Ca5(PO4)3F:Ce,Mn荧光粉的老化性能研究

通过对一系列Ca5(PO4)3F:Ce和Ca5(PO4)3F:Ce,Mn(以下简称FAP:Ce和FAP:Ce,Mn)样品在荧光灯中和在强紫外光(185nm+254nm)辐照下,发光效率衰减规律及样品漫反射光谱的变化的研究,并与普通卤粉((F,Cl)AP:Sb,Mn)进行对比,发现了该材料的老化速率与样品组分的关系,即随着材料中Ce浓度的增大和氧空位的增多,老化速率变快。并根据Ryan老化理论,对材料老化的物理机制进行了初步的推测。

DEPRECIATION PROPERTIES OF Ca5(PO4)3F:Ce,Mn

As a promising phosphor for fluorescent lamp,Ce-Mn activated fluo-rinphosphate(FAP:Ce,Mn) has been studied in these years. The lumen efficiency of this phosphor is very high, but one drawbacks of it is its low lumen maintenance in lamp. The depreciation rate of. FAP:Ce, Mn in lamp is about twice as much as that of Halophosphor ((F,Cl) AP:Sb, Mn). To improve the application of this phosphor, it is essential to study the depreciation properties of FAPCCe, Mn.In this paper, the depreciation of FAP:Ce, Mn both in lamp and under the UV radiation of (185+254) nm is reported, the key factors which affect phosphor depreciation are analyzed and possible mechanism of its depreciation is conjectured.The samples were prepared from solid state reaction. The 40W fluorescent lamps were made with ordinary technique and its lumen output in different operating time was measured. A 25W low pressure Hg discharge lamp was used as the source of UV radiation. Efficiency of samples in different radiation time was measured and the diffuse reflection spectra of samples were measured as well.Depreciation curves of lumen efficiency of FAP:Ce, Mn and (F,Cl) AP:Sb, Mn in fluorescenct lamps are shown in Fig.1. It can be seen that the depreciation processes of the two phosphors are very similar, but the depreciation rate of FAP:Ce, Mn is about twice as much as that of (F, Cl)AP:Sb, Mn.Depreciation curves of efficiency of FAP:Ce, Mn and (F,Cl)AP:Sb, Mn under UV radiation of 254nm are shown in Fig.2.It shows that the depreciation rate of FAP:Ce, Mn is about 3 times as much as that of (F,Cl)AP:Sb, Mn. Two main factors affect the depreciation properties of FAP:Ce, Mn particularly. Ce concentration and the atmosphere in which the sample isprepared,Fig. 3 and 4 show the effect of Ce concentration on the depreciation rate, and the absorption properties of the phosphor. The depreciation rate of FAP:Ce, Mn is almost directly proportional to the Ce concentration. And when Ce exists,the absorption of the sample in some wavelength areas markedly increases after UV radiation. Fig. 5 and Table 1 show the relationship between the forming atmosphere and depreciation of FAP:Ce, Mn.The sample prepared in reductive atmosphere is apt to depreciate and shows more intensive absorption in some areas after UV radiation than that made in air.According to the analysis by comparing the depreciation action between FAP:Ce, Mn and(F, Cl)AP.Sb, Mn both in lamp and under UV radiation, it can be concluded that the depriciation of the two phosphors belongs to the same, sort, caused by the formation of colour center in phosphor crystal by UV radiation.