Ce3+掺杂Li2O-MgO-Al2O3-SiO2玻璃的结构与荧光猝灭现象

采用熔融淬冷法制备了不同浓度Ce³⁺离子掺杂的20Li₂O-5MgO-20Al₂O₃-55SiO₂玻璃闪烁材料。采用X射线衍射(XRD)、高分辨透射电镜(HRTEM)技术、密度检测等方法研究了玻璃的微观结构随Ce³⁺离子掺杂浓度的变化规律, 采用荧光分光技术检测了玻璃的紫外光致激发光谱(PLE)、发射光谱(PE)。研究结果表明: 在不对称的晶体场作用下, Ce³⁺离子5d能级被劈裂为5个组分; 随着玻璃基质内Ce³⁺离子掺杂浓度增大, 玻璃的非晶化程度加深; 5d能级的劈裂宽度随之增大, 由此导致激发带向低能量端展宽、发射光谱明显红移; Ce³⁺离子的荧光发射强度随Ce³⁺离子掺杂浓度先升高、后降低, 浓度猝灭过程成为其荧光发射效率降低的主要原因。

Structure and Fluorescence Quenching of Li2O-MgO-Al2O3-SiO2 GlassesDoped with Trivalent Cerium

20Li₂O-5MgO-20Al₂O₃-55SiO₂ glass doped with different concentrations of Ce³⁺ ions was synthesized by using melt-quenching method. The glass density as a function of Ce³⁺ ions doping concentration was tested by Archimedes’ method. The structural characteristics of Ce³⁺-doped 20Li₂O-5MgO-20Al₂O₃-55SiO₂ were detected by using X-rays diffraction (XRD), high resolution transmission electron microscope (HRTEM) techniques. The photoluminescence excitation (PLE) and emission (PL) spectra were recorded in a spectrofluorimeter by photon counting techniques. Results showed that 5d energy level of Ce³⁺ ion was splitted to five components under the strong crystal filed surrounding Ce³⁺ ions. The higher the doping concentration of Ce³⁺ ions, the higher the degree of non-crystalline configuration of lithium magnesium aluminosilicate glass was. With the increase of the degree of non-crystalline configuration, the splitting width of 5d energy level increased, resulting in the redshift of excitation and emission spectra apparently. The PL emission intensity first increased, and then decreased with the increase of Ce³⁺ ions doping concentration. The concentration quenching processes were found to be the key reason for the reduction of the PL emission efficiency.