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Investigations of VO2+ doped SrZn2(PO4)2 nanophosphors by solution combustion synthesis
摘要： VO2+ doped SrZn2(PO4)2 nanophosphor is prepared using solution combustion synthesis. The prepared nanophosphor is studied by structural and spectral characterizations XRD, SEM with EDS, TEM, FT-IR, Optical absorption, EPR, and PL. XRD analyses the monoclinic phase of the prepared sample and the crystallite size determined to be in the order below 60 nm. SEM and TEM micrographs show the agglomerated stone-like structures for VO2+ doped SrZn2(PO4)2 nanophosphors. FT-IR spectrum exhibits various vibrational modes for PO4 3- anionic groups and other related groups. Optical absorption spectrum exhibited characteristic VO2+ bands in visible region and the crystal field and tetragonal field parameters are evaluated as Dq = 1461, Ds = -3035 and Dt = 602 cm-1. EPR spectrum shows well resolved hyperfine octet structure for VO2+ doped nanophosphor. The spin Hamiltonian parameters (g), hyperfine coupling constants (A) are calculated and are satisfying the condition g║<g┴<ge and A║ > A┴. From Optical and EPR data, VO2+ ions with the host ligands are identified as tetragonal distortion in octahedral site symmetry. PL spectrum illustrates, emission peaks in blue and green regions and its CIE and CCT parameters are evaluated, which are useful in LEDs and lightening devices.
关键词： Electron paramagnetic resonance,SrZn2(PO4)2 nanophosphor,Photoluminescence,tetragonal distortion,solution combustion
更新于2025-11-21 11:18:25
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Multicolour tuning and perfect white emission from novel PbWO4:Yb3+:Ho3+:Tm3+ nanophosphor
摘要： Upconverting (UC) nanoparticles have been an eye-candy for the people of optical world in the past decade because of their stupendous luminescence properties, photostability, effective quantum efficiency and most of all for its voluminous power of converting Infra-red (IR) waves into visible radiation. In this article, we have successfully synthesized novel Yb3+, Ho3+, Tm3+ doped lead tungstate nanophosphor by facile hydrothermal technique, where the product can also be scaled up in a large quantity. The phase purity and structure of the samples were characterized using X-Ray diffractometer and the structural morphology was studied using FEG TEM which shows formation of nano sphere of about 30-40 nm. Photoluminescence studies of the nanophosphor were carried out using spectroflurophotometer which shows red, green and blue emission due to the energy level transitions viz 5F5 → 5I8 and 5S2/5F4 → 5I8 of Ho3+,1G4 → 3H6, of Tm3+ respectively. The pumping power variation data was recorded using variable power which implies that the UC mechanism is a mixture of two and three photon process. The biexponential decay kinetics experiment was also done using the pulse mood laser source which shows the mean lifetime of 21.09 μs, 12.03 μs and 29.43 μs for blue, green and red emission respectively. Due to the perfect intermixing of the red, green and blue emission in the optimum sample a bright white light is obtained with CIE coordinates indexed as (0.34573,0.3449). The correlated colour temperature (CCT) values of the bright white light was calculated using McCamy’s approximations and it was found to be 4960 K which is almost equivalent to the colour “Horizon Daylight”. The colour temperature found after calculation, must be eye-friendly and hence perfect for using in optoelectronics applications.
关键词： Luminescence,White Light,Upconversion,Hydrothermal,Nanophosphor
更新于2025-09-23 15:23:52
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Luminescence enhancement of spherical Sr3La(PO4)3:Eu3+ red nanophosphor with core–shell configuration and added sensitizer for low-voltage field-emission lamp
摘要： Spherical red Sr3La(PO4)3:Bi3+,Eu3+ (SLPO:Bi3+,Eu3+) nanophosphors were synthesized by coprecipitation and thermal annealing for a low-voltage field-emission lamp (FEL). The luminescence intensity of the phosphor was improved using a coreeshell configuration with SiO2 as the core with a diameter of 360 nm and 5e15-nm-thick phosphor as the shell. A 4.4-fold enhancement in the external quantum efficiency (EQE) was obtained. A bright red cathodoluminescence was observed from a 0.25-cm2 FEL at 400 V. The excitation energy efficiently cascade-transferred through the Bi3+ sensitizer to the Eu3+ activator. A coreeshell SLPO:Bi3+,Eu3+ nanophosphor with a maximum EQE of 25.4% and high color purity of 99.7% was obtained when 5-mol% Bi3+ was doped. The energy transfer mechanism and model of the phosphor are proposed.
