scholarly journals ESR identification of the nitrogen acceptor in 2H-polytype synthetic MoS2: Dopant level and activation

AIP Advances ◽  
2017 ◽  
Vol 7 (10) ◽  
pp. 105006 ◽  
Author(s):  
B. Schoenaers ◽  
A. Stesmans ◽  
V. V. Afanas’ev
Keyword(s):  
Dopant Level

Effect of MWCNT doping on the structural and optical properties of PVC/PVDF polymer blend

2017 ◽  
Vol 13 (2) ◽  
pp. 4640-4647
Author(s):  
A. M. Abdelghany ◽  
M.S. Meikhail ◽  
S.I. Badr ◽  
A. S. Momen
Keyword(s):  
Surface Damage ◽  
X Ray Diffraction ◽  
Dopant Content ◽  
Casting Technique ◽  
Transmission Electron ◽  
Dopant Level ◽  
Before And After ◽  
Carbon Nano Tubes ◽  
Small Band ◽  
Vibrational Bands

Thin film samples of pristine polyvinyl chloride (PVC), poly vinyldine fluoride (PVDF) in combination with their blend in addition to samples containing factorial mass fraction of multi wall carbon nano-tubes (MWCNTs) in the dopant level were prepared via routine casting technique using tetrahydrofurane (THF) as a common solvent. X-ray diffraction and transmission electron microscopy (TEM) depict the nano-scale (15-25 nm) of functionalized MWCNTs with no surface damage results from functionalization process.X-ray diffraction (XRD) shows a semi-crystalline nature of PVDF with evidence for more than one phase namely a and b phases. The fraction of b phase was calculated and correlated to the dopant content. FTIR optical absorption spectra revels a preservation of the main vibrational bands before and after addition of MWCNTs in the doping level with a presence of new small band 1151 cm-1 assigned for the interaction and complexation between constituents.

Formation of Cobalt Doped Zinc Oxide Photocatalyst for Methyl Orange Degradation

2017 ◽  
Vol 264 ◽  
pp. 211-214 ◽  
Author(s):  
Farah Iddayu Abu Bakar ◽  
Katerina Anak Birang ◽  
Mohd Azam Mohd Adnan ◽  
Jeefferie Abd Razak ◽  
Syahriza Ismail
Keyword(s):  
Zinc Oxide ◽  
Methyl Orange ◽  
Sol Gel ◽  
Morphological Observation ◽  
X Ray Diffraction ◽  
Methyl Orange Degradation ◽  
Zno Nanostructure ◽  
Dopant Level ◽  
And Performance ◽  
Co Doped

The formation of cobalt (Co) doped zinc oxide (ZnO) as photocatalyst for photodegradation of methyl orange dye was investigated. The ZnO photocatalyst was produced with different concentration of Co by using sol gel method. The hexagonal wurtzite and zincite structure were successfully formed through this method. The morphological observation of nanorod and nanodisk structure formed was done by Field Emission Scanning Electron Microscope (FESEM). While, the structural properties of Co doped ZnO were identified by X-ray Diffraction (XRD) and Raman spectroscopy. The degradation performance of methyl orange was assessed and performance of photocatalytic activity was correlated to the amount of dopant level and oxygen vacancy of photocatalyst. There is an optimum amount of Co that can be doped into ZnO nanostructure in order to provide better degradation of methyl orange.

Visualization of different carrier concentrations in n-type-GaN semiconductors by phase-shifting electron holography with multiple electron biprisms

Microscopy ◽  
2019 ◽  
Vol 69 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Kazuo Yamamoto ◽  
Kiyotaka Nakano ◽  
Atsushi Tanaka ◽  
Yoshio Honda ◽  
Yuto Ando ◽  
...  
Keyword(s):  
Focused Ion Beam ◽  
Ion Beam ◽  
Phase Shifting ◽  
Active Layer Thickness ◽  
Electron Holography ◽  
Wide Field ◽  
Transmission Electron ◽  
Dopant Level ◽  
Phase Profile ◽  
Phase Resolution

Abstract Phase-shifting electron holography (PS-EH) using a transmission electron microscope (TEM) was applied to visualize layers with different concentrations of carriers activated by Si (at dopant levels of 1019, 1018, 1017 and 1016 atoms cm−3) in n-type GaN semiconductors. To precisely measure the reconstructed phase profiles in the GaN sample, three electron biprisms were used to obtain a series of high-contrast holograms without Fresnel fringes generated by a biprism filament, and a cryo-focused-ion-beam (cryo-FIB) was used to prepare a uniform TEM sample with less distortion in the wide field of view. All layers in a 350-nm-thick TEM sample were distinguished with 1.8-nm spatial resolution and 0.02-rad phase-resolution, and variations of step width in the phase profile (corresponding to depletion width) at the interfaces between the layers were also measured. Thicknesses of the active and inactive layers at each dopant level were estimated from the observed phase profile and the simulation of theoretical band structure. Ratio of active-layer thickness to total thickness of the TEM sample significantly decreased as dopant concentration decreased; thus, a thicker TEM sample is necessary to visualize lower carrier concentrations; for example, to distinguish layers with dopant concentrations of 1016 and 1015 atoms cm−3. It was estimated that sample thickness must be more than 700 nm to make it be possible to detect sub-layers by the combination of PS-EH and cryo-FIB.

