助熔剂对绿色荧光粉Ba2 SiO4∶Eu2+ 颗粒形貌及发光性能的影响

采用高温固相法在弱还原气氛下合成了Ba₂SiO₄∶Eu²⁺绿色荧光粉,利用X射线衍射、扫描电子显微镜和荧光分光光度计考察了不同助熔剂对Ba₂SiO₄∶Eu²⁺荧光粉的结晶度、物相纯度、颗粒形貌和发光强度的影响,并详细讨论了不同助熔剂在荧光粉制备过程中的作用机理。结果表明:不加助熔剂时样品存在BaSi₂和SiO₂杂相;利用NH₄F、Na₂CO₃或H₃BO₃作为助熔剂时会抑制BaSi₂杂相的形成,而BaF₂作助熔剂可以得到纯的斜方晶系。与未加助熔剂合成的荧光粉相比,添加质量分数为2% 的BaF₂、NH₄F或Na₂CO₃后合成样品的发光强度分别提高了138%,81%和34%;而质量分数为2%的H₃BO₃作助熔剂时,荧光粉的发光强度反而降低了14%。BaF₂作助熔剂合成的荧光粉颗粒形貌接近球形,以NH₄F、Na₂CO₃或H₃BO₃作助熔剂合成的荧光粉颗粒形貌分别为不规则片状、纺锤体形和不规则多边形大颗粒。

Effect of Fluxes on Morphology and Luminescent Properties of Ba2SiO4:Eu2+ Green Phosphor

A series of Ba2SiO4∶Eu2+ green phosphors have been synthesized by high temperature solid state method.The effects of different fluxes on the crystal structure,surface morphology and spectral characteristics of Ba2SiO4∶Eu2+ phosphors were systematically investigated by X-ray powder diffraction(XRD),scanning electron microscopy(SEM) and fluorescence spectrophotometer.The function mechanism of different fluxes on the preparation of Ba2SiO4∶Eu2+ phosphors have also been discussed.XRD results show that the Ba2SiO4∶Eu2+ phosphor without flux has the impurity phase of BaSi2 and SiO2 during firing,while fritted with NH4F,Na2CO3 or H3BO3 flux,the impurity phase of BaSi2 can be suppressed.BaF2 flux can get the pure orthorhombic.By comparing the influence of different fluxes on the emission of Eu2+,it was found that the emission intensity of the Ba2SiO4∶Eu2+ phosphor with 2% mass fraction of BaF2,NH4F or Na2CO3 flux improved by 138%,81%,34% than that of the powder without the flux material,while the luminescent intensity reduced 14% when using 2% mass fraction of H3BO3 as flux.The phosphor powders were spherical-like shapes using BaF2 as the flux,while the phosphor powder prepared with NH4F,Na2CO3 or H3BO3 as flux had the irregular laminated structure,spindle shape and irregular polygon,respectively.