Search

Abstract An efficient and cost-effective technique, solution combustion synthesis was used to synthesize Dy3+ doped SrGdAlO 4 nanophosphor utilizing urea as a suitable fuel. The tetragonal phase and nano-crystallinity of the synthesized phosphor belonging to I 4/ mmm space group was confirmed by powder X-ray diffraction (PXRD) and transmission electron microscope (TEM) technique respectively. Various crystal structure parameters and refined atomic positions of host matrix and SrGd 0.95 Dy 0.05 AlO 4 nanophosphor were determined by Rietveld refinement. The two intense bands i.e. blue and yellow bands were observed in photoluminescence emission spectrum recorded at 352 nm excitation wavelength, associated to transitions 4F 9/2 → 6H 15/2 (484 nm) and 4F 9/2 → 6H 13/2 (575 nm) respectively. Photometric characterizations revealed the emission of white color by the synthesized nanophosphor proving its wide applications in WLEDs (white light emitting diodes). Band gap values calculated using diffuse reflectance spectra (DRS) were found to vary in the range of 5.50 eV–5.59 eV for host and doped lattice system. Keeping in mind, the concentration quenching phenomenon, SrGd 0.95 Dy 0.05 AlO 4 was considered as optimized nanophosphor for WLEDs. Highlights • An efficient solution combustion route was adopted to synthesize SrGdAlO 4 :Dy3+ nanophosphor. • PXRD and TEM revealed the tetragonal phase and nano-crystalline nature of the synthesized phosphor. • White light emission via synthesized nanophosphor was confirmed by photometric characterizations. • Energy band gap values and CCT values for SrGdAlO 4 :Dy3+ nanophosphors were determined for the first time. [ABSTRACT FROM AUTHOR]

• An ecological urea combustion method is adopted to develop novel Sr 5 Al 2 O 8 :Sm3+, Er3+ & Dy3+ nanomaterials. • Intricate crystal framework and tricolor luminescence have been carefully inspected. • Energy band gap, decay lifetime, color purity and CCT have been calculated. • Promising materials for nUV excited WLEDs, lasers and optical sensors. Dud-white emanation from current phosphor-based white-LEDs (pb-WLEDs) has now emerged as primary gridlock for their commercialization. Thus, coupling of green–blue-red (G-B-R) multi-phase or white single-phase phosphors with near-UV LED chips, clarifies such snags. Heeding the innovative solution, the authors have successfully manufactured novel Sr 5 Al 2 O 8 :Sm3+, Er3+ and Dy3+, via adopting a propitious urea combustion approach. Photoluminescence spectra realized the remarkable orange (599 nm), green (548 nm) and near-white (575 nm) emission. Thereafter, laudable colorimetric performance of nanomaterials with improved color-coordinates, color purity & CCT, suggest their promising usage in photonic appliances like pb-WLEDs, bio-probes, solar cells, telecommunication, lasers and optical sensors. [ABSTRACT FROM AUTHOR]

A highly efficient solution combustion technique involving simple procedure and less energy consumption was adopted to prepare a homogeneous crystalline Ba 3 Y 4 O 9 :Sm3+ down-conversion nanophosphor emitting bright reddish orange light. The structural features of the synthesized nanophosphors were characterized by powder X-ray diffraction (PXRD), scanning electron microscope (SEM), transmission electron microscope (TEM), high resolution transmission electron microscope (HRTEM), selected area energy diffraction (SAED) and energy-dispersive X-ray analysis (EDAX) techniques. Moreover, the photoluminescent features of the nanocrystalline phosphors were described by photoluminescence decay curves, excitation and emission spectra. Upon near-ultraviolet (NUV) excitation (410 nm), the emission spectra demonstrate the most prominent peak at 607 nm due to 4G 5/2 → 6H 7/2 transition. The optimum mol% of dopant (Sm3+) ion for doping in this particular host matrix was found to be 3; thus, a concentration quenching (CQ) phenomenon was observed beyond x = 0.03 in the synthesized Ba 3 Y 4(1- x) O 9 : 4 x Sm3+ nanophosphors. The most appropriate reason for CQ mechanism was reckoned to be radiative-reabsorption phenomenon and dipole-dipole (d-d) interactions. The CIE chromaticity coordinates for the optimum nanophosphor were found to lie in orange-red region that confirm its characteristic light emission. The results indicate the promising applications of the synthesized reddish-orange light emitting Ba 3 Y 4 O 9 : Sm3+ nanophosphor in white light emitting diodes (WLEDs). Image 1 • Ba 3 Y 4 O 9 :Sm3+ nanophosphors are prepared via solution combustion synthesis (SCS). • SEM, TEM, HRTEM, SAED characterizations are done to explore morphology aspects. • EDAX study revealed the elemental analysis in the prepared optimum nanophosphor. • The detailed crystal structure and photoluminescence study is done successfully. [ABSTRACT FROM AUTHOR]

