Gd2O2S:Tb scintillation ceramics fabricated from high sinterability nanopowders via hydrogen reduction

Abstract

Crystallized Gd2(OH)4SO4·nH2O precursor was synthesized in hot water bath using oxide powders and concentrated sulfuric acid as raw materials. Calcining the precursor in air produced the intermediate product Gd2O2SO4 and Gd2O2S powders with high phase purity was obtained by hydrogen reduction. The Gd2O2S powders showed layered structure and severe agglomeration with SBET = 6.321 m2/g. Using this powders, a two-step sintering method comprised of pre-sintering in vacuum and hot isostatic pressing post-treatment was introduced for the fabrication of Gd2O2S:Tb ceramics. The relative density increased from 95.7% in pre-sintered body to 99.2% in final ceramics. Densification processes and chemical homogeneity of the ceramics were discussed. Photoluminescence and X-ray excited luminescence of the final ceramics demonstrated a bright green emission centered at 545 nm due to the 5D4 -7F5 transition of Tb3+.