WorldWideScience

Sample records for chemical vapour process

  1. Aluminium nitride coatings preparation using a chemical vapour deposition process

    Energy Technology Data Exchange (ETDEWEB)

    Armas, B.; Combescure, C.; Icaza Herrera, M. de; Sibieude, F. [Centre National de la Recherche Scientifique (CNRS), 66 - Font-Romeu (France). Inst. de Science et du Genie des Materiaux et des Procedes

    2000-07-01

    Aluminium nitride was obtained in a cold wall reactor using AlCl{sub 3} and NH{sub 3} as precursors and N{sub 2} as a carrier gas. AlCl{sub 3} was synthesized << in situ >> by means of an original method based on the reaction of SiCl{sub 4(g)} with Al{sub (S)}. The substrate used was a cylinder of graphite coated with SiC and heated by high frequency induction. The deposition rate was studied as a function of temperature in the range 900 - 1500 C, the total pressure varying from 2 to 180 hPa. At low temperatures an Arrhenius type representation of the kinetics for several pressures indicated a thermally activated process with an apparent activation energy of about 80 kJ.mol{sup -1}. At high deposition temperatures, the deposition rate was almost constant, indicating that the growth was controlled by a diffusion process. The influence of gas composition and total AlCl{sub 3} flow rate was also discussed. The different layers were characterised particularly by means of X-ray diffraction and SEM. The influence of temperature and total pressure on crystallization and morphology was studied. (orig.)

  2. Optimization of process parameter for synthesis of silicon quantum dots using low pressure chemical vapour deposition

    Indian Academy of Sciences (India)

    Dipika Barbadikar; Rashmi Gautam; Sanjay Sahare; Rajendra Patrikar; Jatin Bhatt

    2013-06-01

    Si quantum dots-based structures are studied recently for performance enhancement in electronic devices. This paper presents an attempt to get high density quantum dots (QDs) by low pressure chemical vapour deposition (LPCVD) on SiO2 substrate. Surface treatment, annealing and rapid thermal processing (RTP) are performed to study their effect on size and density of QDs. The samples are also studied using Fourier transformation infrared spectroscopy (FTIR), atomic force microscopy (AFM), scanning electron microscopy (SEM) and photoluminescence study (PL). The influence of Si–OH bonds formed due to surface treatment on the density of QDs is discussed. Present study also discusses the influence of surface treatment and annealing on QD formation.

  3. Investigation of the nucleation process of chemical vapour deposited diamond films

    International Nuclear Information System (INIS)

    The primary aim of this work was to contribute to the understanding of the bias enhanced nucleation (BEN) process during the chemical vapour deposition (CVD) of diamond on silicon. The investigation of both the gas phase environment above the substrate surface, by in situ mass selective energy analysis of ions, and of the surface composition and structure by in vacuo surface analytic methods (XPS, EELS) have been carried out. In both cases, the implementation of these measurements required the development and construction of special experimental apparatus as well. The secondary aim of this work was to give orientation to our long term goal of growing diamond films with improved quality. For this reason, (1) contaminant levels at the diamond-silicon interface after growth were studied by SIMS, (2) the internal stress distribution of highly oriented free-standing diamond films were studied by Raman spectroscopy, and (3) an attempt was made to produce spatially regular oriented nuclei formation by nucleating on a pattern created by laser treatment on silicon substrates. (orig.)

  4. Autonomous Chemical Vapour Detection by Micro UAV

    OpenAIRE

    Kent Rosser; Karl Pavey; Nicholas FitzGerald; Anselm Fatiaki; Daniel Neumann; David Carr; Brian Hanlon; Javaan Chahl

    2015-01-01

    The ability to remotely detect and map chemical vapour clouds in open air environments is a topic of significant interest to both defence and civilian communities. In this study, we integrate a prototype miniature colorimetric chemical sensor developed for methyl salicylate (MeS), as a model chemical vapour, into a micro unmanned aerial vehicle (UAV), and perform flights through a raised MeS vapour cloud. Our results show that that the system is capable of detecting MeS vapours at low ppm con...

  5. Autonomous Chemical Vapour Detection by Micro UAV

    Directory of Open Access Journals (Sweden)

    Kent Rosser

    2015-12-01

    Full Text Available The ability to remotely detect and map chemical vapour clouds in open air environments is a topic of significant interest to both defence and civilian communities. In this study, we integrate a prototype miniature colorimetric chemical sensor developed for methyl salicylate (MeS, as a model chemical vapour, into a micro unmanned aerial vehicle (UAV, and perform flights through a raised MeS vapour cloud. Our results show that that the system is capable of detecting MeS vapours at low ppm concentration in real-time flight and rapidly sending this information to users by on-board telemetry. Further, the results also indicate that the sensor is capable of distinguishing “clean” air from “dirty”, multiple times per flight, allowing us to look towards autonomous cloud mapping and source localization applications. Further development will focus on a broader range of integrated sensors, increased autonomy of detection and improved engineering of the system.

  6. Optical monitoring of surface processes relevant to thin film growth by chemical vapour deposition

    International Nuclear Information System (INIS)

    This thesis reports on the investigation of the use of reflectance anisotropy spectroscopy (RAS) as an in-situ monitor for the preparation and oxidation of GaAs(100) c(4x4) surfaces using a CVD 2000 MOCVD reactor. These surfaces were oxidised using air. It was found that it was possible to follow surface degradation using RA transients at 2.6eV and 4eV. From this data it was possible to speculate on the nature of the surface oxidation process. A study was performed into the rate of surface degradation under different concentrations of air, it was found that the relation between the air concentration and the surface degradation was complicated but that the behaviour of the first third of the degradation approximated a first order behaviour. An estimation of the activation energy of the process was then made, and an assessment of the potential use of the glove-box for STM studies which is an integral part of the MOCVD equipment was also made. Following this, a description is given of the construction of an interferometer for monitoring thin film growth. An investigation is also described into two techniques designed to evaluate the changes in reflected intensity as measured by an interferometer. The first technique uses an iteration procedure to determine the film thickness from the reflection data. This is done using a Taylor series expansion of the thin film reflection function to iterate for the thickness. Problems were found with the iteration when applied to noisy data, these were solved by using a least squares fit to smooth the data. Problems were also found with the iteration at the turning points these were solved using the derivative of the function and by anticipating the position of the turning points. The second procedure uses the virtual interface method to determine the optical constants of the topmost deposited material, the virtual substrate, and the growth rate. This method is applied by using a Taylor series expansion of the thin film reflection

  7. CdTe thin film solar cells produced using a chamberless inline process via metalorganic chemical vapour deposition

    International Nuclear Information System (INIS)

    Cd1−xZnxS and CdTe:As thin films were deposited using a recently developed chamberless inline process via metalorganic chemical vapour deposition (MOCVD) at atmospheric pressure and assessed for fabrication of CdTe photovoltaic (PV) solar cells. Initially, CdS and Cd1−xZnxS coatings were applied onto 15 × 15 cm2 float glass substrates, characterised for their optical properties, and then used as the window layer in CdTe solar cells which were completed in a conventional MOCVD (batch) reactor. Such devices provided best conversion efficiency of 13.6% for Cd0.36Zn0.64S and 10% for CdS which compare favourably to the existing baseline MOCVD (batch reactor) devices. Next, sequential deposition of Cd0.36Zn0.64S and CdTe:As films was realised by the chamberless inline process. The chemical composition of a 1 μm CdTe:As/150 nm Cd0.36Zn0.64S bi-layer was observed via secondary ions mass spectroscopy, which showed that the key elements are uniformly distributed and the As doping level is suitable for CdTe device applications. CdTe solar cells formed using this structure provided a best efficiency of 11.8% which is promising for a reduced absorber thickness of 1.25 μm. The chamberless inline process is non-vacuum, flexible to implement and inherits from the legacy of MOCVD towards doping/alloying and low temperature operation. Thus, MOCVD enabled by the chamberless inline process is shown to be an attractive route for thin film PV applications. - Highlights: • CdS, CdZnS and CdTe thin films grown by a chamberless inline process • The inline films assessed for fabricating CdTe solar cells • 13.6% conversion efficiency obtained for CdZnS/CdTe cells

  8. Biocompatibility of chemical-vapour-deposited diamond.

    Science.gov (United States)

    Tang, L; Tsai, C; Gerberich, W W; Kruckeberg, L; Kania, D R

    1995-04-01

    The biocompatibility of chemical-vapour-deposited (CVD) diamond surfaces has been assessed. Our results indicate that CVD diamond is as biocompatible as titanium (Ti) and 316 stainless steel (SS). First, the amount of adsorbed and 'denatured' fibrinogen on CVD diamond was very close to that of Ti and SS. Second, both in vitro and in vivo there appears to be less cellular adhesion and activation on the surface of CVD diamond surfaces compared to Ti and SS. This evident biocompatibility, coupled with the corrosion resistance and notable mechanical integrity of CVD diamond, suggests that diamond-coated surfaces may be highly desirable in a number of biomedical applications. PMID:7654876

  9. Vapour liquid equilibrium measurements for process design

    OpenAIRE

    Uusi-Kyyny, Petri

    2004-01-01

    In recent years it has become increasingly important to develop new oxygenate and isooctane technologies and processes that meet the continuously stricter environmental requirements. Some of the new process schemes use renewable raw materials in order to meet the European Union biofuel requirements. One of the most important requirements for the design of such separation processes includes the knowledge of vapour liquid equilibrium (VLE) behaviour. There are methods to estimate VLE but for th...

  10. Study of a new hybrid process combining slurry infiltration and Reactive Chemical Vapour Infiltration for the realisation of Ceramic Matrix Composites

    International Nuclear Information System (INIS)

    Ceramic matrix composites were originally developed for aerospace,military aeronautics or energy applications thanks to their good properties at high temperature. They are generally made by Chemical Vapor Infiltration (CVI). A new short hybrid process combining fiber preform slurry impregnation of ceramic powders with an innovative Reactive CVI (RCVI) route is proposed to reduce the production time. This route is based on the combination of Reactive Chemical Vapour Deposition (RCVD), which is often used to deposit coatings on fibres, with the Chemical Vapor Infiltration (CVI).In RCVD, the absence of one element of the deposited carbide in the initial gas phase involves the consumption/conversion of the solid substrate. In this work, the RCVD growth and the associated consumption were studied with different parameters in the Ti-H-Cl-C chemical system. The study has been completed with the chemical products analysis, combining XRD, XPS and FTIR. Then, the partial conversion of sub-micrometer carbon powders into titanium carbide and the consolidation of green bodies by RCVI from H2/TiCl4 gaseous infiltration were studied. The residual porosity and the final TiC content were measured in the bulk of the infiltrated powders by image analysis from scanning electron microscopy. Depending on temperature, few hundred micrometers-depth infiltrations are obtained.Finally, the results have been transposed to the RCVI into CMC-type pre-forms. Despite a minimal TiC content of 25% in the overall preform, the results shown a bad homogeneity of the infiltration and a poor cohesion of fibres with RCVI consolidated powder of their environment. (author)

  11. The Chemical Vapour Deposition of Tantalum - in long narrow channels

    DEFF Research Database (Denmark)

    Mugabi, James Atwoki

    use as a construction material for process equipment, with the cheaper alternative being the construction of equipment from steel and then protecting it with a thin but efficacious layer of tantalum. Chemical Vapour Deposition (CVD) is chosen as the most effective process to apply thin corrosion......Tantalum’s resistance to corrosion in hot acidic environments and its superior metallic properties have made it a prime solution as a construction material or protective coating to equipment intended for use in such harsh chemical and physical conditions. The high price of tantalum metal limits its...... protective layers of tantalum because of the process’ ability to coat complex geometries and its relative ease to control. This work focuses on studying the CVD of tantalum in long narrow channels with the view that the knowledge gained during the project can be used to optimise the commercial coating...

  12. Optical monitoring of surface processes relevant to thin film growth by chemical vapour deposition Oxidation; Surface degradation

    CERN Document Server

    Simcock, M N

    2002-01-01

    This thesis reports on the investigation of the use of reflectance anisotropy spectroscopy (RAS) as an in-situ monitor for the preparation and oxidation of GaAs(100) c(4x4) surfaces using a CVD 2000 MOCVD reactor. These surfaces were oxidised using air. It was found that it was possible to follow surface degradation using RA transients at 2.6eV and 4eV. From this data it was possible to speculate on the nature of the surface oxidation process. A study was performed into the rate of surface degradation under different concentrations of air, it was found that the relation between the air concentration and the surface degradation was complicated but that the behaviour of the first third of the degradation approximated a first order behaviour. An estimation of the activation energy of the process was then made, and an assessment of the potential use of the glove-box for STM studies which is an integral part of the MOCVD equipment was also made. Following this, a description is given of the construction of an inte...

  13. Light-induced chemical vapour deposition painting with titanium dioxide

    Science.gov (United States)

    Halary-Wagner, E.; Bret, T.; Hoffmann, P.

    2003-03-01

    Light-induced chemical vapour deposits of titanium dioxide are obtained from titanium tetra-isopropoxide (TTIP) in an oxygen and nitrogen atmosphere with a long pulse (250 ns) 308 nm XeCl excimer laser using a mask projection set-up. The demonstrated advantages of this technique are: (i) selective area deposition, (ii) precise control of the deposited thickness and (iii) low temperature deposition, enabling to use a wide range of substrates. A revolving mask system enables, in a single reactor load, to deposit shapes of controlled heights, which overlap to build up a complex pattern. Interferential multi-coloured deposits are achieved, and the process limitations (available colours and resolution) are discussed.

