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.

多元醇法是生产金属微米和纳米颗粒的一种资源高效的方法。在这个过程中，金属盐溶于多元醇中，然后在T=300°C以下的温度下还原金属阳离子。多元醇既是溶剂和还原剂，也是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，还获得了二元和多元金属间化合物的纳米颗粒。与传统的熔炼或烧结工艺相比，反应温度相对较低，也可能导致动力学控制的结晶和亚稳相，这是经典合成路线难以或无法获得的。在利用微波辐射快速加热反应混合物时，多元醇反应通常能够高效地进行，并生成具有一定颗粒大小和形貌的均匀产物。尽管多元醇过程已有30多年的历史，经过大量的实验研究和理论考虑，但对其氧化还原机理知之甚少。在本项目中，多元醇还原反应的反应机理主要是通过EX和原位技术来阐明的。对反应机理的了解对于开发新的三元金属间化合物相的合成途径是至关重要的，这些合成途径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.