PHOTOREFRACTION IN Li-RICH LiNbO₃:Mg:Fe CRYSTALS

The ability of Li-rich LiNbO₃:Mg(5mol%):Fe(0.lwt%) to resist photorefraction is found to be comparable to that of LiNbO₃:Mg(5mol%), even though the photorefraction sensitive dopant Fe is added. The nuclear quadrupole splitting and isomer shift of ⁵⁷Fe in Li-rich LiNbO₃: Mg⁵⁷Fe and LiNbO₃:⁵⁷Fe are quite different. The electron spin resonance spectra of the two kinds of crystals are significantly different, too. The enhanced resistance to photorefraction may be due to the change in occupation sites of Fe ions.