High Luminescence Intensity Research Articles

Fresh hetero-metallic compound as luminescent sensor for detection of CS2 and inhibitory activity on children diabetes.

The combination of the dicarboxylate ligand of 2-aminoterephthalic acid (H2L), Cd(NO3)2·4H2O, and KNO3 under hydrothermal condition formed a fresh hetero-metallic coordination polymer, namely, [CdK2(L)2(H2O)4]n (1). The compound exhibited a high luminescence intensity at normal environment as well as high sensitivity and selectivity in the measurement of CS2. The effect of the fresh compound on childhood diabetes was investigated. A blood glucose monitor was utilized to assess the blood glucose level of the body after the addition of the compound. Moreover, the relative expression level of the insulin recipient on hepatocytes was assessed by real time RT-PCR.

Enhanced afterglow performance of Zn2SiO4:Mn2+ by Pr3+ doping and mechanism

High luminescence intensity and long persistent duration is desired for practical application of long persistent materials. But it still remains challenging due to insufficient phosphors to meet the commercial request and a general lack of understanding of luminescence mechanism. In this work, green persistent luminescent phosphor Zn2SiO4:Mn2+,Pr3+ was first synthesized by traditional solid-state reaction method with self-made SiO2 submicrospheres as silicon source. The morphology, crystal structure, photoluminescence and the long afterglow performance have been investigated systematically. Interestingly, the longest persistent luminescence is observed for 0.025 Mn2+, 0.001 Pr3+ co-doped Zn2SiO4 with a persistent time of ∼2640 s at (0.32 mcd/m2), which is 20 times longer than those of Zn2SiO4 host or single Mn2+ doped Zn2SiO4 phosphors. The possible persistent mechanism has been discussed. The finding will be beneficial for developing persistent phosphors with superior functionalities.

Study of synthesis temperature effect on β-NaGdF4: Yb3+, Er3+ upconversion luminescence efficiency and decay time using maximum entropy method

Upconversion materials have several advantages for many applications due to their great potential in converting infrared light to visible. For practical use, it is necessary to achieve high intensity of UC luminescence, so the studies of the optimal synthesis parameters for upconversion nanoparticles are still going on. In the present work, we analyzed the synthesis temperature effect on the efficiency and luminescence decay of β-NaGd0.78Yb0.20Er0.02F4 (15–25 nm) upconversion nanoparticles with hexagonal crystal structure synthesized by anhydrous solvothermal technique. The synthesis temperature was varied in the 290 °C–320 °C range. The synthesis temperature was shown to have a significant influence on the upconversion luminescence efficiency and decay time. The coherent scattering domain linearly depended on the synthesis temperature and was in the range 13.1–22.3 nm, while the efficiency of the upconversion luminescence increases exponentially from 0.02 to 0.10% under 1 W cm−2 excitation. For a fundamental analysis of the reasons for the upconversion luminescence intensity dependence on the synthesis temperature, it was proposed to use the maximum entropy method for luminescence decay kinetics processing. This method does not require a preliminary setting of the number of exponents and, due to this, makes it possible to estimate additional components in the luminescence decay kinetics, which are attributed to different populations of rare-earth ions in different conditions. Two components in the green luminescence and one component in the red luminescence decay kinetics were revealed for nanoparticles prepared at 290 °C–300 °C. An intense short and a weak long component in green luminescence decay kinetics could be associated with two different populations of ions in the surface quenching layer and the crystal core volume. With an increase in the synthesis temperature, the second component disappears, and the decay time increases due to an increase in the number of ions in the crystal core volume and a more uniform distribution of dopants.

