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Fe chemical symbol12/14/2023 ![]() Several forms of the hydrated oxide of Fe(III) exist as well. When alkali is added to solutions of soluble Fe(III) salts, a red-brown gelatinous precipitate forms. ![]() Several hydrates of Iron(III) oxide exist. Molten Fe 2O 3 is expected to have a coordination number of close to 5 oxygen atoms about each iron atom, based on measurements of slightly oxygen deficient supercooled liquid iron oxide droplets, where supercooling circumvents the need for the high oxygen pressures required above the melting point to maintain stoichiometry. Īdditionally, at high pressure an amorphous form is claimed. Research has revealed epsilon iron(III) oxide in ancient Chinese Jian ceramic glazes, which may provide insight into ways to produce that form in the lab. It can also be prepared by oxidation of iron in an electric arc or by sol-gel precipitation from iron(III) nitrate. The epsilon phase is also metastable, transforming to the alpha phase at between 500 and 750 ☌ (930 and 1,380 ☏). Material with a high proportion of epsilon phase can be prepared by thermal transformation of the gamma phase. Preparation of the pure epsilon phase has proven very challenging. The epsilon (ε) phase is rhombic, and shows properties intermediate between alpha and gamma, and may have useful magnetic properties applicable for purposes such as high density recording media for big data storage. It can be prepared by reduction of hematite by carbon, pyrolysis of iron(III) chloride solution, or thermal decomposition of iron(III) sulfate. The β-phase is cubic body-centered (space group Ia3), metastable, and at temperatures above 500 ☌ (930 ☏) converts to alpha phase. Several other phases have been identified or claimed. ![]() The ultrafine particles can be prepared by thermal decomposition of iron(III) oxalate. Another method involves the careful oxidation of iron(II,III) oxide (Fe 3O 4). It can be prepared by thermal dehydratation of gamma iron(III) oxide-hydroxide. It is ferromagnetic and finds application in recording tapes, although ultrafine particles smaller than 10 nanometers are superparamagnetic. It occurs naturally as the mineral maghemite. It is metastable and converted from the alpha phase at high temperatures. pressure, particle size, and magnetic field intensity. Its magnetic properties are dependent on many factors, e.g. It is easy to prepare using both thermal decomposition and precipitation in the liquid phase. It is antiferromagnetic below ~260 K ( Morin transition temperature), and exhibits weak ferromagnetism between 260 K and the Néel temperature, 950 K. It occurs naturally as the mineral hematite which is mined as the main ore of iron. Α-Fe 2O 3 has the rhombohedral, corundum (α-Al 2O 3) structure and is the most common form. In the γ polymorph, some of the Fe sit on tetrahedral sites, with four oxygen ligands. That is, each Fe center is bound to six oxygen ligands. In the main one, α, iron adopts octahedral coordination geometry. Structure įe 2O 3 can be obtained in various polymorphs. 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 however, in chemistry, rust is considered an ill-defined material, described as Hydrous ferric oxide. As the mineral known as hematite, Fe 2O 3 is the main source of iron for the steel industry. It is one of the three main oxides of iron, the other two being iron(II) oxide (FeO), which is rare and iron(II,III) oxide (Fe 3O 4), which also occurs naturally as the mineral magnetite. Iron(III) oxide or ferric oxide is the inorganic compound with the formula Fe 2O 3. Chemical compound Iron(III) oxide in a vial
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