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Luminescent, optical, magnetic and metamaterial behavior of cerium complexes
摘要： The complexes of cerium with nitrogen, oxygen and sulfur donor ligands were prepared by conventional method. These newly synthesized complexes were characterized by FTIR, UV-Vis, DART Mass, TGA, PXRD, SEM and TEM techniques. The magnetic studies were carried out by the vibrating sample magnetometer. The optical constants were measured by absorption and reflection spectra as a function of wavelength. The concentration dependence of refractive index and absorption were observed by the experimental method, which reveals that these parameters are affected by change in concentration. The optical band gap obtained from Tauc-plot indicates its probability to be a good semiconductor. The luminescence behavior of these cerium complexes were observed by the absorption and emission spectra and the emission life time were calculated by their life time spectra.
关键词： Optical band gap,Luminescence,Refractive index,Magnetic studies
更新于2025-09-23 15:23:52
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Fabrication and mid-infrared property of Er:CaF2 transparent ceramics
摘要： High doped Er:CaF2 transparent ceramics (up to 10.0 at.%) were fabricated by hot pressing nanopowders which were synthesized by co-precipitation method. The composition and micrographs of the powders were characterized. The mid-infrared emission spectra and lifetimes of the 4I13/2 energy level of Er:CaF2 transparent ceramics were investigated for the first time. The mechanisms of energy transfer processes based on the emission spectra of different wavelengths were discussed. The enhanced 2.7 μm emission intensity and the reductions of near-infrared fluorescence lifetimes were observed indicating that the high concentrations of Er3+ ions are beneficial to overcome the self-termination effect and realize 2.7 μm laser output. It can be seen from these results that high concentrations Er-doped CaF2 transparent ceramics can be considered as promising host materials for the applications of mid-infrared lasers.
关键词： Transparent ceramic,Mid-infrared,Luminescence lifetime,Nanoparticle
更新于2025-09-23 15:23:52
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Enhancing Diamond NV Center Density in HPHT Substrate and Epitaxy Lateral Overgrowth Layer by Tungsten Pattern
摘要： The Nitrogen Vacancy (NV) center distribution in epitaxial lateral overgrowth (ELO) single crystal diamond layer grown on tungsten patterned HPHT substrate by microwave plasma chemical vapor deposition (CVD) system has been investigated. It has been found that in ELO diamond layer densities of NV0 and NV- center above the tungsten metal are enhanced. Meanwhile, in patterned high-pressure and high-temperature (HPHT) substrate the density of NV- center beneath the tungsten metal is much higher than that of NV0. The HPHT substrate doesn't contain NV centers before CVD growth, and there is almost no NV center in the region without tungsten metal after growth.
关键词： Defects,Carbon materials,Epitaxial growth,Luminescence,Crystal growth
更新于2025-09-23 15:23:52
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Identification and structures of the X-ray induced luminescence centers in the zeolites Zr,X,Cs,Na-LTA, X = Cl, Br, and I
摘要： Zr4+ and halide anions were introduced into zeolite A (LTA) by treating Cs,Na-A with ZrX4(g), X = Br and I, under anhydrous conditions. The crystal structures of Zr,Br,Cs,Na-A and Zr,I,Cs,Na-A were determined by single-crystal crystallography with compositional confirmation by scanning electron microscopy energy-dispersive X-ray (SEM-EDX) analysis. Their X-ray induced luminescence (XIL) properties were thoroughly studied. These structures and XIL properties were compared with those of previously reported Zr,Cl,Cs,Na-A. In both structures, most Na+ and Cs+ ions occupy positions similar to those found in Cs,Na-A and Zr,Cl,Cs,Na-A. About 9% of the large cavities of Zr,Br,Cs,Na-A are centered by ZrBr6 2- ions. In Zr,I,Cs,Na-A, about 6% are centered by ZrI6 2-. These octahedral ZrX6 2- ions are each held in place and stabilized in their large cavities by 24 bonds between all six of its halide ions and eight surrounding Cs+ ions. They are further bridged by 8-ring Cs+ ions to form a cubic 3-dimensional Cs11ZrX6 9+ continuum in the surface volume of the crystal. Their XIL domain peaks have red-shifted from 495 nm for Zr,Cl,Cs,Na-A, to 520 nm for Zr,Br,Cs,Na-A, and to 640 nm for Zr,I,Cs,Na-A. This may be because the self-trapped excitons (STE) of ZrBr6 2- and ZrI6 2- have smaller band gaps than that of ZrCl6 2-, a result of the valence band maximum 4p energy level in Br- being higher (5p in I- even higher) than the 3p energy level in Cl-.
