铅激活二硅酸钡合成条件的研究

在一定量的激活剂PbO2和助熔剂BaCl2,BaSO4存在下,通过碳酸钡和二氧化硅之间的固相反应制备光致发光材料二硅酸钡铅BaSi2O5:Pb2+。为了使获得的产品是具有上述化学计量的化合物,以及具有最好的发光性能,我们用正交设计方法安排了一系列条件试验。试验结果指出,在合成二硅酸钡铅发光材料的反应中,反应温度和SiO2/BaCO3的摩尔比是最重要的因素。反应温度应高于1100℃,SiO2/BaCO3的摩尔比应在2.3—2.8之间。其它重要因素有:激活剂PbO2加入量在0.04—0.17摩尔之间对产物发光强度均无明显影响,以0.08摩尔为最好。由于PbO2在高温时分解及挥发,实际进入晶体的Pb2+量仅为0.8%(摩尔百分)。助熔剂BaCl2及BaSO4的加入量分别以0.16摩尔及0.17摩尔为最好。灼烧时间以5小时为最好。根据最佳条件所制备得到BaSi2O5:Pb2+发光材料在254nm激发下,它的发射光谱峰值为351.9nm,半高宽为39nm,它的发光强度为国内同类商品的111%,为日本东芝SPD-8S的108%。用它制作紫外荧光灯管时,涂敷性能也较好。

OPTIMIZATION OF THE METHOD FOR PREPARING PHOSPHOR BaSi2O5:Pb2+

The phosphor BaSi2O5:Pb2+ has been widely used in manufacturing of black light lamps.However, the detailed information about its preparation can not be found in the literature.The aim of this research is to work out the optimum conditions for preparing BaSi2O5:Pb2+ having efficient emission in ultraviolet.A solid state reaction between barium carbonate and silicic acid in the presence of activating agent PbO2 and some fluxes was studied with the aid of orthogonalizing method of the experimental design.The optimum reaction conditions are found to be as follows.The excess silicic acid must be used to inhibit the formation of other barium silicates so as to ensure the product being of a sanbornite structure.The mole ratio of SiO2/BaCO3 is 2.3-2.8.The activating agent, lead oxide, should be added in a large amount.The mole ratio of PbO2/BaCO3 is 0.04-0.17.Because of the volatility of lead oxide at high firing temperature.some loss of lead occurs.The actual concentration of divalent lead remained in the phosphor is determined to be about 0.8 mole by atomic emission spectroscopy.The addition of fluxes BaF2, BaCl2 and BaSO4 promote the solid reaction.Firing should be proceeded at the temperature above 1100℃The excitation and emission spectra of BaSi2O5:Pb2+ obtained in our laboratory are studied and they are as same as the commercial products.Furthermore, its integration intensity of luminescence is higher than that of the commercial phosphors and is evaluated to be 108% of that of Toshiba phosphor SPD-8S.