Synthesis of green-emitting gd2 o2 s:Pr3+ phosphor nanoparticles and fabrication of translucent gd2 o2 s:Pr3+ scintillation ceramics

Abstract

A translucent Gd2 O2 S:Pr ceramic scintillator with an in-line transmittance of ~31% at 512 nm was successfully fabricated by argon-controlled sintering. The starting precipitation precursor was obtained by a chemical precipitation route at 80◦ C using ammonia solution as the precipitate, followed by reduction at 1000◦ C under flowing hydrogen to produce a sphere-like Gd2 O2 S:Pr powder with an average particle size of ~95 nm. The Gd2 O2 S:Pr phosphor particle exhibits the characteristic green emission from3 P0,1 →3 H4 transitions of Pr3+ at 512 nm upon UV excitation into a broad excitation band at 285–335 nm arising from 4f2 →4f 5d transition of Pr3+. Increasing Pr3+ concentrations induce two redshifts for the two band centers of 4f2 →4f 5d transition and lattice absorption on photoluminescence excitation spectra. The optimum concentration of Pr3+ is 0.5 at.%, and the luminescence quenching type is dominated by exchange interaction. The X-ray excited luminescence spectrum of the Gd2 O2 S:Pr ceramic is similar to the photoluminescence behavior of its particle. The phosphor powder and the ceramic scintillator have similar lifetimes of 2.93–2.99 µs, while the bulk material has rather higher external quantum efficiency (~37.8%) than the powder form (~27.2%).