Papers by Keyword: Luminescence Property

Abstract: Introduction of metallic nanoparticles into glasses can obviously improve the up-conversion luminescence efficiency through surface plasmon resonance (SPR). In this research, the Er³⁺/Yb³⁺ co-doped TeO₂-ZnO-Bi₂O₃ glasses containing silver nanoparticles and nanocrystals were prepared by direct current(DC) electric field assisted heat treatment, to study the effect of silver nanoparticles on the up-conversion luminescence properties of Er³⁺. The results show that, although the introduction of AgNO₃ will weaken the thermal stability of TZB-ErYb to some extent, the number and size of silver nanoparticles can be increased after DC electric field treated at 100°C for 10 minutes. Meanwhile, the nanocrystals do not grow too large to affect the up-conversion emission intensity of Er³⁺. The up-conversion emission intensity of Er³⁺ in TZB-ErYb-6AgNO₃-100°C-150V-10min is 43 times stronger than that of TZB-ErYb. These results indicate that DC electric field assisted heat treatment can synergistically adjust the silver nanoparticles and nanocrystals and is a promising method to improve the luminescence properties of tellurite glasses.

Abstract: Europium doped lithium barium borate glasses were fabricated by conventional melt-quench method and were analyzed their physical, optical and luminescence properties through absorption, excitation, emission and decay analysis at room temperature. The experimental data revealed that the five discrete absorption bands peaking at 393, 464, 532, 2032 and 2212 nm due to the transitions from ⁷F₀ ground state level to various excited states of Eu³⁺ ions. The luminescence of Eu³⁺ in visible bands were observed under 394 nm pumping.

Abstract: Efficient and well-grown SrAl₂O₄:Eu,Dy phosphors were synthesized by an innovative melt synthesis method. The luminescent intensity and after-grow intensity of the SrAl₂O₄:Eu,Dy phosphors synthesized by the melt synthesis method are comparable to those of the sample synthesized by a conventional solid state reaction. Sintered phosphor balls with excellent luminescent characteristics were obtained.

Abstract: Spherical YAG:Ce³⁺ phosphors were synthesized by three different routes namely sol-gel method, co-precipitation method and solvethermal method. The microstructure, crystallization and luminescent properties of the phosphors were studied in order to find the best processing parameter for spherical shape and good luminescence properties of YAG:Ce³⁺ phosphor. Adding citric acid to the precursor solution resulted in the formation of spherical particles in sol-gel method. YAG:Ce³⁺ phosphor made by co-precipitation method was separated with PEG2000, and its spherical particles of size was around 500nm. The hydro-thermal method could get perfect spherical appearance, but it needed heat treatment improve the luminescence property.

Abstract: Rare earth metal complexes have special characteristics, such as extremely narrow emission bands and high internal quantum efficiencies, which are suitable to be used as the emission materials, chemistry and biological technology. Ternary nano complex of terbium gatifloxacin phenanthroline was synthesized.The composition and structure of ternary complex were characterized by element analysis, Mass Spectrometry (MS), UltraViolet Absorption Spectrometry (UV) and fluorescence spectra(FS). The influences of solubility, thermal stability and luminescent properties of complex as well as addition of phenanthroline secondary ligands on the fluorescence spectra of the ternary complexes were studied. The results of fluorescence spectra analysis showed that partial energy was transferred from Characterization to terbium ions by intramolecular energy transfer processes, meanwhile, the addition of phenanthroline can effectively increase the luminescence intensity of terbium icons. The complex possessed well luminescence and showed characteristic emission peaks of Tb³⁺ under UV light excitation and emitted strong green fluorescence. Moreover, in an ITO/PVK/Tb(GFLX)₃Phen/Al device, Tb³⁺ ion can be excited by intramolecular ligand-to-metal energy transfer process. The main peak of emission at 545 nm is attributed to ⁵D₀→⁷F₂ transition of the Tb³⁺ ion, and this process results in the enhancing green emission. Biological actrivity properties of the rare earth complex was well studied.

