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Optical Pressure Sensor Based on the Emission and Excitation Band Width (FWHM) and Luminescence Shift of Ce3+ Doped Fluorapatite – High-Pressure Sensing
摘要： A novel, contactless optical sensor of pressure based on the luminescence red-shift and band width (full width at half maximum - FWHM) of the Ce3+-doped fluorapatite - Y6Ba4(SiO4)6F2 powder, has been successfully synthesized via a facile solid-state method. The obtained material exhibits a bright blue emission under UV light excitation. It was characterized using powder X-ray diffraction, scanning electron microscopy and luminescence spectroscopy, including high-pressure measurements of excitation and emission spectra, up to above ≈30 GPa. Compression of the material resulted in a significant red-shift of the allowed 4f→5d and 5d→4f transitions of Ce3+ in the excitation and emission spectra, respectively. The pressure-induced monotonic shift of the emission band, as well as changes in the excitation/emission band widths, have been correlated with pressure for sensing purposes. The material exhibits a high pressure sensitivity (dλ/dP ≈0.63 nm/GPa), and outstanding signal intensity at high-pressure conditions (≈90% of the initial intensity at around 20 GPa) with minimal pressure-induced quenching of luminescence.
关键词： Ce3+ doping,Contactless pressure gauge,Y6Ba4(SiO4)6F2 apatite phosphors,Lanthanide ions (Ln3+),Compression in DAC,Luminescent functional materials
更新于2025-09-23 15:23:52
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Preparation and Luminescence Properties of Ba5Si8O21 Long Persistent Phosphors Doped with Rare-Earth Elements
摘要： The phosphors of formula Ba5Si8O21:Eu2+,Dy3+ were synthesized and studied in order to improve their properties. Their synthesis conditions were evaluated as a function of precursors, crucible composition, flux agents, dopants and temperatures. The samples were characterised by means of a systematic investigation through elemental, kinetic, mineralogical (both qualitative and quantitative), and morphological analysis. This study allows for a careful evaluation of the parameters that influence the formation and properties of Ba5Si8O21:Eu2+,Dy3+ phosphors. As for the synthesis conditions, the use of Na2SiO3, BaCO3 and NH4Cl as precursors was very important to reduce the temperature and time of synthesis. The reducing atmosphere produced with purified coal was cheaper and gave results similar to the more traditional gas mixture (H2/N2). At the end of this study, a phosphor with improved long persistent phosphorescence (LPP) characteristics was obtained with Ba/Si = 0.7, Eu/Si = 2.8 × 10?3 and Dy/Si = 3.6 × 10?3 following a 6 h-synthesis in a quartz crucible.
关键词： barium silicates,kinetic analysis,luminescence,quantitative phase analysis,phosphors
更新于2025-09-23 15:22:29
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Comparative study on blue-turquoise silicate apatite phosphors prepared via different synthesis routes
摘要： Different types of gel precursors were obtained via microwave-assisted precipitation, gel-combustion, sol–gel, and Pechini methods in order to prepare Ca2Y7.76Ce0.12Tb0.12(SiO4)6O2 phosphors with apatite structure. The processes involved during the thermal treatment of precursors were revealed by TGA– FT-IR coupling. ICP-OES reveals that the incorporation degree of dopants (Ce3+, Tb3+) in silicate lattice are close to theoretical values while Ca2+ and Y3+ values shows differences depending on the synthesis route. The phosphors composition, morphology, structure, and optical characteristics are revealed by SEM, XRD, FTIR, and luminescent investigations. Pure hexagonal apatite with crystallite size of 76.5 nm was identi?ed in sample prepared by gel-combustion, while cubic-Y2O3 and monoclinic-Y2SiO5, as secondary phases, were found in precipitated samples. The purity phase was enhanced by increasing the TEOS amount during precipitation. As a result of the Ce3+ incorporation into different symmetry sites, the excitation spectra are dominated either by 321 or 360 nm band. Turquoise emission of apatites is shifted toward blue region by increasing the excitation wavelength from 231 to 360 nm.
