Luminescence Of Dy3 Research Articles

Preparation and luminescence of Dy3+/Tm3+ co-doped Ca3NbGa3Si2O14 glass-ceramics for w-LED

In this work, a series of Dy3+ and Dy3+/Tm3+ ion activated Ca3NbGa3Si2O14 glass-ceramics were prepared by traditional melt crystallization method, and report on the structural, optical, and energy transfer (ET)-based photoluminescence (PL) properties of glass-ceramics co-doped Dy3+/Tm3+. The preparation of glass-ceramics was studied by DTA, XRD, SEM, and UV–vis photometer technology, phase composition, transmittance, optimum heat treatment conditions, and luminescence properties. The best heat treatment procedure for obtaining transparent and well-formed glass-ceramics is crystallization at 820 °C for 5 h. The spectra excited by Tm3+ and Dy3+ have intersections at 352 nm and 365 nm, which means that CNGS: Dy3+/Tm3+ can be effectively excited by 352 nm and 365 nm ultraviolet light. Under the excitation of 352 nm ultraviolet light, four main emission peaks corresponding to 1D2 →3F4, 4F9/2 → 6H15/2, 4F9/2 → 6H13/2, 4F9/2 → 6H11/2 were found at 456 nm, 484 nm, 577 nm, and 663 nm, respectively. When the optimal concentration (4 at.%) of Dy3+ is Co-doped with a different amount of Tm3+, the luminous color can be adjusted by adjusting the doping amount of Tm3+ and changing the excitation wavelength. There is an overlapping region between the emission spectrum of Tm3+ doped glass and the excitation spectrum of Dy3+ doped glass, which indicates that there is energy transfer between Tm3+ and Dy3+. In addition, CNGS: Dy3+/Tm3+ CIE coordinates show that the color coordinates (0.3324, 0.3352) when y = 0.02 under 365 nm excitation are closest to the standard white light (0.333, 0.333), indicating that this glass has potential applications in WLED devices.

Preparation and luminescence of Dy3+ doped glass-ceramics containing ZnMoO4

Dy3+ doped ZnMoO4 glass-ceramics was prepared by traditional melt crystallization method. The crystalline phase, microscopic morphology, transmittance, the optimal heat treatment condition and luminescence properties of the samples were discussed. The emission peaks are located at 482 nm, 574 nm and 663 nm due to 4F9/2→6H15/2, 4F9/2→6H13/2 and 4F9/2→6H11/2 transitions of Dy3+ under 387 nm. When the doped concentration of Dy3+ exceeded 0.4%, it was proved that the multi-stage interaction between adjacent ions causes concentration quenching by calculating the critical distance between Dy3+. The chromaticity coordinate (CIE) showed the luminescence color of the samples in the white light region, indicating that Dy3+ doped glass-ceramics containing ZnMoO4 were expected to be applied in white-light emitting diode (w-LED).

Broadband mid-infrared emission in Dy3+/Er3+ co-doped tellurite glass

Broadband mid-infrared luminescence in Dy3+/Er3+ co-doped tellurite glasses was reported in this work. The doped tellurite glasses were prepared using conventional melt-quenching technique, and their structural property and thermal stability were analyzed by the X-ray diffraction (XRD) pattern, Raman spectrum and differential scanning calorimeter (DSC) curve. Judd-Ofelt theory was applied to the absorption spectra to evaluate the spectroscopic properties like radiative transition probability, branching ratio and radiative lifetime of Dy3+ and Er3+ ions. The photoluminescence measured under excitation of 808 nm laser diode (LD) displayed an ultra-broadband mid-infrared band emission with full width at half maximum (FWHM) of ~358 nm in tellurite glass with appropriate amount of Dy3+-Er3+ combination. This broadband mid-infrared band emission located in the range of 2550–3200 nm and originated from the spectral overlapping of 2.85 μm band emission of Dy3+:6H13/2 → 6H15/2 transition and 2.7 μm band one of Er3+:4I11/2 → 4I13/2 transition. Furthermore, the time resolved fluorescence decay behavior demonstrated the existence of energy transfer between Dy3+ and Er3+ ions which is responsible for the broadband luminescence, and the energy transfer efficiency was estimated. The present results indicate that tellurite glass co-doped with Dy3+-Er3+ ions is promising for applications in mid-infrared band luminescent sources and tunable lasers.

