Manish Kumar Mishra; P.M. Mishra; Vikas Dubey; Isharat Khan; Taranjeet Sachdev
Abstract
Herein review work for luminescence property of materials, their detection techniques and the possibilities for combining the Luminescence properties of materials & MEMS technology is reported. The core objective of this review work is to through light on the probable areas and prospects of integration ...
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Herein review work for luminescence property of materials, their detection techniques and the possibilities for combining the Luminescence properties of materials & MEMS technology is reported. The core objective of this review work is to through light on the probable areas and prospects of integration of microelectromechanical systems (MEMS) dependent sensing and actuating devices with using the wide-ranging properties of luminescent substances, which can be able to symbolize a new species of genetically engineered sensing and actuating devices. This work discusses about the various visible features and advantages with the applications of such genetically engineered micro-organisms/systems as environmentally friendly bio-correspondents. In this work the various fabrication technique for luminescence material-based semiconductors are discussed, which are similar to the fabrication of MEMS devices.
S.P. Puppalwar; M.S. Mendhe; S.J. Dhoble
Abstract
Tb 3+ /Sm 3+ single as well as co-doped LaMgAl11O19 (LMA) phosphors have been synthesized by a low-temperature solution combustion method. The X-ray diffraction pattern, photoluminescence properties and energy transfer (ET) processes between rare earth (RE) ions, were investigated in detail. The mechanism ...
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Tb 3+ /Sm 3+ single as well as co-doped LaMgAl11O19 (LMA) phosphors have been synthesized by a low-temperature solution combustion method. The X-ray diffraction pattern, photoluminescence properties and energy transfer (ET) processes between rare earth (RE) ions, were investigated in detail. The mechanism of energy transfer (ET) from Tb3+ to Sm3+ was seen as the dipole–dipole interaction. Efficient ET from Tb3+ to Sm3+ ions was observed, leading to color-tunable emissions of LMA:0.02Tb3+ , x Sm 3+ (x = 0.005 to 0.02 mol) phosphors. The efficiency of the ET gradually increased with increase in the Sm 3+ ion concentration, reaching a maximum of 78.28% at Tb3+ ion concentration 0.02mol. The critical distance (Rc) among sensitizer and activator by the concentration quenching method was estimated to be 27.96 Å. The LMA: Tb3+ , Sm3+ phosphors exhibited the emission peaks in the blue ( 5D3→ 7FJ = 5, 4, 3, and 2), green ( 5D4→ 7FJ = 6, 5, and 4), and orange-red ( 4G5/2→ 6HJ = 5/2, 7/2, and 9/2) regions under the excitation wavelength of 375 nm. As a consequence of fine-tuning of the emission composition of the Tb3+ and Sm3+ ions, multicolor emitting luminescence properties can be achieved in a single host lattice LMA.
Sandra Dias; S. B. Krupanidhi
Abstract
The Cu2SnS3/AZnO p-n heterojunction was fabricated and the structural and optical properties of the films were studied. The phase formation and the crystallite size of the films was analysed using X-ray diffraction. The morphology was studied using field emission scanning electron microscopy and transmission ...
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The Cu2SnS3/AZnO p-n heterojunction was fabricated and the structural and optical properties of the films were studied. The phase formation and the crystallite size of the films was analysed using X-ray diffraction. The morphology was studied using field emission scanning electron microscopy and transmission electron microscopy. The temperature dependent photoluminescence studies were conducted from 123 K to 353 K. The various possible transitions corresponding to the luminescence peaks were indexed. The intensities of the peaks were found to decrease with increase in temperature whereas there was found to be no change in the energy of emission. The chromaticity coordinates for the CTS/AZO heterojunction for different temperatures were found and it corresponded to white light emission at all temperatures.
Devender Singh; Suman Sheoran; Vijeta Tanwar
Abstract
In this review article, different synthetic procedures and characterization techniques used for the development of materials are discussed briefly. The stability and high luminous intensity of silicate materials makes them practically important in the field of white light emitting diodes (WLEDs). During ...
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In this review article, different synthetic procedures and characterization techniques used for the development of materials are discussed briefly. The stability and high luminous intensity of silicate materials makes them practically important in the field of white light emitting diodes (WLEDs). During the experimental designing of our research, we have understood carefully the theoretical and methodological strategy regarding the synthesis of phosphors and then, a large number of silicate-based luminescent materials have been prepared using sol-gel technology. Among them, a series of silicate materials having composition M(2-x)EuxSi2O7 (M = Y, Gd, La and x = 0.03 moles) have been described in this review prepared with sol-gel process. Intense peak in europium (III) doped M2Si2O7 silicates originate from 5 D0→ 7 F2 transition of Eu 3+ ion available in crystal lattices. X-ray diffraction pattern have triclinic structure for Y2Si2O7 and Gd2Si2O7 silicate phosphors. However, hexagonal and monoclinic structures are obtained for La2Si2O7 material at different temperatures employed for further annealing. Transmission electron microscopic analysis is used to study the morphology and particle size of prepared phosphors. Excellent luminescence response of these silicate phosphors make them suitable for photonic applications and also open up new avenues for solid-state lighting, cathode ray tubes, fluorescent lamps and scintillators etc.
