Amount Of Dy3 Research Articles

Dy3+ doped KCa(PO3)3 phosphor for white light generation: structural and luminescent studies

Using the traditional solid-state reaction approach, Dy3+ ions doped KCa(PO3)3 phosphors have been synthesized to investigate their luminescent properties to produce high-quality white light for solid-state lighting applications, particularly in white LEDs. x-ray diffraction (XRD) patterns were used to examine the structure and phase of the phosphors. Using scanning electron microscopy (SEM), the morphology of the as-synthesized phosphor has been investigated. Fourier transform infrared spectroscopy (FT-IR) has been used to investigate several vibrational bands seen in the phosphor. Using diffuse reflectance spectra (DRS), the as-synthesized phosphors’ optical band gap values have been estimated. When Dy3+ ions are excited at 350 nm, the photoluminescence (PL) spectra characteristics observed for the activated KCa(PO3)3 phosphor show strong white area emission due to both 575 nm, which is related to the 4F9/2 → 6H13/2 and 482 nm that is ascribed to 4F9/2 → 6H15/2 transition of Dy3+ ions. Additionally, the concentration quenching of Dy3+ ions doped at 4 mol% is seen in the PL spectra. Based on the observed PL spectra, the computed CIE chromaticity coordinates for the optimised KCa(PO3)3 phosphors are located in the deep white area. The lifespan of the as-titled phosphors decreases as the amount of Dy3+ ions increases in the host lattice. Additionally, the PL decay profiles shows a dual exponential behaviour when excited at 350 nm, with an emission wavelength at 575 nm. The lifetime values were used to calculate the quantum efficiency of the as prepared phosphors. On the basis of the results of the aforementioned studies, we wish to project Dy3+ ion doped KCa(PO3)3 phosphors as white light generating materials in w-LEDs and for other photonic applications.

Intrinsic magnetic-optical features of Dy3+ ion substituted NiCuZn nanospinel ferrites via sonochemical approach

Ni0·4Cu0·2Zn0.4DyxFe2-xO4 (x ≤ 0.10) (NCZDy) nanospinel ferrites (NSFs) were prepared by an ultrasonication approach assisted sol-gel synthesis methodology. The cubic spinel structures of products were verified by XRD (X-ray powder diffraction) study. Intrinsic vibrational absorption bands of nanoparticles for their octahedral band (υ2) at 417 cm−1 and tetrahedral (υ1) band at 563-580 cm−1 were detected by FT-IR (Fourier-transform infrared) analysis. Magnetic studies by VSM (Vibrating sample magnetometry) confirmed the soft ferromagnetic nature of all products at 15 K and 300 K temperatures. As the amount of Dy3+ rises, saturation and remanent magnetization (Ms and Mr) values first increase for x = 0.02 composition; then they start to decrease with further rising the Dy3+ content. FC (Field-cooled) and ZFC (zero field-cooled) magnetization studies reveal that the irreversible temperature is above 300 K and the samples display spin glass behavior. Mössbauer spectra (MOS) were acquired to calculate hyperfine parameters by room-temperature (RT) spectra fitting and results indicated Dy3+ ions occupy octahedral sites. The optical investigation showed NCZDy (x ≤ 0.10) NSFs carry out a direct band character, and band gap values lay between 1.69 and 2.33 eV. All samples absorb the light within the visible region which is evident from the % Diffuse Reflectance Spectroscopy (DRS) results.

Structural and Luminescence Analysis of Low Temperature Solution Combustion Derived White Light Emitting Y2(1-x)Dy2xZr2O7 Nanophosphors for WLEDs

White light emitting dysprosium doped rare-earth zirconate Y2(1-x)Dy2xZr2O7 (x = 0.5 to 5 mol%) crystalline phosphors in nano-regime were obtained using urea supported solution combustion methodology at low temperature 650 ºC. Presence of fluorite structure having cubic symmetry with Fm3m space group was analyzed by powder X-ray diffraction patterns. Spherical shaped nanoparticles with clear boundaries were observed by surface morphological studies. Diverse elements Y, Zr, Dy and O were present in the optimized nanophosphors as examined by energy dispersive X-ray analysis. Upon near ultraviolet (NUV) excitation at 354 nm wavelength, the Y2(1-x)Dy2xZr2O7 phosphors displayed the characteristic white light emanation resulted from blue and yellow emission owing to 4F9/2→6H15/2 (450-525 nm) and 4F9/2→6H13/2 (525-650) transitions, respectively. With the doping of 1.5 mol% amount of Dy3+ ions in Y2(1-x)Dy2xZr2O7 powders showed maximum photoluminescence emission, above which intensity was quenched due to dipole-dipole interactions. In addition, Y1.97Dy0.03Zr2O7 nanopowders exhibit CIE colour coordinates (0.2605, 0.3145) residing in white region. The closeness of this value to the white emission coordinates of the National Television System Committee (NTSC) endorsed Y2(1-x)Dy2xZr2O7 nanophosphors as fascinating candidate for displays and white light emitting diodes.

