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Multicolor emitting Dy3+/Eu3+ coactivated lithium zinc borate (LZB) glasses were prepared by the melt-quenching method and their structural, vibrational, morphological, and luminescence properties were investigated. Dy3+ glasses exhibited blue, yellow, and red photoluminescence (PL) bands at 481 nm (4F 9/2 → 6H 15/2), 576 nm (4F 9/2 → 6H 13/2), and 665 nm (4F 9/2 → 6H 11/2) under 386 nm excitation. Eu3+ glasses exhibited strong orange and reddish-orange emissions at 589 nm (5D 0 →7F 1) and 612 nm (5D 0 →7F 2) at 393 nm of excitation. 0.5 mol% Dy3+ is codoped with various Eu3+ concentrations and the energy transfer mechanism is analyzed from the spectral overlay of Dy3+ emission and Eu3+ absorption, Dy3+/Eu3+ PL, and decay profiles as well as from energy transfer parameters. Dy3+/Eu3+ codoped glasses stimulated under different excitation wavelengths of Dy3+ (349, 363, and 386 nm) displayed a decline in the intensity of Dy3+ PL bands and a simultaneous rise in Eu3+ PL bands, demonstrating efficient energy transfer from Dy3+: 4F 9/2 → Eu3+: 5D 0 due to dipole-dipole interaction. The energy transfer process is supported by a decrement in the lifetimes of Dy3+ when co-doped with Eu3+ compared with singly doped Dy3+ones. The color coordinates and corresponding color temperatures were shifted from neutral to a warm white light region depending on the Eu3+ concentration. The aforementioned results demonstrate the importance of the near-ultraviolet-driven LZB: Dy3+/Eu3+ glasses for their potential application in warm white light and multicolor emitting devices. [ABSTRACT FROM AUTHOR]

Crystal structure of Eu3+ doped MgAl 2 O 4 (MAO) phosphors synthesised by solid state reaction method was investigated using X-ray diffraction. Raman peaks appeared at 307 cm−1, 408 cm−1, 668 cm−1 and 767 cm−1 were assigned to F 2g (1), F 2g (2), E g and A 1g respectively. Spherical morphology and microstructural analysis of synthesised phosphors was analysed by Field emission scanning electron microscope (FESEM) high resolution transmission electron microscope (HRTEM) and energy dispersive X-ray analysis (EDAX) was used to establish the chemical composition of the phosphors. Optical properties were analysed by photoexcitation (394 nm) and photoluminescence (PL) spectra displayed all the characteristic emission of Eu3+ related to transition 5D 0 to 7F j (j = 0, 1, 2, 3, 4). The emission color was observed in red region and it was confirmed by the Commission Internationale de l'Eclairage (CIE) chromatic coordinate graph. The color purity and quality (correlated color temperature- CCT value) of red light was observed in 0.9% Eu3+ doped MAO to be 90.76% and 2097K respectively. Electrochemical evaluation of Eu3+ doped MAO was performed through cyclic voltammetry (CV) studies. [ABSTRACT FROM AUTHOR]

Lithium zinc barium borate glasses were synthesized using the melt-quenching method and doped with Ce3+, Er3+, and their combination. The study examines the influence of Ce3+ on the photoluminescence of Er3+ in these glasses. X-ray diffraction confirmed the amorphous nature of both undoped and doped glasses, while Fourier-transform infrared spectroscopy showed the conversion of BO 3 to BO 4 units, and Raman spectroscopy indicated a phonon energy around 1136 cm−1. The Ce3+-doped glasses exhibited a blue emission at 447 nm due to the 5d→4f 1 transition. Co-doping with Ce3+ and Er3+ led to decreased visible upconversion emissions but significantly enhanced near-infrared emissions at 1.53 μm. This enhancement is attributed to reduced non-radiative decay and improved energy transfer between Er3+ and Ce3+ ions, facilitated by the phonon energy of host glass. The 1.53 μm emission intensity in Ce3+/Er3+ co-doped glass was about 60% higher than in singly Er3+-doped samples, highlighting the potential of Ce3+ co-doping for broad amplification at 980 nm excitation. [ABSTRACT FROM AUTHOR]

Ce3+/Li+-activated barium aluminate phosphor (BAO) was synthesized by conventional solid-state reaction method. The crystal structure of the synthesized phosphor was analyzed by X-ray diffraction (XRD) and Raman spectroscopy analysis. Fourier transformed infrared spectrum results revealed the characteristic vibration bands present in the synthesized phosphor. Surface composition analysis of the prepared samples was examined using X-ray photoelectron spectroscopy (XPS). Photoluminescence emission band observed at 589 nm was assigned to 5D excited level corresponding to 2F5/2 transition in yellow region under the excitation wavelength of 320 nm. Yellow light emission was confirmed by the Commission Internationale de L'Eclairage (CIE) chromatic coordinate graph. The synthesized phosphors BAO: 0.5Ce3+, BAO: 0.5Ce3+, 0.1Li+ displayed a color purity and lifetime decay of 78.4%, 81.3% and 4.333 ns, 4.738 ns, respectively. [ABSTRACT FROM AUTHOR]

Double perovskite Sm2CoFeO6 (SCFO) compound has been synthesized by the conventional solid-state reaction route for the first time. The Rietveld refinement has been carried out using the X-ray diffraction data; it confirms the single-phase formation of orthorhombic structure with the Pnma space group. UV-DRS results show that SCFO was observed in semiconducting behavior. Spin–phonon coupling of SCFO was observed from Raman spectroscopy investigation. The Raman analysis and group theory confirms that the IR and Raman active modes of SCFO. The amount of Sm, Co, Fe and O elements in the SCFO compound was examined by energy-dispersive spectroscopy (EDS) with the assistance of field emission scanning electron microscopy (FE-SEM) analysis. The photoluminescence excitation and emission spectra of SCFO were examined. The results show that the phosphor is excited in the region from 320 to 500 nm, and it emits orange at 607 nm, due to the resultant of 4G5/2 → 6H7/2 transitions. The SCFO compound exhibited ferromagnetic behavior, which is confirmed by VSM analysis. The obtained results demonstrated that SCFO double perovskite is extensive for application of spintronic devices and LED’s. [ABSTRACT FROM AUTHOR]

Trivalent Dysprosium (Dy3+) activated garnet structured Li 7 La 3 Zr 2 O 12 (LLZO) phosphors were synthesized by conventional solid state reaction method. The phase structure of the prepared Dy3+ doped LLZO powders was confirmed by X-ray diffraction and Raman spectroscopy studies. Field Emission Scanning Electron Microscopy (FESEM) studies indicated a change in morphology and an increase in the area of the intergranular Li–Al–O liquid layer is observed with the increase of Li and dopant concentrations. Composition analysis of the prepared samples was examined by X-ray photoelectron spectroscopy (XPS) analysis. PL emission band observed at 579 nm was assigned to4F 9/2 - 6H 13/2 transition in yellow region under the ultraviolet excitation wavelength of 351 nm. White light emission was confirmed by the Commission Internationale de L'Eclairage (CIE) chromatic coordinate graph. Thermoluminescence studies were carried out and the results indicated that the grown phosphors are suitable for industrial dosimetric applications where high doses are needed to be measured. [ABSTRACT FROM AUTHOR]

