Synthesis of Reddish Pink Pigment by Addition of Mg²⁺ into (Al, Cr)₂O₃ Corundum

Abstract

It is known that the colors of inorganic pigments can be changed by adding of small amount of mineralizers. In this research, the effect of Mg²⁺ on the coloring of (Al, Cr)₂O₃-pigment was investigated. The Mg²⁺-added pigments consisted of (Al, Cr)₂O₃ corundum and Mg(Al, Cr)₂O₄ spinel. It was verified that the lattice constants of the corundum phase were not affected by the addition of Mg²⁺. The valence of Cr in (Al, Cr)₂O₃ and in Mg(Al, Cr)₂O₄ were trivalent as found by X-ray photoelectron spectroscopy. The color changing of the pigments was due to the content of Cr³⁺ in the Mg(Al, Cr)₂O₄.