Eu2+掺杂CaSi2O2N2荧光粉发光性能

采用固相反应法合成了组成为Ca_1-xEu_xSi₂O₂N₂的Eu²⁺掺杂CaSi₂O₂N₂荧光粉.通过荧光光谱对样品的发光性能进行了研究,发现Eu²⁺掺杂CaSi₂O₂N₂荧光粉发射光谱为宽波段的单峰结构,主要包含绿光和黄光区,发射峰在556~568 nm.从发射光谱的宽带特征来看,CaSi₂O₂N₂:Eu²⁺的发射主要对应着Eu²⁺离子4f⁶5d→4f⁷跃迁.从激发光谱所覆盖的范围还可以看到,样品可以有效的被UV蓝-光激发,这意味着该类荧光粉在白光LED方面有可能得到广泛的应用.另外,样品的发光性能与激发离子的浓度有着很大关系.激发离子浓度增大时,发射光谱会发生明显红移.利用这一性质,可以通过改变Eu²⁺浓度来调节荧光粉的发光范围,从而满足不同场合的需要.同时,Eu²⁺浓度提高,样品发射光谱的强度也会随之增强,在x=0.06时发射强度达到最大值,之后继续增加Eu²⁺浓度,强度不仅没有增加反而降低,即出现浓度猝灭现象.

Luminescence Properties of Eu2+-doped CaSi2O2N2 Phosphors

Eu2 -doped CaSi2O2N2(Ca1-xEuxSi2O2N2) has been prepared by solid-state reaction method,and the optical properties of the alkaline-earth silicon-oxynitride phosphor have been investigated.Eu2 -doped CaSi2O2N2 displayed a single broad emission band peaking at 556~568 nm depending on the europium concentration.The emission bands in the spectra of Eu2 -doped CaSi2O2N2 were assigned to the allowed transition of Eu2 from the lowest crystal field component of 4f65d to 4f7 ground-state level.It has been demonstrated that the Eu2 -doped CaSi2O2N2 phosphor absorbs strongly the UV-blue part of the electromagnetic spectrum which makes this material attractive as the conversion phosphor for white light-emitting diodes(LEDs) applications.We have also shown that the optical properties depend greatly on the Eu2 concentration.A systema-tic red shift of the emission band is observed as the Eu2 concentration increases.The results indicate the photoluminescence properties can be tailored by controlling the Eu2 concentration.Moreover,for all samples,starting at low Eu2 concentration,the emission intensity rises to a maximum at a Eu2 concentration of x=0.06 and falls again when the Eu2 concentration continues to increase.This decrease in emission intensity beyond a critical concentration can be explained by concentration quenching,which is mainly caused by the energy transfer between Eu2 ions.