EPR AND INFRARED-ABSORPTION STUDY IN MGO CO-DOPED LINBO3 CRYSTALS

In this work the electron spin resonance (ESR) and OH- infrared absorp tion spectroscopies have been used in the study of LiNbO3:Cr3+ crystal s codoped with MgO. It has been confirmed that the principal defect si te at low MgO concentration is the Cr3+(Li+) centre. For MgO concentra tion higher than 4%, Cr3+ ions located in Nb5+ site is the dominant ce ntre. The OH- infrared absorption bands at 2827 nm and 2851 nn are att ributed to the OH--Mg2+(Nb5+) and Cr3+(Li+)-OH--Mg2+(Nb5+) clusters re spectively. Evidence supporting this assignment is presented.