Synthesis and Luminescence Study of n‐UV Excitable Tm 3+ ‐Activated Blue Phosphor (original) (raw)
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2010
Nanocrystalline powder of Tm 3+ doped lutetium oxide, Tm:Lu 2 O 3 , has been synthesized by the sol-gel Pechini method. Differential thermal analysis, X-ray powder diffraction and transmission electron microscopy were used to investigate the effect of Tm 3+ ion on the structure and morphology of samples. In all cases, the obtained nanoparticles crystallize in the cubic system, with space group of symmetry Ia3. The mean particle size was 100-200 nm with crystallite size of 20-30 nm. Optical absorption and cathodoluminescence spectra were recorded. The cathodoluminescence spectra showed an intense blue emission associated to the 1 G 4 3 H 6 transition. CIE chromatic coordinates, dominant wavelength and color purity were determined for the evaluation of this material as a potential blue phosphor.
Simultaneous influence of Zn2+/Mg2+ on the luminescent behaviour of La2O3:Tm3+–Yb3+ phosphors
RSC Advances, 2014
The structural characterizations of La 2 O 3 phosphors doped/codoped with Tm 3+ and Yb 3+ ions synthesized by the urea assisted solution combustion technique were performed using X-ray diffraction analysis, Fourier transform infrared spectroscopy and scanning electron microscopy. Codoping with Zn 2+ /Mg 2+ ions causes an increase in the particle size and aggregation for the La 2 O 3 :Tm 3+ -Yb 3+ phosphor. The upconversion (UC) study under 980 nm excitation shows four UC emission bands centred around 476 nm ( 1 G 4 / 3 H 6 ), 653 nm ( 1 G 4 / 3 F 4 ), 702 nm ( 3 F 2 / 3 H 6 ) and 795 nm ( 1 G 4 / 3 H 5 ). The effect of codoping with Zn 2+ and Mg 2+ ions in the Tm 3+ -Yb 3+ codoped La 2 O 3 phosphor was investigated. Decay curve analysis of the prepared phosphors was done to understand the mechanism of the upconversion emission intensity variation due to codoping with Zn 2+ /Mg 2+ ions. The purity of colour emitted from the sample does not show any change with variations in pump power density.
Structural and luminescence properties of yellow phosphors prepared by a modified sol-gel method
MRS Communications, 2017
The structural properties of clinopyroxene NaScSi 2 O 6 have been investigated using the X-ray powder diffraction refinement, and the luminescence properties of Eu 2+ and Eu 2+ /Mn 2+-activated NaScSi 2 O 6 have been studied to explore the new materials for phosphor-converted white light ultraviolet light-emitting diodes (UV-LEDs). Eu 2+ was introduced into the NaScSi 2 O 6 host in the reducing atmosphere, and the preferred crystallographic positions of the Eu 2+ ions were determined based on the different structural models of the NaScSi 2 O 6 host. The as-obtained NaScSi 2 O 6 :Eu 2+ phosphor shows greenish yellow emission with the broad-band peak at 533 nm, and efficient energy transfer (ET) takes place between Eu 2+ and Mn 2+ in NaScSi 2 O 6 , leading to a series of color-tunable phosphors emitting at 533 and 654 nm for the designed NaScSi 2 O 6 :Eu 2+ ,Mn 2+ phosphors under excitation at 365 nm. The ET mechanism of Eu 2+ and Mn 2+ has also been evaluated. We have demonstrated that NaScSi 2 O 6 :Eu 2+ and NaScSi 2 O 6 :Eu 2+ ,Mn 2+ materials exhibit great potential to act as the effective phosphors for UV-LEDs.
Luminescent properties of La2LiTaO6:Mn4+ and its application as red emission LEDs phosphor
Applied Physics A, 2014
A novel phosphor, Mn 4? doped La 2 LiTaO 6 , was developed by solid-state reaction method. The luminescent spectra and emission efficiencies of La 2 LiTaO 6 :-Mn x 4? (x = 0.001, 0.003, 0.005 and 0.01) were discussed. The effects of co-doped charge compensation ions, M = Mg 2? , Ca 2? , Na ? , were investigated, respectively. The excitation spectra indicated that La 2 LiTaO 6 :Mn 4? could be effectively excited by both NUV light and blue light. The emission spectra of the phosphor exhibit a broadband ranging from 670 to 720 nm with the maximum at about 709 nm in deep red region. The co-doping of Mg 2? could significantly improve the luminescent properties of La 2 LiTaO 6 :Mn 4?. Thus, phosphor La 2 LiTaO 6 :-Mn 4? , Mg 2? can serve as a key component to improve color rendering of blue-chip white-LEDs.
Blue-yellow emissive LaAlO3:Dy3+ phosphor for high bright white light-emitting diodes
Bulletin of Electrical Engineering and Informatics, 2023
LaAlO3:Dy3+ (LAO:Dy3+) with blue-yellow emission for brilliant white light of light-emitting diodes (LEDs) was prepared using gel-combustion process. The chemical content of the created material was confirmed using energy dispersive X-ray analysis (EDX). The transmission electron microscopy was used to examine the phosphor crystal size and morphology. The luminescence analysis showed that LAO:Dy3+ phosphors exhibited peaks at 482 nm (blue) and 574 nm (yellow), attributed to the transitions 4F 9/26H 15/2 and 4F 9/26H 13/2, respectively. The investigating of correlated color temperature (CCT) and Commission International de L'Eclairage (CIE) described that the phosphor LAO:Dy3+ helped to attained good CCT coordination and bright cool-white emission under ultraviolet (UV) stimulation. However, when using in white LED fabrication, the concentration of LAO:Dy3+ should be modified to fulfill the need from manufactures. According to results from this work, the white light luminescence intensity and color rendering performance may be reduced if the LAO:Dy3+ is high (>10%) because of too much scattering. On the other hand, such scattering improvements offered by LAO:Dy3+ phosphor is beneficial to reduce the color deviance for better color uniformity of light.