Yb3+/Er3+codoped La 10 W 22 O 81 (LWO) nanophosphor rods have been successfully synthesized by a facile hydrothermal assisted solid state reaction method, and their upconversion photoluminescence properties were systematically studied. X-ray diffraction patterns revealed that the nanophosphors have an orthorhombic structure with space group Pbcn (60). A microflowers-like morphology with irregular hexagonal nanorods was observed using field emission scanning electron microscopy for the Yb3+(2 mol%)/Er3+(2 mol%):LWO nanophosphor. The shape and size of the nanophosphor and the elements along with their ionic states in the material were confirmed by TEM and XPS studies, respectively. A green upconversion emission was observed in the Er3+: LWO nanophosphors under 980 nm laser excitation. A significant improvement in upconversion emission has been observed in the Er3+: LWO nanophosphors by increasing the Er3+ ion concentration. A decrease in the upconversion emission occurred due to concentration quenching when the doping concentration of Er3+ ions was greater than 2 mol%. An optimized Er3+(2 mol%): LWO nanophosphor exhibited a strong near infrared emission at 1.53 μm by 980 nm excitation. The green upconversion emission of Er3+(2 mol%): LWO was remarkably enhanced by co-doping with Yb3+ ions under 980 nm excitation because of energy transfer from Yb3+ to Er3+. The naked eye observed this upconversion emission when co-doping with 2 mol% Yb3+. In order to obtain the high upconversion green emission, the optimized sensitizer concentration of Yb3+ ions was found to be 2 mol%. The upconversion emission trends were studied as a function of stimulating laser power for an optimized sample. Moreover, the NIR emission intensity has also been enhanced by co-doping with Yb3+ ions due to energy transfer from Yb3+ to Er3+. The energy transfer dynamics were systematically elucidated by energy level scheme. Colorimetric coordinates were determined for Er3+ and Yb3+/Er3+: LWO nanophosphors. The energy transfer mechanism was well explained and substantiated by several fluorescence dynamics of upconversion emission spectra and CIE coordinates. The results demonstrated that the co-doped Yb3+(2 mol%)/Er3+(2 mol%): LWO nanophosphor material is found to be a suitable candidate for the novel upconversion photonic devices. [ABSTRACT FROM AUTHOR]

Zn1-xNixO (x = 0.00, 0.01, 0.02, 0.03, and 0.04)-diluted magnetic semiconductor nanoparticles were synthesized via a simple combustion method at 500 °C. The structural analysis confirmed that the formation of hexagonal wurtzite structure with average particle size around 35 nm. Energy dispersive analysis of X-rays (EDAX) spectra confirmed the existence of Zn, Ni, and O in the synthesized samples with near stoichiometric ratio. A spherical morphology was noticed for all the samples; however, the size of the particle decreases with increasing Ni concentration. Diffuse reflectance spectra (DRS) show that the band shifts towards higher energies from 3.29 to 3.35 eV with Ni substitution. From the photoluminescence (PL) spectra, three emission peaks were noticed at wavelengths around 520, 580, and 700 nm and are attributed to the different defects. Magnetic studies confirmed the ferromagnetic nature of the samples. Three percent of Ni-doped ZnO has larger saturation magnetization (Ms) and is suitable for magnetic memory devices. [ABSTRACT FROM AUTHOR]

Synthetic garnets are a group of oxide materials that play a vital role in the development of solid state lasers, magnetic and optic-electronic devices. The analysis on the solubility of rare-earth elements in the well-crystallized system has led to the discovery of peculiar oxide materials with multifunctional properties. By following the above importance, Aluminium ion (Al3+) substituted Dysprosium Iron Garnet compounds with the chemical formula of Dy3Fe5−xAlxO12 (x = 0–0.5) have been synthesized by the solid state reaction method and the effect of substitution of non-magnetic ions into the magnetic sub-lattices have been analyzed. The Rietveld refinement of powder x-ray diffraction patterns confirms that the pure Dy3Fe5O12 compound crystallizes with cubic (Space group: Ia3d) superstructure whereas all the Al3+ substituted samples exhibit the coexistence of cubic (Ia3d) and trigonal Fe2O3 (R3c) phases. The energy gap values of the prepared compounds is found to be around 1.6 eV which reveals the semiconducting nature and the decreasing trend of band gap values may be due to the growth factor of crystallites, structural disorder and distortion introduced into the crystal lattice. From the Micro-Raman analysis, it is found that the substituted Al3+ ions starts filling into both tetrahedral and octahedral positions and the assignments of vibrational modes observed from Raman spectra confirm the incorporation of Al3+ ions into the Dy3Fe5O12 garnet structure. From the magnetization analysis, it is found that the response of super-exchange interaction between Fe3+ ions in the a and d sites of Dy3Fe5O12 compound leads to net magnetic moment and the substitution of Al3+ ions preferably replaces Fe3+ ions in d sites and suggests the decrease in net magnetization values. From the photoluminescence studies, it is noticed that the luminescence behavior of Al3+ ions substituted Dy3Fe5−xAlxO12 compounds are due to the superposition of a broad emission band and reveals the variation in concentration of Al3+ ions in the prepared compounds. An interesting point to note is that, a well saturated "soft" ferroelectric hysteresis loop is obtained in both pure and Al3+ substituted Dy3Fe5−xAlxO12 compounds, and the observed electric hysteresis loops are found to be influenced by the factors such as capacitance nature, resistivity effects and leakage current of the compounds. Hence, the study on effect of trivalent non-magnetic ion substitution in a hard magnetic Dy3Fe5O12 system leads to interesting intrinsic magnetic and ferroelectric properties and found suitability for the fabrication of energy storage and optoelectronic devices. [ABSTRACT FROM AUTHOR]