Energy transfer and control of color luminescence in Dy3+/Tb3+ co-doped transparent oxyfluorosilicate glass ceramics containing LiYF4 nanocrystals

Dy3+/Tb3+ co-doped oxyfluoride glass ceramics (GC) containing lithium tetrafluoroyttrium (LiYF4) and yttrium fluoride (YF3) nanograins were prepared by a traditional melt-quenching approach. The crystalline phases and morphologies of the GCs were investigated. The GCs showed enhanced green emission from Tb3+ ions and the quenching of Dy3+ emission because of the efficient energy transfer from Dy3+ to Tb3+ ions. The electric dipole-dipole interactions were responsible for the energy transfer mechanism between Dy3+ and Tb3+ ions. The energy transfer efficiencies of these glass ceramics were calculated from their decay curves. The Dy3+/Tb3+ co-doped oxyfluoride GCs with various visible emissions were found to be potential candidates for white-light emitting diode applications.

Influence of Y3+ ions on the optical properties of Dy3+-activated LaF3 single crystal

In this exploration, the 2 at% Dy3+ and 3 at% Y3+ codoped LaF3 single crystal was grown by the temperature gradient technique. The influence of non-optically-active Y3+ ions on the luminescence of Dy3+ ions in LaF3 crystals has been explored. Geometry optimization demonstrates that the crystallographic symmetry for Dy3+ ions can be distorted from C2 to lower symmetry C1. Low temperature excitation and emission spectra prove that Dy3+ ions occupy the same kind of spectroscopic site in Dy3+/Y3+ codoped LaF3 crystals. The Judd-Ofelt (J-O) theory analysis and room temperature fluorescence emission spectra have testified that the fluorescence emission intensity of Dy3+ with Y3+ is several times than that without Y3+ in LaF3 at yellow and mid-infrared region. Codoping with non-optically-active Y3+ ions could weaken the concentration quenching effect of Dy3+ and strengthen the luminescence intensity of Dy3+ ions.

Realization of warm white light and energy transfer studies of Dy3+/Eu3+ co-doped Li2O-PbO-Al2O3-B2O3 glasses for lighting applications

The spectroscopic exploration of Dy3+/Eu3+co-doped Li2O–PbO–Al2O3–B2O3 (LiPbAlB) glasses have been performed through absorption, photoluminescence, colour coordinates, correlated colour temperatures (CCT) and decay spectral profiles. The bonding parameters, energy band gaps and nephelauxetic ratios are discussed by using optical absorption spectra. The luminescence of Dy3+/Eu3+co-doped glasses was tuned from cool white to warm white light under different selected ultraviolet excitation wavelengths such as 348 nm, 365 nm, 384 nm and 393 nm. The 4F9/2 → 6H13/2, 6H15/2 transition of Dy3+ and 5D0→7F2 transition of Eu3+ are responsible for the generation of warm white light from the as-prepared glasses. Dexter theory revealed the dipole-dipole (d-d) mechanism could be the foremost channel responsible for non-radiative energy transfer among Dy3+ (sensitizer) and Eu3+ (activator) constellations. The colour coordinates (x, y) of the as-synthesized co-doped glasses under 348 nm excitation confers the good white emission. The lifetime diminutions with increase in Eu3+ ions concentration and maximum energy transfer efficiency (ηT = 12.25%) was observed for glass 0.5 mol% Dy3+ and 5 mol% Eu3+ co-doped LiPbAlB glass (glass DE5). The aforementioned results suggest that the Dy3+/Eu3+co-doped LiPbAlB glasses driven by UV LEDs might be suitable for the fabrication of cool/warm white as well as reddish-orange lighting devices.

Ln3+ (Ln = Eu, Dy) - doped Sr2CeO4 fine phosphor particles: Wet chemical preparation, energy transfer and tunable luminescence

The Sr2CeO4:Ln3+ (Ln = Eu, Dy) fine phosphor particles were prepared by a facile wet chemical approach, in which the consecutive hydrothermal-combustion reaction was performed. The doping of Ln3+ into Sr2CeO4 has little influence on the structure of host, and the as-prepared samples display well-crystallized spherical or elliptical shape with an average particle size at about 100–200 nm. For Eu3+ ions-doped Sr2CeO4, with the increase of Eu3+-doping concentration, the blue light emission band with the maximum at 468 nm originating from a Ce4+ → O2− charge transfer of the host decreases obviously and the characteristic red light emission of Eu3+ (5D0→7F2 transition at 618 nm) is enhanced gradually. Simultaneously, the fluorescent lifetime of the broadband emission of Sr2CeO4 decreases with the doping of Eu3+, indicating an efficient energy transfer from the host to the doping Eu3+ ions. The energy transfer efficiency from the host to Eu3+ was investigated in detail, and the emitting color of Sr2CeO4:Eu3+ can be easily tuned from blue to red by varying the doping concentration of Eu3+ ions. Moreover, the luminescence of Dy3+-doped Sr2CeO4 was also studied. Similar energy transfer phenomenon can be observed, and the incorporation of Dy3+ into Sr2CeO4 host leads to the characteristic emission of 4F9/2 → 6H15/2 (488 nm, blue light) and 4F9/2 → 6H13/2 (574 nm, yellow light) of Dy3+. The Sr2CeO4:Ln3+ fine particles with tunable luminescence are quite beneficial for its potential applications in the optoelectronic fields.