关键词： ZrBr6 2- and ZrI6 2-,Crystal structure,Extraframework Zr4+,Luminescence,Zeolite A
更新于2025-09-23 15:23:52
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Luminescence properties of a family of lanthanide metal-organic frameworks
摘要： Two isostructural series of lanthanide metal-organic frameworks denoted as SUMOF-7II (Ln) and SUMOF-7IIB (Ln) ( Ln = La, Ce, Pr, Nd, Sm, Eu, and Gd) were synthesized using4,4',4''-(pyridine-2,4,6-triyl)tris(benzoic acid) (H3L2) and a mixture of H3L2 and 4,4′,4′′-(benzene-1,3,5-triyl)tris(benzoic acid) (H3BTB) as linkers, respectively. Both series were characterized usingpowder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermal analysis (TGA), and photoluminescence spectroscopy. Photoluminescence measurements show that Eu-MOFs demonstrate a red emission while Pr- and Nd-MOFs display an emission in the near-infrared (NIR) range. On the other hand, La-, Ce-, Sm- and Gd-MOFs exhibit only a ligand-centered emission. The average luminescence lifetimes in the SUMOF-7IIBseries are 1.3-1.4-fold longer than the corresponding ones in the SUMOF-7II series. SUMOF-7IIs show a good photo- and thermal stability. Altogether, the properties of SUMOF-7II and SUMOF-7IIB render them promising materials for applications including sensing, biosensing, and telecommunications.
关键词： Lanthanide MOFs,Antenna Effect,Photostability,Photophysical Properties.,Metal-Organic Frameworks,Luminescence
更新于2025-09-23 15:23:52
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Spectroscopic peculiarities of excitation and emission processes as well as relaxation dynamic of excited states in doubly and triply doped Gd3Ga3Al2O12:Ln3+ (Ln3+=Eu3+, Tb3+, Ce3+) crystals
摘要： Spectroscopic properties of Gd3Ga3Al2O12 (GGAG) single crystals co-doped with various configurations of (Eu + Tb); (Eu + Ce); (Tb + Ce) and (Eu+ Tb + Ce) ions have been investigated. The effect of distinct Ln3+ co-doping variations on luminescence of garnet crystals was studied using the different excitation wavelengths. The Ln3+-Ln3+ and host-Ln3+ interplays have been considered in doubly and triply doped GGAG:Ln3+. The crystals containing cerium ions are characterized by mainly broadband emission in the 450–750 nm spectral region that is adequately modified in green and red spectral range in the samples co-doped with terbium and europium, respectively. The Eu3+ luminescence in materials under study is selectively excited employing solely f-f europium transitions. Contrary to that, emission of terbium and cerium occur as result of interaction with Gd3+ and adjacent co-dopants.
关键词： GGAG garnet crystals,Luminescence,Ln-Ln energy transfer
更新于2025-09-23 15:23:52
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Amine salts assisted controllable synthesis of the YVO4:Eu3+ nanocrystallines and their Luminescence properties
摘要： The Eu3+ doped YVO4 nanocrystallines with various morphologies were successfully synthesized by an amines (TETA, ETA and EDA) assisted hydrothermal process. By rationally adjusting the adding amount of TETA, ETA and EDA, the trepang-like, globular-like and pineapple-like Eu3+ doped YVO4 nanostructures can be conventionally obtained. The as-prepared products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The XRD patterns indicate that these samples are all of the tetragonal structure. The SEM and TEM results show that the amines additives play an important role in morphology formation. Furthermore, the fluorescence properties of those samples are also systematically studied. Under the excitation of 280 nm, Eu3+ doped YVO4: nanostructures emit strong red fluorescence due to the transitions of 5D1-7F1 and 5D0-7FJ (J =1, 2, 3 and 4) of Eu3+ ions. The intensity of red fluorescence is related to not only the concentrations of Eu3+, but also the types of adding amines. The effective luminescence lifetimes of the trepang-like Y0.9Eu0.1VO4 nanocrystallines, the globular-lik and pineapple-like Y0.95Eu0.05VO4 nanocrystallines are 0.91 ms, 1.02 ms and 1.14 ms, respectively. It is believed that this study is beneficial to promote the development of color display industry.