  14. Chemical Vapour Deposition of Gas Sensitive Metal Oxides

    Directory of Open Access Journals (Sweden)

    Stella Vallejos

    2016-03-01

    Full Text Available This article presents a review of recent research efforts and developments for the fabrication of metal-oxide gas sensors using chemical vapour deposition (CVD, presenting its potential advantages as a materials synthesis technique for gas sensors along with a discussion of their sensing performance. Thin films typically have poorer gas sensing performance compared to traditional screen printed equivalents, attributed to reduced porosity, but the ability to integrate materials directly with the sensor platform provides important process benefits compared to competing synthetic techniques. We conclude that these advantages are likely to drive increased interest in the use of CVD for gas sensor materials over the next decade, whilst the ability to manipulate deposition conditions to alter microstructure can help mitigate the potentially reduced performance in thin films, hence the current prospects for use of CVD in this field look excellent.

  15. Surface chemical studies of chemical vapour deposited diamond thin films

    International Nuclear Information System (INIS)

    Polycrystalime diamond grown by low pressure chemical vapour deposition (CVD) techniques has emerged in recent years as a new material with applications in such areas as optics, electronics, radiation detectors, chemical sensors and electrochemistry. A main aim of this thesis has been to advance current knowledge of the surface chemical properties of CVD diamond to underpin the development of our understanding of the properties and potential applications of this material. Cl2 is found to adsorb dissociatively on the clean, hydrogen-free diamond surface up to sub-monolayer coverage with a sticking probability of ∼1.2x10-3. Adsorption is a non-activated process, and the sticking probability and extent of coverage decreased with increasing temperature. This was shown to contrast with the behaviour found for the interaction of chlorine with the hydrogenated diamond surface where increased sticking probabilities and saturation surface coverages were observed, and where the reactivity also increased with temperature. Thermal desorption of atomic Cl occurred over a broad temperature range m both chemisorption systems, indicating the presence of more than one binding state. Atomic hydrogen was successful in efficiently etching the bound Cl from the surface. XeF2 was found to adsorb dissociatively onto the clean diamond surface to give up to monolayer coverages of F, which formed two distinct binding states. The first state, populated at low coverage, was predominantly covalent in character, while the second state, occurring at high surface coverages, had more ionic bonding character. Pre-hydrogenation of the diamond surface increased the reactive sticking probability observed, but decreased the extent of coverage by blocking reactive sites. The semi-ionic F was readily etched by atomic hydrogen, and underwent thermal desorption at temperatures as low as 300 deg C. The covalent form was more stable, being seemingly resistant to etching and persistent to high temperatures

  16. Chemical Vapour Deposition of Large Area Graphene

    OpenAIRE

    Larsen, Martin Benjamin Barbour Spanget; Bøggild, Peter; Booth, Tim; Jørgensen, Anders Michael

    2015-01-01

    Chemical Vapor Deposition (CVD) is a viable technique for fabrication of large areas of graphene. CVD fabrication is the most prominent and common way of fabricating graphene in industry. In this thesis I have attempted to optimize a growth recipe and catalyst layer for CVD fabrication of uniform, single layer, and high carrier mobility large area graphene. The main goals of this work are; (1) explore the graphene growth mechanics in a low pressure cold-wall CVD system on a copper substrate, ...

  17. Chemical vapour deposition synthetic diamond: materials, technology and applications

    OpenAIRE

    Balmer, R. S.; Brandon, J R; Clewes, S L; Dhillon, H. K.; Dodson, J M; Friel, I.; Inglis, P. N.; Madgwick, T D; Markham, M. L.; Mollart, T P; Perkins, N.; Scarsbrook, G. A.; Twitchen, D. J.; Whitehead, A J; Wilman, J J

    2009-01-01

    Substantial developments have been achieved in the synthesis of chemical vapour deposition (CVD) diamond in recent years, providing engineers and designers with access to a large range of new diamond materials. CVD diamond has a number of outstanding material properties that can enable exceptional performance in applications as diverse as medical diagnostics, water treatment, radiation detection, high power electronics, consumer audio, magnetometry and novel lasers. Often the material is synt...

  18. Chemical vapour deposition of metal oxides and phosphides.

    OpenAIRE

    Binions, R.

    2006-01-01

    This thesis investigates the deposition of thin films of main group metal phosphide and main group metal oxide compounds on glass substrates by the use of dual source atmospheric pressure chemical vapour deposition. Binary phosphide systems with tin, germanium, silicon, antimony, copper or boron have been examined. Binary oxide systems of gallium, antimony, tin or niobium have also been investigated. Additionally these systems were deposited on gas sensor substrates and evaluated as metal oxi...

  19. Microscopic characterisation of suspended graphene grown by chemical vapour deposition

    OpenAIRE

    Bignardi, Luca; van Dorp, Willem F; Gottardi, Stefano; Ivashenko, Oleksii; Dudin, Pavel; Barinov, Alexei; de Hosson, Jeff Th. M.; Stöhr, Meike; Rudolf, Petra

    2013-01-01

    We present a multi-technique characterisation of graphene grown by chemical vapour deposition (CVD) and thereafter transferred to and suspended on a grid for transmission electron microscopy (TEM). The properties of the electronic band structure are investigated by angle-resolved photoelectron spectromicroscopy, while the structural and crystalline properties are studied by TEM and Raman spectroscopy. We demonstrate that the suspended graphene membrane locally shows electronic properties comp...

  20. Laser-Induced Chemical Vapour Deposition of Silicon Carbonitride

    OpenAIRE

    Besling, W.; van der Put, P.; Schoonman, J.

    1995-01-01

    Laser-induced Chemical Vapour Deposition of silicon carbonitride coatings and powders has been investigated using hexamethyldisilazane (HMDS) and ammonia as reactants. An industrial CW CO2-laser in parallel configuration has been used to heat up the reactant gases. HMDS dissociates in the laser beam and reactive radicals are formed which increase rapidly in molecular weight by an addition mechanism. Dense polymer-like silicon carbonitride thin films and nanosized powders are formed depending ...

  1. Componentry, constructive and process solutions of sodium vapour precipitation problem

    International Nuclear Information System (INIS)

    Sodium vapour trap for periodic operation (SVT) is installed to present of sodium vapour emissions after response of safety valve on tanks with sodium and to provide protection from sodium vapour during planned argon blowing from tanks. It is recommended that SVT be placed directly above tanks with sodium. But the main problem of BN-600 and BN-800 componentry (grouping) is the lack of premises. So, the recommended placement is impossible. The principal scheme of SVT piping BN-800. Argon purification from sodium vapor is carried out by air refrigerating. Refrigerating degree is regulated by control valve on the air delivery pipe to SVT. There is montejus tank in the scheme of SVT piping for liquid sodium drainage that is condensed in SVT. Sodium drainage pipe is combined with argon delivery pipe (line E). There are two main problems with the present construction of SVT based on operation experience of BN-600: 1. The horizontal pipeline 'Ar+Na' before the SVT entrance is a dangerous section of this piping. Electric heating of this pipeline is always 'on'. Inspite of this, sodium vapour condenses before SVT. It means that the pipeline becomes progressively clogged up. 2. Two substances (argon with sodium vapour and liquid sodium) are moving towards each other in one pipeline (line E). This is the most probable place of clogging by sodium, especially branch-pipe in the connection point of line E with SVT. Sodium cruds turn into solid state in the process of argon delivery pipe clogging.In most cases solid scrubs melting temperature exceeds 400-500C depending on chemical composition of crud (for example caustic soda - 1200C). It means that it is almost impossible to heat the pipeline to restore its passability. The only measure in this case is the change of pipe section during BN stop. The first problem can be solved by: - Increasing the diameter (which was DN40 in the project of BN-600, and is DN80 in BN-800); - Increasing the temperature of electric heating

  2. Chemical Vapour Deposition of Large Area Graphene

    DEFF Research Database (Denmark)

    Larsen, Martin Benjamin Barbour Spanget

    be eliminated. Further opportunities arise when exchanging the copper foil for copper thin film on a wafer e.g. better integration with current cleanroom processing of devices and better control over the copper crystallinity. Typical strategies for controlling the temperature during CVD fabrication of graphene...

  3. Properties of alumina films by atmospheric pressure metal-organic chemical vapour deposition

    NARCIS (Netherlands)

    Haanappel, V.A.C.; Corbach, van H.D.; Fransen, T.; Gellings, P.J.

    1994-01-01

    Thin alumina films were deposited at low temperatures (290–420°C) on stainless steel, type AISI 304. The deposition process was carried out in nitrogen by metal-organic chemical vapour deposition using aluminum tri-sec-butoxide. The film properties including the protection of the underlying substrat

  4. Chemical vapour deposited diamonds for dosimetry of radiotherapeutical beams

    International Nuclear Information System (INIS)

    This paper deals with the application of synthetic diamond detectors to the clinical dosimetry of photon and electron beams. It has been developed in the frame of INFN CANDIDO project and MURST Cofin. Diamonds grown with CVD (Chemical Vapour Deposition) technique have been studied; some of them are commercial samples while others have been locally synthesised. Experiments have been formed using both on-line and off-line approaches. For the off-line measurements, TL (thermoluminescent) and TSC (thermally stimulated current) techniques have been used

  5. Chemical vapour deposited diamonds for dosimetry of radiotherapeutical beams

    Energy Technology Data Exchange (ETDEWEB)

    Bucciolini, M.; Mazzocchi, S. [Firenze Univ., Firenze (Italy). Dipartimento di Fisiopatologia Clinica; INFN, Firenze (Italy); Borchi, E.; Bruzzi, M.; Pini, S.; Sciortino, S. [Firenze Univ., Firenze (Italy). Dipartimento di Energetica; INFN, Firenze (Italy); Cirrone, G.A.P.; Guttone, G.; Raffaele, L.; Sabini, M.G. [INFN, Catania (Italy). Laboratori Nazionali del Sud

    2002-07-01

    This paper deals with the application of synthetic diamond detectors to the clinical dosimetry of photon and electron beams. It has been developed in the frame of INFN CANDIDO project and MURST Cofin. Diamonds grown with CVD (Chemical Vapour Deposition) technique have been studied; some of them are commercial samples while others have been locally synthesised. Experiments have been formed using both on-line and off-line approaches. For the off-line measurements, TL (thermoluminescent) and TSC (thermally stimulated current) techniques have been used.

  6. Microscopic characterisation of suspended graphene grown by chemical vapour deposition

    Science.gov (United States)

    Bignardi, Luca; van Dorp, Willem F.; Gottardi, Stefano; Ivashenko, Oleksii; Dudin, Pavel; Barinov, Alexei; de Hosson, Jeff Th. M.; Stöhr, Meike; Rudolf, Petra

    2013-09-01

    We present a multi-technique characterisation of graphene grown by chemical vapour deposition (CVD) and thereafter transferred to and suspended on a grid for transmission electron microscopy (TEM). The properties of the electronic band structure are investigated by angle-resolved photoelectron spectromicroscopy, while the structural and crystalline properties are studied by TEM and Raman spectroscopy. We demonstrate that the suspended graphene membrane locally shows electronic properties comparable with those of samples prepared by micromechanical cleaving of graphite. Measurements show that the area of high quality suspended graphene is limited by the folding of the graphene during the transfer.

  7. Microscopic characterisation of suspended graphene grown by chemical vapour deposition.

    Science.gov (United States)

    Bignardi, Luca; van Dorp, Willem F; Gottardi, Stefano; Ivashenko, Oleksii; Dudin, Pavel; Barinov, Alexei; De Hosson, Jeff Th M; Stöhr, Meike; Rudolf, Petra

    2013-10-01

    We present a multi-technique characterisation of graphene grown by chemical vapour deposition (CVD) and thereafter transferred to and suspended on a grid for transmission electron microscopy (TEM). The properties of the electronic band structure are investigated by angle-resolved photoelectron spectromicroscopy, while the structural and crystalline properties are studied by TEM and Raman spectroscopy. We demonstrate that the suspended graphene membrane locally shows electronic properties comparable with those of samples prepared by micromechanical cleaving of graphite. Measurements show that the area of high quality suspended graphene is limited by the folding of the graphene during the transfer. PMID:23945527

  8. Graphene growth from reduced graphene oxide by chemical vapour deposition: seeded growth accompanied by restoration

    OpenAIRE

    Sung-Jin Chang; Moon Seop Hyun; Sung Myung; Min-A Kang; Jung Ho Yoo; Lee, Kyoung G.; Bong Gill Choi; Youngji Cho; Gaehang Lee; Tae Jung Park

    2016-01-01

    Understanding the underlying mechanisms involved in graphene growth via chemical vapour deposition (CVD) is critical for precise control of the characteristics of graphene. Despite much effort, the actual processes behind graphene synthesis still remain to be elucidated in a large number of aspects. Herein, we report the evolution of graphene properties during in-plane growth of graphene from reduced graphene oxide (RGO) on copper (Cu) via methane CVD. While graphene is laterally grown from R...

  9. Control of surface and bulk crystalline quality in single crystal diamond grown by chemical vapour deposition

    OpenAIRE

    Friel, I.; Clewes, S L; Dhillon, H. K.; Perkins, N.; Twitchen, D. J.; Scarsbrook, G. A.

    2009-01-01

    In order to improve the performance of existing technologies based on single crystal diamond grown by chemical vapour deposition (CVD), and to open up new technologies in fields such as quantum computing or solid state and semiconductor disc lasers, control over surface and bulk crystalline quality is of great importance. Inductively coupled plasma (ICP) etching using an Ar/Cl gas mixture is demonstrated to remove sub-surface damage of mechanically processed surfaces, whilst maintaining macro...

  10. Fundamental Studies of the Chemical Vapour Deposition of Graphene on Copper

    OpenAIRE

    Lewis, Amanda

    2014-01-01

    The chemical vapour deposition (CVD) of graphene is the most promising route for production of large-area graphene films. However there are still major challenges faced by the field, including control of the graphene coverage, quality, and the number of layers. These challenges can be overcome by developing a fundamental understanding of the graphene growth process. This thesis contributes to the growing body of work on graphene CVD by uniquely exploring the gas phas...

