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Maghemite (Fe 2 O 3, γ-Fe 2 O 3) is a member of the family of iron oxides. It has the same formula as hematite , but the same spinel ferrite structure as magnetite ( Fe 3 O 4 ) and is also ferrimagnetic .
Maghemite differs from magnetite in that all or most of the iron is in the trivalent state (Fe 3+) and by the presence of cation vacancies in the octahedral sites. Maghemite has a cubic unit cell in which each cell contains 32 oxygen ions, 21 1 ⁄ 3 Fe 3+ ions and 2 2 ⁄ 3 vacancies. The cations are distributed randomly over the 8 tetrahedral ...
Iron(III) oxide in a vial. Iron(III) oxide or ferric oxide is the inorganic compound with the formula Fe 2 O 3.It occurs in nature as the mineral hematite, which serves as the primary source of iron for the steel industry.
Ferrite nanoparticles or iron oxide nanoparticles (iron oxides in crystal structure of maghemite or magnetite) are the most explored magnetic nanoparticles up to date.Once the ferrite particles become smaller than 128 nm [22] they become superparamagnetic which prevents self agglomeration since they exhibit their magnetic behavior only when an external magnetic field is applied.
Iron(II,III) oxide, or black iron oxide, is the chemical compound with formula Fe 3 O 4.It occurs in nature as the mineral magnetite.It is one of a number of iron oxides, the others being iron(II) oxide (FeO), which is rare, and iron(III) oxide (Fe 2 O 3) which also occurs naturally as the mineral hematite.
Iron oxide pigment. The brown color indicates that iron is at the oxidation state +3. Green and reddish brown stains on a limestone core sample, respectively corresponding to oxides/hydroxides of Fe 2+ and Fe 3+.
Maghemite is a polymorph of hematite (γ-Fe 2 O 3) with the same chemical formula, but with a spinel structure like magnetite. Large deposits of hematite are found in banded iron formations. Gray hematite is typically found in places that have still, standing water, or mineral hot springs, such as those in Yellowstone National Park in North ...
Figure 6:Reaction Coordinate Diagrams showing reactions with 0, 1 and 2 intermediates: The double-headed arrow shows the first, second and third step in each reaction coordinate diagram. In all three of these reactions the first step is the slow step because the activation energy from the reactants to the transition state is the highest.