Abstract: Terbium-activated CaIn2O4:xTb (x =0.12%, 0.5%, 1.0% and 2%) nanocrystals have been produced by combustion synthesis using glycine as a fuel in a preheated furnace at 500°C. The nanocrystals obtained were characterized by scanning electron microscopy and X-ray diffraction (XRD) techniques. The prepared nanocrystals under a UV source revealed green luminescence that was attributed to the transition from 5D4 excited state to 7F5 ground state of Tb3+ ions. In addition, the dependence of the luminescence intensity on Tb3+ concentration and effect of glycine to nitrate ratio on the particle size of the nanocrystals have also been discussed. [Copyright &y& Elsevier]

[Display omitted] • Phase-pure garnets based Y 3 Al 5 O 12 (YAG):Er3+ NPs have been developed via combustion technique. • Absolute YAG phase development has been confirmed via X-ray powder diffraction technique. • Down-conversion PL was thoroughly scrutinized via PL spectra, decay-time, QE and color parameters. • Potential candidate for optical-sensors, lasers and cool-WLEDs. New generation electro-optic appliances, mainly white-LEDs (light emitting diodes) foster excellent energy-efficacy, low cost, high lumen yield and environment friendly features. Y 3 Al 5 O 12 (YAG):Er3+ nanophosphors (NPs) have been developed via combustion technique. Owing to near-UV excitation (379 nm), vivid-green emission was acquired in the fabricated phosphor materials. The best possible luminous intensity has been ascertained at × = 0.02 Er3+content, with laudable quantum-efficiency (85.37%), suitable CCT (7246 K) and a high color-purity (82.30%). All the derived results predicate their effective performance in optical-sensors, lasers and cool-WLEDs. Moreover, the current findings can be protracted to develop other green-glimmering nanophosphors. [ABSTRACT FROM AUTHOR]

Trivalent dysprosium doped ternary aluminate oxide based SrGd 2 Al 2 O 7 nanocrystalline phosphors were synthesized via an efficient single step solution combustion process. The estimated value of optical band gap energy for the optimized nanophosphor and host matrix were found to be 5.58 eV and 5.76 eV respectively. Diverse crystalline features were elucidated via analyzing PXRD patterns and Rietveld refined results of host matrix and optimal SrGd 1.94 Dy 0.06 Al 2 O 7 nanophosphor. Diverse elements present in the optimized nanophosphor were found to be Sr, Gd, Dy, Al and O as revealed via energy diffraction X-ray analysis (EDAX). The surface morphological features and the particle size of the optimum nanosample were disclosed by scanning electron microscope (SEM) and transmission electron microscope (TEM) practices. The characteristic emission spectra recorded using excitation wavelength of 350 nm display two strong peaks at 484 nm and 578 nm that were allotted to 4F 9/2 → 6H 15/2 and 4F 9/2 → 6H 13/2 respective transitions. The evaluated critical distance value was ensured to be much higher than 5 Å indicating no chance of occurrence of concentration quenching (CQ) as a result of exchange interactions amongst dopant ions. Dipole-dipole interactions in the midst of adjoining Dy3+ ions were observed to be an appropriate cause for following CQ trend. Based on outcomes of Correlated Color Temperature (CCT) and International Commission on Illumination (CIE), it was quite obvious that the prepared nanomaterial will prove to be absolutely beneficial for applications related to lightning and display systems. Thus, it can be concluded that a new window opens for white light emitting diode (WLED) applications using the synthesized nanophosphors. [ABSTRACT FROM AUTHOR]