  11. Laser induced chemical vapour deposition of TiN coatings at atmospheric pressure

    OpenAIRE

    Croonen, Y.; Verspui, G.

    1993-01-01

    Laser induced Chemical Vapour Deposition of a wide variety of materials has been studied extensively at reduced pressures. However, for this technique to be economically and industrially applicable, processes at atmospheric pressure are preferred. A model study was made on the substrate-coating system molybdenum-titaniumnitride focussing on the feasibility to deposit TiN films locally at atmospheric pressure. The results of this study turned out to be very promising. A Nd-YAG laser beam ([MAT...

  12. Purification of Single-walled Carbon Nanotubes Grown by a Chemical Vapour Deposition (CVD) Method

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A procedure for purification of single-walled carbon nanotubes(SWNTs) grown by the chemical vapour deposition (CVD) of carbon monooxide has been developed. Based on the result from TGA/DTA of as-prepared sample, the oxidation temperature was determined. The process included sonication, oxidation and acid washing steps. The purity and yield after purification were determined and estimated by TEM. Moreover, for the first time, a loop structure for CVD SWNTs has been observed.

  13. Evaluation of niobium dimethylamino-ethoxide for chemical vapour deposition of niobium oxide thin films

    International Nuclear Information System (INIS)

    Chemical vapour deposition (CVD) processes depend on the availability of suitable precursors. Precursors that deliver a stable vapour pressure are favourable in classical CVD processes, as they ensure process reproducibility. In high vacuum CVD (HV-CVD) process vapour pressure stability of the precursor is of particular importance, since no carrier gas assisted transport can be used. The dimeric Nb2(OEt)10 does not fulfil this requirement since it partially dissociates upon heating. Dimethylamino functionalization of an ethoxy ligand of Nb(OEt)5 acts as an octahedral field completing entity and leads to Nb(OEt)4(dmae). We show that Nb(OEt)4(dmae) evaporates as monomeric molecule and ensures a stable vapour pressure and, consequently, stable flow. A set of HV-CVD experiments were conducted using this precursor by projecting a graded molecular beam of the precursor onto the substrate at deposition temperatures from 320 °C to 650 °C. Film growth rates ranging from 8 nm·h−1 to values larger than 400 nm·h−1 can be obtained in this system illustrating the high level of control available over the film growth process. Classical CVD limiting conditions along with the recently reported adsorption–reaction limited conditions are observed and the chemical composition, and microstructural and optical properties of the films are related to the corresponding growth regime. Nb(OEt)4(dmae) provides a large process window of deposition temperatures and precursor fluxes over which carbon-free and polycrystalline niobium oxide films with growth rates proportional to precursor flux are obtained. This feature makes Nb(OEt)4(dmae) an attractive precursor for combinatorial CVD of niobium containing complex oxide films that are finding an increasing interest in photonics and photoelectrochemical water splitting applications. The adsorption–reaction limited conditions provide extremely small growth rates comparable to an atomic layer deposition (ALD) process indicating that HV

  14. Evaluation of niobium dimethylamino-ethoxide for chemical vapour deposition of niobium oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Dabirian, Ali [Laboratory for Photonic Materials and Characterization, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 17, 1015 Lausanne (Switzerland); Kuzminykh, Yury, E-mail: yury.kuzminykh@empa.ch [Laboratory for Photonic Materials and Characterization, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 17, 1015 Lausanne (Switzerland); Laboratory for Advanced Materials Processing, Empa, Swiss Federal Laboratories for Materials Science and Technology, Feuerwerkerstrasse 39, 3602 Thun (Switzerland); Wagner, Estelle; Benvenuti, Giacomo [3D-Oxides, 70 Rue G. Eiffel Technoparc, 01630 St Genis Pouilly (France); ABCD Technology, 12 route de Champ-Colin, 1260 Nyon (Switzerland); Rushworth, Simon [Tyndall National Institute, Lee Maltings, Dyke Parade, Cork (Ireland); Hoffmann, Patrik, E-mail: patrik.hoffmann@empa.ch [Laboratory for Photonic Materials and Characterization, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 17, 1015 Lausanne (Switzerland); Laboratory for Advanced Materials Processing, Empa, Swiss Federal Laboratories for Materials Science and Technology, Feuerwerkerstrasse 39, 3602 Thun (Switzerland)

    2014-11-28

    Chemical vapour deposition (CVD) processes depend on the availability of suitable precursors. Precursors that deliver a stable vapour pressure are favourable in classical CVD processes, as they ensure process reproducibility. In high vacuum CVD (HV-CVD) process vapour pressure stability of the precursor is of particular importance, since no carrier gas assisted transport can be used. The dimeric Nb{sub 2}(OEt){sub 10} does not fulfil this requirement since it partially dissociates upon heating. Dimethylamino functionalization of an ethoxy ligand of Nb(OEt){sub 5} acts as an octahedral field completing entity and leads to Nb(OEt){sub 4}(dmae). We show that Nb(OEt){sub 4}(dmae) evaporates as monomeric molecule and ensures a stable vapour pressure and, consequently, stable flow. A set of HV-CVD experiments were conducted using this precursor by projecting a graded molecular beam of the precursor onto the substrate at deposition temperatures from 320 °C to 650 °C. Film growth rates ranging from 8 nm·h{sup −1} to values larger than 400 nm·h{sup −1} can be obtained in this system illustrating the high level of control available over the film growth process. Classical CVD limiting conditions along with the recently reported adsorption–reaction limited conditions are observed and the chemical composition, and microstructural and optical properties of the films are related to the corresponding growth regime. Nb(OEt){sub 4}(dmae) provides a large process window of deposition temperatures and precursor fluxes over which carbon-free and polycrystalline niobium oxide films with growth rates proportional to precursor flux are obtained. This feature makes Nb(OEt){sub 4}(dmae) an attractive precursor for combinatorial CVD of niobium containing complex oxide films that are finding an increasing interest in photonics and photoelectrochemical water splitting applications. The adsorption–reaction limited conditions provide extremely small growth rates comparable to an

  15. Chemical vapour deposition synthetic diamond: materials, technology and applications

    Science.gov (United States)

    Balmer, R. S.; Brandon, J. R.; Clewes, S. L.; Dhillon, H. K.; Dodson, J. M.; Friel, I.; Inglis, P. N.; Madgwick, T. D.; Markham, M. L.; Mollart, T. P.; Perkins, N.; Scarsbrook, G. A.; Twitchen, D. J.; Whitehead, A. J.; Wilman, J. J.; Woollard, S. M.

    2009-09-01

    Substantial developments have been achieved in the synthesis of chemical vapour deposition (CVD) diamond in recent years, providing engineers and designers with access to a large range of new diamond materials. CVD diamond has a number of outstanding material properties that can enable exceptional performance in applications as diverse as medical diagnostics, water treatment, radiation detection, high power electronics, consumer audio, magnetometry and novel lasers. Often the material is synthesized in planar form; however, non-planar geometries are also possible and enable a number of key applications. This paper reviews the material properties and characteristics of single crystal and polycrystalline CVD diamond, and how these can be utilized, focusing particularly on optics, electronics and electrochemistry. It also summarizes how CVD diamond can be tailored for specific applications, on the basis of the ability to synthesize a consistent and engineered high performance product.

  16. Plasma Enhanced Chemical Vapour Deposition of Horizontally Aligned Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Matthew T. Cole

    2013-05-01

    Full Text Available A plasma-enhanced chemical vapour deposition reactor has been developed to synthesis horizontally aligned carbon nanotubes. The width of the aligning sheath was modelled based on a collisionless, quasi-neutral, Child’s law ion sheath where these estimates were empirically validated by direct Langmuir probe measurements, thereby confirming the proposed reactors ability to extend the existing sheath fields by up to 7 mm. A 7 mbar growth atmosphere combined with a 25 W plasma permitted the concurrent growth and alignment of carbon nanotubes with electric fields of the order of 0.04 V μm−1 with linear packing densities of up to ~5 × 104 cm−1. These results open up the potential for multi-directional in situ alignment of carbon nanotubes providing one viable route to the fabrication of many novel optoelectronic devices.

  17. Thermoluminescence characterisation of chemical vapour deposited diamond films

    CERN Document Server

    Mazzocchi, S; Bucciolini, M; Cuttone, G; Pini, S; Sabini, M G; Sciortino, S

    2002-01-01

    The thermoluminescence (TL) characteristics of a set of six chemical vapour deposited diamond films have been studied with regard to their use as off-line dosimeters in radiotherapy. The structural characterisation has been performed by means of Raman spectroscopy. Their TL responses have been tested with radiotherapy beams ( sup 6 sup 0 Co photons, photons and electrons from a linear accelerator (Linac), 26 MeV protons from a TANDEM accelerator) in the dose range 0.1-7 Gy. The dosimetric characterisation has yielded a very good reproducibility, a very low dependence of the TL response on the type of particle and independence of the radiation energy. The TL signal is not influenced by the dose rate and exhibits a very low thermal fading. Moreover, the sensitivity of the diamond samples compares favourably with that of standard TLD100 dosimeters.

  18. Spontaneuos and Parametric Processes in Warm Rubidium Vapours

    Directory of Open Access Journals (Sweden)

    Dąbrowski M.

    2014-12-01

    Full Text Available Warm rubidium vapours are known to be a versatile medium for a variety of experiments in atomic physics and quantum optics. Here we present experimental results on producing the frequency converted light for quantum applications based on spontaneous and stimulated processes in rubidium vapours. In particular, we study the efficiency of spontaneously initiated stimulated Raman scattering in the Λ-level configuration and conditions of generating the coherent blue light assisted by multi-photon transitions in the diamond-level configuration. Our results will be helpful in search for new types of interfaces between light and atomic quantum memories.

  19. Laser diagnostics of chemical vapour deposition of diamond films

    CERN Document Server

    Wills, J B

    2002-01-01

    Cavity ring down spectroscopy (CRDS) has been used to make diagnostic measurements of chemically activated CH sub 4 / H sub 2 gas mixtures during the chemical vapour deposition (CVD) of thin diamond films. Absolute absorbances, concentrations and temperatures are presented for CH sub 3 , NH and C sub 2 H sub 2 in a hot filament (HF) activated gas mixture and CH, C sub 2 and C sub 2 H sub 2 in a DC arc plasma jet activated mixture. Measurements of the radical species were made using a pulsed dye laser system to generate tuneable visible and UV wavelengths. These species have greatest concentration in the hottest, activated regions of the reactors. Spatial profiling of the number densities of CH sub 3 and NH radicals have been used as stringent tests of predictions of radical absorbance and number densities made by 3-D numerical simulations, with near quantitative agreement. O sub 2 has been shown to reside in the activated region of the Bristol DC arc jet at concentrations (approx 10 sup 1 sup 3 molecules / cm...

  20. The atmospheric chemical vapour deposition of coatings on glass

    CERN Document Server

    Sanderson, K D

    1996-01-01

    The deposition of thin films of indium oxide, tin doped indium oxide (ITO) and titanium nitride for solar control applications have been investigated by Atmospheric Chemical Vapour Deposition (APCVD). Experimental details of the deposition system and the techniques used to characterise the films are presented. Results from investigations into the deposition parameters, the film microstructure and film material properties are discussed. A range of precursors were investigated for the deposition of indium oxide. The effect of pro-mixing the vaporised precursor with an oxidant source and the deposition temperature has been studied. Polycrystalline In sub 2 O sub 3 films with a resistivity of 1.1 - 3x10 sup - sup 3 OMEGA cm were obtained with ln(thd) sub 3 , oxygen and nitrogen. The growth of ITO films from ln(thd) sub 3 , oxygen and a range of tin dopants is also presented. The effect of the dopant precursor, the doping concentration, deposition temperature and the effect of additives on film growth and microstr...

  1. Photo Initiated Chemical Vapour Deposition To Increase Polymer Hydrophobicity.

    Science.gov (United States)

    Bérard, Ariane; Patience, Gregory S; Chouinard, Gérald; Tavares, Jason R

    2016-01-01

    Apple growers face new challenges to produce organic apples and now many cover orchards with high-density polyethylene (HDPE) nets to exclude insects, rather than spraying insecticides. However, rainwater- associated wetness favours the development of apple scabs, Venturia inaequalis, whose lesions accumulate on the leaves and fruit causing unsightly spots. Treating the nets with a superhydrophobic coating should reduce the amount of water that passes through the net. Here we treat HDPE and polyethylene terephthalate using photo-initiated chemical vapour deposition (PICVD). We placed polymer samples in a quartz tube and passed a mixture of H2 and CO through it while a UVC lamp (254 nm) illuminated the surface. After the treatment, the contact angle between water droplets and the surface increased by an average of 20°. The contact angle of samples placed 70 cm from the entrance of the tube was higher than those at 45 cm and 20 cm. The PICVD-treated HDPE achieved a contact angle of 124°. Nets spray coated with a solvent-based commercial product achieved 180° but water ingress was, surprisingly, higher than that for nets with a lower contact angle. PMID:27531048

  2. Characterization of Defects in Chemical Vapour Deposited Diamonds

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ming-Long; XIA Yi-Ben; WANG Lin-Jun; GU Bei-Bei

    2005-01-01

    @@ Room-temperature Raman and PL spectra, photocurrent (PC) and thermally stimulated current (TSC) were measured to investigate the mid-gap defects in diamonds grown by using a hot-filament chemical vapour deposition (CVD) technique. The [Si-V]0 centres caused by the Si-C bonds in diamond grains and at grain boundaries are located at 1.68eV. We firstly detect the level 1.55eV by using PL and it is tentatively attributed to the zero-phonon luminescence line or vibronic band of the [Si-V]0 induced by the Si-O bonds. The 2.7-3.2eV and 1.9-2.1 eV PC peaks were detected and discussed. The [N-V] complex may be attributed to these defect levels.Some shallow energy levels lower than 1.0eV were also observed in the CVD diamond.

