The envisaged design and developme nt of individual mate rials to excavate a broader spectrum of desired properties and offer multiple applications are highly necessitating.Keeping this in mind,a series of forsterite-...The envisaged design and developme nt of individual mate rials to excavate a broader spectrum of desired properties and offer multiple applications are highly necessitating.Keeping this in mind,a series of forsterite-structured Mg_(2)GeO_(4):Eu^(3+)(1 mol%-9 mol%)nanophosphors was synthesized via a solution combustion method using oxalyl dihydrazide as a fuel.The X-ray diffraction patterns confirm the orthorhombic crystal system with a Puma space group.Morphological results clearly show irregularly shaped cluster-like structures with aggregation of the particles.Employing diffuse reflectance spectra,the optical energy band gap of the Mg_(2)GeO_(4):Eu^(3+)(1 mol%-9 mol%)nanophosphors was estimated and obtained to be~4.12-4.32 eV.The photoluminescence emission spectra exhibit intense peaks at^(5)79,589,610,661,and 707 nm,which are due to characteristic^(5)D_(0)→^(7)F_(0),^(5)D_(0)→^(7)F_(1),^(5)Do→^(7)F_(2),^(5)D_(0)→^(7)F_(3)and^(5)D_(0)→^(7)F_(4)transitions of Eu^(3+)ions,respectively.The Commission International de L'Eclairage color coordinates are gradually tuned from pale red(0.5980,0.4012)to a pure red(0.6385,0.3611)region.Thermoluminescence glow peaks showcase excellent super-linear response at low doses ofγ-irradiations,indicating that the prepared phosphor can be used in thermoluminescent personal dosimetry which is a biological tissue equivalent.The aforementioned results demonstrate that the prepared Mg_(2)GeO_(4):Eu^(3+)(1 mol%-9 mol%)nanophosphors are considered an excellent candidate for dual applications,i.e.,red component in future generation white-light-emitting diodes(WLEDs)and personal dosimetric applications.展开更多
In the present work, TiO2:Eu^(3+) (1 mol%e11 mol%) nano powders(NPs) were prepared via a facile one-pot hydrothermal method by using Epigallocatechin Gallate(EGCG) as bio-surfactant. The optimized TiO2:Eu^(3+) (5 mol%...In the present work, TiO2:Eu^(3+) (1 mol%e11 mol%) nano powders(NPs) were prepared via a facile one-pot hydrothermal method by using Epigallocatechin Gallate(EGCG) as bio-surfactant. The optimized TiO2:Eu^(3+) (5 mol%) NPs can be used as fluorescent labeling agent for visualizing of latent fingerprints(LFPs) on various porous and non-porous surfaces. The obtained results exhibit well defined ridge details with high sensitivity, selectivity, and low background hindrance which show greater advantages as compared to conventional powders. We demonstrated the viability of high-performance security labels thorough excellent luminescence for practical anti-mimetic applications. Morphology of the prepared samples is highly dependent on pH, concentration of the bio-surfactant, temperature and time durations.Photoluminescence(PL) emission spectra exhibit intense red emission at ~ 615 nm due to electric dipole transition(~5 D_0/~7 F_2). Photometric(CIE and CCT) results clearly show the intense warm red emission of the optimized samples. Therefore, this work offers a superior and universal luminescent label, which can be applied to visualize miniature LFPs particulars for individualization and consequently display great prospective in forensic investigation.展开更多
Latent fingerprints (LFPs) were the most significant identification method for individualization. Most commonly available fingerprints (FPs) in crime spot investigation were latent and patent types. Generally,LFPs wer...Latent fingerprints (LFPs) were the most significant identification method for individualization. Most commonly available fingerprints (FPs) in crime spot investigation were latent and patent types. Generally,LFPs were invisible and thus the effective visualization technique necessitates for the analysis of such FPs. In the past years, many traditional visualization techniques have been employed, but suffered with low resolution, sensitivity, contrast and high background noise. To overcome such limitations, we synthesized Sm^(3+) doped CaSiO_3 nanophosphors (NPs) via an ultrasound irradiation route using mimosa pudica (m. p.)leaves extract as a bio-surfactant. The morphological behavior of the prepared samples was extensively studied by varying the concentration of the m. p. extract, ultrasound irradiation duration, pH level of the precursor solution and sonication power. The photoluminescence (PL) emission spectra exhibit characteristic peaks at～561,601 and 647 nm, which were attributed to^5G_(5/2)→~6H_J(J=5/2,7/2 and 9/2) transitions of Sm^(3+) ions.The Judd-Ofelt(J-O) intensity parameters and other radiative properties were estimated using PL data. The Commission International de I'Eclairage (CIE) color coordinates were positioned in orange-red region shows average correlated color temperature (CCT) value of～3576 K. The optimized samples can be used as a labeling agent for the visualization of LFPs on various porous and non-porous surfaces under normal light irradiation. The visualized FPs reveals well defined ridge characteristics, namely whorl, loop,arch, bifurcation, eye, island, bridge, sweat pores, etc, with high sensitivity, selectivity, low contrast and background hindrance. Aforementioned results evidence that the prepared CaSiO_3:Sm^(3+) NPs were promising luminescent materials for solid state lighting and forensic applications.展开更多
