采用传统的高温固相法合成了一种新型的绿色荧光粉Sr3Y(PO4)3∶Ce^3+,Tb^3+,利用X射线衍射(XRD)和荧光光谱(PL)对该材料的晶体结构和光学性能进行表征。结果分析表明,制得样品的XRD图谱不含Sr3Y(PO4)3以外的杂峰,稀土掺杂并未改变基质的晶体结构,得到的样品为纯相的磷酸钇锶。从本文实验中明显观察到Sr3Y(PO4)3∶Tb^3+的激发光谱和Ce^3+的发射光谱在320~390nm有重叠,表明在Sr3Y(PO4)3基质中可存在从Ce^3+到Tb^3+的能量传递。在紫外光(315nm)激发下该荧光粉发射出了Ce^3+的蓝光(320~420nm)和Tb^3+的黄绿光(480~500nm)和(530~560nm),当Ce^3+的浓度为7%,Tb^3+的浓度由1%增大到50%时,通过Ce^3+的4f→5d电子跃迁将能量传递到Tb^3+,然后发生^5 D4→^7 Fj电子跃迁,该荧光粉发射光谱可由蓝光逐渐调节为黄绿光。本文绘制了Ce^3+,Tb^3+的能级和Sr3Y(PO4)3∶Ce^3+,Tb^3+荧光粉中的能量转移过程示意图,并详细阐述了由Ce^3+到Tb^3+的能量传递过程。通过对比Ce^3+和Tb^3+的发光强度以及由Ce^3+到Tb^3+能量转移效率的相对变化,可以得出,随着掺入的Tb^3+浓度不断增加,Tb^3+的发射强度(^5 D4→^7 Fj)和能量转移效率(Ce^3+到Tb^3+)也在增大,而Ce^3+的发射强度却有了明显的下降。当Tb^3+的浓度为50%时能量转移效率可高达80%。通过CIE色度图也可以看出,当Tb^3+浓度不断增大,样品的色坐标从图中的蓝色区域移动到绿色区域。所以在紫外光激发下,Ce^3+和Tb^3+共掺Sr3Y(PO4)3可作为一种绿光荧光粉应用在白光LED或LCD背光源上。
A novel green light-emitting phosphor Sr3Y(PO4)3Ce^3+,Tb^3+was synthesized by the traditional high temperature solid state reaction method.Luminescence mechanism and crystal structure were investigated by X-Ray Diffraction(XRD)and photoluminescence spectra(PL).The XRD patterns demonstrate that the samples belong to the single phase of Sr3Y(PO4)3in experimental doping concentrations range.Obviously,the excitation band of Sr3Y(PO4)3∶Tb^3+and the emission of Sr3Y(PO4)3∶Ce^3+have a significant spectral overlap in the wavelength range of 330~380nm,which implies the great possibility of an efficient ET from Ce^3+to Tb^3+.Under the 315 nm ultraviolet excitation,a blue emission(320~420nm)from Ce^3+and a yellowishgreen emission(480~500,530~560nm)from Tb^3+were obtained from Sr3Y(PO4)3∶Ce^3+,Tb^3+.When the Ce^3+concentration was 7%,the emission could be adjusted from blue to green region by tuning the Tb^3+doping concentrations from 1% to50% through an energy transfer process.This text plot the schematic energy levels of Ce^3+,and Tb^3+with electronic transitions and energy transfer processes in Sr3Y(PO4)3∶Ce^3+,Tb^3+,which disclose the electron motion processes of Sr3Y(PO4)3 ∶Ce^3+,Tb^3+.From the dependence of relative emission intensity of Ce^3+,Tb^3+(^5 D4→^7Fj)and ET efficiency from Ce^3+to Tb^3+on the concentrations of Tb^3+,It can be seen that the relative intensity of Tb^3+and the values ofηETincrease gradually with the increasing of Tb^3+as well as the relative intensity of Ce^3+decreases remarkably.The largest energy transfer efficiency reaches as high as 80% when the concentration of Tb^3+was 50%,demonstrating the efficient energy transfer from Ce^3+to Tb^3+.The CIE chromaticity coordinate positions are plotted,as can be seen the emitting color of Ce^3+and Tb^3+singly doped Sr3Y(PO4)3∶Ce^3+,Tb^3+phosphor are blue and yellowish green,respectively.The emitting color of samples