Ketki S. Dhoble; J. A. Wani; S. J. Dhoble
Abstract
Phosphate based compounds doped with rare earth ions are promising luminescent materials for many applications including solid state lighting. In this work photoluminescence properties of K2SrP < sub>2O7:RE 3+ (RE = Sm, Tb, Eu, Dy) phosphors are presented for the first time. K2SrP < sub>2O7:RE ...
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Phosphate based compounds doped with rare earth ions are promising luminescent materials for many applications including solid state lighting. In this work photoluminescence properties of K2SrP < sub>2O7:RE 3+ (RE = Sm, Tb, Eu, Dy) phosphors are presented for the first time. K2SrP < sub>2O7:RE 3+ phosphors activated with the trivalent rare earth ions were synthesized by combustion method. Phosphors were characterized for phase purity, morphology and luminescent properties. Elemental analysis was done through energy dispersive spectroscopy (EDS). The emission and excitation spectra were followed to study the luminescence characteristics of K2SrP < sub>2O7:RE 3+ phosphors. The as prepared powders of RE 3+ doped K2SrP < sub>2O7 emit red, green and yellowish white light as a result of f-f transitions. The study is novel as no such luminescence data are available for this compound.
Abstract
The motivation of this work is to apply a new model, which we had called the Global Reactions Model (GRM), for the theoretical study of the optical and electronics properties of Silicon Rich Oxides (SRO) structures regardless of the technique used to fabricate such structures. Recently we published the ...
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The motivation of this work is to apply a new model, which we had called the Global Reactions Model (GRM), for the theoretical study of the optical and electronics properties of Silicon Rich Oxides (SRO) structures regardless of the technique used to fabricate such structures. Recently we published the Global Reactions Model (GRM) to describe a set of chemical reactions that could hypothetically occur during the process of obtaining silicon rich oxide (SRO) films, notwithstanding of the technique used to grow such films. Particularly, chemical reactions that occur during the process of growing of SRO films by Low Pressure Chemical Vapor Deposition (LPCVD) and Hot Filament Chemical Vapor Deposition (HFCVD) techniques were emphasized in these models. We suggest and evaluate either some types of molecules or resulting nanostructures and we have predicted theoretically, by applying the density functional theory (DFT), the contribution that they may have to the phenomenon of luminescence. We calculated the luminescent spectra of the as grown and the annealed structures. In this work we focused in siloxanes species presumably found in SRO.
Amrita Das; Vishal Shama
Abstract
In the present study, we investigate upon the synthesis and characterization of inorganic Eu 3+ doped Al2O3 nanophosphor for its structural and luminescent properties. The luminescent nanopowder was prepared using a combustion method in which the stoichiometric ratio of oxidizers and fuel was fixed to ...
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In the present study, we investigate upon the synthesis and characterization of inorganic Eu 3+ doped Al2O3 nanophosphor for its structural and luminescent properties. The luminescent nanopowder was prepared using a combustion method in which the stoichiometric ratio of oxidizers and fuel was fixed to one, with varying concentration of Eu 3+ ions acting as an activator. The prepared powder showed excellent thermal stability. For the identification of the phase and structure of the powder synthesized, X-ray diffractometer was used. From the XRD analysis, it is revealed that the rhombohedral crystallite phase of α-alumina was formed. The type of morphology and particle size was ascertained by Filed Emission-Scanning Electron Microscope (FE-SEM) and it was found that particles were having irregular spherical shape. A qualitative analysis of these nanophosphor particles was made using an Energy dispersive X-ray detector (EDS) and it was found that the samples were composed of Al, O and Eu ions. Photo-luminescence (PL) spectra were obtained using Spectrofluorometer absorption. The intense band position was observed at 618 nm and other less intense bands were also seen at 592 nm, 601 nm, 631 nm, while two weak bands were observed at 660 nm and 718 nm, when excited at 226 nm. The CIE color space chromaticity diagram was calculated from the CIE Calculator program using obtained PL spectra. The prepared nanophosphor powder was tested for latent fingerprint detection in forensic applications. The synthesized nanophosphor was successfully used as a latent fingerprint developing powder on various non-porous surfaces for forensic application.
