ABSTRACT: In the present work, orthorhombic NiS nanoparticles were obtained by chemical precipitation method using tri ethanol ammine (TEA) as a capping agent. The nickel sulfide nanoparticles were characterized by X-ray diffraction (XRD), UV-visible spectrophotometry (UV-vis), photoluminescence (PL) and micro Raman techniques. The X-ray diffraction pattern of the sample indicated the formation of orthorhombic structure of NiS. Absorption due to band edge and defect levels was observed in the absorption spectrum of nickel sulphide nanoparticles.Emission peaks due to defect levels was observed in the photoluminescence spectrum.
1100 C). A noteworthy feature was delineated as the rutile phase partially transforms to anatase again at 1,200 C. Moreover these different nano-objects have been further evaluated for their performance as luminescent materials. Acknowledgment One of the authors (MD) acknowledges the financial support from Department of Science and Technology (Grant no. 91330). S. Bhandari acknowledges University Grants Commission (UGC) for junior research fellowship. Drs. D.P. Singh, D. Gupta and D. Harnath are gratefully acknowledged for recording XRD, Raman spectroscopy, and photoluminescence data.
hydrothermal method. These nanostructures were analyzed by X-ray diffraction (XRD), field-emission gum scanning electron microscopy (FEG-SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDXS), ultraviolet–visible (UV–vis) spectroscopy, and photoluminescence (PL) measurements. XRD patterns confirmed that this material crystallizes in a monoclinic structure. FEG-SEM and TEM micrographs indicated that the rice-like morphologies were formed due to an increase in the effective collisions between the nanoparticles during the MH processing. The EDXS spectrum was used to verify the chemical compositional of this oxide. UV–vis spectrum revealed that this material have an indirect opti- cal band gap. When excited with 488 nm wavelength at
XRD technology can be used for phase identification, structural analysis and grain size determination. X-ray diffraction studies were carried out to study the structural evolution of europium oxide nanoparticles dispersed in silica matrix. XRD pattern of the sample N3 annealed at 1000 o C has been shown in Fig. 3.1. The XRD pattern of this sample revealed that sudden heating at much higher temperature produces mixed crystalline phases of Eu 2 O 3 and silica. During the synthesis of nanopowder we got different type of structure at different
solvothermal route. In this synthesis, thiosemicarbazide and thioglycolic acid were used as sulfur sources. The effects of different parameters such as type of precursor and time on the morphology and particle size of the samples have been investigated. The nanostructures were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X- ray analysis (EDX), Fourier transform infrared (FT-IR) and photoluminescence (PL) spectroscopy. The fill factor (FF), open circuit voltage (V oc ), and short circuit current (I sc ) were obtained by
In this study Cu 2+ +Eu 3+ doped ZnO solid solution powders were synthesized by solution combustion method maintaining the Eu 3+ ion concentration fixed at 3%Wt and after annealing at 900 ˚C by 24 h. From the XRD study it is confirmed that the ZnO hexagonal wurtzite structure is conserved after the introduction of the Cu 2+ ion in the ZnO structure, and the same XRD study showed the presence of the minority phases Eu 2 O 3 and
ders were analyzed by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Fourier trans- form Raman microscopy and ultraviolet visible absorption spectroscopy (UV-vis spectra) as well as photoluminescence (PL) measurements. Based on the results, these materials revealed nanorod morphology. PL spectra obtained at room temperature for - and -CoMoO 4 particles exhibited maximum components around the blue light emission. The results
speed spreads the colloid droplets of Au nanoparticles; and high spin provides the adequate outward centrifugal force to overcome the interparticle interactions, avoiding nanoparticle conjugation. The results pointed that the nanowire diameter decreases with increase of separation distance. This diameter also depends on the growth temperature and catalyst nanoparticle size. At high temperature (850-900 °C), however, the diameter does not depend on the catalyst nanoparticle size. Smaller diameter (< 50 nm) can be obtained using lower growth temperature (800 °C) and smaller catalyst nanoparticle size. The band gap of these nanowires also depends on its diameter, increasing from 4.70 to 4.80 eV. Besides these values, XRD and Raman measurements can demonstrate that changes in their respective graphs occur due to the changes in structural strain with nanowire diameter (Kumar, Kumar, and Singh, 2017).
