X-ray natural linear dichroism (XNLD) applied to the determination of relaxations around transition metal impurities in α-Al2O3

Abstract

The local environments around substitutional Cr3+ or Fe3+ ions in doped α-Al2O3 have been studied experimentally by dichroic x-ray absorption at the Cr and Fe K-edges in single crystals. A reliable method has been applied to remove diffraction peaks. This paper shows that the dichroic EXAFS analysis leads to the precise determination of the environment around impurity ions in α-Al2O3. The Cr or Fe coordination shell in doped α-Al2O3 is similar to the one of Cr in α-Cr2O3 or of Fe in α-Fe2O . Aluminum or oxygen atoms at a farther distance are weakly affected by the presence of the impurity.