scholarly journals Red Fluorescence in Doped LaF3:Nd3+, Sm3+ Nanocrystals Synthesized by Microwave Technique

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
S. G. Gaurkhede ◽  
M. M. Khandpekar ◽  
S. P. Pati ◽  
A. T. Singh
Keyword(s):  
Electron Microscope ◽  
Energy Gap ◽  
Second Harmonic ◽  
Emission Spectra ◽  
Luminescent Properties ◽  
Average Crystalline Size ◽  
Tem Analysis ◽  
Visible Absorption ◽  
Microwave Technique ◽  
20 Nm

Hexagonal shaped LaF3 nanocrystals (NC) doped by Nd3+ and Sm3+ ions are synthesized using microwave technique. The prepared LaF3 sample was characterized by XRD to confirm the average crystalline size of the particle is close to 20 nm (JCPDS standard card (32-0483) of pure hexagonal LaF3 crystals). The Transmission Electron Microscope (TEM) analysis which indicates the size of the primary and secondary particle is in the range between 15 nm–20 nm. Scanning Electron Microscope (SEM) and Energy Dispersive X-ray (EDAX) spectrometry have been carried out. The functional groups of the synthesized nanoparticles were confirmed by Fourier transform infrared spectroscopy (FTIR). The luminescent properties of the nanoparticles have been observed by excitation and emission spectra. Energy transfer from Nd3+ to Sm3+ has been observed. The transparency of the crystals has been confirmed using UV-VIS spectra. UV-Visible absorption spectrum indicates an energy gap of 4.9 eV and shows presence of wide transparency window. Non Linear Optical (NLO) properties of the synthesized nanoparticles have been studied. It has been found that Second Harmonic Generation (SHG) efficiency of LaF3=Nd3+, Sm3+ is less than pure Potassium Dihydroxyl Phosphate (KDP) crystals.

TiO2 Nanoparticles Synthesized with Ti(SO4)2 as Precursor via the Hydrothermal Method and their Optical Absorption Properties

2017 ◽  
Vol 727 ◽  
pp. 280-283
Author(s):  
Xiao Ming Fu
Keyword(s):  
Hydrothermal Method ◽  
Ph Value ◽  
Blue Shift ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Absorption Properties ◽  
Tem Analysis ◽  
Visible Absorption ◽  
Transmission Electron ◽  
20 Nm

Anatase TiO2 particles of about 20 nm in the diameter were successfully synthesized with Ti (SO4)2 as titanium source and stronger ammonia water as precipitant at 240°C for 48 h with pH=5 using the hydrothermal method. The samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and ultraviolet-visible absorption spectroscopy (UV-VIS). XRD analysis showed that the phase of the samples was anatase TiO2. TEM analysis confirmed that TiO2 particles of about 50 nm in the diameter were obtained when the pH value was 0.12. With the increasement of the pH value, the size of as-prepared TiO2 particles became remarkably fine. However, with the further increase of the pH value, the size of TiO2 particles was not obvious. TiO2 particles of about 20 nm in the diameter were obtained when the pH value was 5. And UV-VIS results showed that the size of anatase TiO2 nanoparticles, which became small, was propitious to the blue shift of their absorption peak.

Hydrothermal Synthesis and Size-Enhanced Chromaticity of Sr2ZnSi2O7:Eu3+ Nanoparticles

2008 ◽  
Vol 8 (3) ◽  
pp. 1449-1453 ◽  
Author(s):  
Junxi Wan ◽  
Youwei Yao ◽  
Guoyi Tang ◽  
Yitai Qian
Keyword(s):  
Bulk Material ◽  
Emission Spectra ◽  
Luminescent Properties ◽  
Blue Shift ◽  
Average Diameter ◽  
Hydrothermal Route ◽  
Excitation Spectra ◽  
Red Phosphor ◽  
Red Phosphors ◽  
20 Nm

Red phosphor Sr2ZnSi2O7:Eu3+ nanoparticles with an average diameter of 20 nm were successfully synthesized via a low-temperature hydrothermal route in order to understand the underlying relationship between size and luminescent properties. The nanometer-sized particles result in a distinct improvement in chromaticity and a high quenching concentration. According to emission spectra, the relative intensity of the 5D0 → 7F2 to 5D0 → 7F1 transitions in nanometer-sized phosphors is higher than that of the corresponding bulk material. The better chromaticity results from the more distorted lattices and relatively lower crystal symmetry around the Eu3+ ions, which is ascribed to the large surface area due to the nanometer size of the phosphor. Moreover, the nanometer-sized Sr2ZnSi2O7:Eu3+ red phosphor exhibits a shorter fluorescent lifetime and a blue-shift in excitation spectra compared to that of its bulk counterpart. These results indicate that size-induced enhancement of luminescent properties is an efficient way to obtain red phosphors with better chromaticity.