Improved Eu3+ red-emitting by charge compensation in Sr0.3Ca0.7(MoO4)2: xDy3+, yEu3+ phosphors

In this study, Sr0.3Ca0.7(MoO4)2:xDy3+, yEu3+ phosphors with and without charge compensation were produced using the coprecipitation method. Their crystal structure, luminescence performances, charge compensation, fluorescence lifetime, thermal extinguishing behavior as well as energy transfer mechanism were explored in detail. The X-ray diffraction patterns show that the appropriate amount of Dy3+/Eu3+ single and co-doped in the lattice has no obvious influence on the crystal structure. The luminescence results showed that Sr0.3Ca0.55(MoO4)2: 0.1Eu3+ with charge compensation exhibited luminescence intensity 4.98 times higher than that of Sr0.3Ca0.6(MoO4)2: 0.1Eu3+ non-charge compensation. The luminescence intensity of Dy3+/Eu3+ co-doped Sr0.3Ca0.7(MoO4)2 phosphors was significantly improved by charge compensation. Furthermore, efficient energy transfer from Dy3+ → Eu3+ was confirmed by emission spectra, excitation spectra, attenuation curves, and thermal quenching curves. This suggests that the charge compensation could significantly improve the Eu3+ red emission. Therefore, the investigated SrCa(MoO4)2: Eu3+, Dy3+ phosphors may be a favorable candidate for promising applications in lighting.

Energy transfer dynamics in thermally stable single-phase LiMgBO3:Tm3+/Dy3+ phosphor for UV triggered white light-emitting devices

We report on thermal-, structural-, optical-, and energy transfer (ET)-based photoluminescence (PL) characteristics of Tm3+ co-doped with Dy3+ in a single-phase LiMgBO3 host material. Tm3+ exhibits vibrant blue emission (1D2→3F4: 456 nm) and Dy3+ displays strong yellowish-white emission (4F9/2→6H13/2: 573 nm) under ultraviolet (UV) excitation. When the optimum concentration (0.03) of Tm3+ is co-doped with different amounts of Dy3+, the PL intensity of Tm3+: 1D2→3F4 declines but increases for Dy3+: 4F9/2→6HJ (J = 11/2, 13/2, 15/2), which suggests ET from Tm3+→Dy3+ and demonstrates electric dipole–dipole interaction with a critical distance of 11.07 Å. The ET between Tm3+ and Dy3+ is validated from the spectral overlap of Tm3+ PL and Dy3+ absorption, Tm3+/Dy3+ PL spectra, Tm3+-dependent lifetimes, and ET parameters such as efficiency and probability. The Commission Internationale de l’Eclairage (CIE) coordinates display the color tunability of Tm3+ phosphor from blue light (0.146, 0.045) to warm white light (0.334, 0.306) with a correlated color temperature (CCT) value of 5,404 K in response to Dy3+ doping. The PL intensity of LiMgBO3:0.03Tm3+/0.05Dy3+ increases nearly two-fold on co-doping with 5% Li+ as a charge compensator. Tm3+/Dy3+/Li+ co-activated material exhibits good thermal stability, retaining 64% of the initial PL intensity, which suggests its practical applicability as UV light triggered white light-emitting devices.

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.

Natural End Member Samples of Pyrope and Grossular: A Cathodoluminescence-Microscopy and -Spectra Case Study

Garnet is one of the most significant minerals in metamorphic rocks, that provides key information on prograde, peak-metamorphic and retrograde parts of the pressure-temperature (PT) path. Such results require a detailed knowledge of its different growth domains. For iron-poor compositions, the cathodoluminescence (CL) microscopy is an important and often overlooked method and allows to identify the internal structures of all garnet grains in one thin section within only a few seconds. The advantage of the CL-microscope is to deliver low magnification images in true color, not only of garnet but also, for instance, of other rock forming silicates, carbonates, sulfates, etc., of metamorphic, but also of sedimentary and magmatic origin, using polished thin sections. Internal structures of grossular from Mexico and pyrope from the Italian Alps were characterized and visualized by CL-microscopy. The different growth domains were additionally studied using CL-spectra and electron microprobe (EMP) analysis. Grossular shows a patchy zonation in its core while in mantle and rim zones oscillatory zoning is observed. It contains zones of anomalous birefringence, zones of orange and bluish luminescence and zones lacking luminescence. Different but low amounts of the activator elements Mn2+ and Eu2+ are responsible for the orange and bluish luminescent domains. Pyrope is also characterized by oscillatory growth zones, shows a dull luminescent core with a change of crystal morphology during growth, and displays an increase of brightness from core towards rim—the outermost rim, however, is lacking luminescence. The different luminescent zones are characterized by different amounts of Dy3+, Tb3+, Sm3+ and Sm2+ as activator elements. Because of slow diffusion rates of activators such as the REEs Sm, Dy and Tb, it can be still possible to visualize possible prograde and/or peak pressure stage growth domains of garnet, even if later high temperature events may have homogenized the major element profiles. Such domains may help to identify respective assemblages of mineral inclusions, and hence these results can represent an integral part of a detailed PT path. Thus the CL-information can be used as an important pathfinder prior to supplementary investigations, as for instance EMP, ion probe, mineral or fluid inclusion studies.