Alkali metal ions(M+ = Na+,Li+,K+) co-doped ZnAl2O4:Eu3+(5 mol%)(ZAE) nanopowders(NPs) were prepared via solution combustion route using Mimosa pudica(MP) leaves extract as a fuel. PXRD results of co-doped samples enh...Alkali metal ions(M+ = Na+,Li+,K+) co-doped ZnAl2O4:Eu3+(5 mol%)(ZAE) nanopowders(NPs) were prepared via solution combustion route using Mimosa pudica(MP) leaves extract as a fuel. PXRD results of co-doped samples enhance the crystallinity and grain growth. Photoluminescence(PL) of the prepared ZAE and ZAE:M+(M+ = Na+, Li+, K+) NPs shows intense emission peaks in the range of 550-750 nm and ascribed to 5D0→7FJ(J=0-4) transitions of Eu3+ ions, respectively. A 2-fold enhancement in PL intensity was observed in Li+ co-doped samples. The optimized ZnAl2O4:Eu3+(5 mol%), Li+(1 wt%)(ZAEL)NPs were used to visualize LFPs on various porous, semi-porous and non-porous surfaces through robust powder dusting technique. The visualized latent fingerprints(LFPs) reveal well defined level 1-3 ridge characteristics under several tests such as fingerprint aging and fresh water treatment for various time durations. The obtained results clearly evidence that the prepared NPs are quite useful for multifunctional applications such as advanced forensic and solid state lightning.展开更多
Latent fingerprints（LFPs） are the major physical evidences for the identification of individuals during crime spot investigation. Till date, numerous methods were followed to visualize LFPs. However, simple,accurate...Latent fingerprints（LFPs） are the major physical evidences for the identification of individuals during crime spot investigation. Till date, numerous methods were followed to visualize LFPs. However, simple,accurate, and cost-effective method has wide scope in advanced forensic field. In our work, Ca2 SiO4：Dy^（3＋）nanopowders（NPs） were fabricated via solution combustion route. The optimized sample was employed for the visualization of overlapped LFPs by the cost effective powder dusting method. The obtained results reveals the complete three levels of ridge characteristics with high sensitivity, reproducibility,selectivity, and reliability on various complex surfaces. The photoluminescence（PL） spectra consist of intense peaks at ～ 480 and 574 nm owing to ~4 F（9/2） →~6 H（15/2） and ~4 F（9/2）→~6 H（13/2） 4 f transitions of Dy3＋ ions,respectively. The photometric properties confirm that the samples exhibit intense white emission with high color purity. Therefore, the prepared NPs could be a definitive choice as an advanced luminescent NPs for forensic, solid state lighting and portable FED devices.展开更多
Nanomaterials have emerged as an active area of research.This is because of their broad spectrum of applications such as sensors,white light emitting diodes(LEDs),electronic displays,and other optoelectronic devices i...Nanomaterials have emerged as an active area of research.This is because of their broad spectrum of applications such as sensors,white light emitting diodes(LEDs),electronic displays,and other optoelectronic devices in the optics and electronic industries owing to their size-and shape-dependent properties.The synthesis technique plays a crucial role in tuning the size and shape of the materials.Herein,we briefly describe these nanomaterials'fundamental aspects,properties,and applications.Various nanomaterial synthesis methods are discussed.Their advantages and disadvantages are highlighted in conjunction with the criteria for selecting a synthesis method.The principle underlying the sonochemical method and its applicability in synthesizing diverse sub-15 nm size nanoparticles(NPs)are presented.The main objective of this article is to review recent studies on lanthanide-doped nanophosphors and the various parameters that play key roles in achieving optimum luminescence emission.Both down-conversion and up-conversion mechanisms are discussed.The importance of the combinations and concentrations of the synthesizer/activator,color tuning,and host material are emphasized.展开更多
基金Project supported by the Department of Science&Technology(DST)(Science and Engineering Research Board(SERB)-Core Research Grant(CRG))Government of India(CRG/2020/006446)。
