Synthesis, morphology, microstructure and magnetic properties of hematite submicron particles
[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...
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Veröffentlicht in: | Journal of alloys and compounds 2011-07, Vol.509 (28), p.7639-7644 |
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Format: | Artikel |
Sprache: | eng |
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► 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. |
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ISSN: | 0925-8388 1873-4669 |
DOI: | 10.1016/j.jallcom.2011.04.117 |