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Polyhedral representation of spinel MgAl 2 O 4. Spinel (/ s p ɪ ˈ n ɛ l, ˈ s p ɪ n əl / [7]) is the magnesium/aluminium member of the larger spinel group of minerals. It has the formula MgAl 2 O 4 in the cubic crystal system. Its name comes from the Latin word spinella, a diminutive form of spine, in reference to its pointed crystals. [5]
Inverse spinel structures have a different cation distribution in that all of the A cations and half of the B cations occupy octahedral sites, while the other half of the B cations occupy tetrahedral sites. An example of an inverse spinel is Fe 3 O 4, if the Fe 2+ (A 2+) ions are d 6 high-spin and the Fe 3+ (B 3+) ions are d 5 high-spin.
The mineral ceylonite has the chemical composition of (Mg, Fe 2+) Al 2 O 4, putting it into a group of minerals known as the spinel group, or the oxide spinels. The oxide spinels have a formula of the model [A][B] 2 O 4; where [A] is commonly Fe 2+, Mg 2+, or Mn 2+, and [B] is Fe 3+, Al 3+, or Cr 3+. It is an iron-rich variety of the spinel ...
There are many mixed oxides containing aluminium where there are no discrete or polymeric aluminate ions. The spinels with a generic formula A 2+ B 3+ 2 O 2− 4 that contain aluminium as Al 3+, such as the mineral spinel itself, MgAl 2 O 4 are mixed oxides with cubic close packed O atoms and aluminium Al 3+ in octahedral positions.
4, a cation ordered member of the spinel structural family (space group Fd3m). In addition to containing inexpensive materials, the three-dimensional structure of LiMn 2 O 4 lends itself to high rate capability by providing a well connected framework for the insertion and de-insertion of Li + ions during discharge and charge of the battery.
Ringwoodite is polymorphous with forsterite, Mg 2 SiO 4, and has a spinel structure.Spinel group minerals crystallize in the isometric system with an octahedral habit. Olivine is most abundant in the upper mantle, above about 410 km (250 mi); the olivine polymorphs wadsleyite and ringwoodite are thought to dominate the transition zone of the mantle, a zone present from about 410 to 660 km
Nickel manganese oxides, [1] or nickel manganates, are spinel structure compounds of Nickel, Manganese and Oxygen of the form: Ni (x) Mn (3-x) O (y) [2] [3] Some common forms are Ni 2 MnO 4, NiMn 2 O 4, and Ni 1.5 Mn 1.5 O 4. They are most commonly formulated for use in thin film resistors and thermistors. [4]
Mn 3 O 4 has the spinel structure, where the oxide ions are cubic close packed and the Mn II occupy tetrahedral sites and the Mn III octahedral sites. [3] The structure is distorted due to the Jahn–Teller effect. [3]