Search query: Laser ablation method cnts

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abstract: A method combining laser ablation cluster formation and vapor liquid solid (VLS) growth was developed for the synthesis of semiconductor nanowires. In this process, laser ablation was used to prepare nanometer diameter catalyst clusters that define the size of wires produced by VLS growth. This approach was used to prepare bulk quantities of uniform single crystal silicon and germanium nanowires with diameters of 6 to 20 and 3 to 9 nanometers, respectively, and lengths ranging from 1 to 30 micrometers. Studies carried out with different conditions and catalyst materials confirmed the central details of the growth mechanism and suggest that well established phase diagrams can be used to predict rationally catalyst materials and growth conditions for the preparation of nanowires.
title: A laser ablation method for the synthesis of crystalline semiconductor nanowires
venue: Science
year: 1998

abstract: Since their discovery [Ijima, 1991, Nature, 354, 56] carbon nanotubes (CNTs) have been widely studied due to their large potential applications. First produced in arc discharge process or by laser ablation, the CNTs grown by catalytic chemical vapor deposition (CCVD) have been showing however a large expansion for the past decade. A fundamental question remains after this 10 year experience: What is actually the role played by the catalyst in the CCVD of CNTs? This review intends to synthesize the data published in the scientific literature on this topic in order to better understand the parameters governing the catalytic properties of the metal nanoparticles. In particular, we will discuss the influence of the composition of the catalyst material, of the morphology of the catalyst nanoparticles, of the support, of the preparation method of the nanoparticles and of the reduction pretreatment.
author_names: Anne-Claire Dupuis
title: The catalyst in the CCVD of carbon nanotubes a review
year: 2005

abstract: Carbon nanotubes (CNTs) have been under scientific investigation for more than fifteen years because of their unique properties that predestine them for many potential applications. The field of nanotechnology and nanoscience push their investigation forward to produce CNTs with suitable parameters for future applications. It is evident that new approaches of their synthesis need to be developed and optimized. In this paper we review history, types, structure and especially the different synthesis methods for CNTs preparation including arc discharge, laser ablation and chemical vapour deposition. Moreover, we mention some rarely used ways of arc discharge deposition which involves arc discharge in liquid solutions in contrary to standard used deposition in a gas atmosphere. In addition, the methods for uniform vertically aligned CNTs synthesis using lithographic techniques for catalyst deposition as well as a method utilizing a nanoporous anodized aluminium oxide as a pattern for selective CNTs growth are reported too.
author_names: Jan Prasek

Jana Drbohlavova

Jana Chomoucka

Jaromir Hubalek

Ondrej Jasek

Vojtech Adam

Rene Kizek
title: Methods for carbon nanotubes synthesis review
year: 2011

abstract: Abstract The laser ablation method was employed to synthesize Ag nanoparticles. With the aid of the surfactants, SDS and CTAB, highly dispersed Ag particles were attained. Using a laser intensity of 120 mJ/pulse particle diameters of 4.2+ 1.9 nm were produced in SDS and 7.8+ 4.5 nm in CTAB. The anionic SDS and cationic CTAB exhibited differential ability in protecting Ag colloids: the particles containing SDS remained stable at least one month, while the CTAB protected Ag precipitated completely within one week. Plausible explanations were given to such stability observations. Moreover, the changes in the ablation laser powers were found to achieve particle size control. Lesser laser intensity of 60 mJ/pulse produced larger particle sizes of 6.8+ 2.7 nm and 9.4+ 5.9 nm in SDS and CTAB, respectively.
author_names: Yu-Hung Chen

Chen-Sheng Yeh
title: Laser ablation method: use of surfactants to form the dispersed Ag nanoparticles
year: 2002

abstract: The carbon nanotube (CNT) represents one of the most unique inventions in the field of nan otechnology. CNTs have been studied closely over the last two decades by many researchers around the world due to their great potential in different fields. CNTs are rolled graphene with SP 2 hybridization. The important aspects of CNTs are their light weight, small size with a high aspect ratio, good tensile strength, and good conducting characteristics, which make them useful as fillers in different materials such as polymers, metallic surfaces and ceramics. CNTs also have potential applications in the field of nanotechnology, nanomedicine, tran sistors, actuators, sensors, membranes, and capacitors. There are various techniques which can be used for the synthesis of CNTs. These include the arc discharge method, chemical vaporize deposition (CVD) the laser ablation method, and the sol gel method. CNTs can be single walled, double walled and multi walled. CNTs have unique mechanical, electrical and optical properties, all of which have been extensively studied. The present review is focused on the synthesis, functionalization, properties and applications of CNTs. The toxic effect of CNTs is also presented in a summarized form.
author_names: Khalid Ibrahim
title: Carbon nanotubes properties and applications: a review
year: 2013