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b. Impurity levels and defects detection:- Radiative transitions involve localized defect levels in semiconductor. Specific defects can be identifying by the photoluminescence energy associated with these levels. Photoluminescence spectrum at low temperature often reveals spectral peaks associated with impurities contained within the host material and the Fourier transform of photoluminescence micro spectroscopy, provides the potential to identify extremely low concentration of unintentional and intentional impurities which can strongly affected the device performance and the material quality.
Congli Sun, Hu Hao, Yi Liang, Bai Xue, Yang Yumeng, Feng Huanhuan, Xu Jingjing, Chen Yua, Jin Yong, Jiao Zhifeng and Sun Xiaosong (2012). Photoluminescence of silicon nanostructures prepared via hydrothermal growth progress. Applied Surface Science, 258, 8078– 8082.
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We have developed a theory of low-temperature, sta- tionary photoluminescence from a pair of spherical quantum dots coupled by the Coulomb interaction in a quantum-dot molecule. The lowest-energy electron–hole-pair states of the dots were assumed to be nearly resonant and characterized by low decay and dephasing rates. The coherent coupling of the quantum dots under these conditions was shown to mani- fest itself in the molecule’s photoluminescence spectrum as a pair of peaks, the intensities and spectral positions of which are determined by the geometry and materials of the dots, as well as by the rates of energy and phase relaxations of their electronic subsystems. We also derived an expression for the photoluminescence differential cross section, which is useful for interpreting and analyzing the secondary emission spec- tra of coherently coupled quantum dots.
The advantage of using photoluminescence for sensing the chemical signature of explosives is that this quenching effect can be monitored by a photodiode and integrated into user-friendly, inexpensive, portable instrumentation. Common explosive/landmine detecting technologies have disadvantages that can potentially be mitigated by chemical sensing; for instance, metal detectors can miss plastic mines, sniffer dogs can be temperamental, and other methods such as Ion Mass Spectrometry do not lend themselves to portability. The use of photoluminescent conjugated polymer films can be adapted for use in varying architectures according to the specific requirement whether this is vapour detection, aqueous environments, forensic
New type of photoluminescence properties of 2,2’:6’,2”-Terpyridine (Terpy) is described. Orthor- hombic form of Terpy crystals, which is known to be inherently nonluminous in the visible region, was found to emit strong green light in the presence of traces amount of impurities. Hydroxy-ter- pyridine, originally included in the Terpy reagent, was found to be the main cause of the green lu- minescence. Tuning of the luminescent color is possible depending on the dopant species.
The powder complex of tris(phenanthroline)cobalt(II) trifluoroacetate (TFA) has been prepared by interaction of cobalt(II) nitrate, phenanthroline (phen) in aqueous solution with drops of ethanol, and an excess of saturated aqueous solution of sodium trifluoroacetate, where upon the yellowish powder was produced. AAS measurment for the metal content, equivalent conductance (1:2), and TGA-DTA of the powder suggest the corresponding formula of [Co(phen) 3 ](TFA) 2 .5H 2 O. The efffective magnetic moment of 4.9 BM indicates the high-spin nature of this complex which corresponds to three unpaired electrons in the electronic configuration of Co(II) with significantly higher than the spin only value due to the orbital contribution. UV-Vis spectrum of the complex reveals the d-d spin-allowed transition bands as well as the MLCT and intraligand band. The estimating transition energy ratio of 2.04 for ν 2 /ν 1 , is clearly in the range for octahedral configuration. The infrared results property indicates the main mode of vibrations for the functional groups of ligand phen and TFA, and thus supports the formula proposed for this complex. The corresponding powder XRD was then refined using Rietica-Le Bail method and found to be fit as triclinic crystal system with space group of PI.
