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Synthesis of Calcium Aluminate-Based Luminophores by the Citrate Nitrate Sol–Gel Process
摘要： Microwave-assisted sol–gel process was used to synthesize calcium aluminate and luminescent materials based on it, which find wide use in the manufacture of construction materials, catalysts, optical emission sources, and display devices. The major processes involved in the formation of crystalline calcium aluminate were identified resorting to powder X-ray diffraction, thermal analysis, scanning electron microscopy, and IR spectroscopy data. Synthetic steps have moderate activation energies in the 44–260 kJ/mol range. Luminescence characteristics of the obtained crystal phosphors were measured. The increase in the synthesis temperature to 1200°C and the increase in the activator concentration to 5 mol % enhance the luminescence of the Eu3+-activated calcium aluminate-based luminophore. Further increase in the concentration of the activator ions leads to luminescence quenching caused by the concentration effect.
关键词： calcium aluminate,sol–gel process,microwave treatment,europium(III) ions,crystal phosphor
更新于2025-09-23 15:21:01
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Manganese doping stabilizes perovskite light-emitting diodes by reducing ion migration
摘要： Lead halide perovskite light-emitting diodes have recently emerged as high-performance devices. However, they degrade rapidly. This degradation has been attributed to the mixed ionic-electronic nature of these perovskites. Manganese doping increases the stability of perovskite light-emitting diodes, but the effects of manganese doping on ion migration are not well understood. We use impedance spectroscopy and transient ion-drift measurements to study the effect of manganese doping on ion migration in PEABr0.2Cs0.4MA0.6PbBr3 quasi-bulk 2D/3D perovskite light-emitting diodes. We find that manganese doping enhances the activation energy for ion migration two fold and reduces the diffusion coefficient. These changes in the behavior of mobile ions help to explain the improved stability in perovskite light-emitting diodes upon manganese doping and lead to a better understanding of the influence of passivating agents on ion migration and thus on the stability of the devices.
关键词： capacitance,perovskites,manganese,mobile ions,transient ion drift,impedance,light-emitting diodes
更新于2025-09-23 15:21:01
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300??keV cobalt ions irradiations effect on the structural, morphological, optical and photovolatic properties of Zn doped TiO2 thin films based dye sensitized solar cells
摘要： Dye Sensitized Solar Cell (DSSC) is a potential too to convert solar energy into electrical energy due to its low cost, ease in synthesis and higher photo electron conversion e?ciency (PEC) in contrast with conventional silicon solar cell. The photo-electrode of DSSC is a key component which is responsible for collection and transportation of electrons through the circuit. Sol-gel route was adopted to manufacture photo anodes of 1% Zinc doped titanium dioxide (Zn–TiO2) where FTO glass was used as substrate. These photo anodes were irradiated by 300 keV Cobalt (Co) ions with di?erent ?uence rates as 2 × 104 atomscm-2s-1 and 4 × 104 atoms cm-2s-1. We investigated the anatase phase of TiO2 using the Raman spectra which also showed that Zn and Co are completely doped in TiO2. UV–visible spectroscopy showed that band gap of ?lms was decreased by doping and ions implantation. Maximum reduction in band gap is observed at the ?uence rate of 4 × 104 atoms cm-2s-1 i.e. 2.77 eV. SEM micrographs showed that the ?lm irradiated with Co ions with ?uence rate of 2 × 104 atoms cm-2s-1 have maximum porosity which supports the maximum dye loading on the surface due to which the e?ciency of DSSC is enhanced. In all cells, N719 dye is used as sensitizer. The solar simulator results indicated the higher e?ciency up to 3.78% is achieved by 300 keV cobalt ions irradiation with ?uence rate of 2 × 104 atoms cm-2s-1. The present work shows that the appropriate percentage of Co ions in Zn–TiO2 layer plays a signi?cant role to escalate the e?ectiveness of DSSC.