Characterization of the influence of fission product doping on the anodic reactivity of uranium dioxide

2007 ◽  
Vol 85 (10) ◽  
pp. 702-713 ◽  
Author(s):  
Heming He ◽  
Peter G Keech ◽  
Michael E Broczkowski ◽  
James J Noël ◽  
David W Shoesmith
Keyword(s):  
Raman Spectroscopy ◽  
Fission Product ◽  
Uranium Dioxide ◽  
Photoelectron Spectroscopy ◽  
Fission Products ◽  
Nuclear Fission ◽  
Lattice Contraction ◽  
Cubic Symmetry ◽  
X Ray ◽  
Dopant Level

The influence of fission product doping on the structure, composition, and electrochemical reactivity of uranium dioxide has been studied using X-ray diffractometry (XRD), scanning electron microscopy (SEM/EDX), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Experiments were conducted on SIMFUEL specimens with simulated burn-ups (increasing doping levels) of 1.5, 3.0, and 6.0 atom%. As the dopant level increased, the lattice contracted, suggesting the dominant formation of dopant-oxygen vacancy clusters. The smaller than expected lattice contraction can be attributed to the segregation of Zr (one of eleven added dopants) to ABO3 perovskite-type phases that SEM/EDX shows also contain Ba, Ce, and possibly some U. Raman spectroscopy shows that doping leads to a loss of cubic symmetry, possibly associated with tetragonal distortions. Raman mapping confirms this loss of cubic symmetry and suggests the specimen is not uniformly doped. Electrochemical experiments show that these distortions lead to a decrease in the oxidative dissolution rate of the UO2 with increased doping density.Key words: UO2, X-ray diffraction, electrochemistry, Raman spectroscopy, nuclear fission products.

scholarly journals Sensitization of Perovskite Strontium Stannate SrSnO3towards Visible-Light Absorption by Doping

2014 ◽  
Vol 2014 ◽  
pp. 1-3 ◽  
Author(s):  
Hungru Chen ◽  
Naoto Umezawa
Keyword(s):  
Solar Energy ◽  
Visible Light ◽  
Band Gap ◽  
Light Absorption ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Visible Light Absorption ◽  
Dopant Level ◽  
Strontium Stannate ◽  
Hybrid Density Functional

Perovskite strontium stannate SrSnO3is a promising photocatalyst. However, its band gap is too large for efficient solar energy conversion. In order to sensitize SrSnO3toward visible-light activities, the effects of doping with various selected cations and anions are investigated by using hybrid density functional calculations. Results show that doping can result in dopant level to conduction band transitions which lie lower in energy compared to the original band gap transition. Therefore, it is expected that doping SrSnO3can induce visible-light absorption.

Thermodynamics of the tetragonal-to-monoclinic phase transformation in fine and nanocrystalline yttria-stabilized zirconia powders

2003 ◽  
Vol 18 (12) ◽  
pp. 2912-2921 ◽  
Author(s):  
Arun Suresh ◽  
Merrilea J. Mayo ◽  
Wallace D. Porter
Keyword(s):  
Particle Size ◽  
Phase Transformation ◽  
Transformation Temperature ◽  
Phase Transformation Temperature ◽  
Scanning Calorimetry ◽  
Fine Grained ◽  
Dopant Level ◽  
M Phase ◽  
Additional Strain ◽  
Enthalpy And Entropy Changes

The current study uses high-temperature differential scanning calorimetry to document the shift in phase-transformation temperature with particle size throughout a series of alloys in the zirconia–yttria system (0–1.5 mol% yttria). The tetragonal-to-monoclinic (T→M) phase-transformation temperature is seen to vary inversely with particle size. It is shown that a simple thermodynamic approach first proposed by Garvie predicts this inverse linear relationship. Subsequent determination of the key thermodynamic parameters therein (e.g., the surface and volume free energy, enthalpy, and entropy changes involved in the phase transformation) allows a complete predictive equation for the T→M phase transformation in the yttria–zirconia system to be developed as a function of particle size and yttria dopant level. The yttria–zirconia phase diagram is then redrawn with grain size as a third variable. It should be stressed that the current analysis is valid for particulate systems only; a parallel paper tackles the problem for fine-grained yttria–zirconia solids, where the approach is similar, but additional strain energy terms come into play.