Organometallic lead halide perovskites are well known for its excellent and unique light-harvesting properties. This brands them as a promising candidate in almost all the optoelectronic devices. Present work demonstrates the synthesis of methylammonium lead bromide, MAPbBr 3 quantum dots (QDs) of diameter less than 4 nm and methylammonium - octylammonium lead bromide core-shell type nanoparticles (CSNPs) with a core diameter of about 1–2 nm surrounded by a shell of thickness 4 nm. The core-shell structure was confirmed from crystal structure analysis – X-ray diffraction pattern, transmission electron microscopy (TEM) images and an increased stokes shift between absorption edge and the photoluminescence emission peak. These core-shell nanoparticles with high photoluminescence quantum yield (PLQY) and color tuning ability were incorporated into poly (methyl methacrylate) (PMMA) matrix to form transparent nanocomposites which were highly stable, with reduced wettability and a high PLQY of 88%. PLQY stability of composites towards humidity was examined by keeping the samples fully immersed in water for 18 h, after which PMMA composites were showing PLQY ∼83%, no considerable difference was found compared to dry composites. Dry films (kept sealed in covers) were found to be relatively stable for about one year retaining PLQY of 13%. The composite films of core-shell particles were used to demonstrate a prototype of down converting light emitting diode (LED), emitting pure green light capable of improving the quality of display devices. Image 1 • Stable perovskite core-shell nanoparticle PMMA composites with very high PL quantum yield (PLQY) were synthesized. • The nanoparticles show a very high PLQY due to large luminescence Stokes shift ∼ 1eV. • Composite films were found stable for about one year retaining PLQY ∼13% which is longer than any other reports. • Films were stable in humid atmosphere. • Composites were used as emitter layer in down converting LED. Its photo stability was excellent. [ABSTRACT FROM AUTHOR]

Abstract Individually and doubly doped Ce3+/Eu3+:CaLa 2 ZnO 5 (CLZO) phosphors were synthesized by a conventional sol-gel method as highly efficient luminescence-based phosphor materials. X-ray diffraction and field-emission scanning electron microscope were used to analyze the structural and morphological properties. The elements and their ionic states were determined by energy-dispersive spectroscopy and X-ray photoelectron spectroscopy studies, respectively. The assignment of the functional groups was analyzed using Fourier-transform infrared spectral studies. Bright red emission was obtained from Eu3+-doped CLZO phosphors due to its hypersensitive transition of 5D 0 →7F 2 at 626 nm with a royal blue excitation source. By increasing the Eu3+ content, the emission features were rapidly enhanced. Moreover, the red emission related to Eu3+ was further increased by the addition Ce3+ ions as a co-dopant along with Eu3+ in the CLZO matrix due to energy transfer. The energy migration from Ce3+ to Eu3+ is systematically illustrated by several fluorescent approaches, such as photoluminescence analysis, spectral overlap, CIE coordinates, lifetime dynamics, luminescence quantum yields, and color purity. Surprisingly, the CIE coordinates were very close to the NTSC coordinate values. Based on the results, these phosphors could be suitable materials for luminescence-based optoelectronic devices. Highlights • Dazzling red emission is obtained from Ce3+/Eu3+: CaLa 2 ZnO 5 phosphors. • Red emission of Eu3+ was remarkably enhanced by co-doping with Ce3+. • Effective sensitization of Ce3+ ions and enhanced quantum yield have been elucidated. • Energy transfer from Ce3+ to Eu3+ ions by several fluorescence dynamics. • Meritorious CCT, CIE coordinates and high red color purity have obtained. [ABSTRACT FROM AUTHOR]

In the present work, we report plasmon induced brightening of dark excitons (XD) in Au nanoparticle (Au-NP) coated monolayer (1L) WSe2. We observed one order enhancement in photoluminescence (PL) intensity and surface enhanced Raman scattering in Au-NP/1L-WSe2 at room temperature (RT). Temperature dependent PL measurements showed enhanced PL emission from RT down to 100 K in contrast to reduced PL emission which is generally observed for pristine 1L-WSe2. We attribute this effect to the out-of-plane electric field induced by the scattering from Au-NPs, which results in the out-of-plane dipole moment and spin-flip of conduction band electrons in Au-NP/1L-WSe2, making XD bright. Our approach provides a facile way to harness excitonic properties in low-dimensional semiconductors, offering simple strategies for quantum optoelectronics. [ABSTRACT FROM AUTHOR]

A simple sol-gel technique is used to synthesize zero-dimensional pure and Er-doped BiFeO3 (BFO) nanoparticles. The effect of Er dopant on morphology, structure, optical, magnetic, and photoluminescence properties of single-phase BFO was studied. X-ray diffraction (XRD) studies reveal that the structural phase transformation is noticed from rhombohedral to orthorhombic with substitution of Er to pure BFO. From scanning electron microscopy (SEM) and transmission electron microscopy (TEM), morphology of the synthesized samples were spherical in shape. Agglomeration and particle size reduced with substitution of Er, particle size is around ∼ 30 nm. Energy-dispersive analysis of X-ray (EDAX) spectra confirms the presence of selective elements in synthesized samples. Fourier transform infrared spectra (FTIR) confirms that all the bonds strongly correspond to BFO. The substitution of Er in BFO nanoparticles also demonstrates a strong reduction in optical band-gap energy compared with pure BFO. Magnetization studies were carried out by using vibrating sample magnetometer (VSM), and the saturation magnetization increases with increasing substitution of Er. A photoluminescence (PL) spectrum reveals that the substitution of Er suppressed the recombination of electron-hole pairs. [ABSTRACT FROM AUTHOR]

Er3+-doped and co-doped (Er3+/Yb3+):polyethylene oxide (PEO)/polyvinylpyrrolidone (PVP) blended polymer composites were synthesized by the traditional solution-casting method. The amorphous nature of the prepared Er3+- and Yb3+-doped polymer composites was confirmed by X-ray diffraction analysis. The interaction between dopant rare earth ions and the blended polymer was systematically elucidated by Fourier transform infrared spectroscopy and Raman spectroscopy analysis. A prominent near-infrared (NIR) emission was observed at 1.53 μm (4I 13/2 →4I 15/2) from the fluorescence spectra of the Er3+:PEO/PVP polymer composites under 980 nm excitation at room temperature. The NIR emission intensity was appreciably increased by increasing the Er3+ ion concentration. The optimized concentration of the Er3+ ions was found to be 0.2 wt%. The emission performance was drastically reduced after the optimized concentration due to the concentration quenching effect. Upon co-doping with Yb3+ to Er3+:PEO/PVP polymer composites, the NIR emission intensity at 1.53 μm (4I 13/2 →4I 15/2) was remarkably improved through energy transfer from Yb3+ to Er3+. The Er3+ NIR fluorescence intensity was increased significantly by increasing the co-doping concentration of Yb3+ in the PEO/PVP polymer composite system. The optimized sensitizing concentration of Yb3+ ions was found to be 0.05 wt% in the PEO/PVP polymer-blended composite system. The energy-transfer phenomenon was elucidated through an energy-level diagram. These co-doped (0.2Er3++0.05Yb3+):PEO/PVP polymer-blended composite materials could be considered as promising candidates for several NIR photonic device applications. This approach of NIR-emitting polymer composites will be useful for various NIR optoelectronic applications. [ABSTRACT FROM AUTHOR]