Influence of Temperature on the Luminescence Properties of MgAl2O4:Dy3+ Ceramics Synthesized by Spark Plasma Sintering

Transparent MgAl2O4:Dy3+ ceramic samples were synthesized by spark plasma sintering. Their optical properties, photo- and cathodoluminescence, the luminescence decay kinetics, and the effect of temperature on spectral and kinetic characteristics of luminescence were studied. The luminescence of Dy3+ ions (458 nm (4I15/2 → 5H15/2), 480 nm (4F9/2 → 6H15/2), 573 nm (4F9/2 → 6H13/2), 665 nm (4F9/2 → 6H11/2), and 750 nm (4F9/2 → 6H9/2)), impurity Cr3+ ions (2Eg → 4A2g), and intrinsic defects (F+-centers, 460 nm) was detected. Thermal quenching of luminescence in the visible spectral range was observed as the temperature varied from 100 to 300 K. It is demonstrated that the patterns of quenching for impurity and intrinsic centers differ in MgAl2O4:Dy3+ ceramics. The mechanisms of thermal quenching are discussed.

PH controlled synthesis of UV excited host-sensitized luminescence in Dy3+ doped Ga2O3

A series of Dy3+-doped Ga2O3 powders were prepared via a simple hydrothermal reaction method, conducted without the use of any surfactants at varying initial pH. X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Photo-Luminescence (PL), UV–Vis–NIR Diffuse Reflectance Spectroscopy (DRS), Electron Probe Micro-Analysis (EPMA) and WDS/EDS were employed to characterize the synthesized powders. The influence of starting solution pH on the growth process of the GaOOH particles and on the host-sensitized luminescence of the Dy3+:Ga2O3 powders were investigated in detail. It is revealed that the active energy transfer processes can be influenced by variation of the Dy3+ concentration, and that a starting solution pH value of 8 is optimal for maximizing Dy3+ incorporation into the Ga2O3 lattice. This work presents a method to produce Dy3+:Ga2O3 with tunable UV-pumped emission, and provides evidence that white emission can be achieved through careful control of dopant concentration, which makes the material attractive for solid state UV pumped-white emission applications.

Solvothermal synthesis, luminescence and energy transfer of Dy3+ and Sm3+ doped NaLa(WO4)2 nanocubes

A series of Dy3+ and/or Sm3+ ions doped NaLa(WO4)2 phosphors have been synthesized by a solvothermal method. The phase, microstructure and luminescence of Dy3+ and/or Sm3+ ions doped NaLa(WO4)2 phosphors have been investigated. The XRD patterns obviously indicate that Dy3+ and/or Sm3+ ions doped NaLa(WO4)2 phosphors have the tetragonal scheelite structure. The SEM images show that the synthesized phosphors have the cubic morphology. The overlap between the emission spectrum of Dy3+ and the excitation spectrum of Sm3+ suggests possible energy transfer from Dy3+ to Sm3+ in NaLa(WO4)2:Dy3+/Sm3+ phosphors and the energy transfer is confirmed by the decreases of Dy3+ emission intensity and the increases of Sm3+ emission intensity for NaLa(WO4)2:Dy3+/Sm3+ phosphors. On the basis of luminescent properties, the possible energy transfer mechanism has been speculated.

Observing quantum control of up-conversion luminescence in Dy3+ ion doped glass from weak to intermediate shaped femtosecond laser fields

Controlling the up-conversion luminescence of rare-earth ions in real-time, in a dynamical and reversible manner, is very important for their application in laser sources, fiber-optic communications, light-emitting diodes, color displays and biological systems. In previous studies, the up-conversion luminescence control mainly focused on the weak femtosecond laser field. Here, we further extend this control behavior from weak to intermediate femtosecond laser fields. In this work, we experimentally and theoretically demonstrate that the up-conversion luminescence in Dy3+ ion doped glass can be artificially controlled by a π phase step modulation, but the up-conversion luminescence control behavior will be affected by the femtosecond laser intensity, and the up-conversion luminescence is suppressed by lower laser intensity while enhanced by higher laser intensity. We establish a new theoretical model (i.e. the fourth-order perturbation theory) to explain the physical control mechanism by considering the two- and four-photon absorption processes, and the theoretical results show that the relative weight of four-photon absorption in the whole excitation process will increase with the increase in laser intensity, and the interference between two- and four-photon absorptions results in up-conversion luminescence control modulation under different laser intensities. These theoretical and experimental works can provide a new method to control and understand up-conversion luminescence in rare-earth ions, and also may open a new opportunity to the related application areas of rare-earth ions.