关键词： Nanophosphor,Sensitizer,Field emission lamp,Coreeshell
更新于2025-09-23 15:23:52
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Intense red emission and two-way energy transfer in Sm3+, Eu3+ co-doped NaLa(WO4)2 phosphors
摘要： NaLa(WO4)2 phosphors with various Eu3+ and Sm3+ concentrations were prepared via a molten salt method. The structure and luminescent properties of the prepared samples were analyzed by the X-ray diffraction (XRD) and fluorescence spectrophotometer. The results show that the crystal phase of all the prepared samples is single tetragonal crystal structure. The energy transfer type between Eu3+ ions is proved to be the exchange interaction and the electron-phonon coupling is weak. With the increase of the Sm3+ concentration, the energy transfer from Sm3+ to Eu3+ in NaLa(WO4)2:0.15Eu3+,xSm3+ is transformed from Eu3+ to Sm3+, and the mechanism for energy transfer is given.
关键词： Nanophosphor powders NaLa(WO4)2: xEu3+ ySm3+,Electron-phonon coupling,Photoluminescence,Energy transfer
更新于2025-09-23 15:21:21
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Bandgap-Tuned CuInS <sub/>2</sub> /ZnS Core/Shell Quantum Dots for a Luminescent Downshifting Layer in a Crystalline Silicon Solar Module
摘要： CuInS2 (CIS) quantum dots (QDs) were investigated as a luminescent downshifting (LDS) material that converts near-ultraviolet (UV) light to visible light and were applied to a single crystalline silicon (c-Si) solar module that has no spectral sensitivity in the near-UV region. The bandgap of the CIS/ZnS core/shell QDs was successfully adjusted to ~3 eV, which was adequate for the LDS layer in solar devices, by changing the molar ratio of Cu/In. CIS/ZnS/ZnS core/shell/shell QDs with 59.9% absolute photoluminescence (PL) quantum yield were prepared by the hot-injection method and embedded in ethylene vinyl acetate copolymer (EVA) resin to fabricate QD@EVA films as the LDS layer. The PL intensity of the QD@EVA films under near-UV excitation monotonically increased with increasing QD concentration. The films were attached to a commercial single c-Si solar module. The advantages and drawbacks of the films were discussed based on the results of incident photon-to-electron conversion efficiency and current-voltage curve measurements.
关键词： CuInS2/ZnS,quantum dot,nanocomposite film,solar module,nanophosphor,luminescent downshifting layer,photoluminescence
更新于2025-09-23 15:21:01
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Luminescence of monoclinic Y2O3:Eu nanophosphor produced via laser vaporization
摘要： Europium doped Y2O3spherical nanoparticles with the diameter ~10 nmobtained via cw laser vaporization are shown to crystallize in monoclinic symmetry class (C2/m space group). The size of nanoparticles established via HRTEM coincides with coherent scattering region established by XRD. Luminescence spectrum in the vicinity of ultranarrow transition demonstrates three peaks consistent with three inequivalent positions of Eu3t ion in monoclinic Y2O3 lattice. Hypersensitive transition dominates in the spectrum, admitting the lack of inversion symmetry at Cs sites occupied by Eu3t. The spectrum of hypersensitive transition is expanded to the red part of spectrum due intense transitions terminating at higher-lying components of crystal-field-split 7F2 energy level. Obtaining chromaticity coordinates (0.669, 0.331)and absolute quantum yield (~21%) is possible using red phosphor based on monoclinic Y2O3:Eu3t.
关键词： Laser vaporization,Monoclinic Y2O3:Eu nanophosphor,Photoluminescence of Eu3t
更新于2025-09-23 15:21:01
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Two- step synthesis and luminescent properties of BaB <sub/>2</sub> O <sub/>4</sub> :Eu <sup>3+</sup> nano/microphosphors prepared from Ba-B-O:Eu <sup>3+</sup> precursor
摘要： The BaB2O4:Eu3+ nano/microphosphors with sphere‐, rod‐, and granular‐like morphologies were successfully obtained by a two‐step method using Ba‐B‐O:Eu3+ as the precursor. The structure, morphology and photoluminescent properties of the products were characterized by Fourier transfer infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), thermogravimetry‐differential thermal analysis (TG‐DTA), scanning electron microscopy (SEM) and photoluminescence (PL). The formation mechanisms of Ba‐B‐O:Eu3+ and BaB2O4:Eu3+ were proposed. The results show that the BaB2O4:Eu3+ could retain the original morphologies of their respective precursors largely. The BaB2O4:Eu3+ prepared by this two‐step method exhibited better morphology, smaller particle size and better crystallinity than when prepared by a solid‐state method. The granular‐like BaB2O4:Eu3+ red phosphor prepared by this two‐step method exhibited stronger PL intensity and better red color purity than when prepared by a solid‐state method.
