Effect of Er3+ substitution on the quality of Mg–Fe spinel pigments

Inorganic pigments containing erbium cations and based on the spinel structure of MgFe2O4 were prepared. This type of spinel compound provides pigments of red to brown colour; an increase in the content of trivalent erbium cations results in pigments of a light brown hue. The pigments displayed good resistance to sunlight but this was reduced as the content of erbium increased. Pigments prepared using mechanoactivation possessed good resistance to sunlight over a range of erbium cation content.