关键词： Silicate apatite,Luminescence,Wet chemical synthesis,Phosphors
更新于2025-09-23 15:22:29
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High concentration Eu3+-doped NaYb(MoO4)2 multifunctional material: Thermometer and plant growth lamp matching phytochrome PR
摘要： Phytochromes PR and PFR are distributed in various organs of plant, phytochrome PR absorbs red light and phytochrome PFR absorbs far-red light, respectively, so the flower induction, etc. can be controlled by changing the ratio of red light to far-red light. The emission of Eu3+ (transition from 5D0/7F2) is located at the red range and matches with the absorption band of PR. Herein, we synthesized successfully NaYb(MoO4)2: Eu3+ phosphors with the high doping concentration (50%) by hydrothermal method with further calcinations. The LED device was also fabricated by the blue InGaN chip combined with the red phosphors NaYb(MoO4)2: 50%Eu3+ based on the excellent luminescent intensity. Moreover, the effect of temperature on the excitation intensity ratio of MoO4 2- to Eu3+ has also been studied, which provided the possibility of simultaneous luminescence and temperature measurement. This work is the first time to use Eu3+ as a red source matching PR, and the red phosphors have potential value to control plant growth.
关键词： Down-conversion luminescence,Temperature sensing,LEDs,Plant cultivation,Red phosphors
更新于2025-09-23 15:22:29
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Luminescent hybrid materials based on metal-organic phosphors in PbF2 powder and PbF2-containing glass matrix
摘要： The new hybrid materials (HM's) are based on the phosphors used in OLED technology in inorganic PbF2-containing matrices: PbF2 powders and low melting PbF2-based oxyfluoride glasses, were synthesized. We used highly effective thermostable phosphors: 4,4,5,5,6,6,7,7,8,8,9,9,9-tridecafluoro-1- (1-methyl-1H-pyrazol-4-yl) nonane-1,3-dione - (1,10-phenanthroline) europium (III), 8-hydroxyquinoline complexes with metals and the individual organic ligand – 4,4,4-trifluoro-1- (2-naphthyl) butane-1,3-dione. Powdered HM's were prepared by co-precipitation from aqueous solutions. The effect of organic molecules or molecular fragments on dimension and morphology of precipitated PbF2 particles, the luminescence properties of HM's were investigated for the samples obtained directly after the precipitation-drying procedure, and after the powders' calcination procedure. The change in the photoluminescence spectra after the heat treatment of the powders is caused by the proceeding of the exchange reaction between the metal complex and the matrix with the formation of Pb-complexes of different coordination is shown. HM (glasses PbF2eB2O3, PbF2eB2O3eSiO2 or PbF2eB2O3eSiO2eZnO phosphor) were obtained by the melt process in which the phosphor powder was submerged into the melt of the pre-synthesized glasses.
关键词： Lead fluoride,Lead fluoride nanoparticles,Hybrid materials,Luminescence,Organic phosphors
更新于2025-09-23 15:22:29
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Photoluminescence Characteristics of Sm3+-doped LnBWO6 (Ln=La, Gd and Y) as New Orange-red Phosphors
摘要： A series of Sm3+-doped LnBWO6 (Ln=La, Gd and Y) phosphors with orange-red light emitting in pure phase were prepared by high temperature solid-state process. The crystal structure, photoluminescence properties, decay lifetimes and thermal stability properties of those as-prepared samples were investigated. Those phosphors can be efficiently excited by near-UV and blue light and emitted orange-red luminescence with color coordinates (0.622, 0.377). Among those LnBWO6 (Ln=La, Gd and Y) hosts, the emission intensities of Sm3+-doped LaBWO6 are the strongest ones. The optimum doping concentration and critical energy transfer distance of Sm3+ ions in LaBWO6 were determined. The fluorescence concentration quenching mechanism was attributed to the dipole-dipole interaction between the Sm3+ ions. The fluorescent thermal quenching studies showed Sm3+ doped LaBWO6 had high thermal-stable properties. The present work suggested that Sm3+-doped LnBWO6 (Ln=La, Gd and Y) as orange-red phosphors exhibited potential application in white LED.
