In the present work, orange-red Sm 3+ doped La 3 Ga 5 SiO 14 phosphors were successfully formed through high temperature solid state method at 1350 °C. The phase purity, size distribution, vibrations, absorption and series of luminescence characteristics were studied, respectively. The X-ray diffraction and Rietveld refinements results show the single phase and crystal lattice information. The results of scanning electron microscope and energy-dispersive spectroscopy demonstrate the basic particle shape and verify the constituent elements for the prepared samples. The infrared spectra clarify the phonon vibration properties of the La 3 Ga 5 SiO 14 :Sm 3+ phosphors. The UV–visible absorption spectra indicate that the absorption properties and the corresponding band gaps. The luminescence results show that the La 3 Ga 5 SiO 14 :Sm 3+ phosphors emit intense orange-red emission peaking at 600 nm as excited at 401 nm. The optimum doping concentration of Sm 3+ ion is x = 0.05 and the mechanism of concentration quenching is from dipole-quadrupole interaction. In addition, the prepared phosphors have good thermostability, and its thermal activation energy is 0.2161 ev. Finally, red and white light emitting diodes were successfully manufactured with 395 nm chip. All experimental results show that the La 3 Ga 5 SiO 14 :Sm 3+ phosphors have good application prospect in light emitting diodes .
Na-Na Zhang,Hong-Yu Wang,Xue-Yuan Yan,Xu-Ping Wang,Bing Liu,Yuan-Yuan Zhang,Yu-Guo Yang
In this work, deep-red-emitting La 3 Ga 5 SiO 14 :Mn 4+ (LGS:Mn 4+ ) phosphors were successfully fabricated using high-temperature solid-state synthesis techniques, and a series of features were characterized. The phase and lattice information of the phosphors were determined through X-ray diffraction and Rietveld refinement. The microstructure and elemental characteristics were analyzed using scanning electron microscope. Infrared spectroscopy revealed the lattice vibration characteristics of the phosphors. The UV-visible absorption spectra demonstrated the absorption characteristics and band gap. Luminescence measurements showed that LGS:0.05 %Mn 4+ phosphors emit the bright deep-red light at 713 nm when excited at 365 nm, which originates from the 2 E g → 4 A 2g transitions of Mn 4+ ions. The optimum doping concentration for Mn 4+ is x = 0.25 mol% and the concentration quenching mechanism is attributed to dipole-dipole interactions. The lifetime of Mn 4+ ion decreases monotonically with the addition of Mn 4+ ions owing to the non-radiative transition effects. In addition, the prepared LGS:0.25 mol%Mn 4+ phosphors exhibit good thermostability, with an activation energy of 0.637 eV
Honglei Yuan,Yanzhi Bai,Gaoliang Wang,Liuyang Xu,Huanxia Jia,Xianke Sun
The broadband near-infrared phosphors are feasible to apply in real-time nondestructive examination . In this work, La 3 Ga 5 SiO 14 :Cr 3+ phosphors with the broadband near-infrared emission have been synthesized using a solid state reaction method. Their optical characteristics were investigated via the measurements of ultraviolet–visible diffused reflectance and luminescence spectra. The occupations of Cr 3+ ions in La 3 Ga 5 SiO 14 host were inquired by the X-ray absorption near edge structure and electron paramagnetic resonance analyses. The results indicate that Cr 3+ ions substitute octahedral and tetrahedral Ga 3+ ions in La 3 Ga 5 SiO 14 host, which results in a sharp emission band coming from the 2 E g → 4 A 2g transitions of Cr 3+ and a wide emission band coming from the 4 T 2g → 4 A 2g transitions of Cr 3+ . The fabricated NIR pc-LED device by combining the synthesized La 3 Ga 5 SiO 14 :0.10Cr 3+ phosphor with a blue LED chip indicates that the La 3 Ga 5 SiO 14 :Cr 3+ phosphors have potential applications in nondestructive examination.
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