PLD Growth of CNTs using a Nanostuctured Ni Buffer Layer: Dependence of H2 partial Pressure

2006 ◽  
Vol 951 ◽  
Author(s):  
Maneesh Chandran ◽  
K. Mohan Kant ◽  
N. Rama ◽  
M.S. Ramachandra Rao
Keyword(s):  
Thin Films ◽  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Partial Pressure ◽  
Buffer Layer ◽  
Good Yield ◽  
Near Infrared ◽  
Hydrogen Atmosphere ◽  
Hydrogen Partial Pressure ◽  
Partial Pressures

ABSTRACTThe effect of hydrogen partial pressure on the growth of CNT thin films using on-axis PLD has been studied. Using nickel as buffer layer, carbon nanotubes can be produced with good yield in Hydrogen atmosphere. We have found strong visible-near infrared (NIR) photoluminescence (PL) from carbon nanotube thin films synthesized under various hydrogen partial pressures. The present result shows that bright, narrow PL from CNTs can be obtained without any post growth processing.

Low Temperature Si Homoepitaxy: Effects of Impurities on Microstructure

1993 ◽  
Vol 312 ◽  
Author(s):  
D. P. Adamst ◽  
D. J. Eaglesham ◽  
S. M. Yalisove
Keyword(s):  
Surface Roughness ◽  
Low Temperature ◽  
Partial Pressure ◽  
Hydrogen Partial Pressure ◽  
Surface Roughening ◽  
Partial Pressures

AbstractHydrogen is shown to influence the surface roughness during low temperature Si MBE. Small partial pressures (1 × 10-7 Torr) of deuterium, introduced during Si growth at 310°C, are sufficient to increase the surface width to ∼30 Å before breakdown of epitaxy. This work is consistent with previous studies of the dependence of epitaxial thickness on hydrogen partial pressure and supports a model in which surface roughening leads to the breakdown of epitaxy.

Optical enzymatic detection of glucose based on hydrogen peroxide-sensitive HiPco carbon nanotubes

2006 ◽  
Vol 21 (11) ◽  
pp. 2817-2823 ◽  
Author(s):  
Chulho Song ◽  
Pehr E. Pehrsson ◽  
Wei Zhao
Keyword(s):  
Carbon Nanotubes ◽  
Hydrogen Peroxide ◽  
Carbon Nanotube ◽  
Near Infrared ◽  
Sodium Dodecyl ◽  
Enzymatic Reaction ◽  
Infrared Region ◽  
Infrared Spectral ◽  
Sensitivity And Selectivity ◽  
Enzymatic Detection

We recently observed that surfactant sodium dodecyl sulfate (SDS)-encased HiPco single-walled carbon nanotubes (SWNTs) respond optically to hydrogen peroxide (H2O2) in the near-infrared region. In this report, we demonstrate that SDS-encased SWNTs immobilized with glucose oxidase (GOx) can be used to optically detect an enzymatic reaction of glucose based on their H2O2 sensitivity as well as pH sensitivity. Only the enzymatic product H2O2 induces the SWNT near-infrared spectral changes in buffer solutions (pH = 6.0), but both H2O2 and gluconic acid products do this in unbuffered solutions. The SWNT optical response to glucose possesses sensitivity and selectivity similar to an electrochemical method using carbon nanotube nanoelectrode arrays. Our results suggest possible carbon nanotube-based optical tools for molecular recognition applications.

Role of Oxygen Vacancies on the Ferroelectric Properties of Pzt Thin Films

1991 ◽  
Vol 243 ◽  
Author(s):  
Chi Kong Kwok ◽  
Seshu B. Desu
Keyword(s):  
Thin Films ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Vacancy Concentration ◽  
Ferroelectric Properties ◽  
Sol Gel ◽  
Low Oxygen ◽  
Partial Pressures ◽  
Pzt Films

AbstractThe properties of ferroelectric thin films can be significantly influenced by the presence of point defects. The concentration of vacancies presented in these thin films is known to be one of the key parameters causing the degradation of these films when these films are subjected to polarization reversals.To study the effects of the vacancy concentration on the ferroelectric properties, sol gel PZT films and powders were annealed in different oxygen partial pressures. For the PZT films, the reduction of oxides to pure metals was not observed even with films annealed at 2×10−5 atmosphere of oxygen partial pressure. Samples annealed at low oxygen partial pressure (for instance, 10−3 and 2×10−5 atmosphere), which has more Pb and O2 depletions and consequently has more Pb and O2 vacancies, cannot be switched easily. The ratios of coercive field after and before fatigue increase as the defect concentrations of the annealed samples increase.

