Photoluminescence of Surface Modified Silicon Carbide Nanowires

2011 ◽  
Vol 1350 ◽  
Author(s):  
Polite D. Stewart ◽  
Ryan Rich ◽  
A. Nemashkalo ◽  
T. W. Zerda
Keyword(s):  
Stress Reduction ◽  
Surface Defects ◽  
Average Diameter ◽  
Silicon Powder ◽  
Amorphous Layer ◽  
Silicon Compounds ◽  
X Ray ◽  
Sic Nanowires ◽  
Surface Modified ◽  
Amorphous Sic

ABSTRACTSiC nanowires were produced from carbon nanotubes and nanosize silicon powder in a tube furnace at temperatures between 1100°C and 1350°C. SiC nanowires had average diameter of 30 nm and very narrow size distribution. The surface of the SiC nanowires is covered by an amorphous layer composed of amorphous SiC and various carbon and silicon compounds. The objective of the research was to modify the surface structure of the SiC nanowires, a step necessary for future surface functionalization. The acid etched nanowires were analyzed using FTIR, TEM, x-ray diffraction, and photoluminescence. The concentration of Si-Ox groups in untreated specimens was estimated to account for 1% of the total mass of a 2 nm thick amorphous layer wrapping around all structures. After treatment in HF this concentration was negligibly small. TEM images show that after treatment the amorphous layer was removed but the diameter of the core remained unchanged. The surface was roughened and multiple pits formed on that surface. X-ray line broadening analysis indicates a significant contribution due to stress caused by dislocations and planar faults. After acid etching line narrowing was observed and attributed to stress reduction and elimination of the smallest wires. The photoluminescence signal from as received samples was very weak but increased greatly after acid treatment, indicating that the signal is related to surface defects. Measurements at low temperatures, 8 K, showed peaks due to point and planar defects.

scholarly journals Ultrasound-Assisted Surface Modification of MWCNT Using Organic Acids

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 72
Author(s):  
Patricia A. de León-Martínez ◽  
Aidé Sáenz-Galindo ◽  
Carlos A. Ávila-Orta ◽  
Adalí O. Castañeda-Facio ◽  
Marlene L. Andrade-Guel ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Organic Acids ◽  
Functional Groups ◽  
Photoelectron Spectroscopy ◽  
Surface Defects ◽  
Low Frequency ◽  
Carbon Surface ◽  
X Ray ◽  
Different Types ◽  
Surface Modified

In the present work, multiple-wall carbon nanotubes (MWCNTs) were surface modified in an environmentally friendly way, using low-frequency ultrasonic energy. This type of modification was carried-out using two different types of organic acids, citric acid (CA) and oxalic acid (OA). The modification of the MWCNTs was confirmed by Fourier-transform infrared spectroscopy (FTIR), where functional groups such as OH, C=O, O–C=O and COOH were detected. By means of Raman spectroscopy, an increase in carbon surface defects was found. On the other hand, using X-ray photoelectron spectroscopy (XPS), oxidation was evidenced on the surface of the modified MWCNT. In both Raman spectroscopy and XPS, the results indicate a greater modification when CA is used, possibly due to the fact that CA has a larger number of functional groups. MWCNT-CA showed good dispersion in methanol, while MWCNT-OA showed good stability in methanol and ethanol. Finally, a 20% removal of creatinine efficiency improvement was found with respect to the unmodified MWCNTs, while no improvement was found in the case of urea and uric acid.

scholarly journals α-Cellulose Fibers of Paper-Waste Origin Surface-Modified with Fe3O4 and Thiolated-Chitosan for Efficacious Immobilization of Laccase

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 581
Author(s):  
Gajanan S. Ghodake ◽  
Surendra K. Shinde ◽  
Ganesh D. Saratale ◽  
Rijuta G. Saratale ◽  
Min Kim ◽  
...  
Keyword(s):  
Enzyme Immobilization ◽  
Photoelectron Spectroscopy ◽  
Cellulose Fibers ◽  
Relative Activity ◽  
Significant Activity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Laccase Immobilization ◽  
Surface Modified

The utilization of waste-paper-biomass for extraction of important α-cellulose biopolymer, and modification of extracted α-cellulose for application in enzyme immobilization can be extremely vital for green circular bio-economy. Thus, in this study, α-cellulose fibers were super-magnetized (Fe3O4), grafted with chitosan (CTNs), and thiol (-SH) modified for laccase immobilization. The developed material was characterized by high-resolution transmission electron microscopy (HR-TEM), HR-TEM energy dispersive X-ray spectroscopy (HR-TEM-EDS), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FT-IR) analyses. Laccase immobilized on α-Cellulose-Fe3O4-CTNs (α-Cellulose-Fe3O4-CTNs-Laccase) gave significant activity recovery (99.16%) and laccase loading potential (169.36 mg/g). The α-Cellulose-Fe3O4-CTNs-Laccase displayed excellent stabilities for temperature, pH, and storage time. The α-Cellulose-Fe3O4-CTNs-Laccase applied in repeated cycles shown remarkable consistency of activity retention for 10 cycles. After the 10th cycle, α-Cellulose-Fe3O4-CTNs possessed 80.65% relative activity. Furthermore, α-Cellulose-Fe3O4-CTNs-Laccase shown excellent degradation of pharmaceutical contaminant sulfamethoxazole (SMX). The SMX degradation by α-Cellulose-Fe3O4-CTNs-Laccase was found optimum at incubation time (20 h), pH (3), temperatures (30 °C), and shaking conditions (200 rpm). Finally, α-Cellulose-Fe3O4-CTNs-Laccase gave repeated degradation of SMX. Thus, this study presents a novel, waste-derived, highly capable, and super-magnetic nanocomposite for enzyme immobilization applications.

scholarly journals On the amorphous layer in bone mineral and biomimetic apatite: A combined small- and wide-angle X-ray scattering analysis.

