Er^(3+)/Yb^(3+)掺杂NaY(MoO_4)_2荧光粉的制备及其上转换发光性能研究

Synthesis and Upconversion Luminescence Properties of Er^(3+)/Yb^(3+) Doped NaY(MoO_4)_2 Phosphor

采用高温固相法合成了一系列Er^(3+)单掺和Er^(3+)/Yb^(3+)共掺NaY(MoO_4)_2荧光粉样品。通过X射线衍射仪、扫描电子显微镜、激光粒度仪和荧光光谱仪分别对样品的相纯度、微观形貌、粒径分布和上转换发光性能进行了表征。在980 nm激光激发下,Er^(3+)单掺和Er^(3+)/Yb^(3+)共掺样品的发射光谱中均能观测到中心波长位于536 nm、560 nm的上转换绿光发射和位于660 nm的红光发射,分别归因于Er^(3+)的~2H^(11/2)→~4I_(15/2)、~4S_(3/2)→~4I_(15/2)和~4F_(9/2)→4I_(15/2)能级跃迁。在Er^(3+)单掺体系中共掺Yb^(3+),可以轻松实现由上转换绿光到红光的转变。NaY_(1-x-y)(MoO_4)_2∶x Er^(3+),y Yb^(3+)样品中最优的Er^(3+)/Yb^(3+)掺杂浓度和最佳的烧结温度为x=0.04、y=0.5、T=850℃。基于泵浦依赖和能级图,在Er^(3+)单掺和Er^(3+)/Yb^(3+)共掺体系上转换发光过程中所涉及的能量转移机制被详细讨论。

A series of Er^(3+)doped and Er^(3+)/Yb^(3+)co-doped NaY(MoO_4)_2 phosphors were synthesized by a high-temperature solid-state method. The phase purity, morphology and particle size distribution of the samples were characterized by X-ray diffraction(XRD), scanning electron microscope(SEM), laser particle analyzer and photoluminescence(PL)spectroscopy. Under 980 nm laser excitation, the green(at 536 nm and 560 nm) and red(at 660 nm) UC emission were observed in both Er^(3+)doped and Er^(3+)/Yb^(3+)co-doped samples, which could be attributed to the^2H^(11/2)→~4I_(15/2)、~4S_(3/2)→~4I_(15/2)and^4F_(9/2)→4I_(15/2) transitions of Er^(3+), respectively. By co-doped Yb^(3+)ions into the Er^(3+)doped system, the UC luminescence can be easily tuned from green to red emission. The Er^(3+)/Yb^(3+)doping concentrations and sintering temperature of NaY1-x-y(MoO_4)_2∶xEr^(3+), yYb^(3+)were optimized to x=0.04, y=0.5 and T=850 ℃. Based on the pump power dependence and energy level diagram, the energy transfer mechanism involved in upconversion luminescence processes of Er^(3+)doped and Er^(3+)/Yb^(3+)co-doped system were investigated in detailed.