  3. Photo Initiated Chemical Vapour Deposition To Increase Polymer Hydrophobicity

    Science.gov (United States)

    Bérard, Ariane; Patience, Gregory S.; Chouinard, Gérald; Tavares, Jason R.

    2016-08-01

    Apple growers face new challenges to produce organic apples and now many cover orchards with high-density polyethylene (HDPE) nets to exclude insects, rather than spraying insecticides. However, rainwater- associated wetness favours the development of apple scabs, Venturia inaequalis, whose lesions accumulate on the leaves and fruit causing unsightly spots. Treating the nets with a superhydrophobic coating should reduce the amount of water that passes through the net. Here we treat HDPE and polyethylene terephthalate using photo-initiated chemical vapour deposition (PICVD). We placed polymer samples in a quartz tube and passed a mixture of H2 and CO through it while a UVC lamp (254 nm) illuminated the surface. After the treatment, the contact angle between water droplets and the surface increased by an average of 20°. The contact angle of samples placed 70 cm from the entrance of the tube was higher than those at 45 cm and 20 cm. The PICVD-treated HDPE achieved a contact angle of 124°. Nets spray coated with a solvent-based commercial product achieved 180° but water ingress was, surprisingly, higher than that for nets with a lower contact angle.

  4. Corrosion resistant coatings (Al2O3) produced by metal organic chemical vapour deposition using aluminium-tri-sec-butoxide

    NARCIS (Netherlands)

    Haanappel, V.A.C.; Corbach, van H.D.; Fransen, T.; Gellings, P.J.

    1993-01-01

    The metal organic chemical vapour deposition (MOCVD) of amorphous alumina films on steel was performed in nitrogen at atmospheric pressure. This MOCVD process is based on the thermal decomposition of aluminium-tri-sec-butoxide (ATSB). The effect of the deposition temperature (within the range 290–42

  5. Process control by optical emission spectroscopy during growth of a-C:H from a CH4 plasma by plasma-enhanced chemical vapour deposition

    DEFF Research Database (Denmark)

    Barholm-Hansen, C; Bentzon, MD; Vigild, Martin Etchells;

    1994-01-01

    During the growth of a-C:H thin films for tribological applications, the characteristic optical emission from a CH4 plasma was used to estimate growth conditions such as the degree of dissociation of the feed gas, the deposition rate and the presence of impurities. Films were fabricated with vari......During the growth of a-C:H thin films for tribological applications, the characteristic optical emission from a CH4 plasma was used to estimate growth conditions such as the degree of dissociation of the feed gas, the deposition rate and the presence of impurities. Films were fabricated...... with various flow rates of CH4. Their thickness, mass density and hydrogen content were determined by a combination of X-ray and neutron reflectivity measurements. Dissociation of the feed gas is determined relatively by monitoring the integrated peak intensity around the CH 431 nm band head as a function...... of the gas flow. Above a certain flow rate the intensity saturates, since the deposition process is limited by the power input. At low flow rates a large fraction of the feed gas is dissociated and the deposition is limited by the supply of feed gas. A relationship was found for the intensity of the CH 431...

  6. Chemically vapour deposited diamond coatings on cemented tungsten carbides: Substrate pretreatments, adhesion and cutting performance

    International Nuclear Information System (INIS)

    Chemical vapour deposition (CVD) of diamond films onto Co-cemented tungsten carbide (WC-Co) tools and wear parts presents several problems due to interfacial graphitization induced by the binder phase and thermal expansion mismatch of diamond and WC-Co. Methods used to improve diamond film adhesion include substrate-modification processes that create a three-dimensional compositionally graded interface. This paper reviews substrate pretreatments and adhesion issues of chemically vapour deposited diamond films on WC-Co. The combined effect of pretreatments and substrate microstructure on the adhesive toughness and wear rate of CVD diamond in dry machining of highly abrasive materials was analyzed. The role of diamond film surface morphology on chip evacuation in dry milling of ceramics was also investigated by comparing feed forces of coated and uncoated mills. The overall tribological performance of diamond coated mills depended on coating microstructure and smoothness. The use of smother films did allow to reduce cutting forces by facilitating chip evacuation

  7. High quality plasma enhanced chemical vapour deposited silicon oxide gas barrier coatings on polyester films

    International Nuclear Information System (INIS)

    Silicon oxide barrier coatings fabricated by a plasma enhanced chemical vapour deposition roll-to-roll process on polyester film have demonstrated impressive properties as a barrier to water vapour permeation. This study highlights the influence of the substrate on these coatings as we find that heat stabilised poly(ethylene terephthalate) (PET), with or without an additional acrylate primer layer, and poly(ethylene naphthalate) (PEN) produce superior composites than untreated PET film in terms of gas barrier. The barrier layers on PET and filled PET substrates, for which the barrier performance is within the detectable range of our measurement, have an activation energy to water permeation that increases with the thickness of the silica. For the thickest silica this is an increase of 26 kJ mol-1 over that from the uncoated substrate. We attribute this to the creation of highly tortuous, size-hindered pathways and the decoupling of defects as the coating is deposited in multiple passes. Using a more sensitive detection technique we measure a water vapour transmission rate value as low as 2 x 10-4 g m-2 day-1 for 1 μm thick coatings on PEN. Such a good barrier is observed for these thick coatings due to the high degree of carbon detected in the films that makes them less brittle than pure SiO2 layers. Substrate surface roughness is found to influence the morphology of the SiOx films but does not seem to adversely affect the barrier performance of the composites

  8. Plasma Assisted Chemical Vapour Deposition – Technological Design Of Functional Coatings

    Directory of Open Access Journals (Sweden)

    Januś M.

    2015-06-01

    Full Text Available Plasma Assisted Chemical Vapour Deposition (PA CVD method allows to deposit of homogeneous, well-adhesive coatings at lower temperature on different substrates. Plasmochemical treatment significantly impacts on physicochemical parameters of modified surfaces. In this study we present the overview of the possibilities of plasma processes for the deposition of diamond-like carbon coatings doped Si and/or N atoms on the Ti Grade2, aluminum-zinc alloy and polyetherketone substrate. Depending on the type of modified substrate had improved the corrosion properties including biocompatibility of titanium surface, increase of surface hardness with deposition of good adhesion and fine-grained coatings (in the case of Al-Zn alloy and improving of the wear resistance (in the case of PEEK substrate.

  9. Nanocomposite Coatings Codeposited with Nanoparticles Using Aerosol-Assisted Chemical Vapour Deposition

    Directory of Open Access Journals (Sweden)

    Xianghui Hou

    2013-01-01

    Full Text Available Incorporating nanoscale materials into suitable matrices is an effective route to produce nanocomposites with unique properties for practical applications. Due to the flexibility in precursor atomization and delivery, aerosol-assisted chemical vapour deposition (AACVD process is a promising way to synthesize desired nanocomposite coatings incorporating with preformed nanoscale materials. The presence of nanoscale materials in AACVD process would significantly influence deposition mechanism and thus affect microstructure and properties of the nanocomposites. In the present work, inorganic fullerene-like tungsten disulfide (IF-WS2 has been codeposited with Cr2O3 coatings using AACVD. In order to understand the codeposition process for the nanocomposite coatings, chemical reactions of the precursor and the deposition mechanism have been studied. The correlation between microstructure of the nanocomposite coatings and the codeposition mechanism in the AACVD process has been investigated. The heterogeneous reaction on the surface of IF-WS2 nanoparticles, before reaching the substrate surface, is the key feature of the codeposition in the AACVD process. The agglomeration of nanoparticles in the nanocomposite coatings is also discussed.

  10. Thermoluminescence Characteristics of a New Production of Chemical Vapour Deposition Diamond

    Energy Technology Data Exchange (ETDEWEB)

    Furetta, C.; Kitis, G.; Brambilla, A.; Jany, C.; Bergonzo, P.; Foulon, F

    1999-07-01

    The dosimetric properties are presented of a recent production of chemical vapour deposition diamond growth. Experimental data concerning the TL response as a function of dose, the energy response and fading behaviour are reported. Very preliminary results suggest that diamond can be used in TL mode as well as an activation detector. (author)

  11. The mechanical properties of thin alumina film deposited by metal-organic chemical vapour deposition

    NARCIS (Netherlands)

    Haanappel, V.A.C.; Gellings, P.J.; Vendel, van de D.; Metselaar, H.S.C.; Corbach, van H.D.; Fransen, T.

    1995-01-01

    Amorphous alumina films were deposited by metal-organic chemical vapour deposition (MOCVD) on stainless steel, type AISI 304. The MOCVD experiments were performed in nitrogen at low and atmospheric pressures. The effects of deposition temperature, growth rate and film thickness on the mechanical pro

  12. Methyldichloroborane evidenced as an intermediate in the chemical vapour deposition synthesis of boron carbide.

    Science.gov (United States)

    Reinisch, G; Patel, S; Chollon, G; Leyssale, J-M; Alotta, D; Bertrand, N; Vignoles, G L

    2011-09-01

    The most recent ceramic-matrix composites (CMC) considered for long-life applications as thermostructural parts in aerospace propulsion contain, among others, boron-rich phases like boron carbide. This compound is prepared by thermal Chemical Vapour Infiltration (CVI), starting from precursors like boron halides and hydrocarbons. We present a study aiming at a precise knowledge of the gas-phase composition in a hot-zone LPCVD reactor fed with BCl3, CH4 and H2, which combines experimental and theoretical approaches. This work has brought strong evidences of the presence of Methydichloroborane (MDB, BCl2CH3) in the process. It is demonstrated that this intermediate, the presence of which had never been formally proved before, appears for processing temperatures slightly lower than the deposition temperature of boron carbide. The study features quantum chemical computations, which provide several pieces of information like thermochemical and kinetic data, as well as vibration and rotation frequencies, reaction kinetics computations, and experimental gas-phase characterization of several species by FTIR, for several processing parameter sets. The main results are presented, and the place of MDB in the reaction scheme is discussed.

  13. Electronic transport and device prospects of monolayer molybdenum disulphide grown by chemical vapour deposition

    OpenAIRE

    Zhu, Wenjuan; Low, Tony; Lee, Yi-Hsien; Wang, Han; Farmer, Damon B.; Kong, Jing; Xia, Fengnian; Avouris, Phaedon

    2013-01-01

    Layered transition metal dichalcogenides display a wide range of attractive physical and chemical properties and are potentially important for various device applications. Here we report the electronic transport and device properties of monolayer molybdenum disulphide (MoS2) grown by chemical vapour deposition (CVD). We show that these devices have the potential to suppress short channel effects and have high critical breakdown electric field. However, our study reveals that the electronic pr...

  14. Expanding Thermal Plasma Chemical Vapour Deposition of ZnO:Al Layers for CIGS Solar Cells

    Directory of Open Access Journals (Sweden)

    K. Sharma

    2014-01-01

    Full Text Available Aluminium-doped zinc oxide (ZnO:Al grown by expanding thermal plasma chemical vapour deposition (ETP-CVD has demonstrated excellent electrical and optical properties, which make it an attractive candidate as a transparent conductive oxide for photovoltaic applications. However, when depositing ZnO:Al on CIGS solar cell stacks, one should be aware that high substrate temperature processing (i.e., >200°C can damage the crucial underlying layers/interfaces (such as CIGS/CdS and CdS/i-ZnO. In this paper, the potential of adopting ETP-CVD ZnO:Al in CIGS solar cells is assessed: the effect of substrate temperature during film deposition on both the electrical properties of the ZnO:Al and the eventual performance of the CIGS solar cells was investigated. For ZnO:Al films grown using the high thermal budget (HTB condition, lower resistivities, ρ, were achievable (~5 × 10−4 Ω·cm than those grown using the low thermal budget (LTB conditions (~2 × 10−3 Ω·cm, whereas higher CIGS conversion efficiencies were obtained for the LTB condition (up to 10.9% than for the HTB condition (up to 9.0%. Whereas such temperature-dependence of CIGS device parameters has previously been linked with chemical migration between individual layers, we demonstrate that in this case it is primarily attributed to the prevalence of shunt currents.

  15. Development and characterization of Undoped Silicon Glass (USG using chemical vapour deposition

    Directory of Open Access Journals (Sweden)

    Jagadeesha T

    2011-02-01

    Full Text Available Sub atmospheric chemical vapour deposition (SACVD is a widely used technique in semiconductor integrated circuit (IC manufacturing, especially to form inter-metal silicon (IMD dioxide thin films. It was designed for commercially available tools in order to satisfy the gap filling requirements necessary for 0.18 and 0.15 lm technology ICs, but it has been successfully extended also for 0.13 lm technological node and over. SACVD technique has a potential impact on device electrical characteristics and metallurgy compatibility, according to process conditions, such as mass flow rate of TEOS, Gasflows, RF power. Present work focuses on development and characterisation of undoped silicate glass that can be used for Flash memory and Logic devices. It is shown that new process yield deposition rate improvement of 51% and throughput improvement of 13%.. Qualitative yield comparison and wafer map to map comparison work is also presented for various technology nodes. Device parameters comparison with the standard process is also included in the present work.