Growth and Characterization of ZnO Thin Films Grown by Pulsed Laser Deposition

2011 ◽  
Vol 383-390 ◽  
pp. 6289-6292
Author(s):  
Jian Ting He ◽  
Bo Xue Tan ◽  
Qin Qin Wei ◽  
Yuan Bin Su ◽  
Shu Lian Yang
Keyword(s):  
Thin Films ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Pulsed Laser Deposition ◽  
Photoelectron Spectroscopy ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Zno Thin Films ◽  
X Ray ◽  
Partial Pressures

ZnO thin films were deposited on n-Si (111) substrates at various oxygen partial pressures by pulsed laser deposition (PLD). X-ray diffraction (XRD), scanning electron microscopy (SEM) were used to analyze the influence of the oxygen partial pressure on the crystallization and morphology of the ZnO thin films. An optimal crystallized ZnO thin film was observed at the oxygen partial pressure of 6.5Pa. X-ray photoelectron spectroscopy (XPS) was used to analyze the surface components and distribution status of various elments in ZnO thin films. It was found that ZnO thin films were grown in Zn-rich state.

scholarly journals A Study On The Fabrication Of Iron Powder From Forging Scale Using Hydrogen

2015 ◽  
Vol 60 (2) ◽  
pp. 1547-1549 ◽  
Author(s):  
S.M. Shin ◽  
D.-W. Lee ◽  
J.-Y. Yun ◽  
CH.-Y. Kang ◽  
J.-P. Wang
Keyword(s):  
Partial Pressure ◽  
Iron Powder ◽  
Metallic Iron ◽  
Hydrogen Partial Pressure ◽  
Hydrogen Gas ◽  
Temperature Reaction ◽  
Reduction Of Iron ◽  
Partial Pressures ◽  
Mean Size ◽  
The Mean

Abstract This study was conducted to investigate the effect of hydrogen content, temperature, reaction time for the reduction of forging scale which is mainly composed of hematite (Fe2O3). All reductive reactions were performed over the temperature range of 700 to 1200°C as well as 0.1 to 1 atm of hydrogen partial pressures. The results showed that the mechanism for the reduction of iron oxides using hydrogen gas was not a simple process, but proceeded in multiple reduction stages thermodynamically. The iron oxide was almost completely reduced to metallic iron powder with 91 wt.% of iron content in the forging scale at 0.1 atm of hydrogen partial pressure. The content of iron was however found to be increased with increasing hydrogen partial pressure from 0.1 to 1 atm with regardless of temperatures. The metallic iron powder was obtained with the mean size of 100 μm and more porous structure was observed.

OPTICAL AND ELECTRICAL PROPERTIES OF VANADIUM NITRIDE THIN FILMS

1999 ◽  
Vol 13 (07) ◽  
pp. 833-839 ◽  
Author(s):  
M. GHANASHYAM KRISHNA ◽  
A. K. BHATTACHARYA
Keyword(s):  
Thin Films ◽  
Partial Pressure ◽  
Total Pressure ◽  
Optical Constants ◽  
Vanadium Nitride ◽  
Nitrogen Partial Pressure ◽  
Dc Magnetron Sputtering ◽  
Partial Pressures ◽  
Similar Dependence ◽  
Quartz Substrates

Vanadium nitride thin films have been deposited on to quartz substrates by dc magnetron sputtering at two different total pressures and a series of nitrogen partial pressures. The spectral transmittance of these films, in the region 350 to 1500 nm, is strongly dependent on the nitrogen partial pressure during sputtering and relatively insensitive to total pressure. The films became more transparent as the nitrogen partial pressure was decreased at a constant total pressure. The optical constants, refractive index and extinction coefficient, exhibited a similar dependence on the nitrogen partial pressure. The sheet resistivity of the films decreased with increasing nitrogen partial pressure. The values of resistivity indicate that the films are semiconducting rather than metalic.

A Flow Sensor for Liquids Based on Single-Walled Carbon Nanotube Thin Films

2007 ◽  
Vol 121-123 ◽  
pp. 75-79 ◽  
Author(s):  
C.L. Cao ◽  
Liang Fang ◽  
K.J. Liao ◽  
F.J. Wei ◽  
L. Li
Keyword(s):  
Thin Films ◽  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Angular Velocity ◽  
Experimental Studies ◽  
Chemical Vapor ◽  
Flow Sensor ◽  
Single Walled Carbon Nanotube ◽  
Single Walled Carbon ◽  
Electron Drag

An angular velocity of flow sensor for liquids based on single-walled carbon nanotube thin films is presented. The carbon nanotubes in this study were fabricated on Si substrate by hot filament chemical vapor deposition (CVD). The experimental results showed that the flow-induced current on the surface of carbon nanotube thin films was closely depended upon the angular velocity, concentration, properties and temperature of the liquids. The current increased with increasing angular velocity, concentration and temperature of the liquids. In this study, the liquids such as water, NaCl solution and other electrolyte were flowing over the sensor. The results obtained were also discussed. The theoretical and experimental studies have shown that there was electronic friction and electron drag effect of carbon nanotubes in flowing liquids. This effect in carbon nanotubes can be used for a new flow sensor.

