Cobalt green

The pigment Rinmans Green (also Rinman - green, cobalt green or zinc green ) is mainly used for oil paints and cement colors. The pigment also called Cobalt Green is a turquoise green powder.

History

The oxide was first mentioned in 1780 by the Swede Sven Rinman ( 1720-1792 ). It is the compound is a solid solution of a few percent CoO in ZnO. The Co ( II) ions occupy lattice sites while the Zn (II ) ions.

Composition

How much cobalt can be incorporated into the wurtzite lattice of zinc oxide before it comes to two-phase nature of the primary precipitation of cobalt oxide is controversial in the literature. Values ​​go from 6.5 % to 30 %.

The green color depends on the cobalt content, with an increasing proportion of the colorant is dark. The annealing temperature has an influence on the hue.

It is a common misconception, the Rinmans Green attributable to a spinel of the type ZnCo2O4, as described in most textbooks, for such spinel zinc and cobalt appear green-black.

Production

Can be prepared from mixtures of Rinmans Green zinc salts with cobalt salts, which are easily decomposed, such as carbonates or oxalates. These salts are pulverized, mixed thoroughly and calcined in a furnace.

Application

Rinmans Green is a popular detection for zinc. Zinc oxide or zinc hydroxide is added to a Magnesiarinne with a small amount of very dilute cobalt nitrate solution. In the faint glow in the oxidizing flame creates Rinmans green.

Spintronics

In 2006, scientists at the University of Washington have found that the compound for use in the Spintroniks technology is. Most materials which exhibit the desired properties must be cooled to less than 75 K (about -200 ° C). Cobalt green, however, operates at room temperature and is thus of interest for the production of new non-volatile magnetic semiconductor memories.