关键词： red phosphors,concentration quenching,energy transfer,white LEDs,luminescent properties
更新于2025-09-23 15:22:29
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Effect of Zn substitution in Cr3+ doped MgAl2O4 mixed spinel nanoparticles on red/NIR emission properties
摘要： Red/Near-infrared (NIR) emitting Mg1-xZnxAl1.98Cr0.02O4 nanoparticles were synthesized by co-precipitation followed by firing(1200°C). Gradual shift of XRD peaks with Zn-content confirmed complete solid-solution formation. HRTEM revealed hexagonal sheet-like structures and lattice fringes revealed their single-crystallinity. Owing to refractory nature of MgAl2O4, particles were smaller(~38nm) in Mg-rich samples and gradually increased(~58nm) with Zn-substitution. Due to trigonal distortion, the fine splitting of the 4T1g level of Cr3+ manifests as asymmetric band(400nm) in the excitation spectrum. Cr3+ emission was clearly observed, comprising of R-line and multi-phonon side-bands on either side, with maximum R-line intensity for x=0.5. With increasing x, side-bands were more pronounced probably due to the band-gap difference of end members. High Dq/B(3.5-3.9), suggested Cr3+ in a strong crystal-field. Racah-parameter(B) variations suggest increased electron delocalization over molecular orbitals for higher Mg2+ substitutions. Longer lifetimes(23-34ms) are well-suited for bioimaging and optoelectronic applications. Such a simple synthesis can be easily extended to other important phosphors.
关键词： MgAl2O4,Luminescence,Nanoparticles,Phosphors,ZnAl2O4,Oxide ceramics
更新于2025-09-23 15:21:21
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Tuning phosphors for better white light
摘要： Light-emitting diodes (LEDs) that produce white light are about to take over the lighting world. The U.S. market share of these super-long-lasting, cool-to-the-touch lights, which use less than a quarter of the energy of conventional incandescent bulbs, sits around 10%. Industry watchers predict that number will exceed 80% by 2030, reducing power consumption in the U.S. by 40%. Chemists are taking a leading role in this technology, which underpins general lighting and electronic displays, by customizing the emission spectrum, stability, and other properties of inorganic phosphors in the LEDs that help produce finely tuned white light.
关键词： energy efficiency,inorganic phosphors,color rendering index,LEDs,white light
更新于2025-09-23 15:21:21
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Synthesis and Luminescence Properties of Nanostructured Gd3 –x – yYbxEryBWO9 Borate Tungstates
摘要： Using the Pechini process in the presence of citric acid and mannitol, followed by annealing in the range 800–1000°C, we have synthesized nanostructured rare-earth borate tungstates crystallizing in hexagonal symmetry (sp. gr. P63): undoped Gd3BWO9 and Gd3 – x – yYbxEryBWO9, containing Yb3+ and Er3+ active ions. We have measured upconversion luminescence spectra of the Er3+ ions in Gd3 – x – yYbxEryBWO9 for the 2H11/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions under excitation by an IR laser (λ = 974 nm). The spectra consist of two groups of broadened bands in the red and green spectral regions. Brighter luminescence is observed in the green spectral region, which contains two bands corresponding to the Er3+ 2H11/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions. We have analyzed the effect of annealing temperature on the upconversion luminescence intensity of Gd3 – x – yYbxEryBWO9 and determined the energy yield of upconversion luminescence in the Gd3 – x – yYbxEryBWO9 borate tungstates. The highest value, Ben = 0.19%, has been obtained for the phosphor with Yb : Er = 7 : 1.
关键词： nanophosphors,rare-earth borate tungstates,upconversion phosphors
更新于2025-09-23 15:21:21
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Enhanced long afterglow of SrAl2Si2O8:Eu2+ by codoping Dy3+
摘要： Eu2+/Dy3+ doped SrAl2Si2O8 phosphors were synthesized by a solid state reaction. The phase and luminescent properties of the synthesized phosphors were investigated by the X-ray powder diffraction, photoluminescence spectra, decay curves and the thermo-luminescence glow curves. The XRD results show that the doped Eu2+/Dy3+ has no influence on the phase of SrAl2Si2O8. The incorporation of Dy3+ could significantly enhance the intensity and prolong the afterglow duration of SrAl2Si2O8:Eu2+. The co-doped Dy3+ ions act as trap centers and trap the electrons generated during exposure of the phosphor to an excitation source, which induces the longer afterglow comparing with Eu2+ singly doped SrAl2Si2O8 phosphor.
关键词： SrAl2Si2O8:Eu2+/Dy3+,luminescent properties,long afterglow,phosphors
更新于2025-09-23 15:21:21