Luminescence and energy transfer in uranium-containing aqueous solutions of dysprosium decatungstate

Samples of uranium-containing liquid luminophores activated with Dy3+ were prepared, and their properties were studied experimentally. Optical excitation of aqueous DyW10O 36 9– solutions leads to the transfer of the excitation energy from the decatungstate ligand to Dy3+, followed by sensitized luminescence of Dy3+.

Structure and luminescence of Dy3+ doped CaO–B2O3–SiO2 glasses

The present work reports structure and luminescence of Dy3+ doped CaO–B2O3–SiO2 glasses prepared by melt quenching technique. The presence of various stretching and bending vibrations of different borate and silicate groups were identified from FTIR spectral measurements. The optical absorption and luminescence spectra were also measured, and their emission spectra exhibit two intense emission bands at around 485nm (blue) and 577nm (yellow) corresponds to 4F9/2→6H15/2 and 4F9/2→6H13/2 transitions, respectively. The emission spectra were characterized through CIE 1931 color chromaticity diagram to explore its suitability for W-LED applications. Furthermore, the proper Y2O3 could change local structure of glass, which makes the UV absorption edge shift to longer wavelength, and it's easier to transfer energy from host to Dy3+ and then enhance the emission of Dy3+.

Dy3+ doped thermally stable garnet-based phosphors: luminescence improvement by changing the host-lattice composition and co-doping Bi3+

Better luminescence of Dy3+ in the garnet matrix were synthesized via sol–gel combustion method through the synergistic effect by co-doping the sensitizer of Bi3+ and changing the composition of the matrix via replacing gadolinium with different contents of Y3+.

White luminescence in Dy3+ doped BiOCl phosphors and their Judd–Ofelt analysis

White-light emitting Dy3+ doped layered BiOCl phosphors were synthesized by the solid state route and their structure was confirmed by the Rietveld refinement method. On substitution of Dy3+ ion to Bi3+-site in BiOCl, the photoluminescence spectra exhibit blue (4F9/2 → 6H15/2), yellow (4F9/2 → 6H13/2) and red (4F9/2 → 6H11/2) emissions which function together to generate white light. It was found that the emission intensity increases up to 9 mol% of Dy3+ and then quenched due to dipole–dipole interaction. Judd–Ofelt theory and radiative properties suggest that the present phosphors have a long lifetime, high quantum efficiency, excellent color purity and better stimulated emission cross-section compared to reported Dy3+ doped compounds. The obtained color chromaticity results are close to the National Television System Committee standard and clearly establish the bright prospects of these phosphors in white luminescence.

Energy transfer mechanism and color controllable luminescence in Dy3+/Eu3+-codoped NaLa(MoO4)2 phosphors

Dy3+/Eu3+-codoped as well as Dy3+-doped NaLa(MoO4)2 phosphors were synthesized via a facile solid-state reaction method. The X-ray diffraction patterns, field-emission scanning electron microscope images, photoluminescence (PL) spectra and decay curves were employed to characterize the synthesized samples. Under the excitation of 387 nm, all the Dy3+-doped NaLa(MoO4)2 phosphors exhibited the characteristic emissions of Dy3+ ions (blue emission at 486 nm: 4F9/2 → 6H15/2 and yellow emission at 573 nm: 4F9/2 → 6H13/2). Furthermore, the PL emission intensity increased with Dy3+ ion concentration and the concentration quenching effect occurred when the Dy3+ ion concentration was over 5 mol%. Meanwhile, color-tunable emissions were observed in Dy3+/Eu3+-codoped NaLa(MoO4)2 phosphors owing to the efficient energy transfer (ET) from Dy3+ to Eu3+ ions. Through theoretical calculation, it was evident that the ET efficiency increased gradually with the increment of Eu3+ ion concentration, reaching ∼ 70% of its maximum value at 9 mol% of Eu3+ ion concentration. Additionally, the ET mechanism between Dy3+ and Eu3+ ions was found to be electric dipole–dipole interaction.

