Ca_(4)HfGe_(3)O_(12)∶Eu^(3+)红色耐高温荧光粉的制备与发光特性研究

Preparation and Luminescent Properties of Ca_(4)HfGe_(3)O_(12)∶Eu^(3+)Red Phosphor with Excellent Thermal Stability

采用固相法合成Ca_(4)HfGe_(3)O_(12)∶xEu^(3+)(CHGO, 0≤x≤0.05)样品。利用X射线衍射(XRD)、瞬态和稳态光谱、热稳定性等手段表征样品的物相结构和发光特性。XRD结果表明,Eu^(3+)成功进入石榴石结构晶格,光谱观察到CHGO∶Eu^(3+)荧光粉可以被紫外光有效激发,在616 nm(5D0→7F2)处表现为较强红色窄带。根据荧光发射光强和荧光寿命的变化趋势,确定最佳Eu^(3+)掺杂浓度为0.04,更多掺杂量引起浓度猝灭现象,猝灭效应来自于Eu^(3+)间偶极-偶极相互作用。依据Eu^(3+)激发光谱分布和寿命衰减行为的不同,证明了Eu^(3+)在CHGO基质中占据两个晶体学格位。CHGO∶0.04Eu^(3+)荧光粉在423 K下的发射光谱积分面积为室温下的94%,表明该样品具有优良的热稳定性和潜在的高温器件应用。CHGO∶0.04Eu^(3+)的色坐标(0.5605,0.3469)和低色温3068 K表明该材料可能是一种潜在暖白照明用红光荧光粉。

The Ca_(4)HfGe_(3)O_(12)∶xEu^(3+)(0≤x≤0.05)phosphors were synthesized by high temperature solid phase method.The phase structure and luminescence characteristics of the phosphors were studied by XRD,emission spectra,lifetime and thermal stability.The XRD results show that Eu^(3+)ions successfully enter the garnet structure lattice,and it is observed from the excitation spectra that the phosphor could be effectively excited by ultraviolet light,showing a strong narrow red band at 616 nm(5D0→7F2).According to the change trend of fluorescence emission intensity and fluorescence lifetime,the optimal Eu^(3+)doping concentration is 0.04,and more doping amount will cause concentration quenching phenomenon.The quenching effect came from the Eu^(3+)dipole-dipole interaction.It is proved that Eu^(3+)occupies two crystallographic sites in CHGO matrix based on the difference of excitation spectra distribution and lifetime decay behavior.It is worth mentioning that the emission spectrum integral area of CHGO∶0.04Eu^(3+)phosphor at 423 K is 94%of that at room temperature,indicating that the sample has excellent thermal stability and potential high temperature device applications.The color coordinates(0.5605,0.3469)and low color temperature 3068 K of CHGO∶0.04Eu^(3+)indicate that the material may be a potential red phosphor for warm white lighting.