Commission International De I-Eclairage Research Articles

Silver nanoparticles enhanced luminescence of dysprosium ions doped silica sol-gel

Silver (Ag) nanoparticles/dysprosium (Dy3+) ions co-doped in silica Xerogel having the composition of 5Ag-5Dy-90SiO2 (mol%) have been prepared using the sol-gel method. Spectral diagnosis of Ag NPs in both collide solutions and silica Xerogels shows a typical surface plasmon resonance (SPR) band centered around 431 nm and 426 nm, respectively. The nanoscale and polycrystalline structure of AgNPs was revealed through FE-SEM and XRD. Fourier transform infrared spectroscopy (FTIR) analysis illustrates the distribution of these ions (Ag, Dy3+) in the porous structures of silica Xerogels, in which this spectrum did not display bands arising from the bonding of such ions with the silica structure. The absorption and photoluminescence (PL) spectra, as a function of Dy3+ concentrations, have been recorded at room temperature. Prominent emission bands of Dy3+ ions have been observed for 4F9/2 → 6H13/2: 575 nm and 4F9/2 → 6H15/2: 482 nm at 350 nm excitation. The PL of the Dy3+ doped and AgNPs/Dy3+ co-doped silica xerogel clearly showed that silver NPs improve the (PL) intensity of the Dy3+ions spectra, and this is due to the strong local electric field induced by SPR of silver NPs in order to energy transfer from the silver NPs to Dy3+ ions. The emission cross-section (σem.) and the radiative lifetime (τrad) of the transtion4F9/2 → 6H13/2 have been determined for doped and co-doped samples. The white light emission has been investigated and observed through the Commission International deI’Eclairage (CIE) chromaticity diagram, where the colour coordinates are in the white range for all co-doped samples.

Improvement of Luminescence Performance by the Addition of KF in the Eu2O3 Doped Li2O-AlF3-NaF-P2O5 Glass for Highly Efficient Reddish-Orange Laser Application

One mol% of europium (Eu3+) with the addition of potassium fluoride in Li2O-AlF3-NaF-P2O5 glass has been prepared using a melt-quenching technique. The fluorescence properties of present glasses were studied by the physical properties, FTIR (Fourier transform infrared spectroscopy), absorption spectra, photoluminescence properties, radiative properties and photometric analysis. The physical properties were measured to know the compactness of the glasses. The structural behavior of groups PO4 and OH of the glasses was discussed through the FTIR spectra. From the FTIR spectra, the OH group of adding KF into the glass showed a low %T intensity due to the hydroxyl group that was consumed by the fluoride content, which confirms the low phonon energy. Using absorption spectra and Judd–Ofelt’s (J–O) theory, the J–O intensity parameters (Ω2, Ω4, and Ω6) and radiative emission properties of excited states of Eu3+ ions are calculated to confirm potential laser applications. Photoluminescence properties generated excitation, emission, and lifetime for the glasses. It is observed that the enhancement of the Eu3+ emission at 613 nm is because of the addition of potassium fluoride. It proved the lifetime associated with the transition from the 5D0 state to be a single exponential. The CIE (Commission International de I’Eclairage) chromaticity diagram estimated the CIE color coordinates and color purity of the prepared glasses. The UV lamp under wavelength at 365 nm achieved reddish-orange emissions, which is suitable for reddish-orange laser applications.

Fabrication of low-cost and fast-response visible photodetector based on ZnS:Mn/p-Si heterojunction

Present communication reports fabrication of visible sensor based on ZnS:Mn/p-Si heterostructure. Herein, Pure and Mn+2 doped ZnS nanocrystalline thin films structures have been deposited on the p-type silicon (Si) substrates using chemical bath deposition technique. The structural, morphological, and optical analysis have been systematically examined using X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet–visible (UV-VIS) and photoluminescence (PL) spectroscopy respectively. Further, the use of the deposited ZnS structures for optical and electrochemical applications was studied using Commission International DeI’Eclairage (CIE) and electrochemical analysis. The electrical properties of the fabricated ZnS:Mn/p-Si heterostructures were explored by illumination visible light of intensity 30 mW/cm2 and calculated all the essential photodetection parameters using the current-voltage (I–V) and current-time (I-T) plots. Enhanced sensitivity (5.01×102), responsivity (7.9 ×10−2 mA/Watt), linear dynamic range (54.03 dB) and external quantum efficiency (16.32%) was observed in ZnS:Mn/p-Si heterostructure device as compared to ZnS/p-Si heterostructure. Hence, the ZnS:Mn/p-Si device shows improved and enhanced optoelectronic performance in comparison to device fabricated using pure ZnS.

