Chromium (IV) oxide

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Crystal structure
Crystal structure of chromium (IV) oxide
__ Cr 4+      __ O 2−
Surname Chromium (IV) oxide
other names

Chromium dioxide

Ratio formula CrO 2
Brief description

brown to black solid

External identifiers / databases
CAS number 12018-01-8
EC number 234-630-4
ECHA InfoCard 100,031,470
PubChem 73415796
ChemSpider 34987119
Wikidata Q2366389
Molar mass 83.99 g mol −1
Physical state



4.89 g cm −3

Melting point

Decomposes above 375 ° C


almost insoluble in water

safety instructions
GHS labeling of hazardous substances
07 - Warning


H and P phrases H: 319
P: 305 + 351 + 338
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 .

Individual evidence

  1. Entry on chromium oxides. In: Römpp Online . Georg Thieme Verlag, accessed on June 13, 2014.
  2. a b c d e Entry on chromium (IV) oxide in the GESTIS substance database of the IFA , accessed on May 27, 2015 (JavaScript required)