Site localization of Cd impurities in Sapphire

G.N. DARRIBA ; M. RENTERÍA ; H.M. PETRILLI ; L.V.C. ASSALI

PHYSICAL REVIEW B

AMER PHYSICAL SOC

Lugar: New York; Año: 2012 vol. 86 p. 752031 - 7520312

1098-0121

By combining first-principles electronic structure calculations and existing time-differential gamma-gamma perturbed angular-correlation experimentswe studied the site localization, the local environment, and the electronic structure of Cd impurities in sapphire (alpha-Al2O3) single crystals in different charged states. The ab initio calculations were performed with the full-potential augmented plane wave plus local orbitals method and the projector augmented wave method.  Comparing the calculated electric-field-gradient tensor at the Cd nuclei in the alpha-Al2O3 host lattice and the corresponding available experimental values, we have seen that it is equally possible for Cd to replace an Al atom (in a negative charge state) or to be placed in an interstitial site (in a neutral charge state). To finally address the issue of the Cd impurity localization, we performed formation energy calculations. These results have shown that Cd placed in the substitutional Al site, in the negatively charged state, is the most probable configuration.Páginas reales 075203-1 a 075203-12