Nanophosphor powders of composition BaLa 2 ZnO 5 :Tb 3+ have been synthesized via using urea assisted solution combustion method using metal nitrates as the precursor materials. The structural, morphological and luminescent properties have been investigated by powder X-ray diffraction (XRD) and photoluminescence (PL) spectroscopy. The Rietveld analysis showed that these nanophosphors crystallize in the tetrahedral phase with the 14 /mcm (140) space group. The crystallite size was determined by Scherer formula and was found to be 70 nm. The photoluminescent excitation of these nanocrystals at 278 nm yielded the characteristic emission peaks at 545 nm and 489 nm due to 5 D 4 → 7 F 5 (magnetic-dipole) and 5 D 4 → 7 F 6 (electric-dipole) transitions, respectively. The optimum activator concentration was found to be 3 mol% and the concentration quenching arising from the over-doping was attributed to the quadrupole–quadrupole interactions. The excellent luminescent profile of these nano-scaled particles suggests their auspicious applications in the solid-state lighting and display technology. [ABSTRACT FROM AUTHOR]

Novel SrZn 1− x Eu x V 2 O 7 nanoparticles were synthesized employing urea assisted solution combustion process. The Rietveld refinement technique was used to study the effect of Eu 3+ doping on the crystal structure of the host lattice. It was found to crystallize in monoclinic lattice with the P12 1 /c1 (14) space group. The photoluminescent spectral analysis showed that upon excitation in the near UV region, these nanophosphors can emit very intense red luminescence (616 nm) corresponding to the hypersensitive 5 D 0 → 7 F 2 transition of Eu 3+ ions. X-ray diffraction studies revealed the low symmetrical co-ordinative environment of the activator ion (trigonal bipyramidal) with no inversion center in the SrZnV 2 O 7 host lattice. The optimum concentration of Eu 3+ ion in SrZnV 2 O 7 for better luminescence was found to be 4 mol% The critical distance for energy transfer (24.1602 Å) imparted the initial idea of intensity variation as a function of dopant concentration. Dipole–dipole (d–d) interactions were successfully accounted for the concentration quenching arising from the over-doping of the activator ions. These near UV light absorbers (395 nm) can be thrivingly used in white LEDs using lnGaN chip system, plasma display panels (PDPs) and solid state laser. [ABSTRACT FROM AUTHOR]

Abstract: Europium doped calcium pyrovanadate nanoparticles Ca2V2O7:Eu3+, having a size of 57–63 nm, were synthesized using combustion process. Structure, morphological and optical properties of nanophosphors have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), fluorescence spectrometry (PL) and Fourier transform infra-red (FT-IR) spectroscopy. X-ray studies shows that a pure triclinic Ca2V2O7 phase was obtained at 900 °C temperature. The red emission observed at 620 nm upon excitation at 305 nm is due to hypersensitive transition 5D0 → 7F2 of luminescent activator Eu3+ location at a site with no inversion symmetry in Ca2V2O7 crystal lattice. High luminescent intensity and easy synthesis technique make this red phosphor a promising candidate for application as luminescent materials. [Copyright &y& Elsevier]

