@article{
author = "Tadić, Marin and Panjan, Matjaž and Lalatone, Yoann and Milošević, Irena and Vučetić Tadić, Biljana and Lazović, Jelena",
year = "2022",
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.",
journal = "Advanced Powder Technology",
title = "Magnetic properties, phase evolution, hollow structure and biomedical application of hematite (α-Fe2O3) and QUAIPH",
volume = "33",
number = "12",
pages = "103847",
doi = "10.1016/j.apt.2022.103847"
}