关键词： hydrothermal,Amine salts,luminescence lifetimes,Eu3+ doped YVO4,fluorescence properties
更新于2025-09-23 15:23:52
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Synthesis of color-tunable CdTe/CdS:Mn core-shell nanocrystal emitters
摘要： This study presents CdTe/CdS:Mn core–shell nanocrystals (NCs) prepared in aqueous media, using thioglycolic acid as capping agent. Firstly, CdTe NCs were synthesized, and then, Mn-doped CdS shell were deposited on the top of the CdTe core under Ar atmosphere. The NCs were structurally and optically characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray (EDX), X-ray photoelectron (XPS), photoluminescence (PL), and Fourier transform infrared (FTIR) spectroscopy. The results obtained from XRD, XPS, PL, and EDX showed that the Mn ions were successfully introduced into the nanocrystalline shells. Moreover, the effect of Mn concentrations on the optical properties of the synthesized core-shell NCs was investigated. The effective band gap of the sample is in an indirect relationship with the Mn : Cd molar ratio, confirmed by PL analysis, and PL emissions can be measured at various wavelengths. The PL spectra showed 990 and 170 percent enhancement in the emission intensity of CdTe/CdS:Mn core/shell NCs (Mn: Cd 2.5%) compared to CdTe NCs and CdTe/CdS core/shell NCs, respectively. Consequently, the introduction of Mn dopants into the core-shell structures not only diminishes the density of quenching centers, but also reduces the effective band gap energies.
关键词： Core/Shell,Doping,Nanocrystals,CdTe/CdS:Mn,Luminescence
更新于2025-09-23 15:23:52
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A highly sensitive photocatalytic plastic optic-fiber sensor for selective detection of phenol in aqueous solutions
摘要： We present a highly sensitive photocatalytic plastic optic-fiber (POF) sensor for the selective detection of phenol in aqueous solutions. To obtain high sensitivity and low limit of detection (LOD) of the sensor, part of the POF cladding was removed and replaced by a Canada balsam doped with GeO2 (CBG); a UV-visible-light-driven photocatalytic material, that is a CdS-sensitized Er3+YAlO3/SiO2/TiO2 (EYST) composite, was coated on the CBG film. To realize highly selective detection of phenol in water, a high phenol permselectivity and pH independence polymer membrane was fixed on the CdS-sensitized EYST-CBG-coated POF. Furthermore, a model was developed to show that the phenol concentration can be determined by measuring the change in transmitted light intensity of the POF sensor and the sensitivity of the sensors can be improved by employing the CdS-sensitized EYST film. The results showed that the proposed photocatalytic POF sensor has a high sensitivity of -0.39 (mg·mL-1)-1 and low LOD of 15 μg·L-1 for the selective detection of phenol in aqueous solutions with pH ranging from 2.0 to 14.0.
关键词： Cds sensitization,Phenol concentration,High sensitivity and selectivity,Upconversion luminescence agent,Plastic optical fiber,TiO2 composite film
更新于2025-09-23 15:23:52
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Photoemission and thermoluminescence characteristics of Dy3+-doped zinc sodium bismuth borate glasses
摘要： The present study reports preparation and characterization of Dy3+-doped PbO free alkali-heavy-metal-borate glasses for luminescent applications. The amorphous nature of the glasses and the presence of various structural groups like BiO6, BO3 and BO4 were confirmed through XRD and FTIR measurements. The Oscillator strength of Dy3+ absorption transitions as well as the bond formed with the O2- ion in the glass network were determined using the absorption spectra. Radiative parameters extracted from Judd-Ofelt theory proved the degree of suitability of prepared glasses for lasing applications. The photoluminescence spectra exhibited the emission characteristics of Dy3+ ions and used to calculate the branching ratio, stimulated emission cross-section and radiative lifetime. Metastable lifetimes of Dy3+ ions were obtained through exponential fitting of respective decay profiles. The luminescence quenching phenomena was reasoned using Inokuti-Hirayama (I-H) model. The optical gain and quantum efficiency values clearly suggested Dy3+ doping at 0.3 mol% was optimum for 587 nm lasing action. Further, CIE chromaticity plot indicated the possible applications in solid state lighting devices. The thermoluminescence glow curves of 0.3 mol% Dy3+-doped glasses were considered for gamma irradiation and kinetic parameters of the same were evaluated using Computerized Glow Curve Deconvolution (CGCD) technique.
关键词： luminescence,kinetic order,Rare earth,Judd-Ofelt parameter,lifetime
更新于2025-09-23 15:23:52