Pragati Malik; Jyoti Singh; Rita Kakkar
Abstract
The primary aim of this review is to survey the literature on the ion sensing ability of quantum dots. Sensing of both cations and anions is important, since both play significant roles in various ecological and biological processes, which makes it important to ensure their concentration at balanced ...
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The primary aim of this review is to survey the literature on the ion sensing ability of quantum dots. Sensing of both cations and anions is important, since both play significant roles in various ecological and biological processes, which makes it important to ensure their concentration at balanced level. Contamination by heavy metal ions and various anions poses a serious threat to humans, aquatic organisms, and to the environment; therefore detection of these ions (in presence of other cations and anions), which are the major cause of environmental pollution is of immense significance at the present time. Owing to their enhanced fluorescence properties and photostability, QDs offer tremendous scope to be used for ion sensing. They offer several advantages over traditional chemical fluorophores. This review throws light on the mechanism adopted by CdSe QDs to act as flourophores. Owing to their enhanced photoluminescence properties, QDs offer selective and sensitive determination of various ions, which is a function of the capping on the surface of the QD nanosensor, i.e. it is possible to tune their sensing ability by changing the capping layer, which influences the QD's interaction with various analytes. Hence, these quantum dots may prove promising candidates in future for sensing approximately all types of analytes.
J. A. Wani; N. S. Dhoble; N. S. Kokode; S. J. Dhoble
Abstract
As host materials, phosphate compounds offer great potential for lanthanides to display luminescence characteristics. In this work luminescence behaviour of Na2CaP < sub>2O7:RE 3+ are presented for the first time. Na2CaP < sub>2O7 novel phosphors activated with the trivalent rare earth ions ((RE = Ce, ...
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As host materials, phosphate compounds offer great potential for lanthanides to display luminescence characteristics. In this work luminescence behaviour of Na2CaP < sub>2O7:RE 3+ are presented for the first time. Na2CaP < sub>2O7 novel phosphors activated with the trivalent rare earth ions ((RE = Ce, Eu, Tb, Sm) were synthesized by solid state diffusion method. Phosphors were characterized for phase purity and luminescent properties. The emission and excitation spectra were followed to explore the luminescence attributes. The as prepared powders of Ce 3+ , Eu 3+ ,Tb 3+ and Sm 3+ doped Na2CaP < sub>2O7 emit near-uv, red, green and orange reddish light as result of f-d and f-f transitions respectively. The study is novel as no such luminescence data are available for this compound. The results are promising in view of the requirement for pc-white LEDs for solid state lighting applications.
G.V. Lokeswara Reddy; L. Rama Moorthy; T. Chengaiah; B.C. Jamalaiah
Abstract
We reported the structure, photoluminescence and energy transfer studies of Dy 3+ /Ce 3+ co-doped YAl3(BO3)4 (YAB) phosphors prepared by solid-state reaction method at 1200 o C/3h. Upon 273 nm UV excitation, the YAB:Ce 3+ phosphor exhibits a sharp emission band with peak maximum at 380 nm related to ...
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We reported the structure, photoluminescence and energy transfer studies of Dy 3+ /Ce 3+ co-doped YAl3(BO3)4 (YAB) phosphors prepared by solid-state reaction method at 1200 o C/3h. Upon 273 nm UV excitation, the YAB:Ce 3+ phosphor exhibits a sharp emission band with peak maximum at 380 nm related to the parity and spin allowed Ce 3+ : 5 d → 4 f transition. When excited with 352 nm, the broad emission band of Ce 3+ contains two components at 390 and 417 nm due to the electric dipole transitions from 5d excited state to the two splitting ground 2 F5/2,7/2 states, respectively. The incorporation of Ce 3+ enhances the luminescence intensity of Dy 3+ due to efficient energy transfer from Ce 3+ to Dy 3+ . The emission spectra of Dy 3+ /Ce 3+ co-doped phosphors under 273 nm excitation display the Dy 3+ : 4 F9/2 → 6 H15/2,13/2,11/2 and the Ce 3+ : 5 d → 4 f transitions. The emission colour can be tuned from blue-to-white as a function of Ce 3+ concentration and/or excitation wavelength. Colour perception has been analyzed by evaluating the Commission International de I’Eclairagein (CIE) chromaticity coordinates. The YAB:Dy 3+ /Ce 3+ phosphors can be significant for current generation UV excited white light emitting diodes.
M. Penchal Reddy; B.C. Jamalaiah; I.G. Kim; D.S. Yoo; R. Ramakrishna Reddy
Abstract
Water-dispersible CdS quantum dots (QDs) were synthesized in a simple one-pot noninjection route. The X-ray diffraction (XRD) pattern of the nanoparticles shows the cubic structure with particle size of the order 5-7 nm which was in good agreement with the transmission electron microscopic (TEM) studies. ...