For XRD, the electroreduced solution was centrifuged and rinsed several times to obtain a precipitate that was dried, pulverized and analyzed. The XRD patterns were obtained with an Empyrean X-ray diffractometer using a Cu-K α radiation (λ = 0.15418 nm) at room temperature in the 2θ range 10 to 90° at 45 kV and 40 mA.
It is also clear that all the peaks in the XRD trace are sharp because of the large crystallite size of the micron range size, which results from the annealing process at high temperature. These kinds of processes are known to increase the atomic arrangement in long order crystals. It’s also known that the relatively small atomic scattering factor of oxygen makes it difficult to distinguish with XRD between the cubic and tetragonal phases of YSZ near the phase boundary (8-10 mol% Y 2 O 3 ) .
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pronounced diffuseness transition [18-22]. The La ions are effective in breaking the long-range order and produce Ti vacancies. This breakage of long-range ordering leads to a reduction of the ferroelectric characteristics and enhances the diffuse phase transition. In our present work, unit cell volume was calculated from XRD diffraction patterns, and the calculation result is listed in Table 1. The calculation result indicated an increase in the unit cell volume after adding NiO. This increase may be due to the Ni ions sub- stituting the Ti ions (at the B site). Therefore, substitution of the Ni ions at the B site may result in breaking the long-range ordering, resulting in a reduction of the ferro- electric behavior with the transition becoming more dif- fuse . Further, with increasing NiO content, the structure of the composites became more heterogeneous. This may contribute to the diffuse phase transition of the samples. From Figure 4, the increase of loss tangent with NiO content implies a higher electrical conductivity of the composites. However, the highest loss tangent in the pre- sent work was lower than 0.035, indicating that the
Powder X-ray diffraction (XRD) patterns of the samples were recorded on a Bruker D8- Advance diffractometer using Cu Kα radiation (λ = 0.15420 nm), scattering angles (2θ) of 4°– 82°, 41 keV, and a cathode current of 20.0 mA. Scanning electron microscopy (SEM) images were obtained using a JEOL JSM-840A SEM equipped with an energy-dispersive spectrometer (EDS). Transmission electron microscopy (TEM) images were obtained using a JEOL JEM-200 CX TEM operated at 200 kV. Raman spectra of the samples were measured at the sample surface using a confocal Raman microscope system equipped with a 514.5 nm Ar laser module (Jobin Yvon-Horiba LabRAM, Olympus BX 41 microscope). The samples were ultrasonicated in EtOH, and they were applied to a glass slide in the form of drops for the analyses. The samples were analysed using a green laser with a 51× maximum magnification and a red laser with a 101× magnification.
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detectors. Data were collected in the 0.25–1.5 µm region with the step of 0.005 µm, at incidence angle of θ = 70°. The photoluminescence (PL) measurements were carried out using the Jobin Yvon-Spex make Spectrofluorometer (Fluorolog version-3; Model FL3-11) with 450W high-pressure xenon arc lamp as excitation source. PL excitation and emission spectra were acquired at room temperature for a spectral resolution of 0.2 nm and slit width of 0.25mm.
the increase of the UVC dose. However, this discoloration indicates the PADC has been degraded under effect of UVC, due to many concurrent chemical processes taking place in PADC which results in several different modes of damage . Ultraviolet radiation of short wavelength (UVC) of 254 nm has enough energy of 4.88 eV to cleave the bonds in PADC chains with the production of free radicals , which initiates further complex reaction to molecular oxygen. The photodegradation will give rise to modifications in the electrochemical and optical properties of PADC. The photoluminescence of a UVC irradiated PADC sample is located between the first order diffraction at 3.54 eV (350 nm) and the second order diffraction at 1.77 nm (700 nm) of the excitation monochromater grating, both diffraction orders are minimized by positioning the PACD at an angle of 30º relative to the excitation light. Photoluminescence spectra shown in the Figure 2, which occurred between first and second order diffractions, revealed the influence of various dose of ultraviolet radiation of 254 nm on the photoluminescence emission of PADC, which was excited with 350 nm.