Eu2+激活的硅酸锶材料的发光特性

采用高温固相法制备了Sr₃SiO₅ : Eu²⁺黄色发光材料,研究了Eu²⁺浓度及共激活剂等对材料发光性能的影响。结果显示,随Eu²⁺浓度的增大,Sr₃SiO₅ : Eu²⁺材料发射强度先增强后减弱,即存在浓度猝灭效应,根据Dexter理论,其浓度猝灭机理为电偶极-偶极相互作用。掺入共激活剂Yb、Tm均能提高材料的发射强度。利用InGaN管芯分别激发Sr_2.98Eu_0.01Tm_0.01SiO₅和Sr_2.98Eu_0.01Yb_0.01SiO₅材料,获得了很好的白光发射。

Luminescence Characteristics of Eu2+ Activated Strontium Silicate Phosphors

Sr_3SiO_5:Eu~(2+) phosphors were synthesized by high temperature solid state reaction. The starting materials are the analytic reagents SrCO_3, SiO_2, Eu_2O_3. After the individual materials were mixed in the requisite proportions sufficiently, the powders were calcined at 1 300 ℃ for 6 h under the ambience of 5% H_2 in N_2 to reduce Eu~(3+) to Eu~(2+). The structure was checked by powder X-ray diffraction (XRD, D/max-rA, Cu Kα, 40 kV, 100 mA). The excitation and emission spectra are measured by a Shimadzu RF-540 fluorescence spectrophotometer. All the photoluminescence properties of the phosphors were measured at room temperature. The obtained products are Sr_3SiO_5:Eu~(2+) phosphors. Effect of Eu~(2+) concentration and co-doping activation on the luminescence characteristics of Sr_3SiO_5:Eu~(2+) phosphors was investigated. The results showed that the emission intensities of Sr_3SiO_5:Eu~(2+) phosphors firstly increase with increasing Eu~(2+) concentration, and then decrease because of concentration quenching. They reach a maximum at 1% Eu~(2+), and the concentration self-quenching mechanism is the d-d interaction according to the Dexter theory. Moreover, the emission intensities can be enhanced by co-doping rare earth ions, such as Tm~(3+) and Yb~(3+). The relative spectra of InGaN-based Sr_(2.98)-Eu_(0.01)Tm_(0.01)SiO_5, Sr_(2.98)Eu_(0.01)Yb_(0.01)SiO_5 or YAG:Ce phosphors were measured. Because Sr_3SiO_5:Eu~(2+) phosphor has longer emission wavelength than YAG:Ce, so the color rendering property of InGaN-based Sr_(2.98)-Eu_(0.01)Tm_(0.01)SiO_5 or Sr_(2.98)Eu_(0.01)Yb_(0.01)SiO_5 is better than that of InGaN-based YAG:Ce. In conclusions, Sr_3SiO_5:Eu~(2+) phosphor is a promising yellow phosphor for white LED manufacture.