复合钙钛矿型NaLaMgWO_6:Eu^(3+)红色荧光材料的制备及发光性能研究

Synthesis and Photoluminescence Properties of Double Perovskite NaLaMgWO_6: Eu^(3+) Red Phosphors

采用固相法合成了新型白光LED用红色NaLa_(1-x)Eu_xMgWO_6(0≤x≤1)系列荧光粉。分别采用X射线衍射、扫描电子显微镜、发光光谱等测试手段分析了粉体样品的物相、形貌与发光性质。XRD分析结果表明:NaLaMgWO_6具有单斜晶系的复合钙钛矿结构,空间群为C2/m。光谱测试结果表明:NaLa_(1-x)Eu_xMgWO_6系列荧光粉均可被近紫外光(397 nm)和蓝光(465 nm)有效激发,其最强发射峰位于617 nm处,属于Eu^(3+)的~5D_0→~7F_2电偶极跃迁。Eu^(3+)的最佳掺杂浓度为x=0.5。对荧光粉的发光浓度猝灭曲线分析表明,在NaLaMgWO_6基质中,Eu^(3+)是通过电偶极-电偶极的多极矩相互作用的方式来实现能量传递的。采用Judd-Ofelt理论计算了基质的折射率、Eu^(3+)离子的辐射跃迁强度参数(?λ)和荧光分支(β)等辐射跃迁参数。

Series of NaLa1-xEuxMgWO6 （0≤x≤1） novel red phosphors were successfully synthesized by the conventional solid state method. The crystal structure, morphology, and luminescence properties of NaLa1-xEuxMgWO6 phosphors were characterized by X-ray powder diffraction （XRD）, scanning electron microscopy （SEM） and fluorescence spectra （PL）, respectively. XRD results show that NaLaMgWO6 phosphor has monoclinic double perovskite structure with space group C2/m. The excitation and emission spectra show that NaLaMgWO6： Eu3＋ phosphor can be effectively excited by near-UV （397 nm） and blue light （465 nm）, and exhibits the strongest red emission peak located at 617 nm, which is ascribed to 5D0→7F2 transition of Eu3＋ ion. The optimal doping concentration of Eu3＋ is determined to be x=0.5. It can be confirmed that the dipole-dipole interaction plays an important role in the energy transfer in NaLaMgWO6： Eu3＋ phosphors through the concentration quenching curve. In addition, Judd-Ofelt theory is employed to evaluate various radiative parameters, such as the refractive index, the J-O parameters （Ωλ） and the branching ration （β）.