Abstract We synthesized a batch of co-doped (Ce3++Sm3+): LBZ glass specimens by melt quenching process and their structural and radiation properties were studied by employing XRD, FE-SEM, optical absorption, photoluminescence and lifetime measurements. UV–Vis–NIR absorption studies of the co-doped (Ce3++Sm3+): LBZ glassy matrix displays pertinent bands of both Ce3+ and Sm3+ ions. Individually doped Sm3+: LBZ glass exhibit bright orange emission at 603 nm (4G 5/2 → 6H 7/2) under the excitation of 403 nm. Nevertheless, the luminescence intensities pertaining to Sm3+ were extraordinarily increased by co-doping with Ce3+ ions to Sm3+: LBZ glassy matrices because of energy transfer from Ce3+ to Sm3+. The fluorescence spectra of co-doped (Ce3++Sm3+): LBZ exhibits characteristic emission bands of Ce3+ (441 nm, blue) and Sm3+ (603 nm, reddish orange) under the excitation of 362 nm. Decay curves of Ce3+ and Sm3+ ions in co-doped glass has been fitted to double exponential nature. The decreasing lifetime of donor ion and rising lifetime of acceptor ion in double doped glass could support the energy transfer from Ce3+ to Sm3+ ions in the host matrix. The CIE coordinates and CCT values were calculated for all the obtained co-doped glassy samples from their luminescence spectra. By adding Ce3+ ions to individually doped Sm3+: LBZ glass matrix, the emitting color changes from reddish orange to white light which resembles the energy transfer from Ce3+ to Sm3+ ions. These studies, perhaps implied that attained co-doped (Ce3++Sm3+): LBZ glassy samples are potential materials for white lighting appliances. [ABSTRACT FROM AUTHOR]

Tin doped ZnS powders (Zn 1−x Sn x S, x = 0.00, 0.02, 0.05&0.08) were synthesized by a simple Solid state reaction and were characterized by Powder X-ray diffractometer (XRD), UV–Vis–NIR diffuse reflectance spectrophotometer, fluorescence spectrophotometer, scanning electron microscope (SEM) and vibrating sample magnetometer (VSM). The XRD studies revealed that no change in crystal structure was observed by the substitution of Sn into ZnS lattice. The crystallite size was calculated by Scherrer's formula and found that the crystallize size of Sn doped ZnS powders were in the range of 35–45 nm. From the diffused reflectance spectra, the band gap values of Zn 1−x Sn x S powders were estimated, and they were found to be in the range of 3.53–3.58 eV. The pure ZnS particles showed higher optical absorption in visible region than that of Sn doped ZnS nano particles. The Photoluminescence (PL) spectra of Zn 1−x Sn x S powders were recorded in the range of 400–700 nm with an excitation wavelength of 360 nm. The Zn 1−x Sn x S powders exhibited ferromagnetism at low temperature (100 K) and super paramagnetism at room temperature (300 K). The strength of magnetization increased with increase of Sn doping concentration from 0.015 emu/g to 0.18 emu/g, when x increased from 0.00–0.05. [ABSTRACT FROM AUTHOR]

A set of co-doped (Ce 3+ /Dy 3+ ): LBZ glasses were prepared by standard melt quenching technique. The pertinent absorption bands were observed in the optical absorption spectrum of co-doped Ce 3+ /Dy 3+ : LBZ glasses. We have been observed a prominent blue and yellow emission pertaining to Dy 3+ ions at 0.5 mol % under the excitation of 385 nm doped glasses. However, the photoluminescence intensities were remarkably enhanced by co-doping with Ce 3+ ions to Dy 3+ : LBZ glasses due to energy transfer from Ce 3+ to Dy 3+ . The emission spectra of co-doped (Ce 3+ /Dy 3+ ): LBZ glass exhibits three strong emissions at 440 nm, 480 nm and 574 nm which are assigned with corresponding electronic transitions of 4 I 15/2 → 6 H 15/2 , 4 F 9/2 → 6 H 15/2 and 4 F 9/2 → 6 H 13/2 respectively. The Commission International de E'clairage coordinates were calculated from their emission spectra of single doped Dy 3+ and co-doped (Ce 3+ /Dy 3+ ): LBZ glasses. The obtained CIE chromaticity coordinates for optimized co-doped glass are found to be very close to the standard white region. Based on the concentration of Ce 3+ , the emitting color of the co-doped glass can be changed from blue to white color. The transformation of the color from blue to white region due to energy transfer from Ce 3+ to Dy 3+ . The energy transfer mechanism was substantiated by various fluorescence dynamics such as overlapped spectral profiles, photoluminescence, lifetime decay and CIE color coordinate analysis. These results could be suggested that the obtained co-doped (Ce 3+ /Dy 3+ ): LBZ glasses are promising candidates for commercial white light applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesis of cubic blue light emitting pure LLZO and orange light emitting LLZO: xSm3+ phosphors by SSR method. • Band gap values of synthesised phosphors for pure and Sm3+: LLZO were calculated to be 4.140 eV and 3.972 eV, respectively. • PL emission band observed at 602 nm was assigned to 4G 5/2 → 6H 7/2 transition in orange region under λ ext of 408 nm. • The blue and orange light emission was confirmed by CIE chromaticity X, Y coordinates. • Color purity and CCT value of 0.5 MW% Sm3+ doped LLZO phosphor was 85.9 % and 2227 K, respectively. Samarium (Sm) activated Li 7 La 3 Zr 2 O 12 (LLZO) phosphors were synthesized by solid state reaction method. Crystal structure of Sm3+ doped LLZO was investigated using X-ray diffraction and Raman spectroscopy analysis. From Raman spectra, the presence of characteristic Raman peak at 110 cm−1 confirms the formation of LLZO. The Raman peaks present at 345 cm−1 and 125 cm−1 correspond to T 2g Raman mode of vibration and E g mode of vibration, respectively. The optical energy band gap values of synthesised phosphors obtained from UV–vis spectroscopy for pure and Sm3+ doped LLZO were calculated to be 4.140 eV and 3.972 eV, respectively. Microstructure and selected area diffraction (SAED) pattern of phosphor was observed by High Resolution Transmission Emission Electron Microscope. Using an excitation wave length of 209 nm, blue emission was observed for pure LLZO and the chromaticity coordinate was found to be at (x = 0.1636, y = 0.0123). Sm3+ doped phosphors showed orange light emission under 408 nm excitation due to transition of 4G 5/2 -6H 7/2 , as observed from the Commission Internationale de l'Eclairage (CIE) chromatic coordinate graph. The maximum intensity of emission was observed in 0.5 % Sm3+ doped LLZO with the calculated color purity and correlated color temperature of 85.9 % and 2229 k, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • White-light-emitting LWO: Dy3+ nanophosphors synthesized using HASS method. • The luminescence of Dy3+ ions was enhanced by increasing the dopant content in LWO. • Color coordinates of LWO: 1.5 mol% Dy3+ close to standard white light coordinates. • The data shows that LWO: 1.5 mol% Dy3+ used for white light applications. • The cytotoxicity in normal and cancerous cells was thoroughly investigated. White-light-emitting La 10 W 22 O 81 (LWO): x Dy3+ (0.5 ≤ x ≤ 10 mol%) nanocrystalline phosphors were developed by a facile hydrothermal assisted solid-state reaction. X-ray diffraction (XRD) pattern indicated that the prepared samples adopted orthorhombic crystal structures. The agglomeration of uniform nanorods was identified from the FE-SEM analysis of the optimized LWO: 1.5 mol% Dy3+ nanocrystalline phosphors. Additionally, transmission electron microscope, scanning transmission electron microscopy, selected area electron diffraction, and X-ray photoelectron spectroscopy were employed to explore the surface morphology, size, interplanar distance, and chemical composition with valence states of the LWO: 1.5 mol% Dy3+ phosphors, respectively. By exciting with 387 nm, the LWO: Dy3+ emission spectra showed two intense peaks at 476 nm (4F 9/2 →6H 15/2) and 571 nm (4F 9/2 →6H 13/2) and a shoulder peak at 659 nm (4F 9/2 →6H 11/2). Optimum emission intensity was achieved for 1.5 mol% Dy3+ in the LWO host lattice. The luminescence quenching beyond 1.5 mol% Dy3+ is attributed to the dipole–dipole interactions when the Dy3+ (donor) and Dy3+ (acceptor) ions are at a critical distance of 58.53 Å. Photometric studies were conducted to evaluate the performance and practical applicability of the phosphors. The CIE chromaticity diagram suggests that the LWO: 1.5 mol% Dy3+ nanophosphor conspicuously exhibits cool white light. Therefore, this material could be a promising and potential white light-emitting nanocrystalline phosphor material for white light emitting diodes (LEDs) under near-UV excitation. In addition, the toxicity of the optimized nanophosphor in normal WI-38 lung fibroblast cells and MCF-7 breast cancer cells was examined. Surprisingly, LWO: 1.5 mol% Dy3+ nanophosphor was found to be non-cytotoxic to normal cells, but extremely toxic to cancer cells. Therefore, the nanophosphor materials can be considered potential candidates for biomedical applications, particularly for cancer treatment. [ABSTRACT FROM AUTHOR]

