单一基质白光荧光粉Na3Sc2(PO4)3∶Tm3+,Dy3+的合成及发光性质

采用高温固相法成功制备了Na₃Sc_2-x-y(PO₄)₃∶xTm³⁺,yDy³⁺荧光粉,利用X射线衍射仪、扫描电子显微镜和荧光光谱仪对荧光粉进行了物相、形貌和发光性能进行了表征。 在Na₃Sc₂(PO₄)₃∶0.06Tm³⁺,yDy³⁺荧光粉中,物质的量分数6%的Tm³⁺和6%的Dy³⁺在360 nm激发下呈现出白光发射,其发射光谱在460~685 nm范围内存在Tm³⁺位于457 nm的特征发射峰,对应于Tm³⁺的³H₆→¹D₂跃迁,以及Dy³⁺位于483、577和672 nm处的3个特征发射峰,分别对应于Dy³⁺的⁴F_9/2→⁶H_15/2、⁴F_9/2→⁶H_13/2和⁴F_9/2→⁶H_11/2的跃迁。 观测到Na₃Sc₂(PO₄)₃∶Tm³⁺荧光粉的发射光谱与Na₃Sc₂(PO₄)₃∶Dy³⁺的激发光谱有较好的重叠,且Tm³⁺的荧光寿命随Dy³⁺浓度的增加逐渐降低,因此在Na₃Sc₂(PO₄)₃∶Tm³⁺,Dy³⁺荧光粉中存在Tm³⁺向Dy³⁺的能量传递。 利用Dexter和Reisfeld近似分析了能量转移机制,发现从Tm³⁺到Dy³⁺的能量传递临界距离为1.6 nm,能量传递过程是通过偶极-偶极相互作用进行的。 Na₃Sc₂(PO₄)₃∶0.06Tm³⁺,0.06Dy³⁺荧光粉具有较好的耐受热猝灭性能,在423、473和523 K时的发射强度分别为298 K时发射强度的97.6%、89.2%和78.6%。 随着Dy³⁺浓度的增加,Na₃Sc₂(PO₄)₃∶0.06Tm³⁺,yDy³⁺荧光粉的发光颜色由蓝色转变为白色,再由白色变黄色。 Na₃Sc₂(PO₄)₃∶Tm³⁺,Dy³⁺荧光粉作为一种可调色或单相白光荧光粉在发光二极管上具有潜在的应用前景。

Synthesis and Luminescence Properties of a Single-Phase White-Emitting and Tunable Color Phosphor Na3Sc2(PO4)3∶Tm3+,Dy3+

A series of NSPO∶0.06Tm³⁺, yDy³⁺(y=0~0.10) phosphors were synthesized by the high-temperature solid-state method, and their phase, morphology and luminescent properties of the phosphors were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and fluorescence spectrometer. Under the excitation of 360 nm, the photoluminescence (PL) spectrum of Na₃Sc₂(PO₄)₃∶Tm³⁺,Dy³⁺ shows the Tm³⁺ characteristic emission peak at 457 nm and three characteristic emission peaks of Dy³⁺ at 483, 577, and 672 nm, respectively. There is an energy transfer from Tm³⁺ to Dy³⁺ ion in Na₃Sc₂(PO₄)₃∶Tm³⁺,Dy³⁺ phosphor due to the good overlap between the emission spectrum of Na₃Sc₂(PO₄)₃∶Tm³⁺ and the excitation spectrum of Na₃Sc₂(PO₄)₃∶Dy³⁺, which is further confirmed by the fluorescence lifetime decrease of Tm³⁺ ion with the increase of Dy³⁺ concentration. The process of energy transfer is via dipole-dipole interaction which is confirmed by applying Dexter and Reisfeld's theory. By increasing the Dy³⁺ concentration, the color coordinates of the Na₃Sc₂(PO₄)₃∶0.06Tm³⁺,yDy³⁺ phosphors could be adjusted from blue to white, and then to yellow. The Na₃Sc₂(PO₄)₃∶0.06Tm³⁺,0.06Dy³⁺ phosphor shows fairly good resistance to thermal quenching with a high preservation of the emission intensities of 97.6%, 89.2% and 78.6% at 423, 473 and 523 K, respectively. These results suggest that the Na₃Sc₂(PO₄)₃∶Tm³⁺,Dy³⁺ phosphors have potential applications as the color-tunable or a single-phase white emitting phosphor in white light-emitting diodes (LEDs).