Synthesis of weakly-agglomerated luminescent CaWO4:Nd3+ particles by modified Pechini method

The specific luminescence behavior of crystalline oxide particles doped with rare earth ions strongly depends on the initial composition of the host material and synthesis conditions. This issue is especially significant for non-isovalent doping in the crystal lattice. In this case, the formation of the structure is accompanied by the formation of point defects serving as charge compensators. The work is devoted to the synthesis of CaWO 4 :Nd 3+ particles in the salt melt (modified Pechini method) and the study of structural and luminescent properties under varying synthesis conditions. It was found that temperature and duration of heat treatment in the salt melt (KCl) affected the crystal structure, the size of coherent scattering regions, luminescence intensity, and lifetime. An increase of heat treatment temperature led to a reduction of luminescence intensity and lifetime due to the formation of point defects. The optimal synthesis conditions for obtaining the highest luminescence intensity of CaWO 4 :Nd 3+ crystalline particles in salt melt were found to be the following Т 1 = 600 °C; t 1 =2 h (the stage of polymer gel thermal treatment), Т 2 = 800 °C; t 2 =1 h (the stage of thermal treatment in KCl salt melt). As-synthesized CaWO 4 :Nd 3+ powders contain both coarse and fine fractions. However weak particle agglomeration allowed obtaining a water dispersion with individual nanoparticles (up to 200 nm) after ultrasonic treatment. According to the obtained results, the synthesized material is characterized by high luminescence intensity and high dispersion, and promising as fluorescent thermometers and biological labels.

Synthesis of manganese activated zinc silicate phosphor by the sol - gel method

The green emitting phosphor based on manganese activated zinc silicate was successfully synthesized by the sol - gel method. This paper reports the synthesis and investigation of how the annealing temperature and concentration affect the photoluminescence properties of the Mn2+ ions in Zn2SiO­4 crystals. The paper also discusses the effect of alkaline ions on the luminous intensity of obtained Zn2SiO4 phosphor. The luminescence intensity is strongly dependent on the manganese doping concentrations; the optimal doping concentration is 1 mol% and the product when calcining the obtained gel at 1100 oC for 60 minutes has highest luminescence intensity. Alkali metal ions added to the composition of raw materials show the effect of enhancing the luminescence intensity of Zn2SiO4:Mn. Samples after the addition of potassium have the highest luminescence intensity; the luminescence intensity has increased by 30% compared to that of the original sample. The synthesized phosphor consists of Zn2SiO4 with rhombohedral structure and emits a green light at the 525 nm wavelength when excited by the 325 nm UV radiation.

Site symmetry dependence on luminescence emission of Y2O3:Eu3+ dispersed in silica matrix

ABSTRACT Lanthanide ion (Ln3+) doped Y2O3 materials are used in making display devices. Ln3+ ions can occupy C2 and S6 sites in Y2O3. In many reported papers, Ln3+ ions occupy more C2 site leading to enhanced luminescence intensity of electric dipole transition as compared to that of magnetic dipole transition. In this study, we have prepared Eu3+ ion doped Y2O3 particles dispersed in silica (SiO2) using urea hydrolysis at 165°C. Among the prepared samples lower heated sample show cubic phase Y2O3 wherease 1400oC show α-Y2Si2O7 and all the samples show the luminescence characteristics of Eu3+. In Y2O3:Eu-SiO2, the as-prepared, 500 and 900°C heated samples show the higher luminescence intensity for the electric dipole transition than that of magnetic dipole transition and it is opposite upon annealed at 1400°C. It confirms that Eu3+ ions in as-prepared, 500 and 900°C heated samples occupy C2 site (asymmetric environment), whereas in 1400°C heated sample, they occupy the S6 site (symmetric environment). However, microparticles of the Y2O3:Eu sample annealed at 1400°C show that Eu3+ ions occupy more C2 site as compared to the S6 site. This study suggests that occupancy of C2 and S6 sites in Y2O3 by Eu3+ ions can be varied by surrounding medium as well as heat-treatment temperature.

Enhanced up-conversion luminescence intensity of NaY(MoO4)2: Ho3+/Yb3+ phosphor by doping with Mg2+ ions for use in high-efficiency optical temperature sensor

The sensitization of Ho3+ ions by Yb3+ ions has been widely studied in traditional up-conversion luminescence materials and has been reported in many studies. This paper aims to further improve the up-conversion luminescence intensity by doping Mg2+ ions, and this enhancement was analyzed by Judd-Ofelt theory. Using the fluorescence intensity ratio method, temperature sensing performance of the phosphor was observed when the temperature was between 323 K and 523 K. Compared with previously reported materials, this phosphor displays excellent temperature sensitivity. The NaY(MoO4)2: Ho3+/Yb3+/Mg2+ phosphor shows good color purity and high up-conversion luminescence intensity, showing broad application prospects for intense green light generation, optical devices, and temperature sensors.