The present paper brings out the results concerning the preparation and optical properties of Sm 3+ and Dy 3+ each ion separately in different concentrations (0.3, 0.5, 1.0 and 1.5 mol.%) and also together doped (x mol.% Dy 3+ + 1.5 mol.% Sm 3+ ): Li 2 O-LiF-B 2 O 3 -ZnO (where x = 0.5, 1.0 and 1.5 mol.%) glasses by a melt quenching method. Structural and thermal properties have been extensively studied for those glasses by XRD and TG/DTA. The compositional analysis has been carried out from FTIR spectral profile. Optical absorption spectral studies were also carried out. Sm 3+ : LBZ glasses have displayed an intense orange emission at 603 nm ( 4 G 5/2 → 6 H 7/2 ) with an excitation wavelength at 403 nm and Dy 3+ : LBZ glasses have shown two emissions located at 485 nm ( 4 F 9/2 → 6 H 15/2 ; blue ) and 574 nm ( 4 F 9/2 → 6 H 13/2 ; yellow ) with an excitation wavelength at 385 nm. Remarkably, it has been identified that the significant increase in the reddish orange emission of Sm 3+ ions and diminished yellow emission pertaining to Dy 3+ ions in the co-doped LBZ glass system under the excitation of 385 nm which relates to Dy 3+ ions. This could be due energy transfer from Dy 3+ to Sm 3+ . The non-radiative energy transfer from Dy 3+ to Sm 3+ is explained in terms of their emission spectra, donor lifetime, energy level diagram and energy transfer characteristic factors. These significantly enhanced orange emission exhibited glasses could be suggested as potential optical glasses for orange luminescence photonic devices. [ABSTRACT FROM AUTHOR]

Er 3+ , Pr 3+ singly doped and co-doped PEO + PVP polymer composites have been synthesized by conventional solution casting method. The structural analysis has been carried out for all these polymer composites from XRD analysis. Raman spectral studies confirm the ion-polymer interactions and polymer complex formation. Thermal properties of pure polymer film has also been clearly elucidated by TG/DTA profiles. Well defined optical absorption bands pertaining to Er 3+ and Pr 3+ are observed in the absorption spectral profile and these bands are assigned with corresponding electronic transitions. The polymer films containing singly doped Er 3+ and Pr 3+ ions have displayed green and red emissions at 510 nm ( 2 H 11/2 → 4 I 15/2 ) and 688 nm ( 3 P 0 → 3 F 3 ) respectively under UV excitation source. Comparing the emission spectra of singly Er 3+ and co-doped Er 3+ + Pr 3+ : PEO + PVP polymer films, a significant red emission pertaining to Pr 3+ ions is remarkably enhanced in co-doped polymer system. This could be ascribed to possible energy transfer from Er 3+ to Pr 3+ in co-doped polymer system. The energy transfer mechanism is clearly demonstrated using their emission performances, overlapped spectral profiles and also life time decay dynamics. Thus, it could be suggested that Er 3+ : PEO + PVP, Pr 3+ : PEO + PVP and (Er 3+ + Pr 3+ ): PEO + PVP blended polymer films are potential materials for several photonic applications. [ABSTRACT FROM AUTHOR]

Eu 3+ :PEO + PVP, Sm 3+ :PEO + PVP and co-doped Sm 3+ + Eu 3+ :PEO + PVP polymer films have successfully been synthesized by solution casting method. For these polymer films, their XRD, FTIR and RAMAN spectral profiles were studied systematically. Both absorption and photoluminescence spectra have been assessed by evaluating their optical properties. The Sm 3+ :PEO + PVP and Eu 3+ :PEO + PVP polymer film has displayed a reddish - orange and red emissions at 596 nm and 619 nm respectively under an UV lamp. A reddish-orange emission was found for Sm 3+ :PEO + PVP polymer film at 596 nm ( 4 G 5/2 → 6 H 7/2 ) and its lifetime has also been evaluated suitably. Red emission at 619 nm ( 4 G 5/2 → 6 H 7/2 ) of Eu 3+ has been identified for Eu 3+ :PEO + PVP polymer film and its lifetime are also evaluated. The photoluminescence efficiency of Eu 3+ ion has been enhanced due to the addition of Sm 3+ by means of an energy transfer process. The energy transfer mechanism, from Sm 3+ to Eu 3+ has been clearly established. At 0.1 wt% concentration of Sm 3+ ions (sensitizer), the photoluminescence efficiency of the Eu 3+ ion (activator) has been significantly enhanced in co-doped sample through energy transfer from Sm 3+ to Eu 3+ in the polymer matrix. The energy transfer process has been analyzed using lifetime decay dynamics. From the obtained results, these polymer materials could be proposed as potential Red luminescent optical materials. [ABSTRACT FROM AUTHOR]