关键词： Dye sensitized solar cells,Ions implantation,TiO2,Co,Zn
更新于2025-09-23 15:21:01
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Copper nanoclusters @ nitrogen-doped carbon quantum dots-based ratiometric fluorescence probe for lead (II) ions detection in porphyra
摘要： A novel ratiometric fluorescence probe was proposed for detecting lead (II) ions (Pb2+) in porphyra, the approach was based on copper nanoclusters and nitrogen-doped carbon quantum dots (CuNCs-CNQDs). In this probe, the CuNCs delivered the response signal, the fluorescence of which was enhanced by Pb2+ due to the aggregation-induced emission enhancement (AIEE) between Pb2+ and CuNCs. The CNQDs provided the self-calibration signal, whose fluorescence remained almost unchanged in coexistence with Pb2+. According to the change of fluorescence intensity ratio between the fluorophores, CuNCs–CNQDs nanohybrid was used as ratiometric probes for the sensitive detection of Pb2+ in the range of 0.010 to 2.5 mg L-1, with a detection limit of 0.0031 mg L-1. Finally, the probe was successfully applied to detect Pb2+ in porphyra with relative standard deviations (RSDs) lower than 5%. This study provides a straightforward, stable, and sensitive approach for detecting Pb2+ in porphyra.
关键词： Lead (II) ions,Ratiometric fluorescence probe,Aggregation-induced emission enhancement,Copper nanoclusters,Nitrogen-doped carbon quantum dots
更新于2025-09-23 15:21:01
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Laser Sources Based on Rare-Earth Ion Doped Tellurite Glass Fibers and Microspheres
摘要： In recent years, huge progress has been made in the development of rare-earth ion doped tellurite glass laser sources, ranging from watt- and multiwatt-level fiber lasers to nanowatt level microsphere lasers. Significant success has been achieved in extending the spectral range of tellurite fiber lasers generating at wavelengths beyond 2 μm as well as in theoretical understanding. This review is aimed at discussing the state of the art of neodymium-, erbium-, thulium-, and holmium-doped tellurite glass fiber and microsphere lasers.
关键词： microsphere laser,tellurite glass fiber,microlaser,rare-earth ions,tellurite fiber laser
更新于2025-09-23 15:21:01
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AIE based “on-off” fluorescence probe for the detection of Cu2+ ions in aqueous media
摘要： A simple hydrazine carboxamide derivative with intramolecular charge transfer and aggregartion induced emission (AIE) properties have been designed and synthesized. The derivative (Probe 1) shows typical AIE characteristic emission in THF-water mixtures and emits yellowish orange color on reaching the water fraction 98%. The probe molecule show selective sensing response for Cu2+ ions via fluorescence turn-off mechanism in aqueous media over other metal ions. The emission changes towards Cu2+ ions could be clearly observed by the naked eyes under 365 nm UV lamp promote the probe molecule as a promising candidate for practical utilization. Furthermore, from the fluorescence titration data, the detection limit for Cu2+ ions was found to be 0.44 μM.
关键词： AIE,visual sensing,Cu2+ ions
更新于2025-09-23 15:21:01
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Bacteria functionalized gold nanoparticle matrix based fiber-optic sensor for monitoring heavy metal pollution in water
摘要： In the present study, E.coli B40 bacteria were explored as possible receptors on localized surface plasmon resonance (LSPR) based biosensor for sensing heavy metal ions viz. mercury (Hg2+) and cadmium (Cd2+) in water. The E.coli B40 bacteria were immobilized on gold nanoparticles (AuNP) coated fiber-optic probes by depositing two bi-layers of oppositely charged polyelectrolytes. The E.coli immobilized sensor probes were subjected to different concentrations of Hg2+ and Cd2+ ions, ranging from 0.5 ppb to 2000 ppb. These metal ions interact with the thiols and other surface groups present on the bacterial cells, resulting in the change of refractive index around AuNP coated sensor probes, thereby modulating the sensor response. The detection was performed by spiking de-ionized (DI) water and tap water with metal ions and the limit of detection was found to be 0.5 ppb. The proposed sensor could detect heavy metal ions within 10 min from a small sample (< 1 ml) and showed good selectivity towards heavy metal ions over other transition metal ions. Control studies performed using amino acids like cysteine as receptors were found to be less sensitive than the proposed scheme using bacterial cells.
