Research of green emitting rare-earth doped materials as potential quantum-cutter (original) (raw)
Related papers
Rare-earth doped phosphors: oldies or goldies
Materials Science and Engineering B-advanced Functional Solid-state Materials, 2003
The scientific research on phosphors has a long history starting more than 100 years ago. But recently the appearance of new kinds of displays and lighting devices (plasma display, fluorescent lamp without mercury, etc.) induced an increase of the research of new phosphors with better luminous efficiency than those available up to now. It has been shown that the behavior of "classical" phosphors in a plasma display panel is quite different than in a cathode ray tube and that the vacuum ultraviolet (VUV) excitation process has to be studied with care in order to improve the phosphors efficiency. That is particularly true in PDPs. It is well established now that a good phosphor for electronic or ultraviolet excitation is not necessarily a good choice for excitation in VUV. This is probably due to the fact that the excitation process is very different in that case and also because the penetration depth of the VUV photons is extremely small inducing a large contribution of the surface of the phosphor. We will illustrate this with some examples. Methods to accelerate luminous intensity decrease under VUV excitation will be described. Low efficiency, fast aging process are both drawbacks that can be solved only in the framework of fundamental studies. Quantum cutting emission may be a solution for the first one but no satisfactory process was proposed for the moment to solve the second.
Why the quest of new rare earth doped phosphors deserves to go on
Optical Materials, 2006
The scientific research on phosphors has a long history starting more than 100 years ago. But recently the appearance of new kinds of displays and lighting devices (plasma display, fluorescent lamp without mercury. . .) induced an increase of the research of new phosphors with better luminous efficiency than those available up to now. It has been shown that the behaviour of ''classical'' phosphors in a plasma display panel is quite different than in a cathode ray tube and that the vacuum ultraviolet (VUV) excitation process has to be studied with care in order to improve the phosphors efficiency. It is well established now that a good phosphor for electronic or ultraviolet excitation, is not necessarily a good choice for excitation in VUV. This is probably due to the fact that the excitation process is very different in that case. We will illustrate this difference on the well-known LaPO 4 :Ce 3+ , Tb 3+ phosphor. The penetration depth of the VUV photons is extremely small inducing a large contribution of the surface of the phosphor. We have shown that, for most phosphors, only a few tens of nanometers of the phosphor grain are really useful and we propose a way to realize phosphors powders using less than 20% of doped materials. However the traps of the material play a crucial role in the fluorescence properties due to the fact that autoionization process is likely when dopant ions absorb high energy photons. Fast aging process is one of the main drawbacks of VUV excitation. We demonstrate this effect on BaMgAl 10 O 17 :Eu 2+ , the blue emitting phosphor widely used up to now in Plasma Displays Panels and fluorescent lamps. Low energetic efficiency is another drawback of VUV excitation that can be solved only in the framework of fundamental studies. Quantum cutting emission may be a solution and calls new research to find good phosphors characterized by a high quantum efficiency, a high fluorescence efficiency and an adapted colorimetry.
Synthesis and characterization of phosphors doped with various rare earths
2011
A blue emission powder phosphor , Sr 2 CeO 4 was prepared using solid-state reaction technique. The powder fired at 1100 0 C for 3 hours gave good luminescence yield. The emission peak of this phosphor is at 470 nm. To use this phosphor in a tricolor lamp effectively, studies have been carried out to see the effect of rare earth dopants on the luminescence spectra of this phosphor. The effect of the dopants on phosphor efficiency has been evaluated and the effect of using these dopants and material characterization of these phosphors using optical and structural techniques are discussed in this paper.
A red phosphor for nUV LED based on (Y, Gd) BO3: Eu3+
Materials Letters, 2010
BO 3 :Eu 3+ based phosphors were prepared by combustion technique followed by solid state sintering in air. The 4f-4f excitation at 394 nm of (Y 0.54 Gd 0.46) x (BO 3) y :Eu 3+ exhibits red emission at 593 nm. Its photoluminescence (PL) efficiency depends critically on the BO 3 to (Y,Gd) molar ratio. Optimal luminescence was obtained at the y/x molar ratio of 1.38. A 12-fold increase in its luminescence efficiency was seen with an increase in Eu concentration from 0.5 to 8.4 mol% at this y/x ratio. At 8.4 mol% of Eu concentration, the PL sensitivity of (Y 0.54 Gd 0.46) x (BO 3) y :Eu 3+ is 40% higher than that of the commercial (Y,Gd)BO 3 :Eu 3+ phosphor. In view of the high luminescence efficiency, this phosphor could serve as a potential candidate for application as a red phosphor for nUV LED apart from its known application in plasma display panels.