  16. Chemical vapour deposition of thermochromic vanadium dioxide thin films for energy efficient glazing

    Energy Technology Data Exchange (ETDEWEB)

    Warwick, Michael E.A. [Department of Chemistry, University College London, Christopher Ingold Laboratories, 20 Gordon Street, London, WC1H 0AJ (United Kingdom); UCL Energy Institute, Central House, 14 Upper Woburn Place, London, WC1H 0NN (United Kingdom); Binions, Russell, E-mail: r.binions@qmul.ac.uk [School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London, E1 4NS (United Kingdom)

    2014-06-01

    Vanadium dioxide is a thermochromic material that undergoes a semiconductor to metal transitions at a critical temperature of 68 °C. This phase change from a low temperature monoclinic structure to a higher temperature rutile structure is accompanied by a marked change in infrared reflectivity and change in resistivity. This ability to have a temperature-modulated film that can limit solar heat gain makes vanadium dioxide an ideal candidate for thermochromic energy efficient glazing. In this review we detail the current challenges to such glazing becoming a commercial reality and describe the key chemical vapour deposition technologies being employed in the latest research. - Graphical abstract: Schematic demonstration of the effect of thermochromic glazing on solar radiation (red arrow represents IR radiation, black arrow represents all other solar radiation). - Highlights: • Vanadium dioxide thin films for energy efficient glazing. • Reviews chemical vapour deposition techniques. • Latest results for thin film deposition for vanadium dioxide.

  17. Comparison of laser-ablation and hot-wall chemical vapour deposition techniques for nanowire fabrication

    International Nuclear Information System (INIS)

    A comparison of the transport properties of populations of single-crystal, In2O3 nanowires (NWs) grown by unassisted hot-wall chemical vapour deposition (CVD) versus NWs grown by laser-ablation-assisted chemical vapour deposition (LA-CVD) is presented. For nominally identical growth conditions across the two systems, NWs fabricated at 850 deg. C with laser-ablation had significantly higher average mobilities at the 99.9% confidence level, 53.3 ± 5.8 cm2 V-1 s-1 versus 10.2 ± 1.9 cm2 V-1 s-1. It is also observed that increasing growth temperature decreases mobility for LA-CVD NWs. Transmission electron microscopy studies of CVD-fabricated samples indicate the presence of an amorphous In2O3 region surrounding the single-crystal core. Further, low-temperature measurements verify the presence of ionized impurity scattering in low-mobility CVD-grown NWs

  18. Structural properties of zinc oxide deposited using atmospheric pressure combustion chemical vapour deposition

    International Nuclear Information System (INIS)

    In this study the deposition of thin zinc oxide (ZnO) films under atmospheric pressure conditions was investigated. The deposition technique applied was combustion chemical vapour deposition (CCVD), at which a propane–air mixture was combusted in a burner. Dissolved zinc nitrate was used as precursor, which was guided as aerosol droplets by the processing gas flow directly into the reaction zone. Fundamental investigations were performed to form undoped ZnO. The structural properties of the films were analysed in dependence of the substrate temperature during the coating process. The presence of crystalline ZnO structures was proved and differences in film growth and crystallite sizes are revealed. Additionally, the particles generated by the CCVD-flame are characterised. The thin films showed a slight excess of Zn and several states of binding energy could be observed by fitting the core level spectra. Scanning and transmission electron microscopy also indicated ordered structures and additionally different orientations of crystallites were observed. - Highlights: • Columnar growth structures of ZnO by CCVD were observed. • The presence of polycrystalline ZnO with (002) as main orientation was confirmed. • Initial particles significantly differ from crystallite sizes of the resulting films. • The films show an excess of Zn with a Zn-to-O ratio of around 1.7

  19. Structural properties of zinc oxide deposited using atmospheric pressure combustion chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Zunke, I., E-mail: iz@innovent-jena.de [Innovent e.V. Technology Development, Department of Surface Engineering, Prüssingstr. 27B, 07745 Jena (Germany); Wolf, S. [University of Jena, Institute for Solid State Physics, Helmholtzweg 3/5, 07745 Jena (Germany); Heft, A.; Schimanski, A.; Grünler, B. [Innovent e.V. Technology Development, Department of Surface Engineering, Prüssingstr. 27B, 07745 Jena (Germany); Ronning, C.; Seidel, P. [University of Jena, Institute for Solid State Physics, Helmholtzweg 3/5, 07745 Jena (Germany)

    2014-08-28

    In this study the deposition of thin zinc oxide (ZnO) films under atmospheric pressure conditions was investigated. The deposition technique applied was combustion chemical vapour deposition (CCVD), at which a propane–air mixture was combusted in a burner. Dissolved zinc nitrate was used as precursor, which was guided as aerosol droplets by the processing gas flow directly into the reaction zone. Fundamental investigations were performed to form undoped ZnO. The structural properties of the films were analysed in dependence of the substrate temperature during the coating process. The presence of crystalline ZnO structures was proved and differences in film growth and crystallite sizes are revealed. Additionally, the particles generated by the CCVD-flame are characterised. The thin films showed a slight excess of Zn and several states of binding energy could be observed by fitting the core level spectra. Scanning and transmission electron microscopy also indicated ordered structures and additionally different orientations of crystallites were observed. - Highlights: • Columnar growth structures of ZnO by CCVD were observed. • The presence of polycrystalline ZnO with (002) as main orientation was confirmed. • Initial particles significantly differ from crystallite sizes of the resulting films. • The films show an excess of Zn with a Zn-to-O ratio of around 1.7.

  20. Properties of alumina films prepared by metal-organic chemical vapour deposition at atmospheric pressure in hte presence of small amounts of water

    NARCIS (Netherlands)

    Haanappel, V.A.C.; Rem, J.B.; Corbach, van H.D.; Fransen, T.; Gellings, P.J.

    1995-01-01

    Thin alumina films were deposited on stainless steel, type AISI 304. The deposition process was carried out in nitrogen with low partial pressures of water (0–2.6 × 10−2 kPa (0−0.20 mmHg)) by metal-organic chemical vapour deposition (MOCVD) with aluminium-tri-sec-butoxide (ATSB) as the precursor. Al

  1. Synthesis of few layer single crystal graphene grains on platinum by chemical vapour deposition

    Directory of Open Access Journals (Sweden)

    S. Karamat

    2015-08-01

    Full Text Available The present competition of graphene electronics demands an efficient route which produces high quality and large area graphene. Chemical vapour deposition technique, where hydrocarbons dissociate in to active carbon species and form graphene layer on the desired metal catalyst via nucleation is considered as the most suitable method. In this study, single layer graphene with the presence of few layer single crystal graphene grains were grown on Pt foil via chemical vapour deposition. The higher growth temperature changes the surface morphology of the Pt foil so a delicate process of hydrogen bubbling was used to peel off graphene from Pt foil samples with the mechanical support of photoresist and further transferred to SiO2/Si substrates for analysis. Optical microscopy of the graphene transferred samples showed the regions of single layer along with different oriented graphene domains. Two type of interlayer stacking sequences, Bernal and twisted, were observed in the graphene grains. The presence of different stacking sequences in the graphene layers influence the electronic and optical properties; in Bernal stacking the band gap can be tunable and in twisted stacking the overall sheet resistance can be reduced. Grain boundaries of Pt provides low energy sites to the carbon species, therefore the nucleation of grains are more at the boundaries. The stacking order and the number of layers in grains were seen more clearly with scanning electron microscopy. Raman spectroscopy showed high quality graphene samples due to very small D peak. 2D Raman peak for single layer graphene showed full width half maximum (FWHM value of 30 cm−1. At points A, B and C, Bernal stacked grain showed FWHM values of 51.22, 58.45 and 64.72 cm−1, while twisted stacked grain showed the FWHM values of 27.26, 28.83 and 20.99 cm−1, respectively. FWHM values of 2D peak of Bernal stacked grain showed an increase of 20–30 cm−1 as compare to single layer graphene

  2. Synthesis of few layer single crystal graphene grains on platinum by chemical vapour deposition

    Institute of Scientific and Technical Information of China (English)

    S. Karamat; S. Sonuşen; Ü. Çelik; Y. Uysallı; E. Özgönül; A. Oral

    2015-01-01

    The present competition of graphene electronics demands an efficient route which produces high quality and large area graphene. Chemical vapour deposition technique, where hydrocarbons dissociate in to active carbon species and form graphene layer on the desired metal catalyst via nucleation is considered as the most suitable method. In this study, single layer graphene with the presence of few layer single crystal graphene grains were grown on Pt foil via chemical vapour deposition. The higher growth temperature changes the surface morphology of the Pt foil so a delicate process of hydrogen bubbling was used to peel off graphene from Pt foil samples with the mechanical support of photoresist and further transferred to SiO2/Si substrates for analysis. Optical microscopy of the graphene transferred samples showed the regions of single layer along with different oriented graphene domains. Two type of interlayer stacking sequences, Bernal and twisted, were observed in the graphene grains. The presence of different stacking sequences in the graphene layers influence the electronic and optical properties;in Bernal stacking the band gap can be tunable and in twisted stacking the overall sheet resistance can be reduced. Grain boundaries of Pt provides low energy sites to the carbon species, therefore the nucleation of grains are more at the boundaries. The stacking order and the number of layers in grains were seen more clearly with scanning electron microscopy. Raman spectroscopy showed high quality graphene samples due to very small D peak. 2D Raman peak for single layer graphene showed full width half maximum (FWHM) value of 30 cm ? 1. At points A, B and C, Bernal stacked grain showed FWHM values of 51.22, 58.45 and 64.72 cm ? 1, while twisted stacked grain showed the FWHM values of 27.26, 28.83 and 20.99 cm ? 1, respectively. FWHM values of 2D peak of Bernal stacked grain showed an increase of 20–30 cm ? 1 as compare to single layer graphene which showed its

  3. High-Rate Growth and Nitrogen Distribution in Homoepitaxial Chemical Vapour Deposited Single-crystal Diamond

    Institute of Scientific and Technical Information of China (English)

    LI Hong-Dong; ZOU Guang-Tian; WANG Qi-Liang; CHENG Shao-Heng; LI Bo; L(U) Jian-Nan; L(U) Xian-Yi; JIN Zeng-Sun

    2008-01-01

    High rate (> 50 μm/h) growth of homoepitaxial single-crystal diamond (SCD) is carried out by microwave plasma chemical vapour deposition (MPCVD) with added nitrogen in the reactant gases of methane and hydrogen,using a polycrystalline-CVD-diamond-film-made seed holder. Photoluminescence results indicate that the nitrogen concentration is spatially inhomogeneous in a large scale,either on the top surface or in the bulk of those as-grown SCDs.The presence of N-distribution is attributed to the facts: (I) a difference in N-incorporation efficiency and (ii) N-diffusion,resulting from the local growth temperatures changed during the high-rate deposition process.In addition,the formed nitrogen-vacancy centres play a crucial role in N-diffusion through the growing crystal.Based on the N-distribution observed in the as-grown crystals,we propose a simple method to distinguish natural diamonds and man-made CVD SCDs.Finally,the disappearance of void defect on the top surface of SCDs is discussed to be related to a filling-in mechanism.

  4. Hybrid chemical vapour and nanoceramic aerosol assisted deposition for multifunctional nanocomposite thin films

    Energy Technology Data Exchange (ETDEWEB)

    Warwick, Michael E.A.; Dunnill, Charles W.; Goodall, Josie; Darr, Jawwad A.; Binions, Russell, E-mail: uccarbi@ucl.ac.uk

    2011-07-01

    Hybrid atmospheric pressure chemical vapour and aerosol assisted deposition via the reaction of vanadium acetylacetonate and a suspension of preformed titanium dioxide or cerium dioxide nanoparticles, led to the production of vanadium dioxide nanocomposite thin films on glass substrates. The preformed nanoparticle oxides used for the aerosol were synthesised using a continuous hydrothermal flow synthesis route involving the rapid reaction of a metal salt solution with a flow of supercritical water in a flow reactor. Multifunctional nanocomposite thin films from the hybrid deposition process were characterised using scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The functional properties of the films were evaluated using variable temperature optical measurements to assess thermochromic behaviour and methylene blue photodecolourisation experiments to assess photocatalytic activity. The tests show that the films are multifunctional in that they are thermochromic (having a large change in infra-red reflectivity upon exceeding the thermochromic transition temperature) and have significant photocatalytic activity under irradiation with 254 nm light.

  5. Kinetically controlled InN nucleation on GaN templates by metalorganic chemical vapour deposition

    International Nuclear Information System (INIS)

    This paper presents a study on the nucleation and initial growth kinetics of InN on GaN, especially their dependence on metalorganic chemical vapour deposition conditions. It is found that the density and size of separated InN nano-scale islands can be adjusted and well controlled by changing the V/III ratio and growth temperature. InN nuclei density increases for several orders of magnitude with decreasing growth temperature between 525 and 375 0C. At lower growth temperatures, InN thin films take the form of small and closely packed islands with diameters less than 100 nm, whereas at elevated temperatures the InN islands grow larger and become well separated, approaching an equilibrium hexagonal shape due to enhanced surface diffusion of adatoms. The temperature dependence of InN island density gives two activation energies of InN nucleation behaviour, which is attributed to two different kinetic processes related to In adatom surface diffusion and desorption, respectively.

  6. Experimental Investigation of Influence of Acoustic Wave on Vapour Precipitation Process

    OpenAIRE

    V. Vekteris; I. Tetsman; V. Moksin

    2013-01-01

    The measurement results of acoustic field parameters above electroplating bath, in presence of water vapour, are analyzed in this work. Suction was created by means of side exhausters. It is obtained that the sound field generator generated a sound level of 130–140 dB at frequency interval between 1 and 10 kHz. It is shown that aerosol coagulation and precipitation processes are intensified under the mentioned conditions. The concentration of vapour and other aerosols in removal air decreases...

  7. The Role of Plasma in Plasma Enhanced Chemical Vapour Deposition of Nanostructure Growth

    Science.gov (United States)

    Hash, David B.; Meyyappan, M.; Teo, Kenneth B. K.; Lacerda, Rodrigo G.; Rupesinghe, Nalin L.

