Continuous Hydrothermal Synthesis of Magnetic Ferrite Nanoparticles: Reaction Monitoring and Application in Additive Manufacturing of Functional Materials

• Applicants: Professorin Dr. Silke Behrens; Professor Dr.-Ing. Thomas Hanemann
• Subject Area: Technical Chemistry
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 556757005

Due to their low cost, interesting magnetic properties and high air stability, ferrites are of great interest for various biomedical and technical applications. This project will address the continuous hydrothermal synthesis of highly crystalline magnetic ferrite nanoparticles of type MFe2O4 with spinel structure and type MFe12O19 with magnetoplumbite structure and their integration into 3D printed, magnetic polymer composite demonstrator devices. The continuous hydrothermal synthesis will be carried out in near- or supercritical water as a sustainable and environmentally friendly reaction medium, and the size, morphology, and surface properties will be tailored for embedding the magnetic nanoparticles in the composite materials by variation of the process parameters and adding organic ligands. Supercritical water (374 °C, 22.1 MPa) is characterized by liquid-like densities and mass transfer properties intermediate between those of gases and liquids, and therefore many interesting properties with respect to nanoparticle synthesis. To specifically tailor particle properties and characteristics, the influence of the reaction parameters (pressure, temperature, mass flows, precursor compounds) on the product properties will be systematically investigated and the reaction will be monitored online using electrochemical impedance spectroscopy (EIS). To enable process integration of EIS and thus online monitoring under near- and supercritical conditions, a microreactor made of borosilicate glass will be specifically developed by additive manufacturing. Subsequently, magnetic particles with optimized magnetic and surface properties will be selected, produced in sufficient quantities and integrated into 3D-printed polymer composite demonstrator devices.

• DFG Programme: Research Grants