Fe2O3 철(III)산화물

[PROF.SKJO]

철산화물:

Iron(II) Oxide (FeO)

Iron(II,III) Oxide (Fe3O4)

Iron(III) Oxide (Fe2O3) = Ferric Oxide

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Fe2O3:

m.p. = 

1,539~1565 oC (decomposes)

105 °C (β-dihydrate, decomposes)

150 °C (β-monohydrate, decomposes)
50 °C (α-dihydrate, decomposes)
92 °C (α-monohydrate, decompose)

Solubility in water: Insoluble

As the mineral known as hematite, Fe₂O₃ is the main source of iron for the steel industry. Fe₂O₃ is ferromagnetic, dark red, and readily attacked by acids. Iron(III) oxide is often called rust, and to some extent this label is useful, because rust shares several properties and has a similar composition. To a chemist, rust is considered an ill-defined material, described as hydrated ferric oxide.

Structure of Fe2O3:

Fe₂O₃ can be obtained in various polymorphs. In the main ones, α and γ, iron adopts octahedral coordination geometry. That is, each Fe center is bound to six oxygen ligands.

Crystal Structure:

Rhombohedral, hR30 (α-form)
Cubic bixbyite, cI80 (β-form)
Cubic spinel (γ-form)
Orthorhombic (ε-form)

Hydrated iron(III) oxides:

Several hydrates of Iron(III) oxide exists. When alkali is added to solutions of soluble Fe(III) salts, a red-brown gelatinous precipitate forms. This is not Fe(OH)₃, but Fe₂O₃·H₂O (also written as Fe(O)OH). Several forms of the hydrated oxide of Fe(III) exist as well. The red lepidocrocite γ-Fe(O)OH, occurs on the outside of rusticles, and the orange goethite, which occurs internally in rusticles. When Fe₂O₃·H₂O is heated, it loses its water of hydration. Further heating at 1670 K converts Fe₂O₃ to black Fe₃O₄ (Fe^IIFe^III₂O₄), which is known as the mineral magnetite. Fe(O)OH is soluble in acids, giving [Fe(OH₂)₆]³⁺. In concentrated aqueous alkali, Fe₂O₃ gives [Fe(OH)₆]³⁻.^[8]

Magnetic recording:

Iron(III) oxide was the most common magnetic particle used in all types of magnetic storage and recording media, including magnetic disks (for data storage) and magnetic tape (used in audio and video recording as well as data storage). However, modern magnetic storage media - in particular, the hard disk drives - use more advanced thin film technology, which may consist of a stack of 15 layers or more.

Photocatalyst

α-Fe₂O₃ has been studied as a photoanode for the water-splitting reaction for over 25 years.

<위 그림 출처 논문: http://onlinelibrary.wiley.com/doi/10.1002/chem.201103147/pdf>

(Synthesis of grafted core–shell γ-Fe2O3-polymer MNPs (Carboxyl-Adembeads, 300 nm) MNP-1–MNP-4 from metallodendritic catalysts 1–4, respectively.)

Unique Magnetic Properties of Single Crystal γ-Fe2O3 Nanowires Synthesized by Flame Vapor Deposition.

Single crystal γ-Fe2O3 nanowires with 40–60 nm diameters were grown for the first time by single-step atmospheric flame vapor deposition (FVD) with axial growth rates up to 5 μm/minute. Because of their superior crystallinity, these FVD γ-Fe2O3 nanowires are single magnetic domains with room temperature coercivities of 200 Oe and saturation magnetizations of 68 emu/g.

출처: Nano Letters (2011): http://pubs.acs.org/doi/abs/10.1021/nl2007533 

Integrated and Segregated Au/γ-Fe₂O₃ Binary Nanoparticle Assemblies^†

http://onlinelibrary.wiley.com/doi/10.1002/anie.201207469/pdf  (Angew. Chem. Int. Ed, Dec/2012)

<Hematite (α-Fe₂O₃) Unit Cell Structure>:

Oxygen atoms are red.

<Above: Hematite (Fe2O3) Structure>

<Above: Hexagonal α-Fe2O3 lattice with anti-ferromagnetic spin arrangements indicated by up (yellow) and down (white) arrows at the Fe sites. Color scheme: Fe = grey and O = red.>

<Above Figure: Schematic illustration of the (a) hexagonal unit cell and (c) the rhombohedral primitive cell of α-Fe2O3. The face-sharing octahedra in (a) and (c) are shown in (b) and (d) respectively. Color scheme: Fe = grey and O = red.>

<Above: Schematic representation of the side and top views of the single Fe-terminated α-Fe2O3(0001)-p(2 × 2) surface structures. The terminating Fe atoms are highlighted in yellow circles in the top view. Color scheme: iron = grey and O = red.>

http://www.mdpi.com/2075-163X/4/1/89/htm