红色荧光粉LiAlSi3O8∶Eu3+的发光性能及热稳定性研究

Study of luminescent properties and thermal stability of red phosphor LiAlSi3O8∶Eu3+

关键词:  红色荧光粉  发光性能  Eu³⁺掺杂  化学共沉淀法  浓度猝灭  热稳定性

Key words:  red phosphor  luminescence property  Eu³⁺ doped  chemical co-precipitation method  concentration quenching  thermal ability

摘要:

为扩大色域的范围,降低白光LED的色温,提高其显色性和稳定性,本文采用化学共沉淀法制备LiAlSi₃O₈∶Eu^{3+红色荧光粉,并利用XRD、紫外-可见吸收光谱仪和荧光光谱仪分别对其结构、吸收和发光性能进行表征。结果表明:Eu3+作为红色发光中心进入基质LiAlSi₃O₈的晶格中形成单一基质荧光粉。样品LiAlSi₃O₈∶Eu3+}在394 nm存在较强的激发和吸收。样品的发射光谱由Eu³⁺的特征跃迁⁵D₀→⁷FJ(J=0~4)组成,主波长为614 nm。浓度淬灭的详细机理是电四极-电四极相互作用。在394 nm激发下,最佳荧光粉LiAlSi₃O₈∶0.05Eu³⁺发射红光,其CIE色坐标为(0.635 4, 0.352 9),色纯度达到87.91%,内量子效率为45.3%。样品具有良好的热稳定性,在473 K时,发光强度可保持初始强度的56%；活化能(ΔE)为0.215 0 eV。将红色荧光粉LiAlSi₃O₈∶0.05Eu³⁺与商用荧光粉BaMgAl₁₀O₁₇∶Eu和SrSi₂O₂N₂∶Eu封装得到白光LED,其相关色温(CCT)为6 161 K,色坐标为(0.308 7, 0.445 5),显色指数(CRI)为80。红色荧光粉LiAlSi₃O₈∶Eu³⁺可应用于近紫外芯片激发的发光二极管器件中。

Abstract:

In order to expand the range of color gamut, reduce the color temperature of white LED, and improve its color rendering, Eu³⁺-doped LiAlSi₃O₈ red phosphor was obtained by chemical co-precipitation method.The structure, absorption and luminescent properties were investigated by XRD (X-ray diffraction), ultraviolet-visible absorption spectrometer and fluorescence spectrophotometer, respectively. Results showed that Eu³⁺served as a red luminescent center that integrated into the lattice of LiAlSi₃O₈ matrix, forming a single matrix phosphor. The sample LiAlSi₃O₈∶Eu³⁺ had strong excitation and absorption at 394 nm. The emission spectrum exhibited characteristic transitions of Eu³⁺ from ⁵D₀ to 7FJ(J=0-4), with a principal wavelength of 614 nm. The detailed mechanism of concentration quenching was quadrupole-quadrupole interactions. Under excitation at 394 nm, the optimal phosphor LiAlSi₃O₈∶0.05Eu³⁺ emitted red light, with CIE chromatic coordinates of (0.635 4, 0.352 9), and a colorr purity of 87.91% and internal quantum efficiency of 45.3%. The luminescent intensity maintained 56% of its initial intensity at 473 K due to its stable thermal ability with an activation energy (ΔE) of 0.215 0 eV. When the red phosphor LiAlSi₃O₈∶0.05Eu³⁺, commercial phosphors BaMgAl₁₀O₁₇∶Eu and SrSi₂O₂N₂∶Eu were packaged, white LEDs are produced, exhibiting a correlated color temperature (CCT) of 6 161 K, CIE chromatic coordinates of (0.308 7, 0.445 5), and a color rendering index (CRI) of 80. This red phosphor can be applied to the light-emitting diode devices excited by near-ultraviolet chips.