Gd2O2S:Tb闪烁陶瓷的制备、微结构与性能研究

Fabrication, microstructure and properties of Gd2O2S:Tb scintillation ceramics

  • 摘要: Gd2O2S:Tb闪烁陶瓷具有高中子吸收截面、高光输出以及优异的光谱匹配性能,解决了传统中子粉体闪烁屏中气泡、粉体颗粒和黏结剂之间存在的光学损耗问题,显著提高了辐照稳定性与使用寿命,因而在中子成像领域展现出良好的应用前景。为制备组分均匀、分散性优异且烧结活性高的Gd2O2S:Tb粉体,本研究以Gd2O3粉体、Tb(NO3)3及H2SO4为初始原料,经90 ℃热水浴反应生成前驱体,随后在空气氛围中煅烧(600 ℃×3 h)得到Gd2O2SO4粉体,再通过氢气还原(750 ℃×2.5 h)制得Gd2O2S:Tb粉体。结合热水浴反应机理分析,通过调控初始Gd2O3粉体的形貌,对Gd2O2S:Tb粉体的形貌特性进行了优化。结果表明,采用商业纳米Gd2O3粉体制备的Gd2O2S:Tb粉体具有较小的片层尺寸、较好的分散性以及较高的烧结活性。以商业纳米Gd2O3粉体为原料制备的Gd2O2S:Tb粉体,经真空预烧(1300 ℃×3 h)结合热等静压烧结后处理(1350 ℃×3 h,176 MPa)所制备的Gd2O2S:Tb陶瓷(厚度为1 mm),表现出最高的光学总透过率(11.3%@545 nm)和最强的X射线激发发光强度。然而,陶瓷内部存在的Gd2O3第二相会对Gd2O2S:Tb陶瓷光学质量的进一步提升产生一定影响。

     

    Abstract: 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.

     

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