2020 ◽  
Author(s):  
Federica Bertolotti ◽  
Francisco J. Carmona ◽  
Gregorio Dal Sasso ◽  
Gloria B. Ramírez-Rodríguez ◽  
José Manuel Delgado-López ◽  
...  
Keyword(s):  
Bone Mineral ◽  
Amorphous Layer ◽  
Wide Angle ◽  
X Ray ◽  
X Ray Scattering ◽  
Biomimetic Apatite ◽  
Ray Scattering

Problems Associated with Kα Doublet in Residual Stress Measurements

1979 ◽  
Vol 23 ◽  
pp. 333-339
Author(s):  
S. K. Gupta ◽  
B. D. Cullity
Keyword(s):  
Residual Stress ◽  
Silicon Powder ◽  
Lattice Parameter ◽  
Diffraction Peak ◽  
Parameter Determination ◽  
X Ray Diffraction ◽  
X Ray ◽  
Analysis Techniques ◽  
The Difference ◽  
Similar Accuracy

Since the measurement of residual stress by X-ray diffraction techniques is dependent on the difference in angle of a diffraction peak maximum when the sample is examined consecutively with its surface at two different angles to the diffracting planes, it is important that these diffraction angles be obtained precisely, preferably with an accuracy of ± 0.01 deg. 2θ. Similar accuracy is desired in precise lattice parameter determination. In such measurements, it is imperative that the diffractometer be well-aligned. It is in the context of diffractometer alignment with the aid of a silicon powder standard free of residual stress that the diffraction peak analysis techniques described here have been developed, preparatory to residual stress determinations.

Corrosion Behaviours of Mo Modified Ti6Al4V Alloy in Hank’s Solution

2009 ◽  
Vol 610-613 ◽  
pp. 1150-1154
Author(s):  
Ai Lan Fan ◽  
Cheng Gang Zhi ◽  
Lin Hai Tian ◽  
Lin Qin ◽  
Bin Tang
Keyword(s):  
Electrochemical Corrosion ◽  
Optical Emission ◽  
Ti6al4v Alloy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffusion Layers ◽  
Modified Layer ◽  
Surface Modified ◽  
Hank’S Solution ◽  
And Diffusion

The Mo surface modified layer on Ti6Al4V alloy was obtained by the plasma surface alloying technique. The structure and composition of the Mo modified Ti6Al4V alloy was investigated by X-ray diffraction (XRD) and glow discharge optical emission spectroscopy (GDOES). The Mo modified layer contains Mo coating on subsurface and diffusion layers between the subsurface and substrate. The X- ray diffraction analysis of the Mo modified Ti6Al4V alloy reveals that the outmost surface of the Mo modified Ti6Al4V alloy is composed of pure Mo. The electrochemical corrosion performance of the Mo modified Ti6Al4V alloy in 25°C Hank’s solution was investigated and compared with that of Ti6Al4V alloy. Results indicate that the self-corroding electric potential and the corrosion-rate of the Mo modified Ti6Al4V alloy are higher than that of Ti6Al4V alloy in 25°C Hank’s solution.

Characterization of Al65.0Cu32.9Co2.1 Alloy Containing Nanofibres

2012 ◽  
Vol 186 ◽  
pp. 212-215
Author(s):  
Jacek Krawczyk ◽  
Włodzimierz Bogdanowicz ◽  
Grzegorz Dercz ◽  
Wojciech Gurdziel
Keyword(s):  
Electron Microscopy ◽  
Average Diameter ◽  
Chemical Compositions ◽  
X Ray ◽  
Transmission Electron ◽  
Orthogonal Set ◽  
T Phase ◽  
Terminal Area ◽  
Scanning Electron

Microstructure of terminal area of Al65Cu32.9Co2.1ingots (numbers indicate at.%), obtained via directional solidification was studied. Scanning Electron Microscopy, Transmission Electron Microscopy and X-ray powder diffraction were applied. Point microanalysis by Scanning Electron Microscope was used for examination of chemical compositions of alloy phases. It was found that tetragonal θ phase of Al2Cu stoichiometric formula was the dominate phase (matrix). Additionally the alloy contained orthogonal set of nanofibres of Al7Cu2Co T phase with the average diameter of 50-500 nm and oval areas of hexagonal Al3(Cu,Co)2H-phase, surrounded by monoclinic AlCu η1phase rim. Inside some areas of H-phase cores of decagonal quasicrystalline D phase were observed.