Effect of Rare Earth Doped Elements and Characterization of LaF3:Ln3+ (Ln3+= Ce3+, Pr3+, Nd3+) Nanocrystals

2012 ◽  
Vol 585 ◽  
pp. 174-178 ◽  
Author(s):  
S.G. Gaurkhede ◽  
M.M. Khandpekar ◽  
S.P. Pati ◽  
A.T. Singh
Keyword(s):  
Rare Earth ◽  
Second Harmonic ◽  
Average Particle Size ◽  
Potassium Dihydrogen Phosphate ◽  
Xrd Analysis ◽  
Dihydrogen Phosphate ◽  
Average Particle ◽  
Tem Analysis ◽  
20 Nm

Abstract. LaF3 nanocrystals doped with lanthanides like Ce3+, Pr3+ and Nd3+ have been prepared using microwave technique. These synthesized crystals have been characterized by X-ray powder diffraction. Well dispersed, elongated, nanorods of hexagonal geometry (approximately 20nm in size) have been found in TEM analysis. The average particle size estimated from XRD analysis is about 20 nm and is in close agreement with the TEM results. Four characteristic peaks one at 3434 cm-1 (broad) and other at 2924, 2853, 1632 cm-1(sharp) have been observed in the FTIR spectra. Intense Blue colour (458 nm) emission has been recorded when crystals are excited with photons of wavelength 254 nm. Non Linear Optical (NLO) properties of the synthesized nanocrystals have been studied. It has been found that second harmonic generation (SHG) efficiency of the prepared samples containing rare earth elements is less than pure Potassium dihydrogen phosphate (KDP) crystals.

scholarly journals Selective Mineralization and Recovery of Au(III) from Multi-Ionic Aqueous Systems by Bacillus licheniformis FZUL-63

Minerals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 392
Author(s):  
Yangjian Cheng ◽  
Zhibin Ke ◽  
Xiaojing Bian ◽  
Jianhua Zhang ◽  
Zhen Huang ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Bacillus Licheniformis ◽  
Photoelectron Spectroscopy ◽  
Precious Metals ◽  
Aqueous Systems ◽  
Tem Analysis ◽  
X Ray ◽  
Practical Applications ◽  
Bacterial Surface ◽  
20 Nm

The recovery of precious metals is a project with both economic and environmental significance. In this paper, how to use bacterial mineralization to selectively recover gold from multi-ionic aqueous systems is presented. The Bacillus licheniformis FZUL-63, isolated from a landscape lake in Fuzhou University, was shown to selectively mineralize and precipitate gold from coexisting ions in aqueous solution. The removal of Au(III) almost happened in the first hour. Scanning electron microscope with X-ray energy dispersive spectroscopy (SEM/EDS-mapping) results and fourier transform infrared spectroscopy (FTIR) data show that the amino, carboxyl, and phosphate groups on the surface of the bacteria are related to the adsorption of gold ions. X-ray photoelectron spectroscopy (XPS) results implied that Au(III) ions were reduced to those that were monovalent, and the Au(I) was then adsorbed on the bacterial surface at the beginning stage (in the first hour). X-ray diffraction (XRD) results showed that the gold biomineralization began about 10 h after the interaction between Au(III) ions and bacteria. Au(III) mineralization has rarely been influenced by other co-existing metal ions. Transmission electron microscope (TEM) analysis shows that the gold nanoparticles have a polyhedral structure with a particle size of ~20 nm. The Bacillus licheniformis FZUL-63 could selectively mineralize and recover 478 mg/g (dry biomass) gold from aqua regia-based metal wastewater through four cycles. This could be of great potential in practical applications.

