Correlation of structural and magnetic properties of Fe3O4 nanoparticles with their calorimetric and magnetorheological performance

► Fe3O4 nanoparticles were obtained by microwave-assisted synthesis ► Nucleation agents affect morphological and magnetic properties of nanoparticles. ► Aqueous ammonia nucleated Fe3O4 nanoparticles show high heating ability in AC magnetic field due to Neel relaxation. ► Suspension of Fe3O4 in silicone oil demonstrates flow resistance under DC magnetic field caused by chain formation. ► Fe3O4 nanoparticles has potential as a hyperthermia mediator and substance for temporary embolization.