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Water-dispersible CdS quantum dots (QDs) were synthesized in a simple one-pot noninjection route. The X-ray diffraction (XRD) pattern of the nanoparticles shows the cubic structure with particle size of the order 5-7 nm which was in good agreement with the transmission electron microscopic (TEM) studies. Selected area electron diffraction (SAED) recognized the cubic structure of CdS. The energy dispersive X- ray spectroscopy (EDAX) analysis confirms the presence of Cd and S elements in the samples. The optical properties are characterized by Ultraviolet-Visible (UV-Vis) absorption and Photoluminescence (PL) spectra. The synthesis parameters of this simple and rapid approach, including the reaction temperature and time, the pH of the reaction solution and the molar ratio of the 3-mercaptopropionic acid (MPA) stabilizer to Cd 2+ , have considerable influence on the particle size and photoluminescence of the CdS quantum dots. The 3-mercaptopropionic acid (MPA) stabilized CdS QDs can be used in solar cells, light emitting diodes, biological imaging etc.
Zhongsen Yang; Guangjun Zhou
Abstract
Hydrophobic CdSe/ZnS quantum dots (QDs) were embedded in a transparent functional silica film with thickness of 10-15 µm using a sol-gel method. Namely, the QDs were prepared through an organic synthesis using hexadecylamine as a capping agent. When partially hydrolyzed 3-aminopropyltrimethoxysilane ...
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Hydrophobic CdSe/ZnS quantum dots (QDs) were embedded in a transparent functional silica film with thickness of 10-15 µm using a sol-gel method. Namely, the QDs were prepared through an organic synthesis using hexadecylamine as a capping agent. When partially hydrolyzed 3-aminopropyltrimethoxysilane (APS) sol was mixed with a toluene solution of the QDs, the ligand exchange occurred. With subsequent addition of pure H2O, the QDs were transferred into APS sol accompanied with a phase separation. The APS sol with the QDs was condensed to adjust its’ viscosity by the evaporation of solvents at room temperature. After that, functional SiO2 films with tunable QD concentrations and high photoluminescence (PL) efficiency were fabricated by a spin-coating strategy using the condensed APS sol with the QDs. The absorbance at first absorption peak of the QDs revealed a liner increase against the QD concentrations in these films. The PL peak wavelength and full width at half maximum of PL spectra of the QDs in these films remained unchange compared with their initial values in toluene. The QDs were mono-dispersed in these films according to transmission electron microscopy observation. Due to unique properties, these films are utilizable for further applications in optical and electronic devices.
Aiyu Zhang; Ping Yang; Yongqiang Cao; Yuanna Zhu
Abstract
Eu, Dy codoped Y2Zr2O7 crystalline powders have been prepared by a simple sol-gel-combustion method. The lumincescence excitation and emission spectra of the products were measured, and the CIE chromaticity was introduced to characterize the color of the phosphor. It was found that the emission color ...
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Eu, Dy codoped Y2Zr2O7 crystalline powders have been prepared by a simple sol-gel-combustion method. The lumincescence excitation and emission spectra of the products were measured, and the CIE chromaticity was introduced to characterize the color of the phosphor. It was found that the emission color of the Eu, Dy codoped Y2Zr2O7 powders depends on the doping concentration of Eu, Dy ions and the excitation wavelength. White light emission has been observed for Y2Zr2O7: 1.5%Eu 3+ , 2.0%Dy 3+ under 350nm excitation, for which the calculated chromaticity coordinate is (0.37, 0.32).
Prashant K. Sharma; Ranu K. Dutta; Avinash C. Pandey
Abstract
Spherical nanoparticles of Y2O3:Eu 3+ with cubic phase has been synthesized by solution combustion method using glycine as chelating agent and urea as fuel. The 1200 °C annealed sample yield intense red luminescence at 610 nm corresponding to 5 D0→ 7 F2 transition of Eu 3+ ion under vacuum ...
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Spherical nanoparticles of Y2O3:Eu 3+ with cubic phase has been synthesized by solution combustion method using glycine as chelating agent and urea as fuel. The 1200 °C annealed sample yield intense red luminescence at 610 nm corresponding to 5 D0→ 7 F2 transition of Eu 3+ ion under vacuum ultraviolet (VUV)/ultraviolet (UV) excitation. Furthermore, the luminescence decay time of the 5 D0→ 7 F2 transition at 610 nm was also calculated against the 147 nm VUV excitation and found to be ~ 4 ms. These highly luminescent spherical nanopartcles of Y2O3:Eu 3+ seems to be one of the promising candidates for modern age display devices.
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