Cobalt(II) oxide

Cobalt(II) oxide is a blackish gray powder used extensively in the ceramics industry as an additive to create blue colored glazes and enamels as well as in the chemical production industry for producing cobalt(II) salts.

Cobalt(II) oxide is a product of Cobalt(II,III) oxide decomposing at 895 °C through the reaction:

2 Co₃O_4(s) → 6 CoO_(s) + O_2(g)

Cobalt(II) oxide is also a product of Cobalt(II) carbonate decomposing through the reaction:

CoCO_3(s) → CoO_(s) + CO_2(g)

Ceramics

Cobalt(II) Oxide has been used for centuries as a coloring agent on kiln fired ceramic glazes, the earliest examples go back to the beginnings of kiln fired pottery. Cobalt(II) Oxide colorants are stable and retain their coloration indefinitely. The oxide is one of the most powerful colorants commonly used in the making of glazes and slips and requires only 1 part oxide to 100,000 parts glazing compound to produce the deep blue shade commonly referred to as cobalt blue. By varying the temperature of the kiln, the potter can adjust the coloring of the oxide ranging anywhere from the familiar blue, to a shade nearing black.

Industrial Uses

As stated earlier, cobalt(II) oxide is used in the production of cobalt(II) salts such as CoCl₂ and Co(NO₃)₂. Cobalt(II) oxide can also be found in animal feed and fertilizer as a supplement to aid in the production of Vitamin B12.