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Divalent europium-doped near-infrared-emitting phosphor for light-emitting diodes
摘要： Near-infrared luminescent materials exhibit unique photophysical properties that make them crucial components in photonic, optoelectronic and biological applications. As broadband near infrared phosphors activated by transition metal elements are already widely reported, there is a challenge for next-generation materials discovery by introducing rare earth activators with 4f-5d transition. Here, we report an unprecedented phosphor K3LuSi2O7:Eu2+ that gives an emission band centered at 740 nm with a full-width at half maximum of 160 nm upon 460 nm blue light excitation. Combined structural and spectral characterizations reveal a selective site occupation of divalent europium in LuO6 and K2O6 polyhedrons with small coordination numbers, leading to the unexpected near infrared emission. The fabricated phosphor-converted light-emitting diodes have great potential as a non-visible light source. Our work provides the design principle of near infrared emission in divalent europium-doped inorganic solid-state materials and could inspire future studies to further explore near-infrared light-emitting diodes.
关键词： divalent europium,Near-infrared luminescent materials,4f-5d transition,light-emitting diodes,phosphor
更新于2025-09-11 14:15:04
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Photometric features and typical white light emanation via combustion derived trivalent dysprosium doped ternary aluminate oxide based nanophosphor for WLEDs
摘要： Trivalent dysprosium doped ternary aluminate oxide based SrGd2Al2O7 nanocrystalline phosphors were synthesized via an efficient single step solution combustion process. The estimated value of optical band gap energy for the optimized nanophosphor and host matrix were found to be 5.58 eV and 5.76 eV respectively. Diverse crystalline features were elucidated via analyzing PXRD patterns and Rietveld refined results of host matrix and optimal SrGd1.94Dy0.06Al2O7 nanophosphor. Diverse elements present in the optimized nanophosphor were found to be Sr, Gd, Dy, Al and O as revealed via energy diffraction X-ray analysis (EDAX). The surface morphological features and the particle size of the optimum nanosample were disclosed by scanning electron microscope (SEM) and transmission electron microscope (TEM) practices. The characteristic emission spectra recorded using excitation wavelength of 350 nm display two strong peaks at 484 nm and 578 nm that were allotted to 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 respective transitions. The evaluated critical distance value was ensured to be much higher than 5 ? indicating no chance of occurrence of concentration quenching (CQ) as a result of exchange interactions amongst dopant ions. Dipole-dipole interactions in the midst of adjoining Dy3+ ions were observed to be an appropriate cause for following CQ trend. Based on outcomes of Correlated Color Temperature (CCT) and International Commission on Illumination (CIE), it was quite obvious that the prepared nanomaterial will prove to be absolutely beneficial for applications related to lightning and display systems. Thus, it can be concluded that a new window opens for white light emitting diode (WLED) applications using the synthesized nanophosphors.
关键词： PXRD,Nanocystalline phosphor,Crystal configuration,EDAX,Dy3+
更新于2025-09-11 14:15:04
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Synthesis and photoluminescence properties of NaBi(WO4)2:Eu3+ red-emitting phosphor for NUV-based WLEDs
摘要： In this work, NaBi(WO4)2:Eu3+ red phosphors were synthesized by high temperature solid-state method. The XRD and Rietveld refinement were used to analyze the crystal structure, and the morphology was investigated by the SEM. Upon excitation with 395 nm, these phosphors exhibited intense red emission at 615 nm attributing to the 5D0→7F2 transition of Eu3+ ions. The optimal doping concentration of Eu3+ ions in NaBi(WO4)2:xEu3+ phosphors was x = 0.8, and the electric dipole-dipole interaction dominates the concentration quenching mechanism. The Judd–Ofelt intensity parameters (?2 and ?4) were determined to confirm the site asymmetry of Eu3+ ions in NaBi(WO4)2 host. Furthermore, the NaBi(WO4)2:0.8Eu3+ phosphor also possesses excellent thermal stability with the PL emission intensity still keep up about 88.2% at 423 K comparing with that at 303 K, meanwhile, the internal quantum efficiency (IQE) of it was measured to be 83.6%. The CIE chromaticity coordinate of NaBi(WO4)2:0.8Eu3+ sample was (0.656, 0.343), and the color purity of it was calculated to be as high as 95.8%. Based on the results above, the NaBi(WO4)2:Eu3+ phosphors are promising red components, which can be utilized in the applications of near-ultraviolet (NUV) pumped WLEDs.
