Synthesis, morphology, microstructure and magnetic properties of hematite submicron particles

• Published in: Journal of alloys and compounds 2011-07, Vol.509 (28), p.7639-7644
• Main Authors: Tadić, Marin, Čitaković, Nada, Panjan, Matjaž, Stojanović, Zoran, Marković, Dragana, Spasojević, Vojislav
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Hematite; Hematite (α-Fe 2O 3); Hydrothermal synthesis; Iron; Magnetic materials; Magnetic properties; Magnetic properties and materials; Magnetic properties of nanostructures; Microstructure; Morin transition; Morphology; Nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals; Nanostructure; Nanostructures; Physics; Scanning electron microscopy; Structure of solids and liquids; crystallography; Transmission electron microscopy
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2011.04.117

[Display omitted] ► Plate-like hematite α-Fe 2O 3 particles were prepared by template-free hydrothermal route. ► The micrographs show a width of the plate-like particles of ∼500 nm and a thickness of ∼100 nm (aspect ratio ∼ 5). ► The HRTEM shows perfect lattice fringes and preferring crystal growth along [0 1 2] direction. ► The values of the coercivity, remanent magnetization and saturation magnetization at room temperature are H C = 1140 Oe, M r = 0.125 emu/g and M S = 2.15 emu/g, respectively. ► The Morin temperature is observed at T M ≈ 250 K. 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.