Ca4LaNbMo4O20:Pr3+荧光粉的发光性质

采用高温固相法成功制备出荧光粉Ca₄LaNbMo₄O₂₀:Pr³⁺,通过X射线衍射分析了样品的结构,其结构与CaMoO₄结构相似。在Ca₄LaNbMo₄O₂₀:Pr³⁺的激发光谱中出现了NbO₄^3-和MoO₄^2-的电荷迁移(CTS)吸收和Pr³⁺离子的4f→4f5d激发跃迁,以及Pr³⁺-金属离子的价间电荷迁移(IVCT)吸收;另外在420~520 nm处,还观测到属于Pr³⁺离子的典型f-f激发跃迁。发射光谱中,在452 nm激发下,主要出现绿光和红光两种发射,其峰值位于490 nm和607 nm处,分别是Pr³⁺的³P₀→³H₄和¹D₂→³H₄的跃迁作用;在紫外287 nm激发下出现NbO₄^3-和MoO₄^2-发射和Pr³⁺离子的4f5d→4f跃迁宽带,以及Pr³⁺离子的4f→4f发射峰。

Photoluminescence Characteristics of Ca4LaNbMo4O20:Pr3+

The phosphor Ca4LaNbMo4O20∶Pr3+ has been prepared by the solid-state method.The photoluminescence(PL) properties have been investigated.The XRD patterns are similar to that of CaMoO4 structure.The excitation spectrum of Ca4LaNbMo4O20 exhibits a broad absorption band at 257 nm,which is attributed to the charge transfer states(CTS) of MoO2-4 and NbO3-4 complexes.The excitation spectrum of Ca4LaNbMo4O20∶Pr3+ shows an absorption band centered at 287 nm,which is attributed to the 4f→4f5d transition of Pr3+.The excitation spectrum of Ca4LaNbMo4O20∶Pr3+ also shows two weak shoulder absorption bands at about 266 and 320 nm,which are originated the charge transfer states(CTS) of MoO2-4 and NbO3-4 complexes and the intervalence charge transfer(IVCT) transition of Pr-metal,respectively.The 4f-4f transitions of Pr3+ are also observed in the region of 420~520 nm.As a result,it can efficiently convert the blue pump light of the Ⅲ-N semiconductor LED into visible wavelength bands.The photoluminescence spectrum of Ca4LaNbMo4O20∶Pr3+ excited with 452 nm shows the green and red emissions originated of the 3P0→3H4(490 nm) and 1D2→3H4(607 nm) transitions of Pr3+ ions,respectively.At excited with an ultraviolet wavelength of 287 nm,the emission spectrum of Ca4LaNbMo4O20∶Pr3+ exhibits the broad emission band centered at 490 nm and several sharp emission peaks at 490,536,561,607 nm.The broad band is belonging to the overlap of the host emission and the 4f5d→4f transition of Pr3+ ions.The sharp emission peaks are attributed to the 3P0→3H4,3P1→3H5,3P0→3H5 and 1D2→3H4 transitions of Pr3+ ions.It is speculated that the energy transfer occurs from the MoO2-4 and NbO3-4 complexes to Pr3+ ions.However,the efficiency of energy transfer is very weak.