Optical absorption studies of the mixed-ion (Cu and Al) doping of sphalerite

Experimental studies to determine whether the presence of aluminum cations can influence the valence state or siting of Cu in sphalerite are described. Absorption spectra of the doped sphalerites are shown in diagrams. It is concluded that doping with Al of a sphalerite containing octahedrally-bonded Cu(II) causes reduction of Cu(II) to Cu(I), and it is suggested that Cu(II) in substitutional and interstitial sites is a strong electron acceptor. The role of such electron transfer reactions in determining the structures of copper sulfides is worth more study.