Chromium (IV) oxide
|__ Cr 4+ __ O 2−|
|Surname||Chromium (IV) oxide|
|Ratio formula||CrO 2|
brown to black solid
|External identifiers / databases|
|Molar mass||83.99 g mol −1|
4.89 g cm −3
Decomposes above 375 ° C
almost insoluble in water
|As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .|
Chromium (IV) oxide (chemical formula CrO 2 ) is the oxide of tetravalent chromium .
Extraction and presentation
It was first synthesized by Norman L. Cox, a chemist at DuPont , by decomposing chromium (VI) oxide in the presence of water at temperatures around 500 ° C and a pressure of 200 MPa.
Chromium (IV) oxide is a brown to black solid. It crystallizes in a tetragonal rutile structure.
The ferromagnetic and electrically conductive crystals are needle-shaped, which makes them suitable for use as magnetic pigments in magnetic tapes . Commercially, it was launched by DuPont as recording material under the brand name Crolyn in the late 1960s .
- ↑ Entry on chromium oxides. In: Römpp Online . Georg Thieme Verlag, accessed on June 13, 2014.