Influence of Formulations on Characteristics of Ruthenium-Based Temperature-Sensitive Paints.

Temperature-sensitive paint (TSP) can optically measure a global temperature distribution using a thermal quenching of dye molecules. The TSP measurement is often used in wind tunnel tests to measure the temperature and flow fields in the aerodynamic field. The measurement accuracy is affected by the characteristics of TSP, such as temperature sensitivity, pressure dependency, luminescent intensity, photostability, and surface condition. The characteristics depend on the formulation of TSP. This study investigates the characteristics of the TSP using dichlorotris (1,10-phenanthroline) ruthenium(II) hydrate (Ru-phen). We compare the characteristics of TSPs using different polymers, solvents, and dye concentrations. The TSPs using polyacrylic acid as a polymer shows linear calibration curves, high luminescent intensity, high photostability, and smooth surface. On the other hand, the TSPs using polymethyl methacrylate have nonlinear calibration curves, low luminescent intensity, strong photodegradation, and a rough surface.

Deep reddish-orange emitting Sr3Gd(PO4)3: Sm3+ phosphors via modified citrate-gel combustion method

The photoluminescence properties of different concentrations of Sm3+ activated Sr3Gd(PO4)3 phosphors synthesized by modified citrate gel-combustion method were investigated for white light emitting diode (w-LED) applications. The studied phosphors were characterized through powder x-ray diffraction (PXRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), photoluminescence excitation, emission and lifetime studies. The PXRD profiles confirmed the body centred cubic structure of undoped and Sm3+ -doped phosphors. The SEM studies showed the distribution and agglomeration of particles. The characteristic emission transitions such as 4G5/2 → 6H5/2 (∼561 nm), 4G5/2 → 6H7/2 (∼598 nm), 4G5/2 → 6H9/2 (∼645 nm) and 4G5/2 → 6H11/2 (∼705 nm) were noticed at their respective positions when excited at 403 nm wavelength. The highest luminescence intensity was found for 1.0 mol% of Sm3+ doped phosphors at 403 nm excitation showing luminescence quenching and it was ascribed to dipole-dipole interaction type of energy transfer among the excited Sm3+ ions at higher concentrations. The reddish-orange color of emitted luminescence was examined by evaluating the chromaticity coordinates. The experimental results confirm the potentiality of studied phosphors for w-LED applications.

Dual-mode luminescent multilayer core-shell UCNPs@SiO2@TEuTbB nanospheres for high-level anti-counterfeiting and recognition of latent fingerprints

Currently, illegal counterfeiting activities are increasing with the continuous developments of society and the fabrication of high security anti-counterfeiting techniques is becoming essential. The lanthanide-doped nanomaterials have great potential in anti-counterfeiting for their high luminescence intensity, narrow half-peak width and high stability. Herein, the dual-mode luminescent UCNPs@SiO2@TEuTbB nanomaterials have been successfully fabricated for anti-counterfeiting. Morphology, structure and luminesce properties of the synthetic samples have been investigated via TEM, XRD, FT-IR, XPS and fluorescence spectroscopy. The results present that the size of the synthetic materials is about 100 nm. The luminesce properties clearly show that the UCNPs@SiO2@TEuTbB nanomaterials can emit strong UC red color under the NIR light. Meanwhile, these materials can emit several DC luminescence colors by adjusting Eu3+ ions concentration under UV lamp. Furthermore, the lanthanide-doped nanomaterials are widely used in recognition of LFPs providing valuable evidence in forensic filed. As a result, the images of LFPs developed by the as prepared materials on various surfaces under UV lamp can be well visualized. The three levels details of fingerprints are clearly visible with high sensitivity, selectivity and contrast. Thus, these results confirm that the synthetized UCNPs@SiO2@TEuTbB nanospheres can provide a foundation for high-level anti-counterfeiting and the detection of fingerprints.

