焦磷酸锶:铕(Ⅱ)的晶体形貌与发光性能的关系

A STUDY ON CRYSTALLINE FORM AND LUMINESCENCE OF Sr_xP_2O_7:xEu(II)

焦磷酸锶:铕(Ⅱ)在紫外光激发下发射蓝紫光,具有较高的光致发光效率,在250～270nm紫外光激发下,量子效率高达80%以上.由于其发射光谱正好与重氮复印感光剂的光谱灵敏区相匹配,荷兰的W.L.Wanmaker于1967年将其作为光复印材料,成功地用作重氮复印光源.此后对铕(Ⅱ)激活的碱土金属焦磷酸盐一类磷光体的研究日趋活跃,多数为合成方法的改进及其在重氮复印中的应用.而其晶体形貌与发光性能的关系未见报导.

The compound Sr_2P_2O_7 activated with divalent europium has been found to be a very efficent phosphor generating deep-blue light useful for the dizo-copying and printing photomechanical processes. In this study it is discovered that the luminescent output of the compound under 2537 A. excitation deeply depends on its crystalline form. Under ordinary conditions, two kinds of the forms of the products, i. e. needle (rod-like) and polyhedron (cobbestone-like) crystals were obtained. The relative luminescence brightness of the polyhedron crystals is found to be as much as 40～50% higher than of the needle crystals. However, X-ray analysis demonstrates that both the needle and polyhedron crystals of Sr_(2-x)P_2O_7:xEu(II)have orthorhombic stucture. Experiments show that the final forms of the products depend on the crystalline shapes of the starting material SrHPO_4. In addition, excitation and diffuse reflection spectra of the products with different forms were measured. In comparison with the needle form, polyhedron crystals show lower diffuse reflection and stronger excitation under UV range. Especially, the illuminance (Lx) of the 40W fluorescent tubes with the polyhedron crystal phosphor is about one and a half times that with the needle crystal phosphor.