High-loaded and transparent La_xCe_1-xF₃-polystyrene nanocomposite scintillators for radiation detection

For radiation detection, sensitivity, response time, and energy resolution are important. Scintillating nanoparticles, in principle, can have enhanced light output in comparison with their bulk materials due to quantum size confinement and increased overlap of electron and hole wave function. However, the aggregation and the loss of transparency at high loading into polymers are the challenging issues for practical applications. Here, for the first time, we report a new method to fabricate the blue-emitting nanocomposites with up to 30 wt% nanoparticle loading. First, the polymerizable surfactant coated La_0.6Ce_0.4F₃ nanoparticles are synthesized, and then, they are loaded up to 30 wt% in a polystyrene matrix. The nanocomposites show an intense luminescence and a good transparency, performing much better than the commercial EJ-200 plastic scintillator. The gamma spectra acquired with the nanocomposite show a photopeak for the Co-57 isotope. The gamma spectra of Cs-137 show a full energy peak at around 622 keV, due to the escape of La and Ce Kα X-rays. The observation of the photopeaks is attributed to the enhanced photoelectric effect as a result of increased effective atomic number (Z_eff). All these indicate that the high loaded nanocomposites are promising for radiation detection and nuclear material surveillance for homeland security.