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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.
When the pattern of localized electrons is polar, the charge ordered state is ferroelectric. Usually the ions in such a case are magnetic and so the ferroelectric state is also multiferroic. [23] The first proposed example of a charge ordered multiferroic was LuFe 2 O 4, which charge orders at 330 K with an arrangement of Fe 2+ and Fe 3+ ions. [24]
IDA sensor for anions such as citrate or phosphate ions have been developed whereby these ions can displace a fluorescent indicator in an indicator-host complex. [5] The so-called UT taste chip (University of Texas) is a prototype electronic tongue and combines supramolecular chemistry with charge-coupled devices based on silicon wafers and ...
In solution, the cations are thoroughly mixed and held close together by the polymer chains. [11] The water is driven off to produce a foam whose organic components are burned off with a calcining step, producing a fine and pure mixed oxide powder, [ 12 ] which may be pressed into a green body and sintered.
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 ...
CdIn 2 S 4 exhibits the spinel structure, which can be described by a cubic unit cell with 8 tetrahedrally coordinated and 16 tetrahedrally coordinated cation sites. The distribution of Cd(II) and In(III) over the cation sites is difficult to elucidate from standard X-ray diffraction techniques because the two species are isoelectronic, but both Raman spectroscopy measurements on synthetic ...
The blue-light sensitive ChR2 and the yellow light-activated chloride pump halorhodopsin together enable multiple-color optical activation and silencing of neural activity. [ 64 ] [ 65 ] Another interesting pair is the blue-light sensitive chloride channel Gt ACR2 [ 66 ] and the red-light sensitive cation channel Chrimson [ 67 ] which have been ...
Hercynite is a spinel of regular symmetry and normal cation distribution, but some disorder occurs in its structure. It consists of ferrous (Fe 2+) ions and aluminium ions (Al 3+); however some ferric ions (Fe 3+) may be located in the structure of hercynite. [5] Melting point of this mineral is inbetween 1,692–1,767 °C (3,078–3,213 °F). [6]