关键词： Thermal stability,NaBi(WO4)2:Eu3+,Photoluminescence,Red phosphor
更新于2025-09-11 14:15:04
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A Mn4+-doped oxyfluoride phosphor with remarkable negative thermal quenching and high color stability for warm WLEDs
摘要： Red-emitting phosphors composed of Mn4+-activated fluorides have attracted considerable interest for their applications in warm white light-emitting diodes (WLEDs). However, in addition to moisture instability, the unsatisfactory thermal stability of these phosphors limits their industrial applications. In this study, a novel red phosphor of CsMoO2F3:Mn4+ was synthesized via simple coprecipitation. This red phosphor exhibits an orthorhombic structure with a bandgap of ~3.43 eV. The Mn4+ ions occupy Mo6+ sites at the centers of [MoO2F4]2- octahedrons. This phosphor shows narrow emission around ～633 nm excited by 450 nm blue-chip with high color purity of 99.58%. Satisfactorily, this phosphor exhibits excellent thermal stability and a strong negative-thermal-quenching. The total PL intensity of CsMoO2F3:3.88%Mn4+ phosphor at 275 K strengthens to ~540% relative to that at 25 K, and its relative emission intensity preserves about 129.3% when the temperature rises from room temperature to 423 K (150 ℃). It also shows admirable color stability with a slight chromaticity shift (ΔE) of only ~33.9 × 10?3 in the temperature region from 298 to 473 K. Furthermore, a warm WLED was fabricated by the mixture of red-emitting CsMoO2F3:3.88%Mn4+ and the yellow-emitting YAG:Ce3+ phosphors with a blue-emitting InGaN LED chip. The device exhibits low correlated color temperature (3983 K) and high color-rendering index (Ra = 81.3). With the increasing drive current from 20 mA to 120 mA, the chromaticity coordinate variation (CCV) is only (-0.0163, 0.0202). All these results indicate that the CsMoO2F3:Mn4+ phosphor holds tremendous potential for practical applications in high-power lighting and display with high-performance WLEDs.
关键词： oxyfluoride,red phosphor,luminescence,negative thermal quenching,Mn4+
更新于2025-09-11 14:15:04
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Understanding Crystal Structure and Site Symmetry of Undoped, Eu3+:Ba2LaSbO6 & Eu3+:BaLaMSbO6 (M = Mg,Ca): Tuning Eu-site Occupancy to Develop Both Orange and Red Phosphor
摘要： Double perovskite antimonates of the type BaLaMSbO6 (M=Mg, Ca) were synthesized by standard solid state route. The compounds were characterized by X-ray diffraction and the crystal structure was refined using Rietveld method. BaLaMgSbO6 and BaLaCaSbO6 crystallized in monoclinic (I2/m) and (P21/n) space group respectively. In both the compounds, La occupied A-site of perovskite, which is 12-coordinated as compared to Ba2LaSbO6 where La ion shifts to B-site octahedral coordination due to larger size of Ba as compared to Mg and Ca. The samples were further characterized using FTIR and the frequency of the octahedral vibration is correlated to the electronegativity of the B-site ions. Photoluminescence study of the title compounds and Ba2LaSbO6 was also studied upon doping with 2 atom% Eu3+ ion, which confirmed that Eu3+ occupies distorted 12-coordinated A-site in BaLaMSbO6 (M=Mg, Ca) and symmetrical octahedral B-site in Ba2LaSbO6. Further, the emission spectrum due to each Eu3+ ion at different crystal site was successfully isolated by TRES study. This enables to understand the structural differences of these compounds. This site selective occupancy of Eu3+ ion also has a direct impact on the light emission, which was found to change from orange to red in a dark room in the order Ba2LaSbO6:Eu → BaLaCaSbO6:Eu → BaLaMgSbO6:Eu. Such study will have high impact in designing new commercial Eu3+ ion doped phosphor materials and tailoring of their optical properties.
