Abstract
We report on hydrothermal synthesis, plate-like morphology, microstructure and magnetic properties of hematite (α-Fe 2O 3) plate-like particles. The sample is obtained immediately after the hydrothermal process without using any template and without further heat treatment. The so-obtained sample is characterized by X-ray powder diffraction (XRPD), energy-dispersive X-ray spectroscopy (EDX), field-emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and superconducting quantum interference device (SQUID) magnetometer. XRPD confirms the formation of a single-phase hematite sample whereas EDX reveals that iron and oxygen are the only components of the sample. SEM, FE-SEM, TEM and HRTEM show that the sample is composed of plate-like particles. The width of the particles is ∼500 nm whereas thickness is ∼100 nm (aspect ratio 5:1). The HRTEM images exhibit well defined lattice fringes of α-Fe 2O 3 particles that confirm their high crystallinity. Moreover, the HRTEM analysis indicates the plate-like particles preferring crystal growth along [0 1 2] direction. Magnetic measurements display significant hysteretic behavior at room temperature with coercivity H C = 1140 Oe, remanent magnetization M r = 0.125 emu/g and saturation magnetization M S = 2.15 emu/g as well as the Morin transition at T M ∼ 250 K. The magnetic properties are discussed with respect to morphology and microstructure of the particles. The results and comparison with urchin-like, rods, spherical, hexagonal, star-like, dendrites, platelets, irregular, nanoplatelets, nanocolumns and nanospheres hematites reveal that the plate-like particles possess good magnetic properties. One may conjecture that the shape anisotropy plays an important role in the magnetic properties of the sample.
Published Version
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