abstract: Abstract Carbon nanotubes (CNTs) were synthesized catalytically by both chemical vapor deposition (CVD) method in C2H2/H2 atmosphere at 600degC and arc discharge (AD) method under helium atmosphere. The structure and morphology of CNTs was determined employing scanning electron microscopy (SEM) and FT Raman spectroscopy. Hydrogen storage capacities were electrochemically measured for undoped and alkali metal (Li, Na and K) doped CVD, AD and laser ablation (LA) grown CNTs. The amounts of hydrogen stored were calculated from the measured discharge capacities. LA grown CNTs produced the highest hydrogen storage capacity of 1.6 wt The alkali metal doped CNTs showed higher hydrogen storage capacities than un doped CNTs. Although the hydrogen storage capacities of Li doped CVD and AD grown CNTs were 6 times higher than that of un doped CNTs, it is only 0.6 wt For Li doped LA grown CNTs, the hydrogen storage capacity reached 2.4 wt The high hydrogen storage capacity of alkali metal doped CNTs seems to be originated from increasing the hydrogen adsorption sites of CNTs due to introducing the doped metals in nanotube bundles and separating the tubes but not from their chemical effects.
author_names: Akm Fazle Kibria

Y H Mo

K S Park

Kee Suk Nahm

Minhee Yun
title: Electrochemical hydrogen storage behaviors of CVD, AD and LA grown carbon nanotubes in KOH medium
year: 2001

abstract: Nowadays, metal nanoparticles (NPs) have been considered as highly promising functional materials, impacting virtually all the fields of science and technologies. Numerous wet chemical approaches have been developed to synthesize metal NPs with various components and structures. Although successful, impurities, such as additives and reaction residuals, usually remain in products. Recently, an alternative method, pulsed laser ablation in liquid (PLAL) phase has attracted increasing attention for colloidal NP preparation, since it can realize a chemical free environment, leading to the formation of a "clean" NP dispersion. This unique feature makes the PLAL method and resulting metal NPs extremely attractive for catalytic applications, since catalytic reaction efficiency is strongly dependent on the surface feature of metal NPs. Usually, a surfactant free, "bare" metal surface is highly desired for catalysis as it favors the access of the reactants to the surface active sites of metal NPs. Due to the absence of ligand or stabilizer molecules on the surface of PLAL NPs, it is expected that these PLAL NPs can exhibit higher catalytic activity in comparison to their chemically synthesized counterparts. In this review, we briefly introduce some recent advances on the synthesis of PLAL metal NPs and some of their important catalytic applications.
author_names: Jianming Zhang

Mohamed Chaker

Dongling Ma
title: Pulsed laser ablation based synthesis of colloidal metal nanoparticles for catalytic applications.
venue: Journal of colloid and interface science
year: 2017

