Nanopowder synthesis enabling 1350 ºC full densification of (Gd,La)2O2S:Pr3+ luminescent ceramics via pressureless sintering and the effect of La3+ doping

Abstract

Pr3+ activated Gd2O2S (Gd2O2S:Pr3+) ceramics are important scintillators for X-ray computed tomography, whose fabrication generally requires harsh sintering conditions, such as 1650–1750 °C for pressureless sintering and ∼1300–1500 °C and tens to hundreds MPa for pressure assisted sintering. We synthesized in this work a series of [(Gd1-xLax)0.99Pr0.01]2O2S (GLOS:Pr3+; x=0, 0,15, 0.3, 0.5, 0.65, 0.8, 1.0) nanopowders of fine crystallite size (∼19–54 nm), high specific surface area (∼13.4–15.8 m2/g) and unimodal size distribution through two-step calcination of coprecipitated amorphous precursors. Dilatometry analysis confirmed that the nanopowders possess excellent sinterability, and fully dense GLOS:Pr3+ ceramics were successfully fabricated via pressureless sintering in an Ar/H2 gas mixture at a temperature as low as 1350 °C. La3+ doping was found to substantially enhance densification/grain growth and the 3P0-3H4 main emission (∼510 nm) of Pr3+, and tends to elongate the fluorescence lifetime of the Pr3+ emission (∼1.89–2.66 μs).