Effect of Gd2O3 concentration on photo and X-rays excited luminescence characteristics of Dy3+-Activated Li2O3–SrO–B2O3 glass

Gd3+ and Dy3+-doped borate glasses are considered attractive candidates for white light emission. In this work, the samples, developed by the melt-quenching route, contain a mixture of Gd3+ and Dy3+ with known molar compositions. The determined physical parameters indicate structural changes. Information regarding the Judd-Ofelt (JO) intensity parameters and spectral radiative features, calculated from absorption spectra and emission properties, respectively, are obtained. Excitation and photoluminescence characteristics of the developed samples are found. The energy transfer (ET) efficiency from Gd3+ → Dy3+ is determined by considering their emission intensities and lifetime. The quantum efficiency (QE) of glasses is evaluated. Inokuti –Hirayama (IH) model shows that the Dy3+ → luminescence center ET is dominated by dipole-dipole coulomb interaction. Due to the excitation of more secondary electrons, the X-ray luminescence shows an intense emission pattern. Furthermore, we find the integral scintillation efficiency to be 8.4% of the commercial BGO scintillator crystal for the 10 mol% Gd2O3-doped glass. Commission International deI’Eclairage (CIE) color coordinates and color correlated temperature (CCT) show the suitability of tested samples for white-light applications.

Green emanating BiOCl:Tb3+ phosphors for strategic development of dermatoglyphics and anti-counterfeiting applications

• Green emitting BiOCl:xTb 3+ (x = 1–9 mol%) nanophosphors are prepared by propellant solution combustion route. • A new fluorescence based platform has been setup for in-situ visualization of latent fingerprints and lip prints by powder dusting method. • Well defined fluorescence fingerprint images on variety of surfaces by revealing type 1–3 ridge characteristics. • Developed latent fingerprints shows superior contrast, sensitivity, efficiency, selectivity and negligible background hindrance. • Fabricated unclonable invisible security ink and make it highly suitable for brush mode. In this work, we reported green emitting Tb 3+ ions (1–9 mol%) doped BiOCl nanophophors (NPs) synthesized by solution combustion route using Mimosa pudica ( M. p. ) plant extract as a bio-fuel. Powder X-ray diffraction (PXRD) patterns exhibit tetragonal structure of matlockite-type P4/nmm space group. Scanning electron microscopy (SEM) reveals that the prepared NPs were shown flake-like morphology. The energy bandgap of BiOCl:Tb 3+ (1–9 mol%) NPs were estimated and found to be in the range ∼3.50–3.53 eV. The photoluminescence (PL) spectra show characteristic emission peaks at ∼489, 545, 591 and 622 nm, which were corresponding to 5 D 4 → 7 F 6, 5 D 4 → 7 F 5 , 5 D 4 → 7 F 4 and 5 D 4 → 7 F 3 transitions of Tb 3+ ions, respectively. The maximum PL intensity was found to be for 5 mol% doped NPs and later diminishes. The diminished PL intensity was mainly ascribed to concentration quenching. The estimated CIE (Commission International de I’Eclairage) co-ordinates were close to the green emission standard values set by the National Television System Committee. The optimized NPs was used for development and visualization of latent fingerprints (LFPs) and lip prints. The developed fingerprints and lips prints revealed level I-III ridge details with high sensitivity, selectivity and without any background hindrance. The developed anti-counterfeiting labels were encrypted only under UV light illumination, but were completely invisible under normal light. These results clearly demonstrated that the optimized NPs can help to narrow the search gap in criminal investigations and forensic purposes.

