Luminescence and color centers from CNGG : Cr3(+) crystal grown by Czochralski method

Ca-3(Nb0.9Ga0.09Cr0.01)(1.875)Ga3O12 (CNGG : Cr3+) single crystals have bee n grown by Czochralski method in the nitrogen with little oxygen. Laser-ind uced broad band fluorescence from the crystal was observed in the region 77 0 nm under the excitation of argon ion laser 488 nm at room temperature. No obvious thermal quenching of fluorescence was observed from 77 to 289 K. N o laser action is observed in this crystal mainly due to the formation of c olor center under the pump of laser diode 680 nm. And the laser-induced col or center occurs also in the crystal when excited by 488 nm laser and can d isappear by itself after a few hours. Persistent color centers were formed during the growth and the oxidation annealing. (C) 2000 Elsevier Science B. V. All rights reserved.