    2004-01-01

    Chemical vapour deposition (CVD) has become the preferred process for high yield growth of carbon nanotubes and nanofibres because of its ability to pattern growth through lithographic positioning of transition metal catalysts on substrates. Many potential applications of nanotubes such as field emitters [1] require not only patterned growth but also vertical alignment. Some degree of ali,ment in thermal CVD processes can be obtained when carbon nanotubes are grown closely together as a result of van der Waals interactions. The ali,onment however is marginal, and the van der Waals prerequisite makes growth of freestanding nanofibres with thermal CVD unrealizable. The application of electric fields as a means of ali,onment has been shown to overcome this limitation [2-5], and highly aligned nanostructures can be grown if electric fields on the order of 0.5 V/microns are employed. Plasma enhanced CVD in various configurations including dc, rf, microwave, inductive and electron cyclotron resonance has been pursued as a means of enabling alignment in the CVD process. However, the sheath fields for the non-dc sources are in general not sufficient for a high degree of ali,pment and an additional dc bias is usually applied to the growth substrate. This begs the question as to the actual role of the plasma. It is clear that the plasma itself is not required for aligned growth as references [3] and [4] employed fields through small applied voltages (3-20 V) across very small electrode spacings (10-100 microns) and thus avoided striking a discharge.

  8. The pyrolytic decomposition of ATSB during chemical vapour deposition of thin alumina films

    OpenAIRE

    Haanappel, V.A.C.; Corbach, van, H.D.; Fransen, T.; Gellings, P.J.

    1994-01-01

    The effect of the deposition temperature and the partial pressure of water on the thermal decomposition chemistry of aluminium-tri-sec-butoxide (ATSB) during metal organic chemical vapour deposition (MOCVD) is reported. The MOCVD experiments were performed in nitrogen at atmospheric pressure. The partial pressure of ATSB was 0.026 kPa (0.20 mmHg) and that of water was between 0 and 0.026 kPa (0–0.20 mmHg). The pyrolytic decomposition chemistry of ATSB was studied by mass spectrometry at tempe...

  9. Fluidization and coating of very dense powders by fluidized bed chemical vapour deposition

    OpenAIRE

    Rodriguez, Philippe; Caussat, Brigitte; Ablitzer, Carine; Iltis, Xavière; Brothier, Méryl

    2013-01-01

    The hydrodynamic behaviour of a very dense tungsten powder, 75 µm in median diameter and 19,300 kg/m3 in grain density, has been studied in a fluidized bed at room temperature using nitrogen and argon as carrier gas. Even if fluidization was achieved, the small bed expansion indicated that it was imperfect. Then, the fluidization was studied at 400 °C in order to investigate the feasibility of coating this powder by Fluidized Bed Chemical Vapour Deposition (FBCVD). In particular, the influenc...

  10. Deposition of diamond and boron nitride films by plasma chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Albella, J.M. [Universidad Autonoma, CSIC, Madrid (Spain). Inst. of Mater. Sci.; Gomez-Aleixandre, C. [Universidad Autonoma, CSIC, Madrid (Spain). Inst. of Mater. Sci.; Sanchez-Garrido, O. [Universidad Autonoma, CSIC, Madrid (Spain). Inst. of Mater. Sci.; Vazquez, L. [Universidad Autonoma, CSIC, Madrid (Spain). Inst. of Mater. Sci.; Martinez-Duart, J.M. [Universidad Autonoma, CSIC, Madrid (Spain). Inst. of Mater. Sci.

    1995-01-01

    The deposition problems of diamond and cubic boron nitride (c-BN) by chemical vapour deposition techniques are reviewed, with major emphasis on the nucleation and reaction mechanisms. A discussion is made of the main deposition parameters (i.e. gas mixture, substrate conditioning, plasma discharges etc.) which favour the formation of the cubic phase. Most of the work is devoted to diamond owing to the large progress attained in this material. In fact, the use of diamond as a hard protective coating is now on a commercial scale. By contrast, the preparation of c-BN layers with good characteristics still needs of further research. ((orig.))

  11. Conductive zinc oxide thin film coatings by combustion chemical vapour deposition at atmospheric pressure

    International Nuclear Information System (INIS)

    We have established a combustion chemical vapour deposition (C-CVD) system for the deposition of zinc oxide (ZnO) at atmospheric pressure. This C-CVD process has the advantage of a short exposure of the substrates to the flame. It is also potentially applicable as an inline coating system. Fundamental studies were performed on undoped ZnO. The specific resistivity of these layers strongly depends on the film thickness and decreases with increasing thickness. As the lowest resistivities, values of about 2.0 · 10−1 Ωcm are achieved. Ultra-violet photoemission spectra show the valence band structure of the deposited ZnO. The work function and valence band edge were determined. UV–vis spectra were taken to investigate the transmission of the coated glass samples. From these spectra the band gap energy was obtained. Raman spectroscopy as well as infrared spectroscopy confirmed the presence of ordered ZnO crystallites. The X-ray diffraction verified this result and illustrates the hexagonal structure. In the mid-infrared range precursor deposits were detected for low substrate temperatures. - Highlights: ► Zinc oxide (ZnO) films are conductive in the range of 2.0 · 10−1 Ωcm. ► X-ray diffraction, Raman and infrared spectroscopy indicate crystalline ZnO films. ► Precursor deposits were proved within the films for low growing temperatures. ► Band gap energy changes are achieved due to different growing temperatures

  12. Comparison of laser-ablation and hot-wall chemical vapour deposition techniques for nanowire fabrication

    Science.gov (United States)

    Stern, E.; Cheng, G.; Guthrie, S.; Turner-Evans, D.; Broomfield, E.; Lei, B.; Li, C.; Zhang, D.; Zhou, C.; Reed, M. A.

    2006-06-01

    A comparison of the transport properties of populations of single-crystal, In2O3 nanowires (NWs) grown by unassisted hot-wall chemical vapour deposition (CVD) versus NWs grown by laser-ablation-assisted chemical vapour deposition (LA-CVD) is presented. For nominally identical growth conditions across the two systems, NWs fabricated at 850 °C with laser-ablation had significantly higher average mobilities at the 99.9% confidence level, 53.3 ± 5.8 cm2 V-1 s-1 versus 10.2 ± 1.9 cm2 V-1 s-1. It is also observed that increasing growth temperature decreases mobility for LA-CVD NWs. Transmission electron microscopy studies of CVD-fabricated samples indicate the presence of an amorphous In2O3 region surrounding the single-crystal core. Further, low-temperature measurements verify the presence of ionized impurity scattering in low-mobility CVD-grown NWs.

  13. Zinc oxide nanostructures by chemical vapour deposition as anodes for Li-ion batteries

    International Nuclear Information System (INIS)

    Highlights: • ZnO nanostructures are grown by simple chemical vapour deposition. • Polycrystalline nanostructured porous thin film is obtained. • Film exhibits stable specific capacity (∼400 mA h g−1) after prolonged cycling. • CVD-grown ZnO nanostructures show promising prospects as Li-ion battery anode. - Abstract: ZnO nanostructures are grown by a simple chemical vapour deposition method directly on a stainless steel disc current collector and successfully tested in lithium cells. The structural/morphological characterization points out the presence of well-defined polycrystalline nanostructures having different shapes and a preferential orientation along the c-axis direction. In addition, the high active surface of the ZnO nanostructures, which accounts for a large electrode/electrolyte contact area, and the complete wetting with the electrolyte solution are considered to be responsible for the good electrical transport properties and the adequate electrochemical behaviour, as confirmed by cyclic voltammetry and galvanostatic charge/discharge cycling. Indeed, despite no binder or conducting additives are used, when galvanostatically tested in lithium cells, after an initial decay, the ZnO nanostructures can provide a rather stable specific capacity approaching 70 μA h cm−2 (i.e., around 400 mA h g−1) after prolonged cycling at 1 C, with very high Coulombic efficiency and an overall capacity retention exceeding 62%

  14. Electric field assisted aerosol assisted chemical vapour deposition of nanostructured metal oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Naik, Anupriya J.T.; Bowman, Christopher; Panjwani, Naitik [Department of Chemistry, University College London, Christopher Ingold Laboratories, 20 Gordon Street, London WC1H OAJ (United Kingdom); Warwick, Michael E.A. [Department of Chemistry, University College London, Christopher Ingold Laboratories, 20 Gordon Street, London WC1H OAJ (United Kingdom); UCL Energy Institute, Central House, 14 Upper Woburn Place, London WC1H 0HY (United Kingdom); Binions, Russell, E-mail: r.binions@qmul.ac.uk [Department of Chemistry, University College London, Christopher Ingold Laboratories, 20 Gordon Street, London WC1H OAJ (United Kingdom); School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom)

    2013-10-01

    Nanostructured thin films of tungsten, vanadium and titanium oxides were deposited on gas sensor substrates from the electric field assisted chemical vapour deposition reaction of tungsten hexaphenoxide, vanadyl acetylacetonate and titanium tetraisopropoxide respectively. The electric fields were generated by applying a potential difference between the inter-digitated electrodes of the gas sensor substrates during the deposition. The deposited films were characterised using scanning electron microscopy, X-ray diffraction and Raman spectroscopy. The application of an electric field, encouraged the formation of interesting and unusual nanostructured morphologies, with a change in scale length and island packing. It was also noted that crystallographic orientation of the films could be controlled as a function of electric field type and strength. The gas sensor properties of the films were also examined; it was found that a two to three fold enhancement in the gas response could be observed from sensors with enhanced morphologies compared to control sensors grown without application of an electric field. - Highlights: • Electric field assisted chemical vapour deposition method • Ability to create high surface area film architectures • Can produce enhanced sensor response • Good control over film properties.

  15. Characterization of Si:O:C:H films fabricated using electron emission enhanced chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Durrant, Steven F. [Laboratorio de Plasmas Tecnologicos, Campus Experimental de Sorocaba, Universidade Estadual Paulista-UNESP, Avenida Tres de Marco, 511, Alto da Boa Vista, 18087-180, Soracaba, SP (Brazil)], E-mail: steve@sorocaba.unesp.br; Rouxinol, Francisco P.M.; Gelamo, Rogerio V. [Instituto de Fisica Gleb Wataghin, Universidade Estadual de Campinas, 13083-970, Campinas, SP (Brazil); Trasferetti, B. Claudio [Present address: Superintendencia Regional da Policia Federal em Sao Paulo, Setor Tecnico-Cientifico, Rua Hugo d' Antola 95/10o Andar, Lapa de Baixo, 05038-090 Sao Paulo, SP (Brazil); Davanzo, C.U. [Instituto de Quimica, Universidade Estadual de Campinas, 13083-970, Campinas, SP (Brazil); Bica de Moraes, Mario A. [Instituto de Fisica Gleb Wataghin, Universidade Estadual de Campinas, 13083-970, Campinas, SP (Brazil)

    2008-01-15

    Silicon-based polymers and oxides may be formed when vapours of oxygen-containing organosilicone compounds are exposed to energetic electrons drawn from a hot filament by a bias potential applied to a second electrode in a controlled atmosphere in a vacuum chamber. As little deposition occurs in the absence of the bias potential, electron impact fragmentation is the key mechanism in film fabrication using electron-emission enhanced chemical vapour deposition (EEECVD). The feasibility of depositing amorphous hydrogenated carbon films also containing silicon from plasmas of tetramethylsilane or hexamethyldisiloxane has already been shown. In this work, we report the deposition of diverse films from plasmas of tetraethoxysilane (TEOS)-argon mixtures and the characterization of the materials obtained. The effects of changes in the substrate holder bias (V{sub S}) and of the proportion of TEOS in the mixture (X{sub T}) on the chemical structure of the films are examined by infrared-reflection absorption spectroscopy (IRRAS) at near-normal and oblique incidence using unpolarised and p-polarised, light, respectively. The latter is particularly useful in detecting vibrational modes not observed when using conventional near-normal incidence. Elemental analyses of the film were carried out by X-ray photoelectron spectroscopy (XPS), which was also useful in complementary structural investigations. In addition, the dependencies of the deposition rate on V{sub S} and X{sub T} are presented.

  16. Zinc oxide nanostructures by chemical vapour deposition as anodes for Li-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Laurenti, M., E-mail: marco.laurenti@iit.it [Center for Space Human Robotics @Polito, Istituto Italiano di Tecnologia, Corso Trento, 21, 10129 Turin (Italy); Department of Applied Science and Technology – DISAT, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Turin (Italy); Garino, N. [Center for Space Human Robotics @Polito, Istituto Italiano di Tecnologia, Corso Trento, 21, 10129 Turin (Italy); Porro, S.; Fontana, M. [Center for Space Human Robotics @Polito, Istituto Italiano di Tecnologia, Corso Trento, 21, 10129 Turin (Italy); Department of Applied Science and Technology – DISAT, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Turin (Italy); Gerbaldi, C., E-mail: claudio.gerbaldi@polito.it [Center for Space Human Robotics @Polito, Istituto Italiano di Tecnologia, Corso Trento, 21, 10129 Turin (Italy); Department of Applied Science and Technology – DISAT, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Turin (Italy)

    2015-08-15

    Highlights: • ZnO nanostructures are grown by simple chemical vapour deposition. • Polycrystalline nanostructured porous thin film is obtained. • Film exhibits stable specific capacity (∼400 mA h g{sup −1}) after prolonged cycling. • CVD-grown ZnO nanostructures show promising prospects as Li-ion battery anode. - Abstract: ZnO nanostructures are grown by a simple chemical vapour deposition method directly on a stainless steel disc current collector and successfully tested in lithium cells. The structural/morphological characterization points out the presence of well-defined polycrystalline nanostructures having different shapes and a preferential orientation along the c-axis direction. In addition, the high active surface of the ZnO nanostructures, which accounts for a large electrode/electrolyte contact area, and the complete wetting with the electrolyte solution are considered to be responsible for the good electrical transport properties and the adequate electrochemical behaviour, as confirmed by cyclic voltammetry and galvanostatic charge/discharge cycling. Indeed, despite no binder or conducting additives are used, when galvanostatically tested in lithium cells, after an initial decay, the ZnO nanostructures can provide a rather stable specific capacity approaching 70 μA h cm{sup −2} (i.e., around 400 mA h g{sup −1}) after prolonged cycling at 1 C, with very high Coulombic efficiency and an overall capacity retention exceeding 62%.