Synthesis and Characterization of CaAl2O4: Dy3+ and CaAl2O4: Sm3+ Phosphor Powders

Calcium aluminate, CaAl2O4 is efficient and well known host material for inorganic phosphors. Although this host structure is mostly doped with Eu2+, different types of rare earth ions have also been studied. In this study, attention was drawn to CaAl2O4 type phosphors doped with Dy3+ and Sm3+ at different concentrations. Ca1-xAl2O4: Dy3+x (x= 0.008, 0.012, 0.02, 0.03) and Ca1-yAl2O4: Sm3+y (y= 0.008, 0.012, 0.02, 0.03) phosphors were synthesized as powder samples through the solid-state reaction method. After heat treatments, monoclinic CaAl2O4 structure was confirmed for all rare earth doped samples by the XRD analysis. PL characteristics of samples depend on activator ion. The PL emission spectra of Dy3+ doped powder samples show two strong bands at 484 nm and 577 nm which are attributed to a typical 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions of Dy3+ ions. Sm3+ activated phosphors have the emission peaks at 565 nm, 604 nm, 649 nm, and 712 nm which are assigned to Sm3+ transitions: 4G5/2 → 6H5/2, 4G5/2 → 6H7/2, 4G5/2 → 6H9/2, 4G5/2 → 6H11/2, respectively. The Commission International De IEclairage (CIE) 1976 chromaticity coordinates were evaluated from the emission spectra in two different rare earth ion doped phosphors, the values (uꞌ = 0.21805, vꞌ = 0.52537) and (uꞌ = 0.36078, vꞌ = 0.54567) were colors of yellow-orange and brick red, respectively. Consequently, synthesized Ca1-xAl2O4: Dy3+x (x= 0.008) and Ca1-xAl2O4: Sm3+y (y= 0.008) phosphors emitting in different color regions can be useful for LED’s and display applications.

Er3+-doped SiO2-based glasses – An exploration of structural, visible, chromatic, and NIR fluorescence characteristics

SiO2-based glasses doped with 1 mol% Er3+ were fabricated via melt-quench process and their structural and visible and NIR (near-infrared) fluorescence features have been investigated. Calculated Judd–Ofelt (J–O) intensity parameters that were deduced from absorption spectra are applied to reckon different radiative factors. Visible emission spectra and decay profiles (for 4S3/2 → 4I15/2 transition) were registered upon λexci.= 379 nm. CIE (Commission International de I'Eclairage), CCT (correlated color temperature), and CP (color purity) values were evaluated from the emission spectra. Also, a NIR luminescence band (4I13/2 → 4I15/2 transition) was identified by 980 nm LD (laser diode). Later, emission cross-section [(σemi) stimulated, (σMemi) from Mccumber theory] values were computed for observed NIR emission. Highest σemi and gain bandwidth (σemi × ∆λeff) were obtained to be 9.18×10−21 cm2 and 517×10−28 cm3 accordingly for 4I13/2 → 4I15/2 transition.

Facile combustion fabrication and optical investigation of novel Er3+-activated BaSrY4O8 green emitter for solid state lighting applications

A simple, non-hazardous and cost effective, solution combustion fabrication route was adopted to prepare novel BaSrY4(1−x)Er4xO8 (x = 0.5−5 mol%) nanocrystals. Investigations related to crystal structure and phase purity of the prepared nanophosphors were made by using X-Ray Diffraction (XRD) based Rietveld refinement analysis technique. Crystallite size of the prepared nanocrystals was analyzed from Transmission Electron Microscopy (TEM) technique and the morphological examinations were done with the help of Scanning Electron Microscopy (SEM) measurements. Optical properties of the fabricated nanophosphors were analyzed from photoluminescence (PL) excitation-emission spectra. By fixing excitation at 379 nm, the emission spectra depicted peak at 549 nm (most intense) corresponding to 4S3/2 → 4I15/2 transition. The optimum content of Er3+ in BaSrY4O8 matrix was determined as x = 0.02. Further, the DR (diffuse reflectance) analysis revealed the band gap (Egap) values for host BaSrY4O8 (5.79 eV) and doped BaSrY3.92Er0.08O8 (5.38 eV) powder samples. CIE (Commission International de I′Eclairage) color coordinates were found to be in green region which proclaims the potential use of combustion fabricated nanophosphors in optical display devices, mainly white LEDs, lasers and optical sensors.

