Lu Liping

Synthesis and luminescence property of Sr3SiO5:Eu2+ phosphors for white LED

Abstract Sr 3 SiO 5 :Eu 2+ yellow phosphors for white LEDs were synthesized by high temperature solid state reaction method under a reductive atmosphere. The crystalline phases were examined with X-ray diffraction (XRD). Luminescence properties were studied, and effects of various fluxing agents BaCl 2 , MgF 2 , CaF 2 and BaF 2 on the emission spectra were also studied. The optimal Eu 2+ concentration and flux were determined. Sr 3 SiO 5 : Eu 2+ was obtained by firing the sample on optimal composition and fabrication process. The sample showed a broad excitation band from 300 to 500 nm and a broad band emission peaking at 561 nm.

Upconversion Luminescence Properties of Ho3+, Tm3+, Yb3+ Co-Doped Nanocrystal NaYF4 Synthesized by Hydrothermal Method

Nanocrystal of upconversion (UC) phosphor Ho3+, Tm3+, and Yb3+, co-doped NaYF4 was prepared by the hydro-thermal method in the presence of the complexing agent EDTA. Under 980 nm diode laser excitation, the impact of different concentrations of Ho3+ ion on the UC luminescence intensity was discussed. The law of luminescence intensity versus pump power shows that the 474 nm blue emission, 538 nm green emission, and 642 nm red emission are all due to the two-photon process, while the 450 nm blue emission is a three-photon process. The UC mechanism and processes were also analyzed. The sample was characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The result shows that Ho3+, Tm3+, and Yb3+ co-doped NaYF4 prepared by the hydrothermal method exhibits a hexagonal nanocrystal.

Optimization of synthesis of upconversion luminescence material NaYF4:Er3+,Yb3+ nanometer-phosphor by low-temperature combustion synthesis method

A kind of Er3+-Yb3+ co-doped natrium yttrium fluoride nanometer-phosphor sensitive to 980 nm was synthesized by the low-temperature combustion synthesis method, which expanded the application range of the low-temperature combustion synthesis (LCS) method which is always used in the synthesis of oxides and compound oxides. The synthesis conditions were optimized with orthogonal experiments and the optimum technological parameters were obtained. Intense upconversion emissions at 522, 540 and 653 nm corresponding to the 2H11/2, 4S3/2, and 4F9/2 transitions to the 4I15/2 ground state were observed when excited by continuous wavelength (CW) laser radiation at 980 nm. The effect of the carbamide amount on the phase formation and the luminescence intensity was analyzed. The average particle size of the sample was 30–40 nm.

Preparation and Study on Spectrum Characteristics of Sr0.99 Ce0.01 HfO3 Nanopowders

Abstract The Sr 0.99 Ce 0.01 HfO 3 nanopowders were synthesized by the co-precipitation method. The calcination temperature and time of the powders were 1200 °C and 2 h, respectively. The powder size of Sr 0.99 Ce 0.01 HfO 3 nanopowders was 15 × 30 nm. There were two excitation bands in the excitation spectra of the Sr 0.99 Ce 0.01 HfO 3 nanopowders, which peaking at 216 and 309 nm, respectively. There were two emission bands in the emission spectra excited by the 220 nm light, which peaking at 398 and 467 nm. And they were corresponding to the 5d→ 2 F 5/2 and the 5d→ 2 F 7/2 transitions of Ce 3+ ions. But there was only one emission band in the emission spectrum excited by the 309 nm light which peaking at 392 nm.

Preparation and Characterization Upconversion Luminescence Material of Yttrium Aluminate Doped with Rare Earth

Abstract Low phonon energy yttrium aluminate was adopted as matrix and the upconversion materials yttrium aluminate co-doped with Yb3+ and Er3+ was synthesized by solid-state reaction method. The X-ray diffraction spectra and the upconversion emission spectra of various samples were measured and the effect of Er3+ concentration, sensitization, fluxing agent and calcining temperature on the luminescence properties was studied. Research results showed that the sample could emit green light at 543 and 570 nm when excited 980 nm laser; the optimum concentration of Er3+ should be 1.0%; sensitization of Yb3+ could enhance luminescent effects of Er3+ obviously; the optimum content of F3BO3 fluxing agent should be 8% and the optimum calcining temperature should be 1500 °C.