable phases which are difficult or not accessible by classical syntheses routes. Polyol reactions often proceed efficiently and to uniform products with defined particle size and morphology when rapid heating of the reactant mixture by microwave radiation is applied.Despite the more than 30 year history of the polyol process with numerous experimental investigations and theoretical considerations, little is known about the redox mechanisms.In this project, the elucidation of the reaction mechanisms of polyol reductions by means of ex and in situ techniques is therefore focused on. The knowledge of reaction mechanisms is of fundamental importance for the development of synthetic pathways for new, ternary intermetallic phases, which are investigated in a second work package.