  17. Characterization of Thin Films Deposited with Precursor Ferrocene by Plasma Enhanced Chemical Vapour Deposition

    Institute of Scientific and Technical Information of China (English)

    YAO Kailun; ZHENG Jianwan; LIU Zuli; JIA Lihui

    2007-01-01

    In this paper,the characterization of thin films,deposited with the precursor ferrocene(FcH)by the plasma enhanced chemical vapour deposition(PECVD)technique,was investigated.The films were measured by Scanning Electronic Microscopy(SEM),Atomic Force Microscopy(AFM),Electron Spectroscopy for Chemical Analysis(ESCA),and superconducting Quantum Interference Device(SQUID).It was observed that the film's layer is homogeneous in thickness and has a dense morphology without cracks.The surface roughness is about 36 nm.From the results of ESCA,it can be inferred that the film mainly contains the compound FeOOH,and carbon is combined with oxygen in different forms under different supply-powers.The hysteresis loops indicate that the film is of soft magnetism.

  18. Orthogonal self-assembly and selective solvent vapour annealing: simplified processing of a photovoltaic blend.

    Science.gov (United States)

    De Luca, Giovanna; Liscio, Andrea; Battagliarin, Glauco; Chen, Long; Scolaro, Luigi Monsù; Müllen, Klaus; Samorì, Paolo; Palermo, Vincenzo

    2013-05-14

    Selective solvent vapour annealing is used on a photovoltaic blend to enhance the interaction between the electron acceptor and the electron donor, simplifying thin films post-processing for photovoltaic applications. A remarkable improvement in the interfacial charge transfer in the bulk hetero-junction is attained, as measured by Kelvin Probe Force Microscopy.

  19. Wetting behaviour of carbon nitride nanostructures grown by plasma enhanced chemical vapour deposition technique

    International Nuclear Information System (INIS)

    Highlights: • Carbon nitride films were prepared by using radio frequency plasma enhanced chemical vapour deposition system by altering the electrode distance. • The effect of electrode distance on surface morphology, surface roughness, chemical bonding and hydrophobic behaviour has been studied. • Hydrophobic behaviour were studied by measuring contact angle and calculating surface energy. • CNx nanostructures show super-hydrophobic behaviour. • We report a tunable transition of hydrophilic to super-hydrophobic behaviour of film as electrode distance is reduced. - Abstract: Tuning the wettability of various coating materials by simply controlling the deposition parameters is essential for various specific applications. In this work, carbon nitride (CNx) films were deposited on silicon (1 1 1) substrates using radio-frequency plasma enhanced chemical vapour deposition employing parallel plate electrode configuration. Effects of varying the electrode distance (DE) on the films’ structure and bonding properties were investigated using Field emission scanning electron microscopy, Atomic force microscopy, Fourier transform infrared and X-ray photoemission spectroscopy. The wettability of the films was analyzed using water contact angle measurements. At high DE, the CNx films’ surface was smooth and uniform. This changed into fibrous nanostructures when DE was decreased. Surface roughness of the films increased with this morphological transformation. Nitrogen incorporation increased with decrease in DE which manifested the increase in both relative intensities of C=N to C=C and N−H to O−H bonds. sp2-C to sp3-C ratio increased as DE decreased due to greater deformation of sp2 bonded carbon at lower DE. The films’ characteristics changed from hydrophilic to super-hydrophobic with the decrease in DE. Roughness ratio, surface porosity and surface energy calculated from contact angle measurements were strongly dependent on the morphology, surface

  20. Thermogravimetric analysis of cobalt-filled carbon nanotubes deposited by chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Ramesh, Babu P. [Materials Ireland Polymer Research Centre, Trinity College, Dublin-1 (Ireland); Blau, W.J. [Materials Ireland Polymer Research Centre, Trinity College, Dublin-1 (Ireland); Tyagi, P.K. [Department of Physics, Indian Institute of Technology, Bombay (India); Misra, D.S. [Department of Physics, Indian Institute of Technology, Bombay (India); Ali, N. [Department of Mechanical Engineering, University of Aveiro, 3810-193 Aveiro (Portugal); Gracio, J. [Department of Mechanical Engineering, University of Aveiro, 3810-193 Aveiro (Portugal); Cabral, G. [Department of Mechanical Engineering, University of Aveiro, 3810-193 Aveiro (Portugal); Titus, E. [Department of Mechanical Engineering, University of Aveiro, 3810-193 Aveiro (Portugal)]. E-mail: elby@mec.ua.pt

    2006-01-03

    In this paper, we report results from an investigation studying the purification of Co-filled carbon nanotubes (CNTs) using Thermogravimetric analysis (TGA). The as-grown CNTs were prepared using Microwave Plasma Chemical Vapour Deposition (MPCVD). Transmission electron microscopy (TEM), Fourier Transform Infrared (FTIR) and Raman spectroscopy were used to characterise the CNT samples. The CNTs produced by MPCVD were filled with cobalt and consisted of thick multi-walls. After TGA purification at 900 deg. C, 30 wt.% Co-filled CNTs remained in the TGA pan. However, while investigating the un-filled commercial CNTs (thin multiwalled), the sample completely burnt out at around 650 deg. C in the TGA furnace. The high thermal stability and the ability of thick-walled CNTs to act as an effective protective shield which prevents the oxidation of encapsulated cobalt have been demonstrated.

  1. Al-Induced Crystallization Growth of Si Films by Inductively Coupled Plasma Chemical Vapour Deposition

    Institute of Scientific and Technical Information of China (English)

    LI Jun-Shuai; WANG Jin-Xiao; YIN Min; GAO Ping-Qi; HE De-Yan

    2006-01-01

    Polycrystalline Si (poly-Si) films are in situ grown on Al-coated glass substrates by inductively coupled plasma chemical vapour deposition at a temperature as low as 350 C. Compared to the traditional annealing crystallization of amorphous Si/Al-layer structures, no layer exchange is observed and the resultant poly-Si film is much thicker than Al layer. By analysing the depth profiles of the elemental composition, no remains of Al atoms are detected in Si layer within the limit (< 0.01 at. %) of the used evaluations. It is indicated that the poly-Si material obtained by Al-induced crystallization growth has more potential applications than that prepared by annealing the amorphous Si/Al-layer structures.

  2. Magnetic and cytotoxic properties of hot-filament chemical vapour deposited diamond

    Energy Technology Data Exchange (ETDEWEB)

    Zanin, Hudson, E-mail: hudsonzanin@gmail.com [Faculdade de Engenharia Eletrica e Computacao, Departamento de Semicondutores, Instrumentos e Fotonica, Universidade Estadual de Campinas, UNICAMP, Av. Albert Einstein N.400, CEP 13 083-852 Campinas, Sao Paulo (Brazil); Peterlevitz, Alfredo Carlos; Ceragioli, Helder Jose [Faculdade de Engenharia Eletrica e Computacao, Departamento de Semicondutores, Instrumentos e Fotonica, Universidade Estadual de Campinas, UNICAMP, Av. Albert Einstein N.400, CEP 13 083-852 Campinas, Sao Paulo (Brazil); Rodrigues, Ana Amelia; Belangero, William Dias [Laboratorio de Biomateriais em Ortopedia, Faculdade de Ciencias Medicas, Universidade Estadual de Campinas, Rua Cinco de Junho 350 CEP 13083970, Campinas, Sao Paulo (Brazil); Baranauskas, Vitor [Faculdade de Engenharia Eletrica e Computacao, Departamento de Semicondutores, Instrumentos e Fotonica, Universidade Estadual de Campinas, UNICAMP, Av. Albert Einstein N.400, CEP 13 083-852 Campinas, Sao Paulo (Brazil)

    2012-12-01

    Microcrystalline (MCD) and nanocrystalline (NCD) magnetic diamond samples were produced by hot-filament chemical vapour deposition (HFCVD) on AISI 316 substrates. Energy Dispersive X-ray Spectroscopy (EDS) measurements indicated the presence of Fe, Cr and Ni in the MCD and NCD samples, and all samples showed similar magnetisation properties. Cell viability tests were realised using Vero cells, a type of fibroblastic cell line. Polystyrene was used as a negative control for toxicity (NCT). The cells were cultured under standard cell culture conditions. The proliferation indicated that these magnetic diamond samples were not cytotoxic. - Highlights: Black-Right-Pointing-Pointer Polycrystalline diamonds doped with Fe, Cr and Ni acquire ferromagnetic properties. Black-Right-Pointing-Pointer CVD diamonds have been prepared with magnetic and semiconductor properties. Black-Right-Pointing-Pointer Micro/nanocrystalline diamonds show good cell viability with fibroblast proliferation.

  3. Microwave plasma-enhanced chemical vapour deposition growth of carbon nanostructures

    Directory of Open Access Journals (Sweden)

    Shivan R. Singh

    2010-05-01

    Full Text Available The effect of various input parameters on the production of carbon nanostructures using a simple microwave plasma-enhanced chemical vapour deposition technique has been investigated. The technique utilises a conventional microwave oven as the microwave energy source. The developed apparatus is inexpensive and easy to install and is suitable for use as a carbon nanostructure source for potential laboratory-based research of the bulk properties of carbon nanostructures. A result of this investigation is the reproducibility of specific nanostructures with the variation of input parameters, such as carbon-containing precursor and support gas flow rate. It was shown that the yield and quality of the carbon products is directly controlled by input parameters. Transmission electron microscopy and scanning electron microscopy were used to analyse the carbon products; these were found to be amorphous, nanotubes and onion-like nanostructures.

  4. Preparation of carbon nanotubes with different morphology by microwave plasma enhanced chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Duraia, El-Shazly M. [Suez Canal University, Faculty of Science, Physics Department, Ismailia (Egypt); Al-Farabi Kazakh National University, 71 Al-Farabi av., 050038 Almaty (Kazakhstan); Institute of Physics and Technology, Ibragimov Street 11, 050032 Almaty (Kazakhstan); Mansurov, Zulkhair [Al-Farabi Kazakh National University, 71 Al-Farabi av., 050038 Almaty (Kazakhstan); Tokmoldin, S.Zh. [Institute of Physics and Technology, Ibragimov Street 11, 050032 Almaty (Kazakhstan)

    2010-04-15

    In this work we present a part of our results about the preparation of carbon nanotube with different morphologies by using microwave plasma enhanced chemical vapour deposition MPECVD. Well aligned, curly, carbon nanosheets, coiled carbon sheets and carbon microcoils have been prepared. We have investigated the effect of the different growth condition parameters such as the growth temperature, pressure and the hydrogen to methane flow rate ratio on the morphology of the carbon nanotubes. The results showed that there is a great dependence of the morphology of carbon nanotubes on these parameters. The yield of the carbon microcoils was high when the growth temperature was 700 C. There is a linear relation between the growth rate and the methane to hydrogen ratio. The effect of the gas pressure on the CNTs was also studied. Our samples were investigated by scanning electron microscope and Raman spectroscopy (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. Functional ZnO/polymer core-shell nanowires fabricated by oxidative chemical vapour deposition

    International Nuclear Information System (INIS)

    Functional ZnO-nanowire/polymer core-shell heterostructures were realized using oxidative chemical vapour deposition (oCVD). This dry and versatile technique allows uniform coating of semiconductor nanowires with polymers and simultaneous doping control of the shell. Here, 100 nm thick, p-doped shells of poly(3,4-ethylenedioxythiophene) (PEDOT) were deposited around n-conductive ZnO nanowires. Energy-dispersive x-ray spectroscopy confirms the incorporation of Br dopants into the PEDOT shell, and the resulting p-conductivity of the polymer shell is demonstrated by electrical measurements on nanowire arrays. Photoluminescence spectroscopy points to reactions of Br with the ZnO surface but proves that the nanowires show only little degradation of their optical properties. (paper)

  6. Characterization of doped hydrogenated nanocrystalline silicon films prepared by plasma enhanced chemical vapour deposition

    Institute of Scientific and Technical Information of China (English)

    Wang Jin-Liang; Wu Er-Xing

    2007-01-01

    The B-and P-doped hydrogenated nanocrystalline silicon films (nc-Si:H) are prepared by plasma-enhanced chemical vapour deposition (PECVD) .The microstructures of doped nc-Si:H films are carefully and systematically char acterized by using high resolution electron microscopy (HREM) ,Raman scattering,x-ray diffraction (XRD) ,Auger electron spectroscopy (AES) ,and resonant nucleus reaction (RNR) .The results show that as the doping concentration of PH3 increases,the average grain size (d) tends to decrease and the crystalline volume percentage (Xc) increases simultaneously.For the B-doped samples,as the doping concentration of B2H6 increases,no obvious change in the value of d is observed,but the value of Xc is found to decrease.This is especially apparent in the case of heavy B2H6 doped samples,where the films change from nanocrystalline to amorphous.