Influence of silver nanoparticles on the luminescence dynamics of Dy3+ doped amorphous matrix

In this work, we report on the deactivation of Dy3+ ions by increase in concentration of silver nanoparticles (NPs) in a silicate glassy system. The quench in luminescence of Dy3+ ions is consistent with increase in the long and short lifetime of 4F9/2 excited state which develops as the concentration of silver NPs increases by heat-treatment duration.

Synthesis of KMgCl3 nanomaterial and luminescence of Ce3+/Dy3+/Eu3+ by different routes

The present KMgCl3 phosphor has been synthesized through wet chemical synthesis (WCS), solid state diffusion (SSD) and Hispersed centrifuge (HC) routes in the same atmospheric conditions and characterized for luminescence properties. XRDs of the sample prepared by all three methods have been placed at the same position, phase and matched well with standard data. The particle size of 20nm of KMgCl3 by a Hispersed centrifuged method was detected using a transmission electron microscope (TEM). The PL emission spectra have been observed for Ce3+ at 353nm and 375nm due to 5d→4f transition, whereas luminescence of Dy3+ efficiently observed at 484nm and 579nm for an excitation of 384nm due to 4F9/2→ 6H15/2 and 6H13/2 (blue–yellow region) transition and Eu3+ is peaking at 596nm and 616nm (λex=394nm) due to level 5D0 to 7Fj (j=0, 1, 2, and 3) radiative transitions. The presented phosphors are excited in the range of 300–400nm which is mercury free excited range. Synthesis and photoluminescence spectra of trivalent Ce, Dy or Eu rare-earths in KMgCl3 are described for all three routes, for the first time in the present work. The CIE chromaticity coordinates were also calculated for KMgCl3:X (Ce3+, Dy3+ and Eu3+) phosphors, which are close to the NTSC standard values. KMgCl3 matrix is not only suitable for different and easy synthesis but efficient luminescence also. The paper discuses the XRD, crystallinity (morphology) and luminescence of Ce, Dy or Eu rare-earths in KMgCl3 synthesized by three (WCS, SSD and HC) different routes.

High-efficiency fluorescence radiation of Dy3+ in alkaline earth borate glasses

Dy3+-doped alkaline-earth borate glasses (LKZBSB) with high quantum yield and multifarious emission channels have been fabricated and efficient warm yellowish-white fluorescence is presented under UV light excitation. Judd–Ofelt parameters Ω2=5.36×10−20cm2, Ω4=1.46×10−20cm2 and Ω6=1.95×10−20cm2 indicate a high asymmetrical and covalent environment in the optical glasses. The maximum stimulated emission cross-sections σem-max corresponding to the 4F9/2→6H15/2, 4F9/2→6H13/2, 4F9/2→6H11/2 and 4F9/2→(6H9/2, 6F11/2) transitions are derived to be 2.64×10−22, 20.07×10−22, 3.45×10−22 and 9.31×10−22cm2, respectively, and the relevant spontaneous emission probabilities Arad are 174.08, 616.07, 68.95 and 87.10s−1. Quantitative characterization reveals that Dy3+-doped LKZBSB glasses exhibit a quantum yield as high as 16.65%, confirming that the effectiveness of the warm yellowish-white luminescence in Dy3+-doped LKZBSB glasses. Multifarious emission channels and high quantum yield illustrate the great advantages of Dy3+-doped LKZBSB glasses in developing fiber-lighting sources, display devices, tunable visible lasers, and optical signal amplifiers.

Synthesis and luminescence of Dy3+-activated NaSrPO4 phosphors for novel white light generation

The Dy3+-doped NaSrPO4 phosphor powders have been synthesized by solid state reaction. All samples were verified to be in a pure NaSrPO4 phase by X-ray diffraction analysis for all the Dy3+ doping concentrations. The room temperature excitation spectra of NaSrPO4:Dy3+ phosphors illustrated that they could easily be excited by UV–Visible light corresponding f − f transitions of Dy3+. The photoluminescence spectra exhibit two main bands centered at 481 nm (blue) and 573 nm (yellow), which originate from the 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions of Dy3+, respectively. The two bands combined to form a white light with the chromaticity coordinates varying with the concentrations of Dy3+. The chromaticity coordinates were measured and mapped in the Commission International de L’Ecllairage 1931 diagram, indicating that they distributed around (0.30, 0.34) of the colorless point D65. The dependence of luminescence intensity onto Dy3+ concentration was investigated and the concentration quenching mechanism for NaSrPO4:Dy3+ was discussed.