文摘The envisaged design and developme nt of individual mate rials to excavate a broader spectrum of desired properties and offer multiple applications are highly necessitating.Keeping this in mind,a series of forsterite-structured Mg_(2)GeO_(4):Eu^(3+)(1 mol%-9 mol%)nanophosphors was synthesized via a solution combustion method using oxalyl dihydrazide as a fuel.The X-ray diffraction patterns confirm the orthorhombic crystal system with a Puma space group.Morphological results clearly show irregularly shaped cluster-like structures with aggregation of the particles.Employing diffuse reflectance spectra,the optical energy band gap of the Mg_(2)GeO_(4):Eu^(3+)(1 mol%-9 mol%)nanophosphors was estimated and obtained to be~4.12-4.32 eV.The photoluminescence emission spectra exhibit intense peaks at^(5)79,589,610,661,and 707 nm,which are due to characteristic^(5)D_(0)→^(7)F_(0),^(5)D_(0)→^(7)F_(1),^(5)Do→^(7)F_(2),^(5)D_(0)→^(7)F_(3)and^(5)D_(0)→^(7)F_(4)transitions of Eu^(3+)ions,respectively.The Commission International de L'Eclairage color coordinates are gradually tuned from pale red(0.5980,0.4012)to a pure red(0.6385,0.3611)region.Thermoluminescence glow peaks showcase excellent super-linear response at low doses ofγ-irradiations,indicating that the prepared phosphor can be used in thermoluminescent personal dosimetry which is a biological tissue equivalent.The aforementioned results demonstrate that the prepared Mg_(2)GeO_(4):Eu^(3+)(1 mol%-9 mol%)nanophosphors are considered an excellent candidate for dual applications,i.e.,red component in future generation white-light-emitting diodes(WLEDs)and personal dosimetric applications.
文摘In the present work, TiO2:Eu^(3+) (1 mol%e11 mol%) nano powders(NPs) were prepared via a facile one-pot hydrothermal method by using Epigallocatechin Gallate(EGCG) as bio-surfactant. The optimized TiO2:Eu^(3+) (5 mol%) NPs can be used as fluorescent labeling agent for visualizing of latent fingerprints(LFPs) on various porous and non-porous surfaces. The obtained results exhibit well defined ridge details with high sensitivity, selectivity, and low background hindrance which show greater advantages as compared to conventional powders. We demonstrated the viability of high-performance security labels thorough excellent luminescence for practical anti-mimetic applications. Morphology of the prepared samples is highly dependent on pH, concentration of the bio-surfactant, temperature and time durations.Photoluminescence(PL) emission spectra exhibit intense red emission at ~ 615 nm due to electric dipole transition(~5 D_0/~7 F_2). Photometric(CIE and CCT) results clearly show the intense warm red emission of the optimized samples. Therefore, this work offers a superior and universal luminescent label, which can be applied to visualize miniature LFPs particulars for individualization and consequently display great prospective in forensic investigation.
基金DST-SERB (Project No.SR/FTP/PS-135/2010), New Delhi, India for the funding of this project
文摘Latent fingerprints (LFPs) were the most significant identification method for individualization. Most commonly available fingerprints (FPs) in crime spot investigation were latent and patent types. Generally,LFPs were invisible and thus the effective visualization technique necessitates for the analysis of such FPs. In the past years, many traditional visualization techniques have been employed, but suffered with low resolution, sensitivity, contrast and high background noise. To overcome such limitations, we synthesized Sm^(3+) doped CaSiO_3 nanophosphors (NPs) via an ultrasound irradiation route using mimosa pudica (m. p.)leaves extract as a bio-surfactant. The morphological behavior of the prepared samples was extensively studied by varying the concentration of the m. p. extract, ultrasound irradiation duration, pH level of the precursor solution and sonication power. The photoluminescence (PL) emission spectra exhibit characteristic peaks at～561,601 and 647 nm, which were attributed to^5G_(5/2)→~6H_J(J=5/2,7/2 and 9/2) transitions of Sm^(3+) ions.The Judd-Ofelt(J-O) intensity parameters and other radiative properties were estimated using PL data. The Commission International de I'Eclairage (CIE) color coordinates were positioned in orange-red region shows average correlated color temperature (CCT) value of～3576 K. The optimized samples can be used as a labeling agent for the visualization of LFPs on various porous and non-porous surfaces under normal light irradiation. The visualized FPs reveals well defined ridge characteristics, namely whorl, loop,arch, bifurcation, eye, island, bridge, sweat pores, etc, with high sensitivity, selectivity, low contrast and background hindrance. Aforementioned results evidence that the prepared CaSiO_3:Sm^(3+) NPs were promising luminescent materials for solid state lighting and forensic applications.
