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.

多元醇工艺是生产金属微米和纳米颗粒的资源节约型方法。在此过程中，金属盐溶解在多元醇中，金属阳离子随后在低于T = 300 ° C的温度下还原。多元醇用作溶剂和还原剂以及表面活性剂，其可以影响颗粒形状和尺寸。通常可以防止颗粒的烧结和聚集。除了元素金属例如银、金或铂之外，还获得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方法相比相对较低的反应温度也可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达到的。当采用微波辐射快速加热反应物混合物时，多元醇反应通常有效地进行，并得到具有确定的颗粒尺寸和形态的均匀产物。尽管多元醇工艺有30多年的历史，有许多实验研究和理论考虑，但对氧化还原机理知之甚少。在本项目中，因此，着重于通过ex和in situ技术阐明多元醇还原的反应机理。反应机理的知识对于开发新的三元金属间相的合成途径具有根本的重要性，在第二工作包中进行研究。

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.