关键词： luminescence,nanophosphor,two‐step method,barium borate
更新于2025-09-19 17:15:36
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Efficient Luminescence of Sr2Si5N8:Eu2+ nanophosphor and its film applications to LED and Solar cell as a downconverter
摘要： Here we present the synthesis of the efficient nanophosphor Sr2Si5N8:Eu2+ (D50 = 144 nm) by a simple milling approach, its strong Rayleigh scattering, and its film applications to white LED and silicon solar cell as a downshifting medium. The final nanophosphor product showed the quantum efficiency comparable to the bulk phosphor which is, to our knowledge, the highest record of nitride nanophosphors. Especially the nanophosphor showed the more tail emission at the shorter-wavelength side of the emission spectrum and the faster thermal quenching with the more spectral broadening along with the temperature due to Rayleigh scattering. Also the lowering in the excitation spectrum was observed due to lower absorbance. Finally, the nanophosphor-dispersed polyvinyl alcohol (PVA) film was made, and its applications to white LED and silicon solar cell as a downshifting medium demonstrated that it gave the high color rendering property in white LED in spite of still lower luminous efficiency, and it caused the increase in efficiency of silicon solar cell.
关键词： nanophosphor,white LED,milling,downconverter,solar cell,Sr2Si5N8:Eu2+
更新于2025-09-19 17:13:59
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Synthesis of BiOCl: Eu3+ Microarchitectures and their WLED’s, Fingerprint Detection and Anticounterfeiting Applications
摘要： BiOCl: Eu3+(1-9mol %) microarchitectures were synthesized by the solution combustion method by employing Barbituric acid as fuel. The crystal structure, morphologies and luminescence properties of Eu3+ doped BiOCl have been systematically investigated by powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM) and spectroscopy respectively. The prime objective of the current effort was first to fabricate highly luminescent nanophosphor for revelation of latent fingerprints, lips prints including infiltrating and non-filtrating surfaces and also to develop luminescent ink for anticounterfeiting applications. Presently the fingerprints developed by using conventional powders have several disadvantages including low sensitivity, high background hindrance, complicated procedure and high toxicity. To encounter this challenge, we explored the optimized BiOCl:Eu3+(3mol %) nanophosphor for detection of latent fingerprints and luminescent anti-counterfeiting ink. The morphology of the phosphor was tuned by adjusting the concentration of fuel. Photoluminescence studies of BiOCl:Eu3+(1-9mol %) exhibited the peaks 5D0 → 7FJ (J = 0, 1, 2, 3, 4) transitions. The CIE and CCT characteristics specify that the synthesized nanophosphor might be immensely show potential red factor for promising applications in WLED’s. The BiOCl: Eu3+ (1-9 mol %) nanopowder also showed clear ridge patterns of level I and level II and further showed sharp image of label when observed in the UV light. The results indicated that the present phosphor could be used in both forensic as well as in anti counterfeiting applications.
关键词： Barbituric acid,BiOCl,morphology,luminescence,photoluminescence,nanophosphor,Eu3+
更新于2025-09-12 10:27:22
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Enhanced red luminescence by gamma irradiation on GdPO4:Er3+@SiO2 nanophosphor
摘要： The influence of gamma radiation on enhancement of red emission from Er3+ doped GdPO4@SiO2 nanophosphors was investigated. The luminescent emission was recorded after photoexcitation at 462 nm. The strong red luminescence at 690 nm corresponds to 4F9/2 → 4I15/2 transition. The luminescence intensity of the prepared phosphor had enhanced 2-4 folds and 4-6 fold after exposing to 150 kGy and 300 kGy gamma radiation, respectively. A linear response between luminescence intensity and irradiation dose was observed through PL dosimetry study. These biocompatible nanophosphors may have promising applications in biomedical and optoelectronic fields.
关键词： Nanophosphor,Gamma radiation,GdPO4,Erbium,Photoluminescence,SiO2
更新于2025-09-09 09:28:46