Sulfidization-free synthesis of well dispersed (Gd,La)2O2S:Pr3+ nanopowders and the effect of La3+ on structure and luminescence

Pr3+ activated Gd2O2S and La2O2S are finding a wide range of luminescence applications but their solid-solution form has rarely been reported in the literature. A series of [(Gd1.0-xLax)0.99Pr0.01]2O2S (x = 0.0–1.0, GLOS:Pr3+) solid-solution phosphor nanopowders were directly produced in this work by calcining their sulfated hydroxide type precursors in flowing hydrogen at 900 °C, without using any of the harmful sulfidization reagents indispensable to other technical routes. The synthesis method also has the significant advantages of fine crystallites (∼20–35 nm), high specific surface area (∼16–21 m2/g) and unimodal particle size distribution (average particle size ∼120–140 nm) of the product. Photoluminescence study indicated that La3+ doping may remarkably enhance Pr3+ luminescence under 263 nm excitation, though tends to lower the thermal stability and elongate the lifetime of the emission. Aside from phosphor application, the thus-synthesized GLOS:Pr3+ powders would be well suited for the sintering of high-quality ceramic scintillators because of their fine particle/crystallite size and unimodal/narrow size distribution.