Hydrothermally synthesized Fe3O4 microparticles: Structural, magnetic, Mössbauer and magneto-hyperthermia properties

We present hydrothermally prepared Fe 3 O 4 microparticles with diverse morphologies such as long micro-rods (LMRs), short micro-rods (SMRs), and micro-disks (MDs) through thermal-reduction of α-Fe 2 O 3 as support during the crystallization processes. The impact of PO 4 3− anions was systematically explored with significant influence on tuning the prepared materials' sizes/shapes and phase composition/stoichiometry. A lower concentration of PO 4 3− anions promotes the growth of a mixed iron-oxide phase, for instance, LMRs/SMRs; whereas a higher one results in a pure single-phase cubic Fe 3 O 4 structure (MDs) The line shape of the Fe2p region using the multiplets splitting model suggests that Fe 3 O 4 is mainly present at the surface as validated through Mossbauer spectroscopy. Magnetization measurements revealed an alteration of the Verwey transition from LMRs/SMRs to MDs. Further, these microstructures were examined for their efficiencies in adjusting the hyperthermia response, with specific absorption rates peaking from 2.8 to 3.4 W/g and are noticeably dominated by the shape anisotropy. • Simple hydrothermal synthesis of α-Fe 2 O 3 micro-particles through variation of PO 4 3− anions concentration. • Thermal reduction of α-Fe 2 O 3 to Fe 3 O 4 using Ar (95 %) and H 2 (5 %) atmosphere. • Detailed structural, magnetic, and Mossbauer properties. • Magneto-hyperthermia properties of materials show specific absorption rates peaking from 2.8 to 3.4 W/g, which is noticeably dominated by shape anisotropy.