abstract: Throughout the history of materials, synthesis has always been a limiting factor, and often a breakthrough in synthesis has paved the way for breakthroughs in the entire field, which is exemplified by the arc discharge method to synthesize fullerenes. In this respect, the history of single walled carbon nanotubes (SWNTs) has been no exception. In the early years after their discovery, work on SWNTs was restricted to microscopic and theoretical research because of their limited availability. Only after the development of improved techniques, such as laser ablation and high yield arc discharge, to synthesize SWNTs with higher yields were researchers able to 'touch' the samples. This led to many breakthrough discoveries, such as metallic and semiconducting behaviors, a 1 TPa Young's Modulus, single electron transistors, and SWNT field effect transistors. The next breakthrough was the synthesis of SWNTs by chemical vapor deposition (CVD) through which scalable, self organized, and patterned carbon nanotubes (CNTs) could be realized. In CVD, CNTs grow from a carbon source, and by improving this source CVD has advanced significantly. CVD started with hydrocarbons, such as methane, ethylene, and acetylene, but these methods only attained low yields and low purities. To improve these characteristics, carbon monoxide was introduced at high pressure, well known as the HiPco process, enabling mass production of SWNTs with high selectivity. An alcohol carbon source was used to realize the first vertically standing SWNTs with a height of 4mm. The CVD concept was expanded by the addition of a second ingredient (growth enhancer) into the growth ambient of normal hydrocarbon CVD, which dramatically increased the growth efficiency to unprecedented levels. Specifically, with an almost background level of water (100 200 ppm) SWNTs have been shown to grow into millimeter scale forests within 10min, with a SWNT/catalyst weight ratio exceeding 50 000% and a carbon purity of over 99.98% This water assisted highly efficient growth, also called 'super growth' has become a very popular method to grow tall, vertically aligned forests. SWNTs grown by this process possess exceptional properties, such as high purity, high surface area, long length, and alignment. These properties have opened up new applications for CNTs, such as 3D microelectromechanical systems (MEMS) stretchable conductors, high power and density supercapacitors, fast moving, lowvoltage actuators, and super tough fibers. These examples highlight how a new growth ambient can open up new possibilities in the CNT field. Here, we demonstrate that highly efficient growth can be achieved not only using water, but also countless other growth enhancers, for instance, alcohols, ethers, esters, ketones, aldehydes, and even carbon dioxide. From our extensive investigation, we have elucidated general rules governing highly efficient growth of CNTs and the fundamental reasons behind them. Specifically, we found that the key for highly efficient growth includes two essential ingredients in the growth ambient: i) a growth enhancer containing oxygen and ii) a carbon source that does not contain oxygen. This result can be explained in general by the fact that a growth enhancer removes the carbon coating that kills the catalyst. This generalized formulation not only cultivates our understanding of CNT growth but also provides a new testbed for studies of innumerably new and totally unexplored growths. Consequently, we believe that the generalized formulation may act as a guide to inspire further transformation and expansion of the world of CNT synthesis. We first wanted to demonstrate that other compounds, such as acetone or CO2, could also invoke highly efficient growth, to prove that water was not the only growth enhancer (Fig. 1a,b) The experimental conditions were similar to those optimized for water assisted CVD, and the details are described elsewhere. For both acetone and CO2 as growth enhancers with ethylene as a carbon source, CNTs grew efficiently into vertically aligned CNT forests as shown by the scanning electron microscopy (SEM) image in Figure 1a. In contrast, forest growth from ethylene alone was very limited (Fig. 1a,d) Growth curves of the forests (Fig. 1b,c) measured by an in situ telecentric height monitoring system with a constant ethylene level and increasing acetone and CO2 level highlight several key features. First, as compared to normal ethylene CVD (no enhancer) even a small amount of acetone 120 ppm) or CO2 1000 ppm) extended both the growth lifetime and increased the growth rate, and dramatically increased the growth yield (forest height) Optimization of all growth parameters, such as temperature, flow rates, etc. was not performed for each growth enhancer. As such, the results
author_names: Don N Futaba

Jundai Goto

Satoshi Yasuda

Takeo Yamada

Motoo Yumura

Kenji Hata
title: General rules governing the highly efficient growth of carbon nanotubes.
venue: Advanced materials
year: 2009

abstract: [1] The "laser ablation split stream" (LASS) technique is a powerful tool for mineral scale isotope analyses and in particular, for concurrent determination of age and Hf isotope composition of zircon. Because LASS utilizes two independent mass spectrometers, a large range of masses can be measured during a single ablation, and thus, the same sample volume can be analyzed for multiple geochemical systems. This paper describes a simple analytical setup using a laser ablation system coupled to a single collector (for U Pb age determination) and a multicollector (for Hf isotope analyses) inductively coupled plasma mass spectrometer (MC ICPMS) The ability of the LASS for concurrent Hf age technique to extract meaningful Hf isotope compositions in isotopically zoned zircon is demonstrated using zircons from two Proterozoic gneisses from northern Idaho, USA. These samples illustrate the potential problems associated with inadvertently sampling multiple age and Hf components in zircons, as well as the potential of LASS to recover meaningful Hf isotope compositions. We suggest that such inadvertent sampling of differing age and Hf components can be a significant cause of excess scatter in Hf isotope analyses and demonstrate that the LASS approach offers a robust solution to these issues. The veracity of the approach is demonstrated by accurate analyses of 10 reference zircons with well characterized age and Hf isotopic composition, using laser spot diameters of 30 and 40 um. In order to expand the database of high precision Lu Hf isotope analyses of reference zircons, we present 27 new isotope dilution MC ICPMS Lu Hf isotope measurements of five U Pb zircon standards: FC1, Temora, R33, QGNG, and 91500.
author_names: Christopher M Fisher

Jeffrey D Vervoort

S Andrew Dufrane
title: Accurate Hf isotope determinations of complex zircons using the "laser ablation split stream" method
year: 2014

abstract: Discovered in 1991, carbon nanotubes (CNTs) have reached the forefront of many industrial research projects. Carbon nanotubes are tubular carbon molecules with remarkable mechanical, chemical, thermal and electrical properties, which make them useful in various applications. This paper reviews three methods of synthesizing the nanomaterial, namely arc discharge, laser ablation and fixed bed/fluidized bed catalytic. These methods have generated a large interest in many industrial companies to date. At the moment, the most critical issue faced by industrial companies is determining the best synthesis method, which will give the most economical large scale production of CNTs. Compared to the other two methods, the catalytic technique to synthesize CNTs is simple, inexpensive, energy efficient and can produce large CNTs quantities of high yield and purity.
author_names: Carole E Baddour

Cedric Briens
title: Carbon Nanotube Synthesis: A Review
year: 2005