Dissolution Characteristics and Morphology of Large-sized Scorodite Particles Synthesized from Fe(II) and As(V) in Aqueous Solution

2012 ◽  
Vol 31 (4-5) ◽  
pp. 451-458 ◽  
Author(s):  
S. Fujieda ◽  
K. Shinoda ◽  
T. Inanaga ◽  
M. Abumiya ◽  
S. Suzuki
Keyword(s):  
Electron Microscopy ◽  
Aqueous Solution ◽  
Surface Defects ◽  
Atmospheric Temperature ◽  
Orthorhombic Structure ◽  
X Ray ◽  
Long Term Storage ◽  
Transmission Electron ◽  
Term Storage

AbstractA novel process for preparing scorodite particles with a diameter of approximately 20 µm from Fe(II) and As(V) in aqueous solution has been developed by DOWA Metals and Mining. In the present study, the dissolution characteristics of iron and arsenic from the scorodite particles synthesized by this process have been investigated under different conditions. The results show that the concentration of arsenic dissolved from the particles in aqueous solution is very low, but it has a complicated dependence on the temperature and pH of the solution. Transmission electron microscopy (TEM) with an energy dispersive X-ray spectrometer (EDS) was used to analyze the morphology, structure, and composition of the scorodite particles. The results indicate that the scorodite particles exhibit a nearly octahedral shape with planes composed of almost (111) planes in the orthorhombic structure. The concentration of iron at the surface of the particles is higher than that of iron inside of the particles. This characteristic morphology, along with the minimal surface defects of the scorodite particles, is considered to be responsible for the low dissolution of arsenic from the particles in aqueous solution. Atmospheric temperature and solution conditions were also found to be important for the safe, long-term storage of arsenic using scorodite particles.

Tribological Behavior of Carbon Nanotubes as an Additive on Lithium Grease

2014 ◽  
Vol 137 (1) ◽  
Author(s):  
Alaa Mohamed ◽  
T. A. Osman ◽  
A. Khattab ◽  
M. Zaki
Keyword(s):  
Carbon Nanotubes ◽  
Arc Discharge ◽  
Average Diameter ◽  
Friction Reduction ◽  
Lithium Grease ◽  
X Ray ◽  
Transmission Electron ◽  
Boundary Film ◽  
Load Carrying ◽  
Worn Surface

Carbon nanotubes (CNTs) with 10 nm average diameter and 5 μm in length were synthesized by electric arc discharge. The morphology and structure of CNTs were characterized by high resolution transmission electron microscopy (HRTEM) and X-ray powder diffraction. The tribological properties of CNTs as an additive on lithium grease were evaluated with a four ball tester. The results show that the grease with CNTs exhibit good performance in antiwear (AW) and decrease the wear scare diameter (WSD) about 63%, decrease friction reduction about 81.5%, and increase the extreme pressure (EP) properties and load carrying capacity about 52% with only 1% wt. of CNTs added to lithium grease. The action mechanism was estimated through analysis of the worn surface with a scanning electron microscope (SEM) and energy dispersive X-ray (EDX). The results indicate that a boundary film mainly composed of CNTs, Cr, iron oxide, and other organic compounds was formed on the worn surface during the friction process.

Synthesis of Silica Modified Large-Sized Hydroxyapatite Whiskers by a Hydrothermal Co-Precipitation Method

2015 ◽  
Vol 645-646 ◽  
pp. 1339-1344 ◽  
Author(s):  
Yan Ting Yin ◽  
Qing Hua Chen ◽  
Ting Ting Yan ◽  
Qing Hua Chen
Keyword(s):  
Bone Repair ◽  
Ethanol Solution ◽  
Morphological Properties ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
New Type ◽  
Ft Ir ◽  
Co Precipitation ◽  
Surface Modified

The objective of this study was to develop a novel silica modified large-sized hydroxyapatite whiskers with improved properties for use in bone repair applications. Large-sized whiskers with a mean length of 250μm were obtained by a hydrothermal co-precipitation method at 150°C, 7.5Mpa in high-pressure reactor. Silica modified hydroxyapatite whiskers were prepared by dissolving TEOS in ethanol solution, then sintering with hydroxyapatite. The compositional and morphological properties of prepared whiskers were studied by means of x-ray diffraction (XRD), Fouier transform infrared (FT-IR), scanning electron microscopy (SEM). The results indicated the evidence of nanosilicon dioxide particles on the surface of HAP whiskers. The size of nanosilicon dioxide particles depends on dropping and stirring rate. Hence, this new type of silica modified large-sized hydroxyapatite whiskers is a valuable candidate for biomedical applications.Key words: hydroxyapatite, hydrothermal co-precipitation, surface modified, whiskers

X-ray diffraction study on surface modified complex strontium titanate microparticles

2003 ◽  
Vol 351 (1-2) ◽  
pp. 295-298 ◽  
Author(s):  
G.Y. Liu ◽  
Y.L. Zhang ◽  
X.M. Feng ◽  
J.K. Liang ◽  
G.H. Rao
Keyword(s):  
Diffraction Study ◽  
Strontium Titanate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Surface Modified
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