Smooth and rapid microwave synthesis of MIL-53(Fe) including superparamagnetic $\gamma \text{-}{\text{Fe}}_2{\text{O}}_3$ nanoparticles

Highlights: •Metal–organic frameworks with superparamagnetic nanoparticles are prepared. •γ-Fe₂O₃ particles of about 80 nm are embedded using microwave synthesis. •A coercivity of only 3 Oe is measured using a novel field correction scheme. •A quick scheme leading to encapsulated superparamagnetic particles is presented. - Abstract: MIL-53(Fe) linked to superparamagnetic $\gamma \text{-}{\text{Fe}}_2{\text{O}}_3$ nanoparticles was created using time-efficient microwave synthesis. Intermediates as well as the final product have been characterized by Dynamic Light Scattering (DLS), Infrared Spectroscopy (FTIR) and Thermal Gravimetric Analysis (TGA). It is found that this route allows the production of Fe nanoparticles with typical sizes of about 80 nm that are embedded inside the metal-organic structures. Detailed magnetization measurements using SQUID magnetometry revealed a nearly reversible magnetization loop indicating essentially superparamagnetic behavior.