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 properties. They address the optical loss issues associated with bubbles, powder particles, and binders in traditional neutron powder scintillation screens, significantly improving irradiation stability and service life, and demonstrating promising application prospects in the field of 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 results show that Gd₂O₂S:Tb powders obtained using commercial nano-Gd₂O₃ powders reveal the smaller lamellar size, better dispersion, and higher sintering activity. The Gd₂O₂S:Tb ceramics (with the thickness of 1 mm) 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 and the highest X-ray excited luminescence intensity. However, the presence of a secondary phase of Gd₂O₃ within the ceramics limits the further improvement in the optical quality of Gd₂O₂S:Tb ceramics.