Correlation study between OSL, TL and PL emissions of yellow calcite

The present study shows morphological characterization, experimental results, theoretical fittings of TL and OSL curves of yellow calcite and the correlation between these emissions.The OSL of the sample raises with dose and was theoretically decomposed into three components with a lifetime span of 0.5, 10, and 28 s. TL peaks at 90 and 126 °C were observed in UV region and they could be correlated with OSL emission; these peaks were deconvoluted using general order kinetic theory (GOK) they supplied an activation energy (E) values of 0.7 and 1.0 eV and kinetic order (b) of 1.2 and 2.0 respectively. Both peaks presented good response with beta irradiation in the range between 5 and 41 Gy. TL glow curve recorded at VIS-UV region showed 4 peaks, after deconvolution applying GOK, the peaks temperatures were determined at 92.9, 118.9, 155 and 452 °C; with E equal 0.7, 0.8, 1.3, and 1.05 eV, and b equal 1.01, 1.30, 2.00, and 1.70, respectively.In addition, photoluminescence (PL) spectra were carried out with excitation at 350 nm and the calcite exhibited four broad bands at 413, 440, 470, and 486 nm, and a small one at 390 nm, which can be associated with oxygen vacancies and Me–O defects. The PL results was converted to CIE (Commission International deI'Eclairage) and the coordinates color of the phosphors were determined, values x = 0.14959, y = 0.11,775 (blue) for non-irradiated sample, and x = 0.14593, y = 0.05921 (purplish blue) to irradiated one.

Eu3+/Eu2+/Tb3+ co-activated single-phase Gd2O2S: A high-performance white light emitting phosphor for light emitting diode

In this work, we report Eu3+/Tb3+/Eu2+ co-activated Gd2O2 S as novel phosphor materials that can be effectively applied in the white-light emitting diode based on a near-UV chip with sensational performances. The luminescent properties and energy transfer mechanism have been thoroughly investigated. The as-prepared europium/terbium co-doped Gd2O2 S phosphors exhibit strong fluorescence with tunable color output under UV-vis light excitation. Furthermore, a high response to ultraviolet illumination of 398 nm wavelength was observed in the excitation spectra, indicating an excellent match with a light-emitting-diode chip in the dominant emissions. It is found that a tricolor (blue, green and red) emission band which results in a white light emission can be acquired when Eu3+, Eu2+ and Tb3+ ions are all co-doped into the single phase Gd2O2S, and an optimum ion doping level (10 at.% Eu and 0.7 at.% Tb) can effectively emit nearly pure white color photoluminescence with lifetime effectively tuned from 0.55 ms to 1.10 ms. The CIE (Commission International de I'Eclairage 1931 chromaticity) is X = 0.3507, Y = 0.3029. It is therefore expected that the newly found phosphor material with high-performance properties possess great potentials for the future advanced white LED applications.

A benign approach for novel synthesis of Eu3+ doped MgNb2O6: Its photoluminescence and photocatalytic studies

The Present work involves the production of Eu3+ (1–11 mol %) doped MgNb2O6 nanophosphors (NPs) by combustion technique using ODH as a fuel for the first time and well characterized. The average crystallite and the energy gap of the samples were found to be in the range of 20–45 nm and 4.65–5.66 eV respectively, TEM results reflects the same crystallite size values. The effect of doping was confirmed by the characteristic emission peaks recorded at ~535, 590, 614, 642 and 698 nm may be attributed to the 4f–4f intra shell transitions (5D0→7Fj=0,1,2,3,4) of Eu3+ cations when bombarded at 395 nm energy. Judd–Ofelt parameters (Ω2, Ω4), transition probabilities (AT), quantum efficiency (η), luminescence lifetime (τrad) are discussed in detail. From the emission spectra, CIE (Commission International de I’ Eclairage) chromaticity co-ordinates and Correlated color temperature (CCT) were estimated. Langmuir-Hinshelwood model was used to study the photocatalytic degradation of AR-88 dye. The above results confirmed that the present phosphor can be potentially used for display and photocatalytic applications.