Effect of annealing atmosphere on the luminescence characteristics of CVD-ZnSe

The influence of the atmosphere of CVD-ZnSe annealing carried out in modes close to the procedure of their doping with iron on the luminescent characteristics of these crystals is investigated. It was found that annealing in the atmosphere of argon and selenium leads to a qualitative change in the impurity-defect composition and to a complex spatial distribution of the luminescent characteristics of CVD-ZnSe, especially in the crystal region at a distance of up to 400 microns from the surface. In the case of annealing in zinc, the luminescent characteristics are more uniform, with the exception of the near-surface zone with a width of about 100 microns, which has a high luminescence intensity in the entire spectral range under study (0.44-0.72 microns). The obtained results are interpreted on the basis of the assumption about the evaporation of zinc during annealing in argon and selenium. Based on the analysis of the spatial distribution of luminescence, assumptions are made about the nature of the observed impurity-defect centers. Keywords: two-photon confocal microscopy, CVD-ZnSe, impurity-defect composition, high temperature annealing.

Synthesis and optical spectroscopy of Na3Y(VO4)2:Eu3+ phosphors for thermometry and display applications.

A new Na3Y(VO4)2:Eu3+ (NYVO:Eu3+) phosphor was prepared using the sol–gel method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to evaluate phase purity and particle size, respectively. The optical properties were investigated by UV-visible absorption, PL, and PLE spectroscopies. The absorption measurements show the formation of the vanadate host by the presence of its characteristic band in the visible region related to VO43− groups. The experimental results show that the NYVO:Eu3+ phosphors exhibit high-brightness and thermally stable emission. Under near-ultraviolet (UV) excitation, both the broadband emission from VO43− groups and the sharp peak emissions from Eu3+ ions are observed. The highest luminescence intensity was achieved for an optimal europium concentration of 15 mol%. The study of the chromaticity parameters of these compounds gives a thermally stable hot emission in the red domain, with a color purity of about 85%, which qualifies the NYVO:Eu3+ compound as a potential phosphor for light-emitting diode (LED) applications. Thermal sensing using NYVO:Eu3+ phosphors are based on monitoring the luminescence intensity ratio between the NYVO host emission and Eu3+ luminescence lines. Notably, the optical thermometry of NYVO:Eu3+ was characterized based on the fluorescence intensity ratio of VO43− and Eu3+ emissions in the 298–440 K range, with maximum absolute and relative sensitivities of 3.4% K−1 and 0.0032 K−1 respectively and a temperature uncertainty of 0.01. NYVO:Eu3+ can then be considered as a potential red phosphor for application in ultraviolet-pumped white light-emitting diodes and as a potential optical thermometer. It provides new possibilities for the design of multifunctional materials for red light-emitting diodes and for non-contact thermometry.

Eu2+ doped halide perovskite KCaCl3 with high-efficiency blue emission and scintillation application

Eu2+ doped KCaCl3 shows high-efficiency blue emission and has high radiation luminescence intensity for scintillation application.

UMA ROTA ALTERNATIVA PARA OBTENÇÃO DE REDES DE COORDENAÇÃO VIA SÍNTESE SOLVOTERMAL UTILIZANDO Eu2O3 E ÁCIDO 2,6-NAFTALENODICARBOXÍLICO

AN ALTERNATIVE ROUTE TO OBTAIN METAL-ORGANIC FRAMEWORKS VIA SOLVOTHERMAL SYNTHESIS USING Eu2O3 AND 2,6-NAPHTHALENODICARBOXYLIC ACID. An alternative route to synthesis of metal-organic frameworks containing Eu(III) ion was proposed via solvothermal process in aqueous medium. The compounds of the minimal formulae [Ln2(NDC)3(H2O)4] were synthesized starting from the mixture of the 2,6-naphthalenedicarboxylic acid with europium(III) oxide. So far, this type of metalorganic framework based on the lanthanide ion synthetic route has not been investigated before as the main metal sources are nitrate and chloride salts. The structural characterizations were performed by FTIR spectroscopy, thermal analysis TG-DSC, and X-ray diffraction. The results of IR and TG were consistent with the structural determination results and complemented by X-ray diffraction patterns. SEM images also corroborate the morphologies found in recent research on this material. The materials obtained shown highintensity luminescence, for the Eu-NDC compound, which corroborates with an energy transfer efficient of the ligand to Eu(III) ion.

