以三价铕离子为单一铕源, 采用化学共沉淀法制备了二价铕与三价铕共掺杂的SrSO4荧光粉体材料.通过X射线衍射仪、扫描电镜、光致发光谱仪对该荧光粉的晶体结构、形貌、光致发光特性进行分析.研究发现: 所合成的SrSO4粉体材料为二价铕与三价铕共掺杂的SrSO4微晶, 其大小在1~10 μm之间.在325 nm 的紫外光激发下该微晶能发射很强的绛红色荧光, 其光致光谱由一个位于379 nm 的宽发光带和位于575 nm、591 nm和612 nm的三个窄发光带组成.基于局域密度近似的密度泛函理论, 计算了SrSO4的能带结构及其氧缺陷能级, 然后以能带结构为基础讨论了二价铕与三价铕共掺杂SrSO4的发光机理.峰位于379 nm的宽发光带可归因于SrSO4微晶中二价铕离子发光中心的4f65d1→4f7的电子跃迁, 而三个红色窄发光峰分别来自三价铕离子5D0→7F0, 5D0→7F1, 5D0→7F2的电子跃迁.实验表明二价铕与三价铕共掺杂的SrSO4能作为高效的绛红色荧光粉.

Bivalent and trivalent Eu ionsco-doped SrSO4 phosphors were synthesized via the precipitation method by using trivalent Eu ions as the sole dopant source. The crystal structure, morphology and photoluminescence of the synthesized SrSO4 phosphors were investigated by the X-ray diffractometer, scanning electron microscope and spectrophotometer, respectively. It was found that the resultant SrSO4 microcrystals are co-doped with both the bivalent Eu ions and the trivalent Eu ions. The typical size of the SrSO4 microcrystals is in the range of 1~10 μm. Under the ultraviolet excitation of 325 nm, the synthesized SrSO4 microcrystals can give off strong purplish pink photoluminescence, which consists of a broad emission band centered at 379 nm and three narrow emission peaks at 575, 591 and 612 nm, respectively. The bandstructures and defect level of SrSO4 are calculated with density functional theory in the framework of local density approximation, and the photoluminescence mechanisms of the bivalent and trivalent Euco-doped SrSO4 are discussed in terms of the calculated bandstructures. The broad emission band centered at 379 nm can be attributed to the transition 4f65d1→ 4f7 of the bivalent Eu ions in the SrSO4 matrix while the three sharp emission peaks at 575, 591 and 612 nm can be assigned to the transitions of trivalent Eu ions from its excited state 5D0 to its ground states 7F0, 7F1 and 7F2,respectively. It has demonstrated that bivalent Eu and trivalent Euco-doped SrSO4 can be utilized as an efficient purplish pink phosphors.