Fabrication, microstructure and properties of Gd₂O₂S:Tb scintillation ceramics

Gd₂O₂S:Tb scintillation ceramics exhibit a high neutron absorption cross-section, high light output, and excellent spectral matching performance. These ceramics eliminate optical losses associated with bubbles, powder particles, and binders commonly observed in traditional neutron powder scintillation screens. Gd₂O₂S:Tb ceramics enhance irradiation stability and extend service life, offering promising applications in neutron imaging. To obtain Gd₂O₂S:Tb powders with homogeneous composition, superior dispersion, and high sintering activity, precursors were synthesized from Gd₂O₃ powders, Tb(NO₃)₃, and H₂SO₄ via a hot water-bath reaction at 90 ℃. The precursors were transformed into Gd₂O₂SO₄ after air calcination at 600 ℃ for 3 h. Subsequent hydrogen reduction at 750 ℃ for 2.5 h yielded Gd₂O₂S:Tb powders with smaller lamellar particle size and more uniform dispersion. The morphology of the Gd₂O₂S:Tb powders was optimized by modulating the morphology of the initial Gd₂O₃ powders in combination with an analysis of the hot water-bath reaction mechanism. The influence of different Gd₂O₃ powders (commercial nano-, precipitation -synthesized, commercial micron-, and ball-milled commercial micron- Gd₂O₃ powders) on the morphology of Gd₂O₂S:Tb powders was investigated. Gd₂O₂S:Tb powders with smaller lamellar size, more uniform dispersion, and higher sintering activity were obtained using commercial nano-Gd₂O₃ powders. The Gd₂O₂S:Tb ceramics prepared from commercial nano-Gd₂O₃ powders via vacuum pre-sintering at 1300 ℃ for 3 h and hot isostatic pressing post-treatment at 1350 ℃ for 3 h under 176 MPa exhibited the highest total optical transmittance of 11.3%@545 nm (1 mm thickness) and the highest X-ray excited luminescence intensity. However, the presence of a secondary phase of Gd₂O₃ within the ceramics limits further improvement in the optical quality of Gd₂O₂S:Tb ceramics.