SrTiO3:Dy3+ nanophosphor: synthesis, characterization and photoluminescence properties

Nanosized phosphor i.e. SrTiO3 (ST) is activated by Dy3+ were synthesized via facial solution combustion method. The obtained nanophosphors were calcinated at 600 °C for 2 h to attain crystallinity of the synthesized product. Further, characterized via PXRD, FT-IR, UV-visible spectroscopy, morphological studies via SEM, TEM. The PXRD pattern showed the cubic phase of the nanophosphor. The size of the particle is measured and it is found around 25–30 nm. The irregular shape of the product is shown by SEM images. Functional groups and band gap of the phosphor is examined by FT-IR and UV-visible spectroscopy respectively. Photoluminescence of ST: Dy3+ was studied to examine the use of nanophospor in white light emitting device. The correlated color temperature (CCT) and commission International deI’Eclairage (CIE) color coordinates (x, y) is computed for optimized phosphor. It is observed that the value of x and y of the nanophosphor is drop in the white region of the CIE diagram and value of CCT is determined to be 4310. Thus, this nanophosphor is highly recommended for display applications.

Effect of Broussonetia papyrifera L. silage on blood biochemical parameters, growth performance, meat amino acids and fatty acids compositions in beef cattle.

ObjectiveThe study was conducted to investigate the effects of Broussonetia papyrifera L. (B. papyrifera) silage on growth performance, serum biochemical parameters, meat quality, and meat amino acids and fatty acids compositions in beef cattle.MethodsSixty-four male Angus beef cattle were assigned to 4 groups with 4 pens in each group and 4 beef cattle in each pen, and fed with the total mixed ration supplemented with 0%, 5%, 10%, or 15% B. papyrifera silage for 100 days (control group, 5% group, 10% group and 15% group) separately.ResultsBeef cattle had significantly higher final body weight (BW) in 15% group, higher average daily gain (ADG) and dry matter intake (DMI) in 5% group, 10% group and 15% group, and higher feed conversion ratio (FCR) in 10% group and 15% group. Significantly higher blood superoxide dismutase (SOD) concentration was noted in 15% group, higher blood total antioxidant capacity (TAC) in 10% group and 15% group, lower 8-hydroxydeoxyguanosine (8-OHdG) and malondialdehyde (MDA) in 15% group. Meat had lower pH in 15% group, higher Commission International DeI’Eclairage (CIE) L* in 5% group, 10% group, and 15% group, and lower drip loss in 15% group. Greater concentration of meat polyunsaturated fatty acids (PUFA) was observed in 10% group and 15% group, and docosahexaenoic acid (DHA) in 15% group.ConclusionDiet with 15% B. papyrifera silage could improve performance and increase final BW, ADG, DMI, and FCR, enhance the antioxidant functions by decreasing blood 8-OHdG and MDA and increasing blood SOD and TAC, improve the meat quality by lowing pH and drip loss and increasing CIE L*, increase the meat PUFA and DHA concentration. Polyphenols and flavonoids might be the main components responsible for the antioxidant activity and anti-biohydrogenation in the B. papyrifera silage. And B. papyrifera silage could be used as a new feedstuff in beef cattle nutrition.

Photoluminescence and cathodoluminescence properties of Na3LuSi2O7:Tb3+ phosphors

Tb3+ doped Na3LuSi2O7(NLSO) phosphors were prepared by a solid state reaction technique. The crystal structures and the influence of Tb3+ concentration on the photoluminescence, cathodoluminescence of the phosphors were investigated. Two groups of emission lines had been observed, which were corresponding to Tb3+ 5D3 → 7FJ (J = 6, 5, 4, 3) and 5D4 → 7FJ (J = 6, 5, 4, 3) transitions. The physical mechanisms for excitation, emission, concentration quenching and the cross-relaxation mechanism between the 5D3 and 5D4 emission were investigated in detail. Cathodoluminescence properties were also studied for the optimized samples as a function of filament current. The Commission International de I-Eclairage (CIE) chromaticity coordinates were calculated for the NLSO:Tb3+ phosphors.