IRJET, 2020
Trivalent and divalent rare earth elements are contributing to tremendous application areas such as several high-tech, eco-friendly, energy consumed economized display devices. Trivalent Erbium doped efficient host materials are widely used for these applications in telecommunication fibre optical devices. Erbium ions are more stronger covalence bond and lower symmetry. Specifically, strong green light emission was observed under reverse bias due to electron. This present paper reviewed and finding more applications to required studies allowing trivalent Erbium doped silicate based nano phosphor is an interesting alternative high performance, higher reactivity energy consumed optical LED's and display devices. CONSIDERATIONS Today's scientific findings and invention improved our life ranging from birth to death. Science made significant contributions to improving the quality of human life style via. Technological inventions on individual part in our eco-friendly societies. Sir Isaac Asimov in his book "Chronology of science and discovery", beautifully described how science has shaped the world and human life from discovery of fire to the 21th century. In last few years science taught us how to utilizing our natural resources wisely to maintained their country as well as continuity of humanity. To improved our new brain level of human society science can play a futuristic technical hero. They are many great scientific discoveries and technological achievement in various streams. Scientists should reflect on the social consequences of the technological applications or dissemination of partial information of their work and explain to the public and truly policy makers the degree of scientific knowledge society in their finding applications. Since 19 th century, Science and technology have both complementary part to each other in our people society. At that time to people are truly independent to destroyed nature and cope with environment change. The relationship between the man and the environment has been established in the early periods to conceptual framework for upgrading the technological aspects is also providing foundational scientific developments and recent approaches. Luminescence is cold emission light source of energy who is the greatest innovative technical research field in new generations. Luminescence phenomenon is not explained in some words but it is clearly described the meaning of light through different languages. Our observation in the colour of the phosphorescence light in a material also excitation spectra of light through scattering. In 19th and early 20th centuries, which was used to heavily doped in different host materials. In luminescence, some energy source kicks an electron of an atom out of transition over (lower-energy) state into (higher-energy) state. We can observe the luminescence phenomenon in nature like, in global-worms, fireflies, and in certain sea bacteria and deep-sea animals [1-4]. Truly described to trivalent and divalent rare earth materials (Eu 2+ , Eu 3+ , Ce 3+ , Tb 3+ , Dy 3+ , Er 3+) are more precious and valuable long persistent phosphors exhibited through UV and visible light excitation. The trivalent rare earth ions exhibited to the conduction band and transition over trapped to electron possibility. Eu 2+ is a most common emission centre in persistent material hosted by the 4f 7 4f 6 5d 1 transition [5-6]. The rare earth doped silicate materials have been widely studied and more possibilities such as tremendous high thermal light emission, more stable, more durable, compactness, eco-friendly, energy saving and more luminescent efficient indicating white LED's [7-8]. F block elements are also called Lanthanide elements [La (57) to Lu (71)]. Erbium is the most efficient trivalent rare earth ion and energy level transition of electron of an atom ground state to excited state (4f 12 , 6s 2). Since 2011, First time investigated silicate-based bio ceramics for tissue engineering. The conventional combustion process has also studied to synthesized divalent Europium doped Ca2MgSiO7 and Sr2MgSiO7 have Akermanite structure who shows that high intense emission spectra of Eu 2+ to glows peak/curves [9].
Europium-doped phosphors for lighting: the past, the present and the future
2011
Europium, the 63 rd element of the periodic table, was isolated and identified as one of the last in the rare earth series by Eugène-Anatole Demarçay in 1901, and named after the European continent. Europium does not occur as a metallic element in nature, as it readily oxidizes. It is found in small quantities (of the order of 1 ppm) in the earth crust. It is mined from a few minerals, where the Eu-content can reach a few tenths of % [1].
