Renping Cao,Dedong Peng,Haidong Xu,Zhiyang Luo,Hui Ao,Siling Guo,Jingwei Fu
Sr 3 (VO 4 ) 2 :Eu 3+ and Sr 3 (VO 4 ) 2 :Eu 3+ , Li + phosphors are synthesized by solid-state reaction method in air. X-ray diffraction patterns indicate that all samples are pure phase Sr 3 (VO 4 ) 2 . The host Sr 3 (VO 4 ) 2 with excitation 348 nm emits yellow-green light. Emission spectrum of Sr 3 (VO 4 ) 2 :Eu 3+ phosphor with excitation 335 nm contains a broad emission band peaking at ∼540 nm due to V 5+ → O 2− charge transfer and some narrow emission bands owing to the 4 f – 4 f electron transations of Eu 3+ ion in the range of 400–780 nm. With excitation 394 nm, only emision bands derived from Eu 3+ ion are observed. Emission intensity of Sr 3 (VO 4 ) 2 :Eu 3+ phosphor can be improved obviously due to charge compensation and fluxing agent role of Li + ion when Li + ion is co-doped. The optimal Eu 3+ doping concentration is ∼5 mol%. The energy transfer process between [VO 4 ] 3− group and Eu 3+ ion is observed and analyzed by emission spectrum in Sr 3 (VO 4 ) 2 :Eu 3+ phosphor. The luminous mechanism of Sr 3 (VO 4 ) 2 :Eu 3+ phosphor is explained by energy transfer and energy level diagram of [VO 4 ] 3− group and Eu 3+ ion.
Renping Cao,Dedong Peng,Haidong Xu,Shenhua Jiang,Ting Fu,Wenjie Luo,Zhiyang Luo
A series of Sr 3 (VO 4 ) 2 :Sm 3+ ,P 5+ ,Na + phosphors are synthesized by using solid-state reaction method in air. The strongest emission band peaking at ∼600 nm is assigned to the 4 G 5/2 → 6 H 7/2 transition of Sm 3+ ion, and the strong excitation peak at ∼402 nm due to 6 H 5/2 → 4 F 7/2 transition indicates that these phosphors can be excited by near ultraviolet light emitting diode chip. Energy transfer (ET) between VO 4 3− group and Sm 3+ ion can be observed. Sr 3 (VO 4 ) 2 :Sm 3+ phosphor with excitation 320 nm exhibits a systematically varied hues from green to yellow by changing Sm 3+ ion concentration from 0 to 6 mol%. The luminous mechanism of Sr 3 (VO 4 ) 2 :Sm 3+ phosphor is explained by using the energy level diagrams of VO 4 3− group and Sm 3+ ion. The luminescence properties of Sr 3 (VO 4 ) 2 :Sm 3+ phosphor can be improved and tuned by codoping the P 5+ and Na + ions due to ET and charge compensation. Lifetimes of Sr 2.925 Sm 0.05 (VO 4 ) 2 , Sr 2.925 Sm 0.05 (V 0.9 P 0.1 O 4 ) 2 , and Sr 2.9 Na 0.05 Sm 0.05 (V 0.9 P 0.1 O 4 ) 2 phosphors are 1.208, 1.219, and 0.796 ms, respectively. The experiment results are helpful to adjust the luminescence properties of Sm 3+ -doped other phosphors.
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