Effects of sintering temperature and doping content on luminescence properties of rare earth (Sm+3, Eu3+, and Dy3+) doped natural fluorapatite

Fluorapatite (FAP), thermally and chemically stable, has a suitable host structure for rare earth elements (REE). Rare-earth elements doped hydroxyapatite and fluorapatite have been known for a long time and have been studied extensively in industry and literature. In this study, REE doped natural fluorapatites (Ca10(PO4)6F2:xLn3+ (where x ​= ​0.5 ​mol for 1-mol FAP and Ln3+: Sm+3, Eu3+, and Dy3+) sintered at 1150 ​°C for 1 ​h. In addition, Ca10(PO4)6F2:xEu3+ (x ​= ​0.1, 0.5 and 1 ​mol for 1-mol FAP) was also conventionally sintered at 1100 ​°C, 1150 ​°C and 1200 ​°C. XRD, FTIR, SEM, and PL analysis investigated the phase evolution, microstructural development, and luminescence properties of the RE-doped FAP structure. No significant change in XRD and FTIR analysis results was observed with the addition of different rare-earth elements to natural fluorapatite compared to undoped natural fluorapatite. The emission spectra of Sm doped FAP, Eu doped FAP, and Dy doped FAP were recorded with an excitation wavelength of 407 ​nm, 281 ​nm, and 389 ​nm, and the strongest emissions were observed at 608 ​nm, 614 ​nm, and 578 ​nm, respectively. The emission intensity of Eu-doped fluorapatites increases with increasing sintering temperature. On the other hand, the emission intensity does not directly increase with the increasing doping content. The highest luminescent intensity was observed for Ca10(PO4)6F2:1Eu3+ sintered at 1200 ​°C in the red region upon excitation under UV radiation. In this study, ultra-high intensity luminescent materials that emit green and orange light were produced by doping Dy3+ and Sm3+ ions, respectively, for the first time to natural fluorapatite. The luminescent FAPs, produced from waste in an eco-friendly way, can be used in LED and bioimaging applications.

Enhancement of the luminescent thermal stability and water resistance of K2SiF6:Mn4+,Na+ by double coating of GQDs and K2SiF6

Nowadays, it is still a big challenge to synthesize Mn4+-doped fluoride red phosphors with high water resistance, luminescent intensity and thermal stability simultaneously. Therefore, KSF:M,N@GQDs@KSF (K2SiF6:0.06Mn,0.10Na@GQDs (12 mg/mol)@K2SiF6(0.2 wt), KSF: K2SiF6, GQDS: OH-contained graphene quantum dots) with high luminescent intensity, high luminescent thermal stability and water resistance have been synthesized via a combination of H2O2-free room temperature reaction method, hydrothermal coating method and room temperature surface coating process. Experimental results show that enhancement of negative thermal quenching (NTQ) effect and water resistance can be synergistically induced by double coating of GQDs and KSF. After being immersed in deionized water for 360 min, emission intensities of the KSF:M,N@GQDs and KSF:M,N@GQDs@KSF are decreased from 100% to 70.57% and 91.63%, respectively, indicating that water resistance of the latter is obviously improved by coating of KSF. The improved water resistance is attributed to preventing hydrolysis of [MnF6]2- on sample’s surface by insoluble coating shell of KSF. A prototype WLEDs (white light-emitting diodes) emitted warm white light (CCT = 4546 K and Ra = 91.3, at a driving current of 20 mA) has been assembled by coating mixture of KSF:M,N@GQDs@KSF, yellow emitting phosphor (YAG:Ce3+) and epoxy resin on blue light InGaN chips. The good performances of the WLEDs suggest that the KSF:M,N@GQDs@KSF has potential applications in blue-based warm WLEDs.

Recent Advances in Mechanoluminescence of Doped Zinc Sulfides

AbstractMechanoluminescence (ML) is the light generation of a material under mechanical stimuli. For more than 400 years, many compounds including inorganic and organic materials present this phenomenon. The general mechanism for the ML emission is the stress‐induced electrification effect combined with the piezoelectric field that lead to trapping and detrapping of the charge carriers. However, an in‐depth investigation and research are required to understand and hypothesize the ML mechanisms and optimum design and synthesis methods for better ML properties. Among the most common materials possessing this phenomenon is the zinc sulfide (ZnS) compounds that show high luminescence intensity and reproducibility. Such properties make them best candidates to be used in potential applications such as light and display devices, stress sensors, and human health monitoring devices. Therefore, this minireview focuses on the recent development and progress in doped ZnS ML compounds, including mechanism, design and synthesis, and the practical applications of such materials.