Investigation on Synthesis and Property of Tb<sup>3+</sup>/Dy<sup>3+</sup> Co-Doped Gd<sub>3</sub>Al<sub>5</sub>O<sub>12</sub> Phosphor

The (Gd0.9-xTb0.1Dyx)3Al5O12 (x=0-0.04, GdAG:Tb3+/Dy3+) solid solution was acquired by calcining their respective precursor prepared via co-precipitation method at 1500 °C. The performance of GdAG:Tb3+/Dy3+ powders was characterized by combined technology of Fourier transform infrared absorption spectra (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) and photoluminescence (PL) spectrum analyses. The metastable Gd3Al5O12 could be stabilized by doping smaller Tb3+ ions of 10 at.%. Under the optimal UV excitation of 275 nm, the GdAG:Tb3+/Dy3+ phosphors exhibit vivid green emission at 548 nm which were attributed to the 5D4→7F5 transition of Tb3+. The CIE chromaticity coordinate was determined at (~0.32, ~0.48) with the color temperature of ~5872 K. Compared to the Dy3+-free (Gd0.9Tb0.1)AG phosphor, the emission intensity of Dy3+-doped phosphors display stronger owing to the efficient energy transfer from Dy3+ to Tb3+. The optimal amount of Dy3+ in GdAG:Tb3+/Dy3+ phosphors was determined to be ~2.5 at.% (x=0.025). The GdAG:Tb3+/Dy3+ phosphors developed in present work are expected to be a new type of green phosphor widely used in the lighting and display areas.

Dy3+-doped Ga–Sb–S chalcogenide glasses for mid-infrared lasers

Novel Ga–Sb–S chalcogenide glasses doped with different amount of Dy3+ ions were prepared. Their thermal stability, optical properties, and mid-infrared (MIR) emission properties were investigated. The glasses show good thermal stability, excellent infrared transparency, very low phonon energy (∼306cm−1), and intense emissions centered at 2.95, 3.59, 4.17 and 4.40μm. Three Judd–Ofelt intensity parameters (Ω2=8.51×10−20cm2, Ω4=2.09×10−20cm2, and Ω6=1.60×10−20cm2) are obtained, and the related radiative transition properties are evaluated. The high quantum efficiencies and large stimulated emission cross sections of the MIR emissions (88.10% and 1.11×10−20cm2 for 2.95μm emission, 75.90% and 0.38×10−20cm2 for 4.40μm emission, respectively) in the Dy3+-doped Ga–Sb–S glasses make them promising gain materials for the MIR lasers.

Crystal Structure and Magnetic Properties of BaFe12 xDyxO19 Powders Prepared using Gel Self-propagating Combustion

The hexagonal BaFe12 xDyxO19 (x 1/4 0.1-0.5) powders are synthesized by the gel self-propagating combustion technique, which is combined with the sol-gel method and self-propagating combustion synthesis. The changes in heat and weight of dry gel during self-propagating combustion are investigated with differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The effects of the molar ratio of citric acid on nitrates (C/N), calcination temperature, and substitution amount of Dy3+ on crystal structure and magnetic properties are studied by means of X-ray diffraction (XRD) and vibrating sample magnetometry (VSM). In gel self-propagating combustion, the formation temperature of barium ferrite is decreased to 850 C. The changes in crystal structure during calcination are tracked. There is no α-Fe2O3 appearing in the powders when C/N is not less than 1.0. After some Fe3+ has been substituted with Dy3+, the magnetic properties are improved. The specific saturation magnetization reaches a maximum of 58.05 Am2/kg, and coercivity reaches a minimum of 420.33 kA/m with the substitution amount x 1/4 0.2. This substituted barium ferrite can be used as a magnetic recording material.

Comparison of the Luminescence Properties of Dy3+ in alpha-Sialon and Oxynitride Glass

Dy-α-sialon and β-Si3N4 materials containing Dy-oxynitride glass were hot pressed at 1800°C for 1 h. The luminescence spectra of Dy3+ in these samples were compared when excited at 350 nm. The results showed that two strong emission bands in the region 470–500 nm and 570-600 nm, associated with the 4F9/2→6H15/2 and 4F9/2→6H13/2 transitions of Dy3+ ions, were observed in Dy-α-sialon. However, no emission peak was detected from the β-Si3N4 sample, despite it containing the same amount of Dy3+ cations. This proved that only the Dy3+ cations in the α-sialon structure, not those in the oxynitride glass, produce the luminescence spectrum.