IMPACT OF Er3+ CONCENTRATION ON LUMINESCENCE IN NaLaF4

In this work, NaLaF4 doped with Er3+ of different concentrations was synthesized. The luminescence spectrum for NaLaF4: Er3+ (0.2 mol%) at 489 nm excitation reveals characteristic Er3+ luminescence bands in the green (540 nm), red (660 nm) and infrared (980 nm) spectral regions. The green luminescence band originated from the S-4(3/2) -> I-4(15/2) transition is the most intensive one in the luminescence spectrum. As the concentration of the activator is increasing, the intensity of all luminescence bands changes significantly. The super-linear increase of the infrared luminescence intensity with increasing Er3+ concentration as well as the quenching of green luminescence at the concentrations exceeding 2 mol% can be attributed to the cross-relaxation process between the activator ions.