关键词： Double perovskites,FTIR spectroscopy,Crystal structure,Phosphor material,Antimonates,Photoluminescence (PL)
更新于2025-09-10 09:29:36
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Nanothick aluminate long-afterglow phosphors using inherited hydrothermal deriving
摘要： A novel strategy of the inherited hydrothermal method was used to prepare SrAl2O4: 0.01Eu2+, 0.01Dy3+ (SAO) without boron (ISAO) and boron-doping (BSAO) via NaAlO2 as an aluminum source and mineralizer at 200 °C for 6–24 h. The investigated optical properties was correlated to phase transformation and phosphor morphology. The main constituting phases of Al2(OOH)2 and SrCO3 transformed to monoclinic SrAl4O7 and mixed monoclinic/hexagonal SrAl2O4 then pure monoclinic SrAl2O4 during di?erent hydrothermal period. The hydrothermally prepared samples exhibited ?ower-like morphology. The annealed plate phosphors with nanothick single crystals inherited from hydrothermal feature. The shift of photoluminescence (PL) peak wavelength corresponded to the phase transformation from SrAl4O7 to SrAl2O4 with hydrothermal time for ISAO and BSAO. The PL intensity increased with hydrothermal time due to achieving the pure SrAl2O4 phase with preferred orientation geometry and further enhanced by boron-doping. The afterglow of BSAO was signi?cantly enhanced than ISAO, solid-state prepared MSAO and commercial SAO at the initial 100 s after excitation cut-o?. The boron doped in the BSAO was scarcely on the grain surface as to small grain size. Thus, the afterglow enhancement should be attributed to the boron in the lattice inducing defect traps. Overall, the inherited hydrothermal and boron-doping derived nanothick SAOs with large surface preferred orientation enhanced the PL and afterglow properties.
关键词： Phosphor,Afterglow,Inherited hydrothermal,Aluminate
更新于2025-09-10 09:29:36
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Novel luminescent PLA/MgAl2O4:Sm3+ composite filaments for 3D printing application
摘要： In this work, luminescent bioplastic composite ?laments for 3D printing were fabricated from polylactic acid (PLA) and samarium doped magnesium aluminate phosphor (MgAl2O4:Sm3+). The phosphor was prepared by a metal-complex decomposition method. The obtained powder was then modi?ed by 3-aminopropyl triethoxysilane to improve compatibility with PLA matrix. Untreated and treated phosphors exhibited characteristic photoluminescent (PL) peaks of Sm3+ ion. Composite ?laments of PLA with different amounts of phosphors (0, 1, 2, 3 and 4 phr) were produced by an extrusion process. Differential scanning calorimetry (DSC) scans have revealed that the phosphor ?llers lowered glass-transition (Tg), crystallization (Tc), and melting (Tm) temperatures of the PLA. PL measurements have shown luminescent properties of 3D printed samples resembling those of phosphor powders. Luminescent intensity was increased with the increasing ratio of phosphors. The phosphors not only developed luminescence but also strengthened mechanical properties of the composites. Furthermore, surface modi?cation was able to improve the mechanical properties of the composite ?laments as evident in a series of mechanical tests.