Synthesis and photoluminescence properties of novel yellow-emitting Ba2Gd5−xDyxB5O17 phosphors

Single phase yellow-emitting Dy3+ ions doped Ba2Gd5B5O17 phosphors were synthesized by solid-state reaction technique at high temperature. The phase identification and photoluminescence properties of as-prepared phosphors were characterized by X-ray diffraction patterns, excitation and emission spectra, decay curves and temperature-dependent luminescence spectral measurements. Under 276 and 354 nm near-UV excitations, the studied phosphors exhibited two intense emission bands in blue (486 nm) and yellow (575 nm) regions due to the magnetic dipole (4F9/2→6H15/2) and electric dipole (4F9/2→6H13/2) transitions, respectively. The optimal doping concentration of Dy3+ ions was found to be x = 0.07 for Ba2Gd5−xDyxB5O17 phosphors. Under 354 nm excitation, the color coordinates (x, y) of Ba2Gd4.93Dy0.07B5O17 phosphor were located in the yellow region of Commission International de I-Eclairage 1931 diagram and hence it can be used as a potential yellow component in the fabrication of white light-emitting diodes. Furthermore, the decay curves were fitted to double-exponential function to find the excited state lifetimes of Dy3+ ions. Besides, the temperature-dependent luminescence measurements were made to explore the thermal stability and activation energy of the concentration-optimized Ba2Gd4.93Dy0.07B5O17 phosphor. The results obtained from the present investigation were discussed in detail and compared with the similar reported literatures.

Synthesis of novel Dy3+ activated Ba2CaZn2Si6O17 phosphors for white light‐emitting diodes

Dysprosium ion (Dy3+ ) activated Ba2 CaZn2 Si6 O17 phosphors were synthesized using high temperature solid-state reaction method. Powder X-ray diffraction (PXRD) analysis confirmed the phase formation of the as-prepared phosphors. Scanning electron microscopy (SEM) analysis disclosed an agglomeration of particles with an irregular morphology. Under 350nm excitation, the emission spectrum of Dy3+ ions showed bands at 481nm (blue), 577nm (yellow) and 674nm (red). The influence of the Dy3+ concentration on its emission intensity was investigated. The optimum concentration of Dy3+ ions in the Ba2 CaZn2 Si6 O17 :Dy3+ phosphors were found to be x = 0.06. The critical energy transfer distance was calculated. The fluorescence lifetime was also determined for Ba2 CaZn2 Si6 O17 :0.06Dy3+ . The Commission International deI'Eclairage (CIE) chromaticity coordinates of the phosphor were calculated to be x = 0.304, y = 0.382. The activation energy for the thermal quenching was calculated to be 0.168eV. These results indicated that the Ba2 CaZn2 Si6 O17 :Dy3+ phosphor might be a potential candidate for near ultraviolet (NUV)-based white light-emitting diodes.

Photoluminescence properties of novel Ba2Lu5B5O17:Eu3+ red emitting phosphors with high color purity for near-UV excited white light emitting diodes.

A series of new red-emitting Ba2Lu4.98−xEuxLa0.02B5O17 (0.1 ≤ x ≤ 1.0) phosphors were synthesized via the high-temperature solid-state reaction method. The phase formation of the as-synthesized Ba2Lu4.48Eu0.5La0.02B5O17 phosphor was confirmed by powder X-ray diffraction analysis. It was found that La3+ doping resulted in the reduction of LuBO3 impurities and thus pure phase Ba2Lu5B5O17 was realised. The morphology of Ba2Lu4.48Eu0.5La0.02B5O17 phosphors was studied by field emission scanning electron microscopy (FE-SEM). As a function of Eu3+ concentration the photoluminescence spectra and decay lifetimes were investigated in detail. Under excitation at 396 nm, a dominant red emission peak located at 616 nm (5D0 → 7F2) indicated that Eu3+ ions mainly occupied low symmetry sites with a non-inversion center in Ba2Lu4.48Eu0.5La0.02B5O17. The optimal Eu3+ ion concentration was found to be x = 0.5 and the critical distance of Eu3+ was determined to be 6.55 Å. In addition, the concentration quenching takes place via dipole–dipole interactions. The phosphors exhibited good CIE (Commission International de I'Eclairage) color coordinates (x = 0.643, y = 0.356) situated in the red region and a high color purity of 97.8%. Furthermore, the internal quantum efficiency and the thermal stability of Ba2Lu4.48Eu0.5La0.02B5O17 phosphors were also investigated systematically. The results suggest that Ba2Lu4.48Eu0.5La0.02B5O17 may be a potential red phosphor for white light-emitting diodes.

