LEDs用KSr_4(BO_3)_3∶Eu^(2+)荧光粉的发光性质

Luminescence Properties of KSr_4( BO_3)_3∶ Eu^(2+) for Light-emitting Diodes

采用固相法合成了KSr4(BO3)3∶x Eu2+(KSB∶x Eu2+)荧光粉,通过X射线粉末衍射(XRD)、扫描电镜(SEM)及光致发光光谱分别研究了样品的晶相、形貌及发光性质。XRD研究结果表明制备的样品为正交晶系的KSr4(BO3)3单相。当Eu2+的掺杂摩尔分数x为1.5%时,在激发光谱250~550 nm范围内观察到了两个宽带激发,可归属为Eu2+的4f7-4f65d1跃迁;在400 nm激发下,发射谱呈现出一个不对称的黄色发射带,峰值位于560 nm处,可归属于Eu2+的4f65d1-4f7跃迁。因在KSr4(BO3)3化合物中存在3个Sr格位,根据其光谱特征可推测发射谱中非对称的发射带来源于多个Eu2+发光中心。

KSr4(BO3)3∶xEu2+( KSB∶x Eu2+) phosphors were synthesized by solid-state reaction method. The phase,morphology,and luminescence properties of the samples were characterized by using XRD,SEM,and photoluminescence spectra. XRD results show that the as-prepared samples are orthorhombic KSr4( BO3)3single-phase. When x = 1. 5%,two broad bands are observed from250 to 550 nm in the excitation spectra,which are attributed to 4f7-4f65d1 transition of Eu2 +. Under the excitation of 400 nm,the emission spectrum shows an asymmetric yellow emission band around560 nm,attributed to 4f65d1-4f7 transition of Eu2 +. Because of three Sr crystallographic sites in KSr4( BO3)3compound,one can infer that the asymmetric emission results from multiple Eu2 +centers by the spectral characteristics.