Radioluminescence studies of colloidal oleate-capped β-Na(Gd, Lu)F4:Ln3+ nanoparticles (Ln = Ce, Eu, Tb)

We report on the synthesis, characterization, and radioluminescence quantification of several new varieties of nanoparticles with the general composition-NaLnF(4), incorporating known luminescent activator/sensitizer pairs. Using Monte Carlo modeling to complement luminescence measurements, we have calculated the radioluminescence yields and intrinsic conversion efficiencies of colloidally-dispersed nanoparticles by comparison to an organic liquid scintillator. While five of the compositions had low to modest radioluminescence yields relative to bulk materials, colloidal -Na(Lu0.65Gd0.2Tb0.15)F-4 displayed a strong output of 39460 photons per MeV absorbed, comparable to some of the best non-hygroscopic bulk crystal scintillators and X-ray phosphors such as Gd2O2S:Tb. Measurements of -Na(Lu0.65Gd0.2Tb0.15)F-4 powder samples revealed persistent luminescence as well as stable charge trapping, warranting further investigation.