关键词： polyelectrolytes,fiber-optic sensor,Bacteria,gold nanoparticles,heavy metal ions,localized surface plasmon resonance
更新于2025-09-23 15:21:01
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Europium and terbium lanthanide ions co-doping in TiO2 photoanode to synchronously improve light-harvesting and open-circuit voltage for high-efficiency dye-sensitized solar cells
摘要： In this study, we explore the effects on the incorporation of europium (Eu3+) and terbium (Tb3+) rare-earth ions into titanium dioxide (TiO2) photoanodes in dye-sensitized solar cells (DSSCs). X-ray photoelectron spectroscopy (XPS) studies affirm that the Eu3+ ions are arranged at the cationic locales of Ti4+ in the matrix whereas the site inhabitance was remunerated by Tb3+ ions, supporting that the anatase phase stays unaltered without generating any new deformities. Additionally, the Eu3+ ions decidedly changed the conduction band minimum of TiO2, actually, Tb3+ ions contrarily conversion because of various vacant trap states in the band gap. Besides, the photoinduced electron transfer estimations show an efficient interfacial charge transfer for co-doped TiO2 (kET = 3.1 ns) contrasted with the bare TiO2 (2.6 ns). DSSCs based on Eu3+/Tb3+ co-doped TiO2 display higher efficiency (9.11%) than those for the bare TiO2 (7.20%) and the exclusively Eu3+ (8.01%) or Tb3+ (7.10%) doped samples, which is ascribed to the joined impact of a faster electron transportation and longer electron lifetime in the co-doped TiO2 film. This work may open another approach to further improve the performance of DSSCs by Eu3+/Tb3+ co-doping technique, advancing the development of DSSCs toward commercial applications.
关键词： Co-doping process,Europium (Eu3+)/terbium (Tb3+) lanthanide ions,Stability,Photoanodes,DSSCs,Titanium dioxide (TiO2) nanopowders
更新于2025-09-23 15:21:01
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Microstructure property study of ZnO single crystal irradiated with 200 MeV 86Kr17+ ions
摘要： ZnO single crystal materials irradiated with 200 MeV energy 86Kr17+ ions have been analyzed by a series of theoretical calculations, Raman spectroscopy and TEM tests, etc. After irradiation by 200 MeV 86Kr17+ ions, two broad vibrational absorption peaks appeared and there is no obvious change in other characteristic peaks. By measuring the Raman spectra of the incident light perpendicular to and parallel to the z axis of the crystal, it was proved that the vibration absorption peak of 526 cm-1 ~ 600 cm-1 is caused by defects related to oxygen vacancy (VO). The experimental data fully proved that ZnO single crystal has good radiation resistance. These data are of great significance for the application of ZnO materials in various new devices in the future.
关键词： ZnO,Transmission electron microscopy,Raman spectra,86Kr17+ ions irradiation
更新于2025-09-23 15:21:01
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[IEEE 2018 IEEE 7th International Conference on Photonics (ICP) - Langkawi, Malaysia (2018.4.9-2018.4.11)] 2018 IEEE 7th International Conference on Photonics (ICP) - Etched Fiber Bragg Grating Sensor for Nitrate Sensing Application
摘要： We demonstrate a reliable method to detect the concentration of Nitrate in water using an etched Fiber Bragg Grating (FBG) sensor. The sensor was etched using 48% Hydrofluoric (HF) acid solution to function as a chemical sensor and interact with Nitrates. The Bragg wavelength ((cid:2)b) shifted due to the changes of Nitrate concentration. The sensitivity achieved by this sensor is 2.4 x 10-3 nm/ppm. The overall shift of the Bragg wavelength is 0.12 nm from 0 – 50 ppm.
关键词： Nitrate ions,Fiber Bragg Grating sensor
更新于2025-09-23 15:21:01