Revista Mexicana de Física, 2018
The effect of Li co-doping on the blue luminescence of Eu2+ doped (La-Al)2O3 phosphors and its incorporation into poly (methyl methacrylate) PMMA films are reported. The phosphors were synthesized by a simple two-step process in which the (La-Al)2O3 powders were obtained by an evaporation method, and the subsequent co-doping with Li+ and Eu2 were made through a solid state reaction in a reductive atmosphere at 1250 0C. The incorporation of those phosphors into PMMA matrix and the synthesis of films with thicknesses between 6 and 12 μm was made by drop-casting. The characteristic blue broad band emission centered at 440 nm associated with the 4f65d1→ 4F7 transition of Eu2+ ions (CIE coordinates 0.6731, 0.3343) was observed when these powders were excited with 297nm light. These luminescence intensity was enhanced when Li was incorporated as co-dopant up to 320% with respect to those phosphors without Li. The luminescent characteristics of these phosphors were preserved when they were...
Journal of Research in Engineering and Applied Sciences, 2018
In the present manuscript we report the structural and optical properties of terbium doped lanthanum orthophosphate nanophosphor capped with assorted capping agents and synthesized by conventional sol-gel method. The fabricated nanophosphor has been characterized using XRD (X-ray diffraction), SEM (Scanning electron microscopy), TG /DTA (thermo gravimetric analysis), PL (Photoluminescence spectroscopy) and FTIR (Fourier transform infra red spectroscopy). The studies explored that host LaPO4 when annealed at higher temperatures of 1000°C exhibit monazite structure which remain unaltered even after the addition of distinct capping agents like polyethylene glycol (PEG), Pyridine (PY) and Polystyrene (PS). The optical emission spectrum has been characterized with a broad band centered at 492nm and another spectral band at 545nm respectively. PL studies reveal that different spectral emission transitions are a consequence of typical 4f-4f intra configurational forbidden transitions of Tb3+. Additions of suitable capping agents have shown improvement in luminescence efficiency due to surface defect passivation. The present work confirms lanthanum orthophosphate nano phosphor doped with Tb3+ as a suitable host for phosphor converted LEDs and solid state lighting.
Bulletin of Electrical Engineering and Informatics, 2023
Researchers propose the phosphors emit many colors SrMg2La2W2O12:Tb3+, Sm3+, Tm3+ (SMLLW:RE3+) (RE3+=Tb3+, Sm3+, Tm3+) synthesized using the solid-status reacting technique as promising downward-transformation luminous substances for diodes emit white illumination and screens in the current study. The structural and binding data given by X-ray diffraction (XRD) data and fourier transform infrared (FTIR) spectroscopy suggest the corresponding orthorhombic configuration and vibrational powers, respectively. The stimulation and radiation bands of color of SMLLW:RE 3+ phosphor show that such phosphors may be successfully stimulated via ultraviolet (UV) illumination and generate green, orange-red, and blue (stands for G, OR , B) illumination, in turn. For different doses of the triggers Tb3+, Sm3+, and Tm3+ within the SMLW phosphor base, luminescence, decomposition periods, Commission Internationale De L'eclairage (CIE) color coordination, along with correlated hue heats (Tcct) are specified. When a triple-doped SMLW phosphor is activated using a ligand-to-metal charge transition (LMCT), it produces G, OR , B hues at the same time and can be adjustable to white light, according to the results. An effective power transfer among rare-earth ions was found and investigated using decay curve analysis. According to the findings, SMLW:RE3+ (RE=Tb, Sm, Tm) are suitable options to use for light-emitting diodes (LEDs) and screens creation.
Luminescence, 2021
Herein, we report the synthesis and study of a new Orange-Red (OR) color emitting phosphors Na2ZnP2O7:xTb 3+ (x= 1, 1.25, 1.5, and 1.75 mol%), using conventional solid-state reaction. The samples crystallographic structures and theirs room temperature photoluminescence properties were carried out by the measurement of X-ray powder diffraction, the excitation and emission spectra, as well as the emission decay curves. X-ray diffraction analysis showed an isostructural tetragonal structure of all the doped materials with no impurities. Several color emissions, corresponding to 5 D4→ 7 F6 (blue), 5 D4→ 7 F5 (green), 5 D4→ 7 F4 (orange) and 5 D 4 → 7 F 3, 2, 0 (red) intraconfigurational transitions were observed and investigated. These colors were dominated by the orange-red colors. It was found that 5 D4 energy level lifetime is independent of Tb 3+ concentration. Various radiative and luminescence parameters such as experimental branching ratio, radiative decay rate and the luminescent quantum efficiencies were calculated and discussed. Also, it was found that the chromaticity diagram calculations illustrated an orange emission for all the studied materials.
Journal of Luminescence, 2009
The photoluminescence (PL) emission and excitation behavior of red-emitting Eu 0.1 Gd x La 1.9Àx TeO 6 (0.02pxp0.1) powder phosphors is reported. Three dominant bands centered at 395, 466 and 534 nm characterized the excitation spectrum. Under the excitation of 395 nm UV light, the emission spectrum exhibits an intense peak centered at 616 nm corresponding to the 5 D 0 -7 F 2 transition of Eu 3+ . Because the f-f transitions are located in the wavelength range of blue or near-UV range, optimized phosphor, Eu 0.10 Gd 0.08 La 1.82 TeO 6 , is a promising material for solid-state lighting based on GaN LEDs applications.