Impurity fluorescence self-quenching in Nd3+: Gd3BWO9 crystalline powders: Experiment and analysis

Abstract

We made precision measurements of fluorescence kinetics of crystalline Gd3BWO9: Nd3+ doped powders at room temperature by the method of gated single photon counting technique in a wide range of Nd3+ concentrations. The powders were synthesized with a high temperature solid-state reaction.We managed to describe the concentration dependence of the impurity fluorescence self-quenching kinetics curves with the constant microparameters of energy migration CDD = 2.97 nm6/ms and quenching energy transfer CDA = 0.43 nm6/ms. The microparameters were found with the direct fitting of the curves to the analytical formula of microscopic theory derived specifically for concentration fluorescence self-quenching accounting energy migration over donors. The obtained ratio of the values of the microparameters z = CDA/CDD = 0.145 indicates a hopping mechanism of fluorescence self-quenching of the 4F3/2 level of the Nd3+ ion. We developed a kinetic method to determine with high accuracy the concentrations of impurity rare-earth ions in crystals at low doping level, which is significantly higher than that for energy-dispersive X-ray spectroscopy (EDS) analysis. For arbitrary systems with fluorescence self-quenching, we obtained an analytical formula that allows us to calculate the value of the activator concentration at which the fluorescence brightness is maximum. For the studied Nd3+: Gd3BWO9 powder samples, the maximum brightness is realized at xmax≈2.98 at.%, which is in good agreement with the experimental value.