Changes in Structural, Morphological, and Corrosion Properties of CrN Thin Film Effected by Varying N2 Pressure in the Sputtering Process

2015 ◽  
Vol 659 ◽  
pp. 555-559 ◽  
Author(s):  
Wichuda Wongtanasarasin ◽  
Rachsak Sakdanuphab ◽  
Kajpanya Suwansukho ◽  
Aparporn Sakulkalavek
Keyword(s):  
Crystal Structure ◽  
Thin Films ◽  
Partial Pressure ◽  
Nitrogen Pressure ◽  
Lattice Parameter ◽  
Corrosion Property ◽  
Face Centered Cubic ◽  
Nitrogen Partial Pressure ◽  
Corrosion Properties ◽  
Partial Pressures

In this study, we investigate a facet of the fabrication process of chromium nitride (CrN) film intended as a protective coating for pineapple blades. CrN thin films were deposited on unpolished stainless steel substrates (AISI304) by DC reactive magnetron sputtering in Ar+N2 gases. In principle, the proportion of nitrogen partial pressure to the total pressure in the sputtering process should have considerable effects on the CrN film’s chemical composition, its crystal structure, its hardness, and its corrosion resistance. We tested this supposition out by using several different nitrogen partial pressures in the sputtering process and observed the films deposited. The coatings were deposited at five different nitrogen partial pressures of 4.0x10-4 mbar, 8.0x10-4 mbar, 1.2x10-3 mbar, 1.6x10-3 mbar, and 2.0x10-3. The deposition times were controlled to achieve 5-µm thick films in each deposition. The films were analyzed by several analytical methods, such as X-ray diffraction (XRD), scanning electron microscope, micro-hardness and potentiostat in pineapple juice. The XRD spectra of the films showed face-centered cubic structure with (200) preferred orientation, positively identifying them as Cr2N and CrN thin films. The calculated d-spacing and lattice parameter of the CrN films increased with increasing nitrogen partial pressure; the ranges were 0.283–0.287 nm and 0.491-0.497 nm, respectively. The cross-section morphology of the CrN films reveals the columnar grain growth with a high density. The crystal structure and the grain texture correspond with the hardness property. The films corrosion potential, an indicator of their corrosion property, was varied from -0.14 to -0.05 volts with varying nitrogen pressure. The most corrosion resistant and the good hardness were the film fabricated at the nitrogen partial pressure of 1.2x10-3 mbar.

Carbon Nanotube Growth from Nanoscale Clusters Formed by Ion Implantation

2005 ◽  
Vol 908 ◽  
Author(s):  
Yongho Choi ◽  
Jennifer Sippel Oakley ◽  
Andrew Rinzler ◽  
Ant Ural
Keyword(s):  
Thin Films ◽  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Ion Implantation ◽  
Silicon Dioxide ◽  
Small Diameter ◽  
Iron Ions ◽  
Nanoscale Clusters ◽  
Carbon Nanotube Growth ◽  
Nanotube Growth

AbstractWe have demonstrated that iron ions implanted into silicon dioxide thin films form nanoscale clusters which can act as catalyst for carbon nanotube growth. We have implanted iron ions with an energy of 60 keV and three different doses (1014, 1015, and 1016 cm-2) into silicon dioxide thin films thermally grown on silicon substrates. We then used chemical vapor deposition (CVD) to grow carbon nanotubes on these ion implanted substrates with methane as the precursor gas. We studied the effect of ion implantation dose on the structural properties of the nanoscale clusters, as well as the carbon nanotubes nucleated from these clusters. The nanoscale clusters and grown nanotubes were characterized by Atomic Force Microscopy and Raman spectroscopy. The electrical characteristics of the as-grown nanotubes were also characterized. We found that growth of low density, horizontal, and small diameter carbon nanotubes on silicon dioxide is possible using this nucleation technique.

Ordered carbon nanotube thin films produced by the trapping of water-soluble single-wall carbon nanotubes at the air/water interface

Carbon ◽  
2007 ◽  
Vol 45 (12) ◽  
pp. 2448-2450 ◽  
Author(s):  
José Luis Hernández-López ◽  
Edgar Rogelio Alvizo-Páez ◽  
Sergio Enrique Moya ◽  
Jaime Ruiz-García
Keyword(s):  
Thin Films ◽  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Water Soluble ◽  
Single Wall Carbon Nanotubes ◽  
Water Interface ◽  
Single Wall Carbon ◽  
Air Water Interface
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