关键词： Polymer composite,3D printing,Samarium doped magnesium aluminate,Polylactic acid,Phosphor
更新于2025-09-10 09:29:36
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Development of up-converting phosphor technology-based lateral flow assay for quantitative detection of serum PIVKA-II: Inception of a near-patient PIVKA-II detection tool
摘要： Background: Development of a test card based on up-conversion phosphor technology-based immune lateral flow (UPT-LF) assay as a near-patient detection tool for serum Prothrombin induced by vitamin K absence or antagonist II (PIVKA-II). Methods: Up-converted phosphor nanoparticles (UCPs) were used to bind to PIVKA-II monoclonal antibodies as labeled probes to develop the test card for detecting serum PIVKA-II. The UPT-LF test card was evaluated by the limit of detection, linearity, stability, recovery rate, precision and interference. Preliminary clinical validation was conducted by detection of 498 serum samples from 228 patients with hepatocellular carcinoma (HCC), 170 patients with liver benign lesion (LBL) and 100 healthy controls (HC). Additionally, the correlation of serum PIVKA-II detection between UPT-LF assay and Chemiluminescence enzyme immunoassay (CLEIA) assay were performed. Results: Modified and activated UCPs bound to monoclonal antibodies powerfully to form the luminescent labeled probes. Limit of detection and linear range of UPT-LF test card for serum PIVKA-II were 2.66 and 4.8–20,000 ng/ml, respectively. Test card had good 25 °C thermal and 4 °C validity period stability, 93.1%–99.2% of recovery rate, 2.6–5.8% and 5.4–8.9% of intra-assay and inter-assay CVs, and strong anti-interference ability for 8 common serum analytes. The sensitivity and specificity (vs LBL + HC group) of test card for HCC were 71.5% and 88.9%, respectively. The R2 between UPT-LF assay and CLEIA assay was 0.901. Conclusions: UPT-LF assay provides a reliable, rapid and convenient test for quantitative detection of serum PIVKA-II as well as diagnosis of HCC by a point of care testing way.
关键词： Point of care testing,Hepatocellular carcinoma,PIVKA-II,Lateral flow assay,Up-conversion phosphor technology
更新于2025-09-10 09:29:36
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Photostimulated and persistent luminescence of samarium ions in BaFCl
摘要： Storage phosphors with e?cient photostimulated luminescence (PSL) and/or persistent luminescence (PersL) are in great demand for a range of applications. In this paper, PSL, PersL and thermoluminescence (TL) of samarium ions doped in a macroscopic and sub-micron crystals of BaFCl are reported, and it is demonstrated that the co-precipitated BaFCl:Sm3+ sub-micron crystals become an e?cient photostimulable X-ray storage phosphor upon annealing in the temperature range of 200–500 °C. The dependence of storage phosphor properties on annealing temperature was investigated and it was found that the X-irradiated co-precipitated BaFCl:Sm3+ crystallites (~400 nm size) showed maximum PSL and PersL from both Sm2+ and Sm3+ ions when annealed at 500 °C for 4 h. From a comparison with data for the macroscopic crystal (~3 mm) and ball-milled nanopowders (~30 nm), it also followed that PSL and PersL in the BaFCl:Sm system is a?ected by the crystal size. TL from Sm2+ of the macroscopic crystal is compared with the TL of sub-micron powders annealed at di?erent temperatures.
关键词： Storage phosphor,Photostimulated luminescence,Samarium,Thermoluminescence,Persistent luminescence
更新于2025-09-10 09:29:36
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MgAl2O4 both as short and long persistent phosphor material: Role of antisite defect centers in determining the decay kinetics
摘要： The present work describes the role of antisite defects centers in determining the phosphor characteristics of MgAl2O4, arising due to inversion nature of the spinel compound. The diverse decay characteristics impart this material both as long persistent bluish phosphor as well as short persistent red phosphors material depending upon the annealing temperature. TL study confirmed the fact that there are several defect centers which acts as electron and hole trap centers inside the band gap. FTIR and DRS study confirmed the presence of antisite defects centers viz. AlMg- or MgAl+, which act as a electron and hole trap centers and thereby delaying the electron-hole recombination process. Lower inversion at higher temperature results in decay in their concentration, as reflected in lifetime values.
关键词： TL,Phosphor,Defect,PL,lifetime
更新于2025-09-10 09:29:36