基金Project supported by the Vision Group of Science and Technology(VGST)Karnataka(VGST/KFIST L-1/2016-17/GRD-489)
文摘Alkali metal ions(M+ = Na+,Li+,K+) co-doped ZnAl2O4:Eu3+(5 mol%)(ZAE) nanopowders(NPs) were prepared via solution combustion route using Mimosa pudica(MP) leaves extract as a fuel. PXRD results of co-doped samples enhance the crystallinity and grain growth. Photoluminescence(PL) of the prepared ZAE and ZAE:M+(M+ = Na+, Li+, K+) NPs shows intense emission peaks in the range of 550-750 nm and ascribed to 5D0→7FJ(J=0-4) transitions of Eu3+ ions, respectively. A 2-fold enhancement in PL intensity was observed in Li+ co-doped samples. The optimized ZnAl2O4:Eu3+(5 mol%), Li+(1 wt%)(ZAEL)NPs were used to visualize LFPs on various porous, semi-porous and non-porous surfaces through robust powder dusting technique. The visualized latent fingerprints(LFPs) reveal well defined level 1-3 ridge characteristics under several tests such as fingerprint aging and fresh water treatment for various time durations. The obtained results clearly evidence that the prepared NPs are quite useful for multifunctional applications such as advanced forensic and solid state lightning.
基金DST-FIST NO.SR/FST/ETT-378/2014 for sanctioning of the projectVGST,Government of Karnataka.India[VGST/KFIST-4/GRD489]for the sanction of this Project
文摘Latent fingerprints（LFPs） are the major physical evidences for the identification of individuals during crime spot investigation. Till date, numerous methods were followed to visualize LFPs. However, simple,accurate, and cost-effective method has wide scope in advanced forensic field. In our work, Ca2 SiO4：Dy^（3＋）nanopowders（NPs） were fabricated via solution combustion route. The optimized sample was employed for the visualization of overlapped LFPs by the cost effective powder dusting method. The obtained results reveals the complete three levels of ridge characteristics with high sensitivity, reproducibility,selectivity, and reliability on various complex surfaces. The photoluminescence（PL） spectra consist of intense peaks at ～ 480 and 574 nm owing to ~4 F（9/2） →~6 H（15/2） and ~4 F（9/2）→~6 H（13/2） 4 f transitions of Dy3＋ ions,respectively. The photometric properties confirm that the samples exhibit intense white emission with high color purity. Therefore, the prepared NPs could be a definitive choice as an advanced luminescent NPs for forensic, solid state lighting and portable FED devices.
文摘Nanomaterials have emerged as an active area of research.This is because of their broad spectrum of applications such as sensors,white light emitting diodes(LEDs),electronic displays,and other optoelectronic devices in the optics and electronic industries owing to their size-and shape-dependent properties.The synthesis technique plays a crucial role in tuning the size and shape of the materials.Herein,we briefly describe these nanomaterials'fundamental aspects,properties,and applications.Various nanomaterial synthesis methods are discussed.Their advantages and disadvantages are highlighted in conjunction with the criteria for selecting a synthesis method.The principle underlying the sonochemical method and its applicability in synthesizing diverse sub-15 nm size nanoparticles(NPs)are presented.The main objective of this article is to review recent studies on lanthanide-doped nanophosphors and the various parameters that play key roles in achieving optimum luminescence emission.Both down-conversion and up-conversion mechanisms are discussed.The importance of the combinations and concentrations of the synthesizer/activator,color tuning,and host material are emphasized.