Sm 3+ :PEO+PVP, Sm 3+ +Tb 3+ :PEO+PVP and Sm 3+ +Tb 3+ +Ag NPs:PEO+PVP polymer films have successfully been synthesized by a solution casting method. For these polymer films, their XRD, FTIR and RAMAN spectral profiles have been analyzed. Both absorption and photoluminescence spectra have been measured in evaluating their optical properties. The Sm 3+ :PEO+PVP polymer film has displayed a reddish-orange emission at 600 nm under an UV lamp and its absorption and emission spectra have also been measured to evaluate its optical characteristics. A reddish-orange emission at 600 nm ( 4 G 5/2 → 6 H 7/2 ) of Sm 3+ has been measured for which lifetime has also been evaluated suitably. The Photoluminescence efficiency of Sm 3+ ion has been enhanced due to the addition of Tb 3+ by means of an energy transfer process. The energy transfer mechanism, from Tb 3+ to Sm 3+ has been explained. In Ag nano-filler embedded in Tb 3+ +Sm 3+ :PEO+PVP polymer system, a different energy transfer process which exists between Ag nano-particles and Sm 3+ ions also taking place in the polymer matrix has been identified. From these results, these films could be suggested as potential reddish-orange luminescent optical materials. [ABSTRACT FROM AUTHOR]

Pure and Dy(1.15, 2.24, 3.33 and 4.02 at.%)-doped ZnO nanoparticles were prepared by the chemical co-precipitation method. The as prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TGA-DTA), Raman spectroscopy, UV–Vis diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) studies. XRD studies confirm both undoped and Dy-doped ZnO nanoparticles reveal wurtzite structure with average grain size in the range of 24–16 nm and are in agreement with TEM analysis. EDS confirms the presence of Dy in Dy-doped ZnO nanoparticles. Raman studies, confirm the wurtzite structure of ZnO nanoparticles besides increase in defects with doping concentration. UV–Vis DRS measurements indicated a blue shift optical band gap with Dy-doping. PL spectrum demonstrated immense enhanced green emission which attributes to the increase in defects concentration. The emissions intensity could be tuned by varying the Dy concentration and excitation wavelength as well for the application of better optoelectronic devices. [ABSTRACT FROM AUTHOR]

Tin sulphide (SnS) thin films were deposited on glass substrate at different substrate temperature (Ts=325°C, 350°C and 375°C) by pyrolytic decomposition using stannous chloride and thiourea as precursor solutions. Also, indium-doped SnS thin films were prepared by using InCl3 as dopant source. The dopant concentration [In/Sn] was varied from 2at% to 6at%. The XRD analysis revealed that the films were polycrystalline in nature having orthorhombic crystal structure with a preferred grain orientation along (111) plane. Due to In doping, the orientation of the grains in the (111) plane was found to be deteriorated. Atomic force microscopy (AFM) measurements revealed that the surface roughness of the films decreased due to indium doping. The optical properties were investigated by measuring the transmittance characteristics which were used to find the optical band gap energy, refractive index and extinction coefficient. The energy band gap value was decreased from 1.60 to 1.43eV with increasing In concentration. The photoluminescence (PL) measurements of thin films showed strong emission band centered at 760nm. Using Hall Effect measurements electrical resistivity, carrier concentration and Hall mobility have been determined. [ABSTRACT FROM AUTHOR]

Abstract: Cr3+ doped β-BaB2O4 nanopowder has been prepared by using co-precipitation method and their spectral properties are studied by various spectroscopic techniques like Powder XRD, EPR, Optical, FT-IR and Photo Luminescence. Powder X-ray diffraction data reveals that the crystal structure belongs to monoclinic and the average crystallite size is evaluated. SEM images showed the surface morphology. Crystal field (Dq), and inter electronic repulsion (B&C) parameters are evaluated from the optical absorption data. From EPR and optical absorption investigations the site symmetry of Cr3+ ion in the prepared sample is ascribed to a distorted octahedron. The CIE chromaticity coordinates are calculated from the emission spectrum as x=0.179 and y=0.174. FT-IR spectrum shows the characteristic vibrational bands related to β-BaB2O4. [Copyright &y& Elsevier]

Lithium zinc borate glasses (LBZ) composed of Li 2 CO 3 -LiF-H 3 BO 3 -ZnO activated with distinct concentrations (0.1–1.0 mol%) of Tb3+ ions were synthesized and explored their structural and optical characteristics. The functional groups and non-crystalline behavior of glasses were validated from the RAMAN and X-ray diffraction analysis, respectively. The optical bandgap was found to be 3.203 eV for (0.5 mol%) Tb3+ contained glass. The excitation spectrum of the same glass discloses a sharp peak at 376 nm (7F 6 →5D 3). Under 376 nm excitation, luminescence spectra of Tb3+ ions incorporated glasses displayed the prominent emission transitions noticed at 5D 4 → 7F 6–3 with a strong green luminescence centered at 543 nm (5D 4 → 7F 5). The optimized concentration of Tb3+ for efficient green color emitting display devices was found to be 0.5 mol%. Lifetime decay analysis was carried out which is well fitted in single exponential function and it was found to be 1.032 ms. CIE color coordinates were estimated for all the procured glasses from their emission spectra and they are reside in the strong green color zone. The obtained green color coordinate values of the optimized glass were closer to the SMPTE and EBU coordinates (0.290, 0.600) for the green illumination appreciably. CCT values of the optimized Tb3+ incorporated glass were lie in the cool green region with high color purity of 82%. From these strong green emission features of the studied glasses, 0.5 mol% Tb3+: LBZ glassy matrix could be suggested as a potential candidate for the application of green laser and display device applications. • Tb3+ activated lithium borate glasses were prepared by melt quenching technique. • Tb3+ activated glasses exhibit dazzling green emission by exciting with 376 nm. • Lifetime was estimated to be 1.032 ms. • Obtained CIE coordinates were closed to SMPTE and EBU for green emission. • 0.5 Tb3+:LBZ glass recommended for green emitting display devices. [ABSTRACT FROM AUTHOR]