Large-scale synthesis of amorphous phosphorus nitride imide nanotubes with high luminescent properties

2005 ◽  
Vol 20 (2) ◽  
pp. 325-330 ◽  
Author(s):  
Qixun Guo ◽  
Qing Yang ◽  
Lei Zhu ◽  
Chengqi Yi ◽  
Yi Xie
Keyword(s):  
Electron Microscope ◽  
Photoelectron Spectroscopy ◽  
Large Scale ◽  
Luminescent Properties ◽  
Atomic Ratio ◽  
Binding Energies ◽  
X Ray ◽  
Microscope Images ◽  
Large Scale Synthesis ◽  
20 Nm

A facile solvothermal approach was successfully developed for the large-scale synthesis of amorphous phosphorus nitride imide (H3xP3N5+x) nanotubes with high luminescent properties by the reaction of 1,3,5-hexachlorotriphosphazene (P3N3Cl6) with sodium amide (NaNH2) at low temperatures. Transmission electron microscope images showed that the inner diameter of nanotubes is 120 ± 20 nm, wall thickness is 40 ± 10 nm, and length ranges from several to ten micrometers. Scanning electron microscope images revealed that the proportion of the nanotubes exceeds 90%. X-ray photoelectron spectroscopy spectra indicated that the binding energies of P2p and N1s are 133.30 and 398.40 eV, respectively, and the atomic ratio of P:N is 3:5.13. The infrared spectra of the sample are comparable to those of the reported HPN2 and HP4N7. Thermogravimetric analysis revealed that the product is very robust in a nonoxidizing atmosphere. The structure and the optical properties of the product and the annealed samples were investigated by x-ray diffraction and photoluminescence measurements, respectively.

A Study on Fabrication, Morphological and Optical Properties of Lead Sulfide Nanocrystals

2008 ◽  
Vol 8 (2) ◽  
pp. 967-972 ◽  
Author(s):  
Jung-Hsuan Chen ◽  
Shen-Chuan Lo ◽  
Chuen-Guang Chao ◽  
Tzeng-Feng Liu
Keyword(s):  
Lead Sulfide ◽  
Pore Diameter ◽  
Energy Gap ◽  
Quantum Confinement Effect ◽  
Porous Alumina ◽  
Blue Shift ◽  
Alumina Membrane ◽  
Tem Analysis ◽  
Pbs Nanocrystals ◽  
20 Nm

To investigate the properties of lead sulfide (PbS) nanocrystals, we have prepared PbS nanocrystals on/in the porous alumina membrane with a pore diameter 20 nm. Utilizing the reaction of Pb wires and the hydrogen sulfide (H2S) gas, PbS nanocrystals produced and grew as the reaction time increased. The composition identification of the nanocrystals was performed by the XPS and EDS analyses. More structure characteristics of the PbS nanocrystals obtained from the TEM analysis. As indicated in the PL spectra, an orange-red emission band appeared and the emission intensities were obviously related to the defects in the nanocrytals. A significant quantum confinement effect made the energy gap of PbS nanocrystals produce a blue shift from 0.41 eV to 1.89 eV. Furthermore, the growth mechanism of the PbS nanocrystals was also discussed.

The effect of Tin additionon on Structural and magnetic properties of the stannoferrite Li0.5+0.5XFe2.5-1.5XSnXO4

2016 ◽  
Vol 12 (3) ◽  
pp. 4307-4321 ◽  
Author(s):  
Ahmed Hassan Ibrahim ◽  
Yehia Abbas
Keyword(s):  
Particle Size ◽  
Fine Particles ◽  
Magnetic Moments ◽  
Lithium Ferrite ◽  
Tem Analysis ◽  
Weiss Temperature ◽  
X Ray ◽  
Two Phases ◽  
Nanocrystalline Ferrite ◽  
20 Nm

The physical properties of ferrites are verysensitive to microstructure, which in turn critically dependson the manufacturing process.Nanocrystalline Lithium Stannoferrite system Li0.5+0.5XFe2.5-1.5XSnXO4,X= (0, 0.2, 0.4, 0.6, 0.8 and 1.0) fine particles were successfully prepared by double sintering ceramic technique at pre-sintering temperature of 500oC for 3 h andthepre-sintered material was crushed and sintered finally in air at 1000oC.The structural and microstructural evolutions of the nanophase have been studied using X-ray powder diffraction (XRD) and the Rietveld method.The refinement results showed that the nanocrystalline ferrite has a two phases of ordered and disordered phases for polymorphous lithium Stannoferrite.The particle size of as obtained samples were found to be ~20 nm through TEM that increases up to ~ 85 nmand isdependent on the annealing temperature. TEM micrograph reveals that the grains of sample are spherical in shape. (TEM) analysis confirmed the X-ray results.The particle size of stannic substituted lithium ferrite fine particle obtained from the XRD using Scherrer equation.Magneticmeasurements obtained from lake shore’s vibrating sample magnetometer (VSM), saturation magnetization ofordered LiFe5O8 was found to be (57.829 emu/g) which was lower than disordered LiFe5O8(62.848 emu/g).Theinterplay between superexchange interactions of Fe3+ ions at A and B sublattices gives rise to ferrimagnetic ordering of magnetic moments,with a high Curie-Weiss temperature (TCW ~ 900 K).

