Lu2SiO5∶Ce荧光粉的热释光特性研究

采用溶胶-凝胶(Sol-Gel)技术,分别在空气中和石墨提供的弱还原气氛下制备出Lu2SiO5∶Ce0.006荧光粉。通过分析样品的结构,光致激发、发射谱和热释光谱等特性,发现弱还原气氛下制备的样品不仅光致发光强度比空气中的强,而且热释光曲线中598K处的高温热释光峰也得到了抑制。进一步考察空气中制备的Lu2SiO5∶Ce0.006,Kx(x=0.01～0.08)荧光粉,结果表明就光致发光和热释光特性而言,K+共掺杂具有与还原气氛类似的作用。综合以上两方面分析结果,可认为598K处热释光峰是由与Ce4+相关的缺陷引起的,并对K+共掺杂LSO∶Ce发光增强的原因给出了合理解释。

Thermoluminescence characteristics of Lu2SiO5 : Ce phosphors

To investigate the origin of the thermoluminescence at high temperature, Lu2SiO5 : Ce0.006 (LSO : Ce) phosphors were prepared by sol-gel chemistry in air and graphite respectively. The patterns of X-ray diffraction, excitation and emission spectra and thermoluminescence curves of these samples were analyzed. In comparison with the phosphors prepared in the air, the luminescence intensity was improved and the thermoluminescence peak at 598 K was restrained for the sample prepared in graphite. It was found that the thermoluminescence peak at 598 K was relevant to Ce4+. In order to achieve more evidences, LSO : Ce0.006, K(x) (x = 0.01-0.08) phosphors were prepared. The structures and spectra of K(+) -codoped samples were also studied. By codoping with K+ ions, the luminescence intensity of LSO : Ce phosphor could be enhanced distinctly, but the crystallinity was not improved. The results of the K(+) -codoped LSO: Ce exhibited that K(+) -codoping could improve the concentration of oxygen vacancy and restrain the peak at 598 K. When K+ ion occupied the position of Lu3+, more oxygen vacancies could be created and Ce4+ turned into Ce3+ simultaneously due to the balance of electric charge, which was consistent with the result of the thermoluminescence. So it can also come to the conclusion that the thermoluminescence peak at 598 K was relevant to Ce4+. The reason for K+ ions enhancing the intensity of LSO : Ce can be attributed to the improvement of concentration ratio for Ce3+/Ce4+.