Structure and Luminescent Properties of Double‐Doped LiNbO3:Zn:Mg Crystals

The correlation between photoluminescence in the near‐IR region and point defect centers in the LiNbO3 crystals co‐doped with Zn and Mg both by homogeneous and direct methods has been studied. X‐ray diffraction (XRD) analysis shows that the LiNbO3:Zn:Mg (4.68:0.9 mol%) crystal obtained by homogeneous doping has the least number of intrinsic defects compared to the others. It has been established that ZnLi defects stimulate photoluminescence (PL) in the near‐IR region of the luminescence spectrum in the LiNbO3:Zn:Mg crystals obtained by homogeneous doping. The LiNbO3:Zn:Mg (4.68:0.90 mol%) crystal has the maximum PL intensity and the LiNbO3:Zn:Mg (3.83:0.97 mol%) crystal has the minimum. Both crystals are doped homogeneously. Such defects as niobium vacancies (VNb) and niobium in the empty octahedron (Nboct) are suggested as luminescence quenchers in the co‐doped crystals. In the directly doped LiNbO3:Zn:Mg crystals impurities are placed in the lithium position. In homogeneously doped crystals the mechanism of magnesium incorporation into the structure depends on the zinc concentration. The ZnLi defects stimulated photoluminescence (PL) in the near‐IR region of the spectrum in the homogeneously doped crystals. The maximum PL intensity was observed in the LiNbO3:Zn:Mg (4.68:0.90 mol%) crystal.