Luminescence properties of Eu3+ doped borate glass ceramics containing Al4B2O9

Borate glass ceramics doped with Eu3+ were prepared by the melt crystallization method. The crystalline phase Al4B2O9 in the glass-ceramics was determined by X-ray diffraction.. The optimal doping concentration of Eu3+ was obtained by the emission spectrum, and the color purity corresponding to the optimal doping concentration was calculated. Compared with glass samples, it is proved that glass ceramics have high luminescence intensity.

Highly Sensitive Luminescent Bioassay Using Recombinant Escherichia coli Biosensor for Rapid Detection of Low Cr(VI) Concentration in Environmental Water.

In this study, we constructed a recombinant Escherichia coli strain with different promoters inserted between the chromate-sensing regulator chrB and the reporter gene luxAB to sense low hexavalent chromium (Cr(VI)) concentrations (<0.05 mg/L); subsequently, its biosensor characteristics (sensitivity, selectivity, and specificity) for measuring Cr(VI) in various water bodies were evaluated. The luminescence intensity of each biosensor depended on pH, temperature, detection time, coexisting carbon source, coexisting ion, Cr(VI) oxyanion form, Cr(VI) concentration, cell type, and type of medium. Recombinant lux-expressing E. coli with the T7 promoter (T7-lux-E. coli, limit of detection (LOD) = 0.0005 mg/L) had the highest luminescence intensity or was the most sensitive for Cr(VI) detection, followed by E. coli with the T3 promoter (T3-lux-E. coli, LOD = 0.001 mg/L) and that with the SP6 promoter (SP6-lux-E. coli, LOD = 0.005 mg/L). All biosensors could be used to determine whether the Cr(VI) standard was met in terms of water quality, even when using thawing frozen cells as biosensors after 90-day cryogenic storage. The SP6-lux-E. coli biosensor had the shortest detection time (0.5 h) and the highest adaptability to environmental interference. The T7-lux-E. coli biosensor—with the optimal LOD, a wide measurement range (0.0005–0.5 mg/L), and low deviation (−5.0–7.9%) in detecting Cr(VI) from industrial effluents, domestic effluents, and surface water—is an efficient Cr(VI) biosensor. This unprecedented study is to evaluate recombinant lux E. coli with dissimilar promoters for their possible practice in Cr(VI) measurement in water bodies, and the biosensor performance is clearly superior to that of past systems in terms of detection time, LOD, and detection deviation for real water samples.

Material properties of IR-to-IR down-converting Er and Nd-Doped ZrO2 nanopowders

Specially tuned luminescent lanthanide-doped IR-to-IR down-converting nanopowders are utilized as taggants to tag and track explosives and valuables. Zirconia (ZrO 2 )-based oxides doped with an Er or Nd dopant offer a cheaper alternative to fluoride taggants. Maximum IR-to-IR down-conversion intensity was achieved with low concentrations (1 mol%) of Er or Nd dopant. Er-doped ZrO 2 powders possessed strong emission bands from 1444 nm to 1600 nm. Nd-doped ZrO 2 powders possessed strong emission bands from 1055 nm to 1151 nm as well as 1323 nm–1473 nm. No visible light emission was detected for any of the doped compositions. For all doped compositions, increasing the phase fraction of monoclinic structure substantially increased the luminescent intensities and is hypothesized to be a result of decreased lattice symmetry and oxygen vacancy concentration decreasing the number of non-radiative pathways for energy transfer. Our results suggest that Er and Nd-doped ZrO 2 represents an excellent candidate for an IR-IR taggant system because it possesses a wide array of unique emission spectra which may be tailored by controlling dopant chemistry, dopant concentration, and annealing temperature. •Rare-earth doped zirconia nanopowders were fabricated using aqueous precursors •Lower symmetry crystal systems had the highest tested luminescence response •The lowest dopant concentrations resulted in the highest luminescence intensity •Each nanopowder tested displayed a unique emission spectrum implying a high tunability