Magnetic properties,phase evolution,hollow structure and biomedical application of hematite (α-Fe2O3) and QUAIPH |
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Affiliation: | 1. Condensed Matter Physics Laboratory, Vinca Institute of Nuclear Sciences – National Institute of the Republic of Serbia, University of Belgrade, POB 522, 11001 Belgrade, Serbia;2. Jo?ef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia;3. Inserm, U1148, Laboratory for Vascular Translational Science, UFR SMBH, Université Paris 13, Sorbonne Paris Cité, F-93017 Bobigny, France;4. HEPIA, University of Applied Sciences of Western Switzerland (HES-SO), Geneva, Switzerland;5. Institute for Mother and Child Healthcare of Serbia, R. Dakica 6-8, 11070 Belgrade, Serbia;6. Faculty of Medicine, University of Belgrade, Serbia;7. Max Planck Institute for Intelligent Systems, Stuttgart 70569, Germany |
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Abstract: | We investigate synthesis, phase evolution, hollow and porous structure and magnetic properties of quasi-amorphous intermediate phase (QUAIPH) and hematite (α-Fe2O3) nanostructure synthesized by annealing of akaganeite (β-FeOOH) nanorods. It is found that the annealing temperature determines the phase composition of the products, the crystal structure/size dictates the magnetic properties whereas the final nanorod morphology is determined by the starting material. Annealing of β-FeOOH at ~300 °C resulted in the formation of hollow QUAIPH nanorods. The synthesized material shows low-cytotoxicity, superparamagnetism and good transverse relaxivity, which is rarely reported for QUAIPH. The QUAIPH nanorods started to transform to porous hematite nanostructures at ~350 °C and phase transformation was completed at 600 °C. During the annealing, the crystal structure changed from monoclinic (akaganeite) to quasi-amorphous and rhombohedral (hematite). Unusually, the crystallite size first decreased (akaganeite → QUAIPH) and then increased (QUAIPH → hematite) during annealing whereas the nanorods retained particle shape. The magnetic properties of the samples changed from antiferromagnetic (akaganeite) to superparamagnetic with blocking temperature TB = 84 K (QUAIPH) and finally to weak-ferromagnetic with the Morin transition at TM = 244 K and high coercivity HC = 1652 Oe (hematite). The low-cytotoxicity and MRI relaxivity (r2 = 5.80 mM?1 s?1 (akaganeite), r2 = 4.31 mM?1 s?1 (QUAIPH) and r2 = 5.17 mM?1 s?1 (hematite)) reveal potential for biomedical applications. |
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Keywords: | Iron oxide Morin transition Synthesis Magnetic properties (SPION) |
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