Abstract: The synthesis of LaSrAl3O7 doped with rare earth (RE) ions Eu3+ and Tb3+ by a single-step solution combustion method has been demonstrated in the present investigation. The structural, morphological and luminescent properties were characterized by XRD, FT-IR, SEM, TEM and PL spectroscopy. The XRD results suggest that LaSrAl3O7 crystallize in a single phase having tetragonal structure with space group P421m. The transmission electron microscope (TEM) and scanning electron microscope (SEM) analysis show that the sample is made up of tetragonal particles with the size between 38 and 78nm. The photoluminescence properties of the samples were investigated by excitation and emission spectra. Under UV excitation (265nm), LaSrAl3O7: Eu3+ shows dominant peak at 619nm in addition to other characteristic peaks of Eu3+. Under 233nm excitation, the characteristic emissions corresponding to 5D3–7F J (J =4–6) and 5D4–7F J (J =3–6) transitions in LaSrAl3O7: Tb3+ nanophosphors are observed. These results indicate that Eu3+ and Tb3+ activated LaSrAl3O7 nanophosphors can be applied for tunable solid state laser materials and plasma display panels. [Copyright &y& Elsevier]

A simple, non-hazardous and cost effective, solution combustion fabrication route was adopted to prepare novel BaSrY 4(1− x) Er 4 x O 8 (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 4S 3/2 → 4I 15/2 transition. The optimum content of Er3+ in BaSrY 4 O 8 matrix was determined as x = 0.02. Further, the DR (diffuse reflectance) analysis revealed the band gap (E gap) values for host BaSrY 4 O 8 (5.79 eV) and doped BaSrY 3.92 Er 0.08 O 8 (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. [Display omitted] • Novel BaSrY 4 O 8 : x Er3+ nanocrystals have been prepared via solution combustion approach. • Cell parameters and refinement factors are evaluated for host and best luminescent composition. • The band-gap energy has been determined using Kubelka-Munk function. • Optical properties have been studied in detail. • Potential candidates for optical display applications, mainly RGB based WLEDs, lasers and optical sensors. [ABSTRACT FROM AUTHOR]

[Display omitted] • The research paper entitled "Probing into multifunctional deep orange-red emitting Sm3+-activated zincate based nanomaterials for wLED applications" highlights significant scopes in the field of luminescent nanomaterials. The main highlights are: • Novel Sm3+-activated BaLa 2 ZnO 5 nanopowders have been fabricated via an energy saving urea combustion route. • In-depth down-conversion photoluminescence has been thoroughly scrutinized. • Rate of non-radiative energy-relocation as well as quantum-efficiency have also been evaluated. • Detailed bandgap as well as Urbach's energy analysis has been conducted via a new empirical relation. • Potential candidate for warm-WLEDs, digital-signs, horticulture, bio-imaging, solar-cells and lasers. Empirical-investigations on deep-orange-red emitting BaLa 2 ZnO 5 :Sm3+ phosphor-powders generated via low-temperature and environmentally-sound urea-combustion route, are presented. In-depth crystallographic-analysis, conducted via XRPD-facilitated-Rietveld-refinement, reveals their tetragonal-crystallinity. Emission-spectra under 413 nm-energization, yields an intense-band at 708 nm, thus imparting deep orange-red color to powders. The best luminous-performance has been marked at × = 0.02 Sm3+content. Also, various radiative-possessions including decay-time, intrinsic life-time, quantum-efficiency and relaxation-rate, which reflect their better luminance-potentiality, have been evaluated. Color-coordinates have realized their deep-orange radiance, which are proximate to those of AMBER LED-NSPAR 70-BS. All-in-all, present work successfully marked their utilization in high-performance warm-wLEDs, signage, bio-imaging, solar-cells and lasing applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Characteristic cool white emitting BaSrY 4 O 8 :Dy3+ nanophosphors are fabricated via solution combustion. • Crystal structure and refinement parameters are analyzed by Rietveld Refinement Technique. • Decay lifetime and energy bang gap of Dy3+ doped nanopowder have been calculated. • CIE coordinates and CCT confirm their cool white light emitting property thus proves them a potential candidate for solid state display and laser devices. Novel orthorhombic symmetry type BaSrY 4(1-x) Dy 4x O 8 (x = 1, 3, 5, 7, 10 mol %) cool white light emitting nanocrystals was synthesized by low temperature based solution combustion approach. Information related to crystallographic analysis was made by utilizing X-ray diffraction and Rietveld-refinement technique. The manufactured nanoparticles exhibit cool white emission corresponding to 4F 9/2 → 6H 15/2 (at 480 nm, blue color), 4F 9/2 → 6H 13/2 (at 572 nm, yellow color) and 4F 9/2 → 6H 11/2 (at 673 nm, a weak red color emission). CIE coordinates and CCT values of optimized nanocrystals were found resemblance with white-coordinates of commercial LEDs and NTSC which prove them a potential candidate for outdoor lightning purpose i.e. in WLEDs. [ABSTRACT FROM AUTHOR]

