溶胶-凝胶法制备BaGd1-xEuxB9O16红色磷光粉的发光

采用溶胶-凝胶法制备出BaGd_1-xEu_xB₉O₁₆红色磷光粉,对过程的物料配比、前驱体处理和晶化温度等制备条件进行了讨论。结果表明,样品在850 ℃下开始晶化,900 ℃时就能够获得较好的晶化产物,结合不同晶化温度下的发光强度比较确定,晶化温度为950 ℃时,BaGd_1-xEu_xB₉O₁₆磷光粉具有较高的结晶状态和发光强度。当Eu浓度x=0.9时具有最大的发光强度;初始原料配比硼酸须按计量过量15%。所得荧光粉的激发光谱峰值为264,394,465,534 nm等,分别归属于Eu-O电荷迁移带及Eu³⁺的⁷F₀-⁵L₆、⁷F₀-⁵D₂和⁷F₀-⁵D₁跃迁,发射光谱呈Eu³⁺的特征红光,最强的发射峰位于614 nm,归属于⁵D₀-⁷F₂跃迁。进一步研究表明该磷光粉中存在着Gd³⁺对Eu³⁺的能量传递。

Structure and Luminescence Properties of BaGd_1-<em>x</em>Eu_<em>x</em>B₉O₁₆ Phosphor Prepared by Sol-gel Method

Rare-earth doped borate phosphor has the advantage of low synthesis temperature, so it is suffered much of recognition in recent decades years. BaLnB₉O₁₆ (Ln=La-Lu, Y) is a fine borate host, which can gained different phosphors by doping of different ions (Ce, Dy, Eu, Tb, Mn). For the before time investigation of borate phosphor, solid-state method was used for preparing, the fabrication temperature is about 1 000 ℃, and more the phenomenon of agglomeration is very grave. We synthesized a Eu³⁺ doped boron-containing phosphor having a formula of BaGd_1-xEu_<em>xB₉O₁₆ by sol-gel method, decreasing the crystallized temperature and avoiding the grave agglomeration.
Using Eu₂O₃, Gd₂O₃, boracic acid, barium carbonate acid as starting materials and citric acid as complexing agent, sol-gel method was used to prepare BaGd_1-xEu_xB₉O₁₆ red phosphor. The influence of preparing condition was discussed, and their structure and luminescence property were characterized by X-ray diffraction (XRD) analysis and fluorescence spectrometry. The investigation showed that the sample can be crystallized under 850 ℃, and gained better crystallized production at 900 ℃. Considering to the luminescence intensity for the samples prepared at different crystallization temperature, BaGd_1-xEu_xB₉O₁₆ phosphor can get better luminescence intensity and better purity.

The investigation showed that there is huge quenching concentration of Eu³⁺ in BaGd_1-xEu_xB₉O₁₆. Its about 90%. For the borate synthesis, boracic acid can be volatilization at high temperature, so 15% excessive boracic was necessary. The investigation found that the phosphor can be excitated by 264, 394, 465, 534 nm; they are assigned to Eu—O energy transfer, ⁷F₀→⁵L₆, ⁷F₀-⁵D₂, ⁷F₀-⁵D₁ transitions, respectively. The samples can emit out characteristic red light of Eu³⁺ with the main peak of 614 nm, which is assigned to ⁵D₀-⁷F₂ transition. The energy transfer between Gd³⁺ and Eu³⁺ exist in this phosphor. Different from the phosphors prepared by solid-state method, the highest excitation position is not from energy transfer, it comes from f-f transition which located at 394 nm. Thats suitable to white LED that can give the excitation of purple ray.