Cobalt(II) oxide
Encyclopedia
Cobalt oxide or cobalt monoxide is an inorganic compound that appears as olive-green to red crystals, or as a greyish or black powder. It is used extensively in the ceramic
s industry as an additive to create blue colored glazes and enamels as well as in the chemical industry for producing cobalt(II) salts.
(rock salt) structure with a lattice constant of 4.2615 Å.
It is antiferromagnetic
below 16 °C.
decomposes to cobalt(II) oxide at 950 °C:
Though commercially available, cobalt(II) oxide may be prepared in the laboratory by electrolyzing a solution of cobalt(II) chloride.
CoCl2 + H2O → CoO + H2 + Cl2
It may also be prepared by precipitating the hydroxide, followed by thermal decomposition:
fired pottery. The additive provides a deep shade of blue named cobalt blue
. The band gap (CoO) is around 2.4 eV.
It also is used in cobalt blue glass.
Ceramic
A ceramic is an inorganic, nonmetallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous...
s industry as an additive to create blue colored glazes and enamels as well as in the chemical industry for producing cobalt(II) salts.
Structure and properties
CoO crystals adopt the periclasePericlase
Periclase occurs naturally in contact metamorphic rocks and is a major component of most basic refractory bricks. It is a cubic form of magnesium oxide ....
(rock salt) structure with a lattice constant of 4.2615 Å.
It is antiferromagnetic
Antiferromagnetism
In materials that exhibit antiferromagnetism, the magnetic moments of atoms or molecules, usuallyrelated to the spins of electrons, align in a regular pattern with neighboring spins pointing in opposite directions. This is, like ferromagnetism and ferrimagnetism, a manifestation of ordered magnetism...
below 16 °C.
Preparation
Cobalt(II,III) oxideCobalt(II,III) oxide
Cobalt oxide is inorganic compound with the formula Co3O4. It is one of two well characterized cobalt oxides. It is a black antiferromagnetic solid...
decomposes to cobalt(II) oxide at 950 °C:
- 2 Co3O4 → 6 CoO + O2
Though commercially available, cobalt(II) oxide may be prepared in the laboratory by electrolyzing a solution of cobalt(II) chloride.
CoCl2 + H2O → CoO + H2 + Cl2
It may also be prepared by precipitating the hydroxide, followed by thermal decomposition:
- CoX + 2 NaOH → Co(OH)2 + Na2X
- Co(OH)2 → CoO + H2O
Reactions
As can be expected, cobalt(II) oxide reacts with mineral acids to form the corresponding cobalt salts:- CoO + 2 HX → CoX2 + H2O
Applications
Cobalt(II) oxide has for centuries used as a coloring agent on kilnKiln
A kiln is a thermally insulated chamber, or oven, in which a controlled temperature regime is produced. Uses include the hardening, burning or drying of materials...
fired pottery. The additive provides a deep shade of blue named cobalt blue
Cobalt blue
Cobalt blue is a cool, slightly desaturated blue color, historically made using cobalt salts of alumina. It is used in certain ceramics and painting; the different cobalt pigment smalt, based on silica, is more often used directly in tinted transparent glasses...
. The band gap (CoO) is around 2.4 eV.
It also is used in cobalt blue glass.