• Ba 3 Y 4 O 9 :Dy3+ nanophosphor was prepared by solution combustion route for first time. • Crystal structure, morphological study of optimized sample was done successfully. • EDAX mapping along with elemental analysis of optimum sample was done effectively. • CCT analysis authenticates the cool white light emission. A simple and highly efficient route of solution combustion process was utilized for preparing a series of white light emanating Ba 3 Y 4(1- x) O 9 : 4 x Dy3+ (x = 0, 1.0, 3.0, 5.0, 10, 15 mol%) nanocrystalline phosphors. The resulted product was claimed to belonging to R3 space group (SG) with trigonal crystal system related to hexagonal crystal family utilizing powder X-ray diffraction (PXRD) technique and Rietveld refinement. The photoluminescence emission spectra comprised of two intense bands; one was yellow band (Y) in consequence of 4F 9/2 → 6H 13/2 transition positioned at 578 nm and another one was blue band owing to 4F 9/2 → 6H 15/2 transition sited at 489 nm. Ba 3 Y 3.88 Dy 0.12 O 9 composition was considered as optimal composition for white light emission amongst the prepared nanophosphors owing to its maximal intense emission. The morphological aspects and elemental composition of the optimized sample were analyzed with the help of scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDAX) studies. CIE (International Commission on Illumination) chromaticity coordinates confirmed the white light emission by all the synthesized nanophosphors that validate their potential applications in white light emitting diodes (WLEDs). Correlated color temperature (CCT) analysis substantiates their applications as cool white light source. [ABSTRACT FROM AUTHOR]

Abstract: ITO and FTO nano-powders were synthesized employing a new route sol–gel combustion hybrid method using acetylene black as a fuel. The dried gels exhibited an auto-catalytic combustion behavior. ITO and FTO nano-powders with narrow size distribution were obtained at 750 °C. Crystal structures were examined by powder X-ray diffraction (XRD) and particle morphology as well as crystal size was investigated by scanning electron microscopy (SEM). The size of the nano-powder was found to be in the range of 16 nm to 33 nm. [Copyright &y& Elsevier]

• Novel color-tuned BLAO:Sm3+ nanocrystals are fabricated for first time via urea combustion route. • Crystal lattice factors and refinement parameters are depicted by Rietveld Refinement Technique. • Energy band gap, refractive index and decay lifetime have been calculated. • Potential candidate for futuristic NUV excited WLEDs and laser devices. Nanomaterials with tuned luminescence are largely approved for their promising performance in near UV-excited white LEDs (light emitting diodes). This work thus, reports a series of new progressive BaLaAlO 4 : Sm3+ based nanomaterials with wide color gamut, developed via urea combustion. Phase purity was disclosed by X-ray diffraction and Rietveld refinement. Emission spectra marked an extraordianry peak at 600 nm. 3.0 mol% was inspected an ideal amount of Sm3+, beyond which electric multipolar interactions led to concentration quenching. Color coordinates justified yellow to reddish orange tuned luminescence, which proved their promising materiality in the solid state illuminants i.e., lasers and WLEDs. [ABSTRACT FROM AUTHOR]

