Is NiAl2O4 a normal spinel?
NiAl2O4 is known to transform from a normal spinel, (Ni2+)[Al 23+ ]O 4, to an inverse spinel, (Al3+)[Ni2+Al3+]O4, and vice versa.
What is the structure of spinel?
The spinel structure Normal spinel structures are usually cubic close-packed oxides with eight tetrahedral and four octahedral sites per formula unit. The tetrahedral spaces are smaller than the octahedral spaces. B ions occupy half the octahedral holes, while A ions occupy one-eighth of the tetrahedral holes.
Is spinel a FCC?
A spinel unit cell is made up of 8 FCC cells. The anions (usually oxide ions: O2-) occupy the FCC lattice points.
What are different types of spinels?
The spinel group is divided into three immiscible series: the spinel (aluminum-spinel) series, in which B is aluminum; the chromite (chromium-spinel) series, in which B is chromium; and the magnetite (iron-spinel) series, in which B is iron.
Why is Fe3O4 inverse spinel?
3) Fe3O4 is an inverse spinel since the Fe(III) ion is a high spin d5 system with zero CFSE. Whereas the divalent Fe(II) is a high spin d6 system with more CFSE. 4) NiFe2O4 is again an inverse spinel since the divalent Ni2+ (a d8 ion) has more CFSE than the trivalent Fe3+ (a d5 ion).
Is spinel a crystal structure?
Cubic crystal systemSpinel / Crystal system
What is spinel and inverse spinel structure?
The key difference between spinel and inverse spinel structure is that in spinel structure, B ions occupy half the octahedral holes while A ions occupy 1/8th of the tetrahedral holes whereas, in inverse spinel structure, all A cations and half of the B cations occupy octahedral sites and the other half of B cations …
What is spinel structure of MgAl2O4?
The spinel structure of MgAl2O4 where the Mg 2+ ions occupy the tetrahedral (A) sites (inside the tetrahedrons) and the trivalent Al 3+ occupy the octahedral (B) sites. The large ions are the oxygen anions. The superexchange interaction takes place between A-B ions through O 2-ions.
Is MgAl2O4 inverse spinel?
Normal and inverse spinel structures a MgAl2O4 normal and b MgGa2O4 inverse ground state atomic configurations. In each case the unit cell is shown by solid black lines. Octahedral and tetrahedral atomic coordination environments are also identified by the coordination polyhedra in each case.
What are the properties of spinel?
Spinel Physical Properties
| Color | Various; red, pink, blue, lavender/violet, dark green, brown, black, colourless |
|---|---|
| Diaphaneity | Transparent to Opaque |
| Mohs Hardness | 7.5–8.0 |
| Specific Gravity | Zn-rich can be as high as 4.40, otherwise it averages from 3.58-3.61 |
| Diagnostic Properties | Hardness, octahedral crystals, vitreous luster |
Does Fe3O4 have spinel structure?
Magnetite, Fe3O4, has an inverse-spinel structure. The unit cell consists of thirty-two oxygen atoms forming a face-centred-cubic (fcc) closed-packing structure, with iron cations located at octahedral and tetrahedral sites [22, 23].
What is the structure of Fe3O4?
Fe₃O₄Iron(II,III) oxide / Formula
What is mgal204?
Magnesium aluminate (MgAl2O4) spinel (MAS) is a synthetic material with cubic crystal structure and excellent chemical, thermal, dielectric, mechanical and optical properties.
What is the hardness of spinel?
7.5 – 8Spinel / Hardness (Mohs hardness scale)
Spinel ranks 8 on the Mohs hardness scale. Spinel ranks 8 on the Mohs scale and has good toughness, making it a durable gem for jewelry. High heat can cause some spinel colors to fade, but spinel is stable when exposed to light and chemicals.
What type of rock is spinel?
Geologic occurrence. Spinel is found as a metamorphic mineral in metamorphosed limestones and silica-poor mudstones.
Is Fe3O4 inverse spinel?
(Fe3O4) has an inverse cubic spinel structure [10].
What type of spinel is Fe3O4?
cubic inverse spinel structure
Magnetite (Fe3O4), or black iron oxide, is a standard ferrite with a cubic inverse spinel structure [1] . It has unique magnetic properties due to the transfer of electrons between Fe 2+ and Fe 3+ ions in the octahedral sites. …
What is magnesium spinel?
Is magnesium oxide organic or inorganic?
inorganic compound
Magnesium oxide (MgO). An inorganic compound that occurs in nature as the mineral periclase. In aqueous media combines quickly with water to form magnesium hydroxide. It is used as an antacid and mild laxative and has many nonmedicinal uses.
What is the spinel structure of MgAl2O4?
For example, Co 3+ is a low spin system even in presence of oxo ligands due to high charge on the ion. 1) MgAl2O4 has normal spinel structure since both the divalent and trivalent ions are non transition metal ions. There is no question of CFSE. 2) Mn3O4 is a normal spinel since the Mn 2+ ion is a high spin d 5 system with zero LFSE.
What is the structure of spinel AB2O4?
CRYSTAL STRUCTURE OF NORMAL SPINELS (AB2O4) A spinel unit cell is made up of 8 FCC cells. The anions (usually oxide ions: O 2-) occupy the FCC lattice points. The divalent A II cations occupy 1/8 th of the tetrahedral voids, whereas the trivalent B III cations occupy one half (1/2) of octahedral voids.
Is NiFe2O4 an inverse spinel?
4) NiFe2O4 is again an inverse spinel since the divalent Ni 2+ (a d 8 ion) has more CFSE than the trivalent Fe 3+ (a d 5 ion). 5) FeCr2O4 is a normal spinel since the divalent Fe 2+ is a high spin d 6 ion with CFSE = 4 Dq and the trivalent Cr 3+ is a high spin d 3 ion with CFSE = 12 Dq. Hence Cr 3+ gets more OSSE while occupying octahedral sites.
What is the spinel structure of Mn3O4?
2) Mn3O4 is a normal spinel since the Mn 2+ ion is a high spin d 5 system with zero LFSE. Whereas, Mn 3+ ion is a high spin d 4 system with considerable LFSE. 3) Fe3O4 has an inverse spinel structure since the Fe (III) ion is a high spin d 5 system with zero CFSE. Whereas the divalent Fe (II) is a high spin d 6 system with more CFSE.