Optical spectroscopy of Ca3Sc2Ge3O12: Ni2+

The optical spectra of Ca3Sc2Ge3O12 (CaSGG) single crystals doped with Ni2+ are presented. Analysis of the absorption spectrum shows that the dopant substitutes mainly for Sc3+ in octahedral sites and, to a lesser extent, Ge4+ in tetrahedral sites. The optical transitions were assigned in the framework of the Ligand Field theory and the Dq, B and C parameters were obtained for both coordination geometries. Three emission transitions were observed in the green, red and infrared regions and were assigned to the T-1(2)(D-1) -->( 3)A(2)(F-3); T-1(2)(D-1) --> T-3(2)(F-3) and T-3(2)(F-3) --> (3)A(2)(F-3) transitions of Ni2+ in octahedral sites, respectively. No luminescence from Ni2+ in tetrahedral sites was observed. (C) 1999 Elsevier Science Ltd. All rights reserved.