Effect of sintering temperature on the photoluminescence properties of red-emitting color conversion glass

The red-emitting color conversion glasses were prepared by cosintering borosilicate glass frits and CaAlSiN3:Eu2+ phosphors at various temperatures in the 600–800 °C range. The effect of sintering temperature on the photoluminescence (PL) and excitation (PLE) of the color conversion glasses was investigated. Characteristics of color conversion glasses, with respect to excitation and emission intensity, quantum yield (QY) and CIE (Commission International de I’Eclairage) chromaticity were analyzed based on excitation and emission spectra. The glass, sintered at 600 °C, showed the best luminescence properties. Then, the intensity of excitation and emission peak decreased with the sintering temperature increasing. All excitation and emission peaks disappeared when the sintering temperature increased beyond 800 °C. The luminescence properties with the higher sintering temperature may be destroyed because of the lattice disturbance of CaAlSiN3 and oxidation of Eu2+, which is caused by reactions between glass matrices and CaAlSiN3:Eu2+ phosphors. The present study may promote the application of the red-emitting color conversion glasses in light emitting diodes encapsulation.

Energy transfer (In3+ → Eu3+) based Polyvinyl Alcohol polymer composites for bright red luminescence

A prominent sensitization effect of In3+ ions is observed in In3++Eu3+: PVA polymer composites under UV excitation. Consequently, it enhances the red emission performance of Eu3+ ions in PVA system. We have successfully synthesized Eu3+: PVA, In3+: PVA and In3++Eu3+: PVA polymer films by traditional solution casting method. The structural and ion-polymer interaction studies have been analyzed from XRD and FTIR spectral profiles. Eu3+ doped PVA polymer composites are exhibited a red emission at 619 nm (5D0→7F2) under 396 nm (7F0→5L6) of excitation. Upon co-doping with In3+ ions in different concentrations to the Eu3+: PVA polymer film, it exhibits predominant red emission than singly doped Eu3+: PVA under 396 nm of excitation due to energy migration from In3+ to Eu3+. Successful emission photons of In3+ ions are collectively absorbed by the Eu3+ ions which lead the improvement of red emission. Optimized sensitization concentration of the In3+ ions has been found to be 0.01 wt%. Possible energy migration phenomenon is elucidated by several fluorescent dynamics. The energy transfer process is substantiated by lifetime decay analysis and overlapped spectral studies. The Commission International de I-Eclairage chromaticity coordinates were calculated. The quantum efficiencies of the Eu3+ ions and In3+ ions in singly doped and co-doped polymer systems have been evaluated. From these results, these co-doped In3++Eu3+: PVA composite polymer films might be proposed as encouraging candidates for bright red fluorescent materials for several photonic applications.

Enhanced photoluminescence behaviour of Eu3+ activated ZnMoO4 nanophosphors via Tb3+ co-doping for light emitting diode

In the present study, structural and photo-luminescence studies of Eu3+ and Tb3+ co-doped ZnMoO4 host matrix has been investigated in detail. ZnMoO4:Eu3+/Tb3+ have been synthesized via a simple and cost effective co-precipitation method. XRD, Raman and FTIR studies confirmed its triclinic structure of Eu3+/Tb3+ co-doped ZnMoO4 host. Emission spectra of the measured samples corroborate the dominant electric dipole transition emission (5D0-7F2) intensity over magnetic dipole transition emission (5D0-7F1) intensity. Moreover, the improvement in red emission (5D0-7F2) for Eu3+(3at%) and Tb3+(2at%) and high asymmetric ratio ∼10.4 is observed which dictates it as a highly red emitter. Additionally, commission international de-I′ Eclairage (CIE) values approaches to NSTC. Color purity of red emission improves after Tb3+ co-doping. Photoluminescence studies reveals that Tb3+ acts as a sensitizer for the Eu3+ activated ZnMoO4 host matrix. Study reveals that Eu3+/Tb3+ co-doped ZnMoO4 can be excited by near UV device, which is bottleneck in the advancement of LEDs technology.