LED用荧光粉Sr（S1-xSex）：Eu^2＋的合成和光谱性质研究

采用高温固相法合成了Sr(S1-xSex)系列硫属化合物掺Eu2 荧光粉.XRD表明荧光粉的组成为单相,而且体系Sr(Sl-xSex):0.005Eu2 中晶胞参数随着组成的变化呈现良好的线性关系,遵守韦加定律.漫反射光谱与激发光谱吻合,说明荧光粉吸收的能量能够有效地激发发光中心而发光,激发光谱中较低能量区域覆盖了400～500 nm的光谱范围,与蓝光LED芯片的发射光匹配.发射光谱呈现的是Eu2 离子的5d→4f特征跃迁发射带,当x由0增加到1.0的过程中,发射峰值波长由617 nm逐渐蓝移到571 nm.不同基质中掺杂的Eu2 离子的荧光寿命均为微秒数量级,与Eu2 离子的4f65d1→4f7跃迁相符合.将荧光粉封装在发蓝色光(λ=460 nm)的GaN芯片上制作了LED器件,测量了器件的发光强度、色纯度和色坐标等参数.Sr(S1-xSex):Eu2 系列硫属化合物掺铕荧光粉能够有效地被GaN芯片发出的蓝色光激发,发出从橙色到红色的可见光,是一类较好的LED用荧光粉.

Synthesis and Spectral Properties of Eu2+-Doped Sr(S1-xSex)Phosphors for LEDs

Eu(2+)-activated Sr((S(1-x)Se(x)) phosphors were synthesized by solid-state reaction at high temperature. XRD patterns indicated that the phosphors are of single phase; the relationship between lattice constant and compositional ratio x is linear, in which the Vegard's law holds. The excitation spectra are consistent with diffuse reflectance spectra, indicating that the energy absorbed by phosphor can be transferred to Eu2+ efficiently. The excitation spectra of these phosphors show broadband, extending from UV to visible light; and they can be matched with the emission wavelength of GaN chip well. The emission spectra exhibit characteristic 4 f6 5d1 -->4f7 transition of Eu2+ ion. With increasing x the emission band shifted to shorter wavelength, which can be explained by the change in crystal field. The decay curve of fluorescence can be well fitted by double exponential equation, and the lifetime of EuZ2+ is of the order of microsecond. The lifetimes are reasonable for the allowed 4f6 5d1 --> 4f7 transition. The electroluminescence spectra of red LED manufactured with phosphors Sr (S(1-x) Se(x)) : Eu2+ were measured and the parameters of them were also measured. In a word, Sr(S(1-x) SeS(x)): Eu2+ are good phosphors for LED application.