BaSi_2O_5∶Pb荧光粉表面性能的改善

Surface Modification of BaSi_2O_5∶Pb Phosphor

BaSi2O5∶Pb(BSP)荧光粉现主要应用于晒黑灯,也常用于其他一些特殊用途的荧光灯,如捕蝇、光催化等。相比其他灯用荧光粉来说,这种荧光粉有一明显缺点,即光衰较大。目前解决这个问题的办法主要通过化学气相沉积法在BSP粉表面包覆Al2O3膜,提出了一种基于液相的表面处理方法,且在较高pH值下进行,该方法通过将荧光粉加入Ba2+离子溶液,使得溶液中Ba2+离子在粉表面富集,再经过滤、灼烧等后处理,得到处理后的BSP粉。以SEM,XPS等方法对其表面形貌和组分进行测试,并以未处理的BSP粉作对照进行发光性能测试,结果表明:阳离子溶液处理后荧光粉在发光性能上有了明显改善,光通维持率明显提高。

Lead-activated BaSi2O5 （BaSi2O5： Pb, BSP） is used as the long wavelength UV phosphor in suntanning lamps, as well as speciality lamps for diazo-printing reprography, lithography, insect traps, photochemical and curing processes. A well-known problem with the use of this material is that its radiance maintenance is poor. That is, lamps employing the BaSi2O5： Pb phosphor exhibit a large decrease in radiant output over time. Presently, the stabilization of the light output of tanning lamps is achieved by the application of an Al2O3 coating onto the surface of BSP particles. This measure requires a gas phase process, since the wet chemical precipitation of Al （OH） 3 has to be performed at an acidic pH, i.e. in an environment which is hazardous to BSP. It is an object to provide a solution based method for BSP that can be performed at a high pH and is thus harmless to the phosphor, and further object to improve the lamp maintenance of BSP phosphor. The method involves adding an amount of a silicate phosphor to a salt solution containing a cation, such as Ba^2 ＋, stirring the solution for a time sufficient to cause the cation to attach to the phosphor surface, separating the cation-treated phosphor from the solution, and annealing the phosphor at a temperature for a time sufficient to increase radiance maintenance of the cation-treated phosphor. The surface morphology and the surface component of cation-treated BSP phosphor were investigated by means of SEM and XPS, respectively. The luminescent performances of the lamps using the cation-treated phosphor and untreated phosphor were tested. The results demonstrate that cation-treated phosphor shows a decrease in the ratio of Si/Ba surface atoms, and lighting test indicates that lamp employing the cation-treated phosphor has a significant improvement in radiance maintenance.