Dopant induced modifications in the physical properties of sprayed ZnO:In films

1993 ◽  
Vol 8 (5) ◽  
pp. 1052-1056 ◽  
Author(s):  
D.J. Goyal ◽  
Chitra Agashe ◽  
M.G. Takwale ◽  
V.G. Bhide ◽  
Shailaja Mahamuni ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Photoelectron Spectroscopy ◽  
Crystal Orientation ◽  
Spray Pyrolysis Technique ◽  
Small Addition ◽  
X Ray ◽  
Dopant Incorporation ◽  
Indium Doping ◽  
Dopant Level ◽  
Compositional Properties

Indium-doped zinc oxide (IZO) films were prepared by the spray pyrolysis technique. The effect of gradual incorporation of indium cations on the structural, electrical, and compositional properties of IZO films was studied in detail. It was observed that even a small addition of indium modifies the preferred growth of IZO film from the [002] direction to the [101] direction. Such a modification in growth pattern is a result of more nucleating centers created by indium doping. Indium dopant improves the electrical properties of the films. The carrier concentration depends mainly on the indium dopant level while the mobility is affected by the changes in crystal orientation that take place due to addition of dopants. X-ray photoelectron spectroscopy results show that indium doping does not lead to any stoichiometric changes in the IZO films and the dopant incorporation in the film is linearly proportional to that in the solution.

Scintillator Material Growth

1982 ◽  
Vol 16 ◽  
Author(s):  
O. H. Nestor
Keyword(s):  
Plastic Deformation ◽  
Large Scale ◽  
Growth Control ◽  
Commercial Production ◽  
Material Growth ◽  
Dopant Level ◽  
Scintillator Material

ABSTRACTSelected aspects of NaI(Tl), Bi4Ge3O12 and CdWO4 growth are addressed. Purity and growth control, dopant level effects, specific imperfections and plastic deformation in large scale commercial production are considered.

Preparation and characterization of transparent Nd:YAG ceramics

2009 ◽  
Vol 17 (1) ◽  
Author(s):  
Z. Librant ◽  
J.K. Jabczyński ◽  
H. Węglarz ◽  
A. Wajler ◽  
H. Tomaszewski ◽  
...  
Keyword(s):  
Pump Power ◽  
Laser Diode ◽  
Duty Cycle ◽  
Slope Efficiency ◽  
Diode Pumping ◽  
Active Elements ◽  
Grain Sizes ◽  
Low Duty Cycle ◽  
Dopant Level

AbstractTransparent Nd:YAG ceramics were produced by solid.state reaction of high.purity (4N) nanometric oxides powders, i.e., Al2O3, Y2O3 and Nd2O3. After sintering, mean grain sizes of 2% Nd:YAG samples were about 20 μm and their transparency were a bit worse than that of 0.9% Nd:YAG single crystal. Two types of active elements: rods and slabs were fabricated and characterized in several diode pumping schemes. In end pumping configuration as a pump source 20.W fiber coupled laser diode operating in low duty cycle regime (1 ms pump duration/20 Hz) was deployed. In the best case, 3.7 W of output power for 18 W of absorbed pump power, M2 < 1.4 were demonstrated for uncoated ceramics Nd:YAG rod of ϕ 4×3mm size in preliminary experiments. For the ceramics of two times lower Nd dopant level above 30% slope efficiency was achieved. In case of Nd:YAG ceramic slab side pumped by 600.W laser diode stack above 12 W was demonstrated with slope efficiency of 3.5%.

Synthesis and Characterization of Antimony-Doped Tin Oxide Nanophase materials for Electrochromic Applications

1997 ◽  
Vol 501 ◽  
Author(s):  
J. Liu ◽  
J. P. Coleman ◽  
P. Madhukar
Keyword(s):  
Tin Oxide ◽  
Tin Dioxide ◽  
Structural Evolution ◽  
Display Devices ◽  
Annealing Conditions ◽  
Dopant Level ◽  
Oxide Phases ◽  
Nanophase Materials ◽  
The Relationship

ABSTRACTAntimony-doped tin oxide (ATO) nanophase materials containing up to 43 mole% antimony have been synthesized by a wet-chemistry method. These ATO materials exhibit enhanced electrochromic properties for display devices. The performance of the display devices is related to the nanostructure of the synthesized ATO materials. The average sizes of the ATO nanocrystallites depend on dopant level, annealing conditions, and synthesis processes. Antimony inhibits the growth of tin dioxide nanocrystallites during annealing at moderate temperatures. At higher annealing temperatures, however, antimony segregates to form separate oxide phases and ATO nanocrystallites grow significantly. A systematic study of the structural evolution of the synthesized ATO materials is presented and the relationship between the nanostructure of the ATO materials and the enhanced performance of the corresponding electrochromic devices is discussed.

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