白光LED用单基质荧光粉BaSrMg(PO_4)_2:Eu^(2+)的制备及发光性能研究

Preparation and Luminescence of Single-Host White-Light-Emitting BaSrMg(PO_4)_2:Eu^(2+) Phosphor for Ultraviolet LEDs

采用高温固相反应法在1 200℃下制备了Eu2+激活的BaSrMg(PO4)2高亮度白光荧光粉,并对其晶体结构和发光性能进行了研究。荧光光谱研究表明该荧光粉的发射光谱由两个谱带组成,其中心分别位于424和585nm处,归结为Eu2+分别占据了基质中Sr2+,Ba2+格位而导致的4f65d1→4f7电子跃迁。两个发射峰的激发光谱均分布在250～400nm的波长范围内,峰值位于360nm左右。表明该荧光粉可被IN-GaN管芯产生的近紫外辐射有效激发,是一种性能良好的白光LED单一基质白光荧光粉。深入考察了基质中不同Ba和Sr的比例、Eu2+掺杂浓度对荧光粉发光强度和色坐标的影响,并可通过改变上述参数实现该荧光粉的色坐标可调性,在最优条件下该荧光粉发光已在白光区域。考察了Eu2+掺杂浓度对荧光粉量子效率的影响,为荧光粉的最佳掺杂浓度提供理论依据。

A single-host white-light-emitting phosphor BaSrMg（PO4）2∶Eu2＋ was prepared by high temperature solid-state reaction method,and the luminescence characteristics and XRD pattern were investigated.The results show that BaSrMg（PO4）2 phase was obtained by sintering at 1 200 ℃ for 3 hours.BaSrMg（PO4）2∶Eu2＋ phosphor exhibits two main emission bands peaking at 424 and 585 nm,respectively.The emission band peaking at 424 nm is attributed to the 4f 65d1→4f7 transition of Eu2＋ substituting Sr2＋,while the emission band peaking at 585 nm originates from the 4f 65d1→4f7 transition of Eu2＋ replacing Ba2＋ in host lattice.The excitation spectra of the two emission peaks are range from 250 to 400 nm and both peaking at 360 nm.The effect of the proportion of Ba and Sr,and the Eu2＋ doping concentration on the emission intensity were discussed in detail.Different chromaticity coordinates were obtained for each phosphor,that is,the chromaticity coordinates of the designed phosphor is tunable for the white-emitting LED or for special purpose.Quantum efficiency was also examined for the phosphors with different Eu2＋ doping concentration,and concentration quenching took place obviously when Eu2＋ doping concentration was lager than 6% in mole ratio.The obtained phosphor BaSrMg（PO4）2∶Eu2＋ can be excited by near ultraviolet radiation effectively and emit full color lighting,which is a promising single-host white-light-emitting phosphor for white LED.