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 is the spinel structure?
Spinel, MgAl2O4 (download cif), is a rare gemstone that was used to imitate rubies. The structure has face-centered cubic symmetry, and is a little heavy to understand. The general formula is AB2O4. The oxygens form an fcc lattice. The A cations occupy tetrahedral holes, and the B cation occupy octahedral holes.
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.
Is spinel a crystal structure?
Cubic crystal systemSpinel / Crystal systemIn crystallography, the cubic crystal system is a crystal system where the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals. Wikipedia
How many octahedral sites are there in spinel?
four octahedral sites
The spinel structure Normal spinel structures are usually cubic close-packed oxides with eight tetrahedral and four octahedral sites per formula unit.
What is the streak of spinel?
White
| Spinel | |
|---|---|
| Mohs scale hardness | 7.5–8.0 |
| Luster | Vitreous |
| Streak | White |
| Diaphaneity | Transparent to opaque |
What is spinel shape?
The normal spine has an S-shaped curve when viewed from the side. This shape allows for an even distribution of weight and flexibility of movement. The spine curves in the following ways: The cervical spine curves slightly inward, sometimes described as a backward C-shape or lordotic curve.
What are spinels and inverse spinel?
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 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 |
How do you identify spinel?
The proper way to analyze whether Spinel is real is to put it under a UV Radiation Light. Set it to long-wave and look for any stones that are particularly glowy. If the stones are glowy, that means it’s synthetic and not natural.
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).