Journal of the American Ceramic Society, 2018
Phosphor materials with ultra-high color purity are highly desired in backlit display of various light-emitting devices. How to achieve high-purity three-primary emission in rare earth ions activated inorganic phosphors has become a hot topic of research. Herein, we reported extremely narrow band and highly efficient blue-violet-emitting Eu 2+-doped Ba 2 B 5 O 9 X (fwhm = 31 nm) and NaBa 4 (AlB 4 O 9) 2 X 3 (X = Cl, Br) (fwhm = 43 nm) phosphors with peak positions around 424-437 nm. Especially, the 31 nm-fwhm Ba 2 B 5 O 9 Cl:Eu sample is the narrowest one among the reported rare earth doped blue-emitting phosphors, whose color purity even exceeded 97%. The EXANES analysis revealed that the Eu mainly existed in the form of +2. The extraordinarily narrow band emission has been analyzed according to the Rietveld structural refinement, which should be attributed to the highly symmetric lattice structures with the flower-like polyhedrons in the studied (alumino)borate matrixes. Significantly, the color gamut of as-prepared blue phosphors combined with the standard green and red phosphors was almost close to that of Rec. 2020 display standards. Finally, the electroluminescence performances of the studied phosphors in WLEDs devices were systematically investigated, which present low color correlated temperatures (CCT = 2578-4836 K), high color rendering indexes (Ra = 91.2-97.6) and high luminescence efficiency (around 13.40 lm/W). All these results demonstrate that the as-prepared phosphors could be superior blue-emitting candidates for backlit display as well as WLEDs.
Journal of Luminescence, 2016
Phosphors for solid-state lighting, based on a number of different compositional schemes and driven by light from blue light-emitting diodes (LEDs) are widely used for lighting applications. The low efficiency of pump LEDs at high drive currents (droop effect) limits the amount of light produced by conventional LED and phosphor combination. Pumping with laser diodes (LDs) can circumvent this limitation. In this paper we report on the characterization of individual and a mixture of KEu(WO 4) 2 (red), BaMg 2 Al 16 O 27 :Eu, Mn (green) and (Sr,Mg) 2 SiO 4 :Eu (blue) phosphors, excited by a CW-driven LD operating at 404 nm. The activator ion in each of these phosphors is, respectively, Eu 3+ , Mn 2+ and Eu 2+. Characteristics of light produced with each phosphor, variations with incident light power and phosphor temperature as well as effects from phosphor ageing are described. Results of comparison between pumping with coherent and incoherent light at the same wavelength are also described.
Photo-luminescence study of red borate phosphor Sr3 Y1−x (BO3)3:xEu3+
2019
The polycrystalline powder sample of Eu 3+ activated strontium yttrium borate phosphor Sr3 Y1-x (BO3)3:xEu 3+ (x = 0.03) was prepared by solution combustion technique. A prepared material was characterized by powder XRD, SEM, PL and FT-IR techniques. Powder XRD confirms the Formation of desired phosphor and its crystal structure. XRD pattern of synthesized phosphor matches with standard pattern given by ICSD File NO. 246230. Particle morphology was studied using SEM. Microstructure of the phosphor consisted of irregular grains with agglomerate phenomena. The average size of synthesized phosphor particles is about 5-10 µm. FTIR confirms the complete removal of nitrates, organic matter and confirms the existence of the [BO3]-groups. A broad excitation band in the wavelength range 200-300 nm centering at 254nm is observed, which can be due to the charge transfer from O-2 to Eu 3+. At 254 nm Photo Luminescence excitation of sample shows intense red emission at 613nm corresponding to 5 D1→ 7 F2 transition of Eu 3+. Intense emission at 613nm is due to electric dipole transition. Low intensity emission due magnetic dipole transition at 595 nm (5 D1 → 7 F1 of Eu 3+) and at 580 nm (5 D1 → 7 F0 of Eu 3+) was also noted. Chromaticity coordinates of sample was found to be X = 0.674719511, Y = 0.325095182, which fall into the red region in the CIE 1931 chromaticity diagram. The Phosphor exhibits intense red emission at 613 nm hence it could be a potential red emitting component in the tricolor lamps and may be used in white light emitting diodes for practical use.