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 s ubstitutes mainly for Sc3+ in octahedral sites and, to a lesser extent, Ge4 + in tetrahedral sites. The optical transitions were assigned in the framew ork 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 luminescenc e from Ni2+ in tetrahedral sites was observed. (C) 1999 Elsevier Science Lt d. All rights reserved.