A cost effective, environmentally benign and most convenient solution combustion scheme was utilized for preparing a series of Sr 6 Y 2-2 x Sm 2 x Al 4 O 15 (x = 0.5–10 mol%) crystalline nanophosphors. The morphological study and phase formation were examined via SEM (Scanning Electron Microscope) image, TEM (Transmission Electron Microscope) micrograph and measured PXRD (powder X-ray diffraction) patterns. The crystal structure information is gathered with the help of Rietveld refinement technique. Photoluminescence excitation-emission spectra revealed about the photometric characteristics of the synthesized down-conversion nanophosphors. The diffuse reflectance spectral measurements yield optical energy band gap of 5.96 eV and 5.88 eV for the host (Sr 6 Y 2 Al 4 O 15) and optimized matrix (Sr 6 Y 1.94 Sm 0.06 Al 4 O 15) respectively. The estimated CIE (international commission on illumination) chromaticity coordinates values were revealed to be located in orange-red section specifying their importance for solid state illumination. The optimum concentration of trivalent samarium ion as a dopant ion for this particular kind of matrix was observed to be 3.0 mol%, since, beyond this concentration, a fall in photoluminescence intensity occurred due to concentration quenching trend. The prominent feature of orange-red light emission by the prepared nanocrystalline phosphors upon excitation via near ultraviolet (NUV) light makes them potential contender for red emitting luminescent optical appliances. Image 1 • Orange-red emanating Sr 6 Y 2 Al 4 O 15 :Sm3+ were prepared via solution combustion route. • PXRD and Rietveld refinement revealed crystalline and crystal structural aspects. • SEM and TEM micrographs unveiled morphological features of prepared nanosamples. • Luminescent features were divulged by photoluminescent excitation-emission spectra. [ABSTRACT FROM AUTHOR]

A facile and less time-consuming technique, namely, solution combustion synthesis (SCS) was employed for generating a series of novel BaY 1- x Zn 3 AlO 7 : x Eu3+ (x = 0.05–0.30) nanophosphor. Powder X-ray diffraction (PXRD) patterns supported with Rietveld refinement technique validated the subsistence of a pure hexagonal BaYZn 3 AlO 7 phase belonging to P63mc (186) space group. Both Scherrer's equation as well as transmission electron microscope (TEM) study, were in strong agreement in terms of nano-size of the synthesized phosphor. The obtained nanostructures display a most prominent peak in their emission spectra at 611 nm owing to 5D 0 →7F 2 transition resulting in red-emission upon excitation by a source of near-ultraviolet (NUV) light (λ ex = 393 nm). The observed CIE coordinates for this strong emission in an optimized nanophosphor (BaY 0.80 Eu 0.20 Zn 3 AlO 7) were 0.592, 0.407. Judd-Ofelt parameter (Ω 2) is evaluated for all compositions of combustion derived nanosamples utilizing their recorded emission spectra by applying Judd-Ofelt theory. The standard host and synthesized nanophosphor containing optimum concentration of Eu3+ i.e. BaY 0.80 Eu 0.20 Zn 3 AlO 7 were examined via diffuse reflectance spectroscopy (DRS) and the evaluated energy band gap were established to be 4.67 eV and 4.61 eV respectively. In addition, dipole-quadrupole interactions were apt to cause the observed concentration quenching (CQ) trend as the value of critical distance evaluated as 11.88 Å. Correlated color temperature (CCT) value for the optimized novel nanophosphor was ∼1714 K confirming their applications in the warm light-emitting diodes (LEDs). Image 1 • Novel BaYZn 3 AlO 7 :Eu3+ nanophosphor is prepared via solution combustion method. • Crystal structure is investigated in detail using Rietveld refinement technique. • Prepared phosphors are explored by SEM, TEM, HRTEM and SAED measurements. • Judd-Ofelt study is carried out effectively. • Red light emission upon NUV excitation indicates their potential role in LEDs. [ABSTRACT FROM AUTHOR]