Abstract: Zn1−x Gd x S (x =0.00, 0.02 and 0.04) nanoparticles were synthesized by facile chemical co-precipitation method using PVP as a surfactant. ZnS nanoparticles could be doped with Gd ions during synthesis without altering the XRD patterns of ZnS. Also, the pattern of the powders showed cubic zincblende structure. The particle size obtained from the XRD studies lies in the range 3–5nm, whereas from TEM analysis it is 4nm for x =0.02 sample. The UV–Vis absorption spectra revealed that Zn1−x Gd x S nanoparticles exhibit strong confinement effect as the blue shift in the absorption spectra with that of the undoped ZnS. The photoluminescence spectra showed enhanced luminescence intensity and the entry of Gd into host lattice. [Copyright &y& Elsevier]

Abstract: Optical absorption and photoluminescent properties of Ho3+/Yb3+ co-doped tellurite and zinc tellurite glasses are investigated. The effect of zinc oxide as a modifier on the luminescence properties of above mentioned samples has been explored. Two intense upconversion emission bands centered at 546 (5F4 + 5S2 → 5I8) and 660nm (5F5 → 5I8) are observed on excitation with 976nm diode laser. Zinc oxide acts as a quencher for 976nm excited upconversion emission. The up and downconversion emission spectra are recorded with 532nm excitation source also. In this case zinc oxide improves the up and downconversion emissions. A large enhancement in upconversion intensity has been observed when Ho3+ ion is co-doped with Yb3+ ion. The dependence of upconversion intensities on excitation power and on temperature has also been studied. The power dependence study shows a quadratic dependence of the fluorescence intensity on the excitation power while a decrement in emission intensity of all the transitions at different rates with increase in temperature is observed in temperature dependence study. The possible mechanisms are also discussed in order to understand the upconversion and energy transfer processes. [Copyright &y& Elsevier]

Abstract: Eu2O3-doped phosphate-based bioactive glasses have been prepared by varying the calcium/potassium to phosphate ratio and their luminescence properties have been studied through absorption and emission spectra and decay rate analysis. Second and fourth rank crystal-field (CF) parameters and the CF strength parameters have been calculated by assuming the C2V symmetry for Eu3+ ions in the present glasses. Judd–Ofelt analysis has been used to derive radiative properties such as transition probabilities, branching ratios, radiative lifetimes and peak-stimulated emission cross-sections for 5D0 → 7FJ (J =0–4) transitions. The relative luminescence intensity ratio of 5D0 → 7F2 and 5D0 → 7F1 transitions has been evaluated to estimate the local site symmetry around Eu3+ ions. The observed 5D0 → 7F0 transition for higher calcium content indicates two distinct sites for Eu3+ ion. Decay rates for the 5D0 level of Eu3+ ions in these glasses have been measured by monitoring the 5D0 → 7F2 transition. The lifetimes of the 5D0 level are found to decrease with increase in calcium contents. [Copyright &y& Elsevier]

Abstract: Fluorophosphate glasses of composition, P2O5 +K2O+KF+MO+Al2O3 +xEu2O3 (M=Mg, Sr and Ba; x=0.01, 0.05, 0.1, 1.0, 2.0, 4.0 and 6.0mol%) were prepared and characterized their optical properties. Crystal-field (CF) analysis revealed a relatively weak CF strength around Eu3+ ions in the Ba based fluorophosphate glasses. The Judd-Ofelt parameters have been estimated from the oscillator strengths of 7F0 → 5D2, 7F0 → 5D4 and 7F0 → 5L6 absorption transitions of Eu3+ ions and were used to evaluate the radiative properties of the 5D0 → 7FJ (J=0–4) transitions. Considerable variation has been observed in the relative intensity ratio of 5D0 → 7F2 to 5D0 → 7F1 transitions of Eu3+ ions due to change in the alkaline earth metal ions. The decay of the 5D0 level shows single exponential and less sensitive to Eu3+ ions concentration as well as MgO/SrO/BaO modifiers. [Copyright &y& Elsevier]

Abstract: Fluorescence spectra of Tb3+ ions in 55.5P2O5–17K2O–14.5BaO–8Al2O3–4AlF3–1.0Tb4O7 (PKBAFTb) glass have been measured as a function of high pressures up to 35GPa at room temperature. A strong red shift of 5D4 → 7F J (J =3, 4 and 5) transitions with different rates is observed under pressure, which is attributed to the increasing spin–orbit coupling constant, ζ 4f. There is a considerable pressure effect on the magnitude of the crystal-field splittings observed for the 5D4 → 7F4 and 7F5 transitions. The increase in Stark splittings observed under pressure is due to pressure induced electrostatic interaction between the 4f electrons and their ligands. Decay times of the emission from the 5D4 level fit to a single exponential function for the entire pressure range studied. Analyses indicate that the luminescence properties under pressure are more or less reversible, which shows the absence of considerable hysteresis in the present studied glass. [Copyright &y& Elsevier]

Abstract: Extrinsic zinc oxide (heavily indium oxide doped), i.e., indium zinc oxide (In2Zn2O5) (IZO) as novel transparent conducting oxide (TCO) thin films were grown by pulsed laser deposition (PLD) technique using Johnson Matthey “specpure” – grade 90% In2O3 mixed 10% ZnO (as commercial indium tin oxide (ITO) composition) pellets. The effects of substrate temperatures and heavy indium oxide incorporation on IZO thin film growth, optical transmission, absorption, reflection and photoluminescence were studied. As well as the feasibility of developing a novel high quality transparent oxide thin films was also studied simultaneously. Also, as a novelty merit we want to emphasize as a interesting physical effect that the average optical transmittance T% (max) ⩾95% of IZO thin films is rivals that of the most TCO films for this conductivity level (of the order of 103 Ω−1 cm−1). This is the first time that we have applied these PLD prepared IZO thin films to iso and hetero semiconductor–insulator–semiconductor (SIS) type solar cells as TCO coatings. The optical parameter values were calculated, diagrammatically enumerated and tabulated. From optical studies, we have observed that the films were act as highly anti-reflective (AR) coatings. From PL study, we have confirmed the purity and high electrical conductivity of the deposited thin films. Supplementary studies on surface, electrical, structural and internal morphology of thin film growth correlated with optical transmission, absorption, reflection and photoluminescence gives added advantages to this work. [Copyright &y& Elsevier]

The main objective of this paper was to enhance the absorption and charge carrier generation rates of DSSC. The functional property of the Eu3+ ion (red light) when infused with the MgAl 2 O 4 host was combined with TiO 2 nanoparticles and the results obtained through various studies are elaborated. The host and the nanoparticles were prepared through solid-state and sol-gel routes, respectively, with their crystalline structure and surface morphology identified by X-ray diffraction and field emission scanning electron microscope. The optical characteristics of the sample were studied through photoluminescence (PL) excitation (394 nm) and PL emission spectral analysis. The MgAl 2 O 4 : Eu3+ phosphor utilized in DSSC for the light down-conversion process converts high-energy incident light into low-radiation light, which further excites the N719 dye to emit charge carriers, thus increasing the conversion efficiency of the dye-sensitized solar cells. The overall conversion efficiency was observed a 4.80 % when 0.9 MW % Eu3+: MgAl 2 O 4 was added to the TiO 2 nanoparticle with an enhanced DSSC performance. [Display omitted] • Fabrication of Dye-sensitized solar cells using down-conversion phosphor material. • MgAl 2 O 4 :0.9 MW % Eu3+ Phosphor with TiO 2 Nanoparticles enhances energy capacity. • Down-conversion phosphors extract light from both the violet and visible ranges. • The conversion efficiency, photocurrent, and photovoltage are maximized. [ABSTRACT FROM AUTHOR]

