Fabrication and Microstructure of Gd2O2S:Tb Scintillation Ceramics from Water-bath Synthesized Nano-powders: Influence of H2SO4/Gd2O3 Molar Ratio

The Gd 2 O 2 S:Tb scintillation ceramics is extensively used for neutron radiography and industrial non-destructive testing due to its bright green emission, high intrinsic conversion efficiency and high thermal neutron capture cross-section.However, the existence of Gd 2 O 3 secondary phase in Gd 2 O 2 S ceramics impedes the scintillation property.In this work, The Gd 2 O 2 S:Tb precursors were synthesized in water-bath with H 2 SO 4 and Gd 2 O 3 as starting materials.Molar ratio of H 2 SO 4 to Gd 2 O 3 defined as n was adjusted to synthesize the precursors., which influence on the properties of the precursors and powders was studied.Chemical composition of the precursors changes with the increase of n, from 2Gdand to Gd 2 (SO 4 ) 3 •8H 2 O (n=3.00).After being calcined and reduced, all the powders form pure Gd 2 O 2 S phase.Morphology of the Gd 2 O 2 S:Tb powders is closely related to the phase composition of the precursor.Increasement of the XEL intensity shows two stages with n increase, corresponding to the phase transition of the precursor, respectively.The Gd 2 O 2 S:Tb scintillation ceramics were therefore fabricated by vacuum pre-sintering and HIP post-treatment.The ceramics were fabricated from the powders prepared with different n, achieving high relative density and XEL intensity, except the ceramics fabricated from the powders prepared with the n=2.00, 2.25, 2.50.The increase of n is beneficial to the removal of the Gd 2 O 3 secondary phase from the Gd 2 O 2 S:Tb ceramics.This work provides a way for eliminating the secondary phase in Gd 2 O 2 S:Tb scintillation ceramics.