Abstract: In this paper, a novel yellow-emitting oxynitride phosphor Sr_3-2xSiO_5-6xN_4x: yCe³⁺, yLi⁺ (0 x 0.33, 0.01 y 0.04) has been reported. The XRD patterns illustrate that the partial substitution of (SiN)⁺ for the (SiO)²⁺ is feasible and the major phase of synthesized samples is isostructural with Sr₃SiO₅. Under blue light excitation, the oxynitride phosphor shows a broad emission about 557 nm, contributing to the 4f5d transition. The PL intensities show a blue shift as the increase of nitrogen content (the locations of peaks move from 559 nm to 549 nm).

Abstract: Properties of Dy³⁺ doped ZnO-BaO-TeO₂ (ZBaT) glass systems with composition 15ZnO-5BaO-(80-x)TeO₂-xDy₂O₃ was measured for the composition range 1x8 (in mol%). The glasses were prepared by normal melt quenching technique and characterized their physical, optical and photoluminescence properties. The optical absorption spectra show peaks at ⁴I_15/2 (466 nm), ⁴F_9/2 (475 nm), ⁶F_3/2 (756 nm), ⁶F_5/2 (804 nm), ⁶F_7/2+ ⁶H_5/2 (904 nm), ⁶F_9/2+ ⁶H_7/2 (1096 nm), ⁶F_11/2 +⁶H_9/2 (1280 nm) and ⁶H_11/2 (1640 nm), reflecting the Dy³⁺ in glass matrices. From the excitation spectra, five obvious excitation peaks were observed as follows: The ground state ⁶H_15/2 to the excited states ⁴M_7/2 + ⁶P_7/2 (351nm), ⁴I_11/2 (366 nm), ⁴I_13/2 + ⁴F_7/2 (385 nm), ⁴G_11/2 (426 nm) and ⁴I_15/2 (450 nm) of Dy³⁺. The emission band at 484, 575 and 661 nm arising from the transition ⁴F_9/2⁶H_15/2, ⁴F_9/2⁶H_13/2 and ⁴F_9/2⁶H_11/2 respectively were observed when the sample was excited by xenon flash lamp at 450 nm. The ZBaT glass doped with 1 mol% of Dy³⁺ gives the highest result for luminescence properties.

Abstract: The ZnO-Bi₂O₃-B₂O₃ (ZBB) glasses with different concentrations of Bi₂O₃ have been prepared by a conventional melt quenching technique and investigated the effect of Bi₂O₃ on the physical, structural and luminescence properties. The density and hardness of glasses are also measured and found to increase with increase of Bi₂O₃ concentration. The IR studies indicate that these glasses are made up of [BiO₃], [BO₃], [BO₄] and [B basic structural units. From optical spectra, the cut-off wavelengths were shifted from 423 nm to 447 nm as the content of Bi₂O₃ increases from 15 to 30 mol%. The photoluminescence spectra exhibit characteristic peaks at 602 nm corresponding to ³P₁ ¹S₀ transitions of Bi³⁺. The decay time for ³P₁ level of Bi³⁺ increases with increase of Bi₂O₃ concentration.

Abstract: Er3+:ZnS quantum dots(QDs) were synthesized by hydrothermal process. The structure, morphology and luminescence properties were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy. It was found that the Er3+:ZnS QDs are zinc blende structure with an average particle size of about 8 nm. In PL spectra, The broad peak of ZnS NCs located at 400nm was commonly assigned to sulfur vacancies. The intensity of exciting peak and emission peak at of Er3+:ZnS QDs decreased with doping concentration increasing.

Abstract: ZnMoO₄:Eu³⁺ red phosphors were prepared by ion exchange method in strong acid media. The structure and morphology of products were characterized through XRD, TG-DTA, TEM, HRTEM and UV-vis after preparation. The luminescence properties of them were investigated with emission and excitation spectra.The results indicate that the ZnMoO₄:Eu³⁺ red phosphors were in rodelike structure and the diameter is about 2μm,the length is about 30μm after the precursor annealed at 800°C for 2 h. The excitation spectra showed effective excitation wavelengths at UV (395 nm) and blue (465 nm) corresponding to the f-f transition of Eu³⁺. These wavelengths coincided with the wavelengths of commercial GaN based LED, so that the phosphor might be a better candidate for red component for white LEDs.