Xinmin Zhang

Synthesis and spectral characteristics of La2MoO6：Ln3＋ （Ln=Eu, Sm, Dy, Pr, Tb） polycrystals

Abstract The novel phosphors of La 2 MoO 6 activated with the trivalent rare earth Ln 3+ (Ln=Eu, Sm, Dy, Pr, Tb) ions were synthesized by solid state reactions at high temperature in air atmosphere, and their phase impurities and luminescent properties were studied. The photoluminescence (PL) excitation and emission spectra, and decay curves were employed to study their luminescence properties. The lifetimes of the characteristic emissions from Ln 3+ ions were in the order of millisecond except Pr 3+ ions. (LaEu 1− x ) 2 MoO 6 was a promising phosphor for practical application and the optimum concentration was x =0.075. The concentration quenching mechanism of Eu 3+ was also discussed by theoretical fitting using Burshtein model.

Photoluminescence properties of (Gd1–xEux)Ba3B9O18 red emitting phosphors

Abstract Eu 3+ -activated GdBa 3 B 9 O 18 phosphors were prepared by solid-state reaction at high temperature, and their photoluminescence (PL) properties were investigated. (Gd 1– x Eu x )Ba 3 B 9 O 18 formed solid solutions in the range x =0–1.0. The optical band gaps calculated from absorption spectra were 5.54 eV for GdBa 3 B 9 O 18 and 5.17 eV for EuBa 3 B 9 O 18 . Unactivated GdBa 3 B 9 O 18 exhibited a typical characteristic excitation and emission of Gd 3+ ion. The (Gd 1– x Eu x )Ba 3 B 9 O 18 phosphors showed well-known Eu 3+ excitation and emission. The energy transfer from Gd 3+ to Eu 3+ was verified with PL spectra. The dependence of PL intensity on Eu 3+ concentration was also studied in detail. The luminescence decay measurements indicated that the lifetimes of 5 D 0 → 7 F 1 transition of Eu 3+ were in the order of millisecond.

Analysis of Energy Transfer and Concentration Quenching in Sm3+-Activated Borate GdB3O6 Phosphors by Means of Fluorescence Dynamics

This article reports on the optical properties of Sm3+-activated GdB3O6 phosphors based on the measurement of their photoluminescence spectra and luminescence decay curves. Energy transfer from Gd3+ to Sm3+ and the concentration quenching of the Sm3+ ion emission are investigated. From the photoluminescence spectra and decay curves, the energy transfer from Gd3+ to Sm3+ is confirmed. The concentration quenching of the Sm3+ ion emission can be ascribed to resonant cross-relaxation. The interaction between the Sm3+ ions is derived of the electric dipole–dipole type through fitting the data with the Inokuti-Hirayama model. The critical distances and energy transfer microparameter for the transfer processes are given. The decay curves of Sm3+4G5/2 level exhibiting a buildup and decay process also confirm the energy transfer from Gd3+ to Sm3+ and between Sm3+ ions.

Luminescence of Eu2+ and Eu2+-Mn2+ in sodium scandium diphosphate NaScP2O7 crystal

Abstract In this work, the photoluminescence (PL) of NaScP 2 O 7 :Eu 2+ and NaScP 2 O 7 :Eu 2+ ,Mn 2+ was investigated. Phase purity was checked using X-ray powder diffractometry (XRD). PL excitation and emission spectra were recorded to elucidate the PL properties of NaScP 2 O 7 :Eu 2+ and NaScP 2 O 7 :Eu 2+ ,Mn 2+ . Furthermore, fluorescence lifetime measurements were performed. PL and lifetime measurements were carried out from 10 to 525 K. Moreover, the Eu 2+ site occupation was discussed. It turned out that the incorporated Eu 2+ ions substituted for Na + site and occupied two different sites. Temperature dependent PL measurements indicated the emission intensity decreased with increasing temperature due to temperature quenching in NaScP 2 O 7 :Eu 2+ . Fluorescence lifetimes of Eu 2+ in NaScP 2 O 7 :Eu 2+ almost did not change with a decay constant τ =∼0.53 μs in the temperature range of 10–280 K, and then shortened due to temperature quenching. The luminescent lifetime reached ∼0.05 μs at T =525 K. Finally, it was found that energy transfer occurred from Eu 2+ to Mn 2+ in co-doped NaScP 2 O 7 :Eu 2+ ,Mn 2+ .