Lithium borate glasses activated with specific concentrations of Ce3+ ions have been processed by melt quenching technique. X-ray diffraction and SEM with EDAX carried out structural and surface morphology with elemental confirmation respectively. The nebulous nature of glassy matrices have been affirmatively confirmed by XRD and it was corroborated with SEM analysis. A distinguished absorption band is noticed in the ultraviolet region and the photoluminescence spectra displays a broad and intense blue emission band in the region from 395 nm to 570 nm which is centered at 447 nm (5d→4f) by exciting with 350 nm in Ce3+: LBZ glassy matrices. The dazzling blue emission intensity was significantly ameliorated by improving the addition of Ce3+ ion concentration in the glass matrix. The blue emission intensity has been found to be decreased at higher concentrations due to concentration quenching and the optimal concentration of Ce3+ ions is estimated to be 0.5 mol%. The fluorescence decay time has been evaluated as 0.86 ms from the decay profile of 0.5 mol% Ce3+: LBZ glass. Chromaticity coordinates were determined from the luminescence spectra, which are found to be falls in the bright blue region. The obtained blue emission CIE coordinates are close to standard EBU and NTSC coordinates for blue illumination. In view of these spectral features, 0.5 mol% Ce3+: LBZ glass could be recommended as promising candidate for the applications of blue emissive photonic devices. [ABSTRACT FROM AUTHOR]

An intense red emission from Eu3+: La 10 W 22 O 81 (LWO) microphosphor rods has been obtained under UV excitation source for latent fingerprint (LFP) imaging. Microphosphor rods of LWO doped with various concentrations of Eu3+ ions were synthesized using a hydrothermal assisted solid-state method. XRD revealed that the microphosphors had an orthorhombic structure with the space group of Pbcn (60). FE-SEM showed that the surface morphology of the optimized Eu3+ (14 mol %): LWO microphosphors were hexagonal rods with pencil-like tips at both ends. TEM evaluation with elemental mapping and XPS analysis confirmed the occurrence of the vital elements in the microrods. FTIR spectral analysis was performed for the analysis of the spectral bands. An intense red emission was obtained from the Eu3+ doped LWO microphosphors under the excitation of 394 nm (7F 0 →5L 6) which could be attributed to the hypersensitive transition of 5D 0 →7F 2 pertaining to the Eu3+ ions. Enhancement of the emission was noticed from the microphosphors when the Eu3+ content was increased. Optimal red emission was obtained with the Eu3+ (14 mol %): LWO microphosphor. The photoluminescence intensity was found to be reduced after optimized concentration due to concentration quenching. The quadrupole–quadrupole interaction is found to be responsible for concentration quenching. The luminescent properties were systematically demonstrated using an energy level scheme diagram. The luminescence lifetime was evaluated for all the concentrations of Eu3+ doped LWO samples. The lifetime decay dynamics has also been clearly elucidated. CIE color coordinates were also evaluated from the luminescence spectra of the microphosphors and they are found to be located in strong red region. A significant luminescence quantum yield was determined for the Eu3+ (14 mol %): LWO microphosphor. The optimized microphosphor was used in detecting LFPs, employing the powder dusting method commonly used in forensic science. We detected the LFP ridge patterns with high sensitivity, reliability, and selectivity by using the optimized microphosphor. Its non-cytotoxic nature was also evaluated using WI-38 cell lines. Results demonstrated that the Eu3+ (14 mol %): LWO microphosphor could be a promising candidate for luminescent applications and LFP applications in forensic investigation preferably. Image 1 • Dazzling red emissive Eu3+: La 10 W 22 O 81 microphosphors were synthesized. • Strong red emission was enhanced by increasing the Eu3+ ion concentration. • Reason for concentration quenching has also been clearly elucidated. • Lifetime, Quantum yield, CIE coordinates and cytotoxicity were extensively studied. • Latent finger print application was performed with optimized sample. [ABSTRACT FROM AUTHOR]

Erbium (Er)-doped ZnO thin films were deposited on glass substrates by nebulizer spray pyrolysis with different doping concentrations (0 wt%, 1 wt%, 3 wt% and 5 wt%). The deposited films are polycrystalline with a hexagonal structure with a (002) predominant plane. The Er-doped ZnO films have greater surface roughness than the undoped ZnO film. The optical transmittance of the undoped ZnO film is about 80% in the visible range. The optical bandgap of the undoped ZnO thin film is 3.29 eV, which is very close to the bulk ZnO. From photoluminescence spectra, sharp UV emission is observed at 385 nm for all the prepared films. The response of the films to ammonia (NH 3) vapour is high when the Er concentration is 3% or less, and for higher concentrations of Er, the response is low. All the deposited Er-doped ZnO films show short response time and recovery time with regard to NH 3. Possible mechanism for the adsorption of NH 3 molecules on the Er-doped ZnO surface at room temperature. (CB, conduction band; VB, valence band) Image 1 • Erbium-doped ZnO thin films were prepared for the first time by cost-effective nebulizer spray pyrolysis. • Raman and photoluminescence studies confirmed the presence of oxygen vacancies for gas sensing. • Er-doped ZnO films exhibited high sensitivity with short response and recovery time. • A possible mechanism for the adsorption of NH 3 molecules on the Er-doped ZnO surface at room temperature is provided. [ABSTRACT FROM AUTHOR]

Abstract: Pure ZnO:Eu3+ nanoparticles (~50nm) were prepared by a solution combustion method. ZnO and Eu2O3 were used as starting materials and dissolved in nitric acid. Citric acid was used as a fuel. The reaction mixture was heated at 350°C resulting into a rapid exothermic reaction yielding pure nanopowders. The atomic weight concentration of Eu3+ doped in ZnO was 20%. Transmission electron microscopy (TEM) was used to study the particle size and morphology. The nanopowders were characterized for phase composition using X-ray diffractrometry (XRD). Particle size distribution (PSD) analysis of ZnO: Eu3+ showed particle sizes ranging from 30 to 80nm.The photoluminescence emission spectra of ZnO:Eu3+ nanostructures showed a strong band emission around 618nm when excited with 515nm wavelength. [ABSTRACT FROM AUTHOR]