Utilizing Nanoprobing and Circuit Diagnostics to Identify Key Failure Mechanism of Otherwise Nonvisible Defects in 20 nm Logic Devices

2014 ◽  
Author(s):  
M.K. Dawood ◽  
C. Chen ◽  
P.K. Tan ◽  
S. James ◽  
P.S. Limin ◽  
...  
Keyword(s):  
Failure Analysis ◽  
Contact Layer ◽  
Fault Isolation ◽  
Tem Analysis ◽  
Logic Devices ◽  
Technology Advancement ◽  
Transmission Electron ◽  
Voltage Contrast ◽  
Almost All ◽  
20 Nm

Abstract In this work, we present two case studies on the utilization of advanced nanoprobing on 20nm logic devices at contact layer to identify the root cause of scan logic failures. In both cases, conventional failure analysis followed by inspection of passive voltage contrast (PVC) failed to identify any abnormality in the devices. Technology advancement makes identifying failure mechanisms increasingly more challenging using conventional methods of physical failure analysis (PFA). Almost all PFA cases for 20nm technology node devices and beyond require Transmission Electron Microscopy (TEM) analysis. Before TEM analysis can be performed, fault isolation is required to correctly determine the precise failing location. Isolated transistor probing was performed on the suspected logic NMOS and PMOS transistors to identify the failing transistors for TEM analysis. In this paper, nanoprobing was used to isolate the failing transistor of a logic cell. Nanoprobing revealed anomalies between the drain and bulk junction which was found to be due to contact gouging of different severities.

Luminescent Properties of Gd2MoO6:Eu3+ Nanophosphor for WLEDs

2021 ◽  
Author(s):  
Yan Chen ◽  
Yuemei Lan ◽  
Dong Wang ◽  
Guoxing Zhang ◽  
Wenlong Peng ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Fluorescence Spectra ◽  
Solvothermal Method ◽  
Luminescent Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron

A series of Gd2-xMoO6:xEu3+(x=0.18-0.38) nanophosphors were synthesized by the solvothermal method. The properties of this nanophosphor were characterized by x-ray diffraction (XRD), transmission electron microscope (TEM), fluorescence spectra and diffuse...

scholarly journals Enhancement on the Tribological Properties of the Multilayer RGO/Al Matrix Composites by Cu-Coating Method

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3163
Author(s):  
Fengguo Liu ◽  
Ning Su ◽  
Renguo Guan
Keyword(s):  
Electron Microscope ◽  
Tribological Properties ◽  
Milled Powder ◽  
Wear Loss ◽  
Matrix Composites ◽  
Tem Analysis ◽  
Lubricating Film ◽  
Coating Method ◽  
Al Matrix Composites ◽  
Al Matrix

Multilayer reduced graphene oxide (mrGO) was chemically modified by electroless plating of copper on surface to form mrGO-Cu. The scanning electron microscope (SEM) and transmission electron microscope (TEM) analysis revealed that nano-Cu particles were uniformly dispersed on the surface of mrGO. The mrGO-Cu powders were further utilized as reinforcements for aluminum (Al) matrix and the mrGO-Cu/Al composite was successfully fabricated through clad rolling of milled powder. The tribological properties of the mrGO-Cu/Al composites were explored. The tribological results show that the mrGO-Cu could reduce the friction coefficient and wear loss of mrGO-Cu/Al composites, since the mrGO-Cu participated in lubricating processes due to the formation of a transfer layer on the contact surface. Furthermore, it is found that the composition of mrGO-Cu could significantly influence the tribological properties of the mrGO-Cu/Al composites. The composites with 4% of mrGO-Cu for composites exhibited the best tribological behavior, which transformed from adhesive wear to abrasive wear, due to the formation of a graphite lubricating film.

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