  7. Electron behaviour in CH4/H2 gas mixture in electron-assisted chemical vapour deposition

    Institute of Scientific and Technical Information of China (English)

    Dong Li-Fang; Ma Bo-Qin; Wang Zhi-Jun

    2004-01-01

    The behaviour of electrons in CH4/H2 gas mixture in electron-assisted chemical vapour deposition of diamond is investigated using Monte Carlo simulation. The electron drift velocity in gas mixture is obtained over a wide range of E/P (the ratio of the electric field to gas pressure) from 1500 to 300000 (V/m kPa-1). The electron energy distribution and average energy under different gas pressure (0.1-20kPa) and CH4 concentration (0.5%-10.0%) are calculated. Their effects on the diamond growth are also discussed. It is believed that these results will be helpful to the selection of optimum experimental conditions for high quality diamond film deposition.

  8. Investigation of Chemical-Vapour-Deposition Diamond Alpha-Particle Detectors

    Institute of Scientific and Technical Information of China (English)

    GU Bei-Bei; WANG Lin-Jun; ZHANG Ming-Long; XIA Yi-Ben

    2004-01-01

    Diamond films with [100] texture were prepared by a hot-filament chemical vapour deposition technique to fabricate particle detectors. The response of detectors to 5.5 MeV 241 Am particles is studied. The photocurrent increases linearly and then levels off with voltage, and 7hA is obtained at bias voltage of 100 V. The timedependent photocurrent initially increases rapidly and then tends to reach saturation. Furthermore, a little increase of the dark-current after irradiation can be accounted for by the release of the charges captured by the trapping centres at low energy levels during irradiation. An obvious peak of the pulse height distribution can be observed, associated with the energy of 5.5 MeV.

  9. Elaboration of Bi 2Se 3 by metalorganic chemical vapour deposition

    Science.gov (United States)

    Giani, A.; Al Bayaz, A.; Foucaran, A.; Pascal-Delannoy, F.; Boyer, A.

    2002-03-01

    For the first time, Bi 2Se 3 thin films were elaborated by metalorganic chemical vapour deposition (MOCVD) using trimethylbismuth (TMBi) and diethylselenium (DESe) as metalorganic sources. The MOCVD elaboration of Bi 2Se 3 was carried out in a horizontal reactor for a substrate temperature ( Tg) varying from 450°C to 500°C, a total hydrogen flow rate DT=3 l min -1, RVI/V ratio >14 and TMBi partial pressure lower than 1.10 -4 atm. By X-ray diffraction and SEM observation, we noticed the polycrystalline structure of the layers typical preferential c-orientation and confirm the hexagonal structure. The microprobe data indicate that the best stoichiometry of Bi 2Se 3 was achieved. These films always displayed n-type conduction, and the maximum value of thermoelectric power α was found to be close to -120 μV/K.

  10. Synthesis of low leakage current chemical vapour deposited (CVD) diamond films for particle detection

    International Nuclear Information System (INIS)

    We report on synthesis of diamond films by direct current glow discharge chemical vapour deposition (CVD) prepared at different deposition conditions, for application in high energy physics. The synthesis apparatus is briefly described. Continuous undoped diamond samples have been grown onto Mo substrates with a deposition area up to 1 cm2 and an electrical resistivity as high as 1013 Ωcm. The deposition parameters are related to the material properties of the diamonds, investigated by optical spectroscopy, electron microscopy and diffraction analysis. Decreasing the linear growth rate results in good quality films with small remnants of graphite-like phases. The high crystalline quality and phase purity of the films are related to very low values of leakage currents. The particle induced conductivity of these samples is also studied and preliminary results on charge collection efficiency are presented. (orig.)

  11. Chemical vapour deposition of tungsten and tungsten silicide layers for applications in novel silicon technology

    CERN Document Server

    Li, F X

    2002-01-01

    This work was a detailed investigation into the Chemical Vapour Deposition (CVD) of tungsten and tungsten silicide for potential applications in integrated circuit (IC) and other microelectronic devices. These materials may find novel applications in contact schemes for transistors in advanced ICs, buried high conductivity layers in novel Silicon-On-Insulator (SOI) technology and in power electronic devices. The CVD techniques developed may also be used for metal coating of recessed or enclosed features which may occur in novel electronic or electromechanical devices. CVD of tungsten was investigated using the silicon reduction reaction of WF sub 6. W layers with an optimum self-limiting thickness of 100 nm and resistivity 20 mu OMEGA centre dot cm were produced self-aligned to silicon. A hydrogen passivation technique was developed as part of the wafer pre-clean schedule and proved essential in achieving optimum layer thickness. Layers produced by this approach are ideal for intimate contact to shallow junct...

  12. Magnetic and cytotoxic properties of hot-filament chemical vapour deposited diamond

    International Nuclear Information System (INIS)

    Microcrystalline (MCD) and nanocrystalline (NCD) magnetic diamond samples were produced by hot-filament chemical vapour deposition (HFCVD) on AISI 316 substrates. Energy Dispersive X-ray Spectroscopy (EDS) measurements indicated the presence of Fe, Cr and Ni in the MCD and NCD samples, and all samples showed similar magnetisation properties. Cell viability tests were realised using Vero cells, a type of fibroblastic cell line. Polystyrene was used as a negative control for toxicity (NCT). The cells were cultured under standard cell culture conditions. The proliferation indicated that these magnetic diamond samples were not cytotoxic. - Highlights: ► Polycrystalline diamonds doped with Fe, Cr and Ni acquire ferromagnetic properties. ► CVD diamonds have been prepared with magnetic and semiconductor properties. ► Micro/nanocrystalline diamonds show good cell viability with fibroblast proliferation.

  13. Low resistance polycrystalline diamond thin films deposited by hot filament chemical vapour deposition

    Indian Academy of Sciences (India)

    Mahtab Ullah; Ejaz Ahmed; Abdelbary Elhissi; Waqar Ahmed

    2014-05-01

    Polycrystalline diamond thin films with outgrowing diamond (OGD) grains were deposited onto silicon wafers using a hydrocarbon gas (CH4) highly diluted with H2 at low pressure in a hot filament chemical vapour deposition (HFCVD) reactor with a range of gas flow rates. X-ray diffraction (XRD) and SEM showed polycrystalline diamond structure with a random orientation. Polycrystalline diamond films with various textures were grown and (111) facets were dominant with sharp grain boundaries. Outgrowth was observed in flowerish character at high gas flow rates. Isolated single crystals with little openings appeared at various stages at low gas flow rates. Thus, changing gas flow rates had a beneficial influence on the grain size, growth rate and electrical resistivity. CVD diamond films gave an excellent performance for medium film thickness with relatively low electrical resistivity and making them potentially useful in many industrial applications.

  14. Scalable route to CH3NH3PbI3 perovskite thin films by aerosol assisted chemical vapour deposition

    OpenAIRE

    Bhachu, D. S.; Scanlon, D. O.; Saban, E. J.; Bronstein, H.; Parkin, I. P.; Carmalt, C. J.; Palgrave, R. G.

    2015-01-01

    Methyl-ammonium lead iodide is the archetypal perovskite solar cell material. Phase pure, compositionally uniform methyl-ammonium lead iodide thin films on large glass substrates were deposited using ambient pressure aerosol assisted chemical vapour deposition. This opens up a route to efficient scale up of hybrid perovskite film growth towards industrial deployment.

  15. Well-controlled metal co-catalysts synthesised by chemical vapour impregnation for photocatalytic hydrogen production and water purification.

    Science.gov (United States)

    Su, Ren; Forde, Michael M; He, Qian; Shen, Yanbin; Wang, Xueqin; Dimitratos, Nikolaos; Wendt, Stefan; Huang, Yudong; Iversen, Bo B; Kiely, Christopher J; Besenbacher, Flemming; Hutchings, Graham J

    2014-10-28

    As co-catalyst materials, metal nanoparticles (NPs) play crucial roles in heterogeneous photocatalysis. The photocatalytic performance strongly relies on the physical properties (i.e., composition, microstructure, and surface impurities) of the metal NPs. Here we report a convenient chemical vapour impregnation (CVI) approach for the deposition of monometallic-, alloyed, and core-shell structured metal co-catalysts onto the TiO2 photocatalyst. The as-synthesised metal NPs are highly dispersed on the support and show narrow size distributions, which suit photocatalysis applications. More importantly, the surfaces of the as-synthesised metal NPs are free of protecting ligands, enabling the photocatalysts to be ready to use without further treatment. The effect of the metal identity, the alloy chemical composition, and the microstructure on the photocatalytic performance has been investigated for hydrogen production and phenol decomposition. Whilst the photocatalytic H2 production performance can be greatly enhanced by using the core-shell structured co-catalyst (Pdshell-Aucore and Ptshell-Aucore), the Ptshell-Aucore modified TiO2 yields enhanced quantum efficiency but a reduced effective decomposition of phenol to CO2 compared to that of the monometallic counterparts. We consider the CVI approach provides a feasible and elegant process for the decoration of photocatalyst materials. PMID:24970298

  16. Nano sized bismuth oxy chloride by metal organic chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Jagdale, Pravin, E-mail: pravin.jagdale@polito.it [Department of Applied Science and Technology (DISAT), Politecnico di Torino, 10129 (Italy); Castellino, Micaela [Center for Space Human Robotics, Istituto Italiano di Tecnologia, Corso Trento 21, 10129 Torino (Italy); Marrec, Françoise [Laboratory of Condensed Matter Physics, University of Picardie Jules Verne (UPJV), Amiens 80039 (France); Rodil, Sandra E. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexicom (UNAM), Mexico D.F. 04510 (Mexico); Tagliaferro, Alberto [Department of Applied Science and Technology (DISAT), Politecnico di Torino, 10129 (Italy)

    2014-06-01

    Metal organic chemical vapour deposition (MOCVD) method was used to prepare thin films of bismuth based nano particles starting from bismuth salts. Nano sized bismuth oxy chloride (BiOCl) crystals were synthesized from solution containing bismuth chloride (BiCl{sub 3}) in acetone (CH{sub 3}-CO-CH{sub 3}). Self-assembly of nano sized BiOCl crystals were observed on the surface of silicon, fused silica, copper, carbon nanotubes and aluminium substrates. Various synthesis parameters and their significant impact onto the formation of self-assembled nano-crystalline BiOCl were investigated. BiOCl nano particles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy and Micro-Raman spectroscopy. These analyses confirm that bismuth nanometer-sized crystal structures showing a single tetragonal phase were indeed bismuth oxy chloride (BiOCl) square platelets 18–250 nm thick and a few micrometres wide.

  17. Controlled n-doping in chemical vapour deposition grown graphene by antimony

    International Nuclear Information System (INIS)

    We have studied the effects of antimony (Sb) doping on graphene grown by chemical vapour deposition without any significant change in its electrical properties. By increasing the metal thickness from 1 to 5 nm, we found a shift in the wave numbers of Raman G and two-dimensional (2D) peaks consistent with n-doping and a change in the Fermi level of the graphene into the conduction band. The relative intensity of the D peak to the G peak did not show a significant change and that of the 2D peak to the G peak remained at a large enough number as a function of metal thickness, implying little degradation by the metal dopants. Transport measurements also confirm the n-doping of graphene through a shift of Dirac point in the transfer characteristics and the quality preservation with little changes in mobility. We also report on the formation of a p–n junction by metal doping on selected areas of the graphene and their electrical properties with transfer characteristics and Hall measurements. (paper)

  18. Control and characterization of individual grains and grain boundaries in graphene grown by chemical vapour deposition

    Science.gov (United States)

    Yu, Qingkai; Jauregui, Luis A.; Wu, Wei; Colby, Robert; Tian, Jifa; Su, Zhihua; Cao, Helin; Liu, Zhihong; Pandey, Deepak; Wei, Dongguang; Chung, Ting Fung; Peng, Peng; Guisinger, Nathan P.; Stach, Eric A.; Bao, Jiming; Pei, Shin-Shem; Chen, Yong P.

    2011-06-01

    The strong interest in graphene has motivated the scalable production of high-quality graphene and graphene devices. As the large-scale graphene films synthesized so far are typically polycrystalline, it is important to characterize and control grain boundaries, generally believed to degrade graphene quality. Here we study single-crystal graphene grains synthesized by ambient chemical vapour deposition on polycrystalline Cu, and show how individual boundaries between coalescing grains affect graphene’s electronic properties. The graphene grains show no definite epitaxial relationship with the Cu substrate, and can cross Cu grain boundaries. The edges of these grains are found to be predominantly parallel to zigzag directions. We show that grain boundaries give a significant Raman ‘D’ peak, impede electrical transport, and induce prominent weak localization indicative of intervalley scattering in graphene. Finally, we demonstrate an approach using pre-patterned growth seeds to control graphene nucleation, opening a route towards scalable fabrication of single-crystal graphene devices without grain boundaries.

  19. Chemical vapour deposition of praseodymium oxide films on silicon: influence of temperature and oxygen pressure

    International Nuclear Information System (INIS)

    Metal-organic chemical vapour deposition (MOCVD) of various phases in PrOx system has been studied in relation with deposition temperature (450-750 deg. C) and oxygen partial pressure (0.027-100 Pa or 0.2-750 mTorr). Depositions were carried out by pulsed liquid injection MOCVD using Pr(thd)3 (thd = 2,2,6,6-tetramethyl-3,5-heptanedionate) precursor dissolved in toluene or monoglyme. By varying deposition temperature and oxygen partial pressure amorphous films or various crystalline PrOx phases (Pr2O3, Pr7O12, Pr6O11) and their mixtures can be grown. The pure crystalline Pr2O3 phase grows only in a narrow range of partial oxygen pressure and temperature, while high oxygen pressure (40-100 Pa) always leads to the most stable Pr6O11 phase. The influence of annealing under vacuum at 750 deg. C on film phase composition was also studied. Near 90% step coverage conformity was achieved for PrOx films on structured silicon substrates with aspect ratio 1:10. In air degradation of Pr2O3 films with transformation to Pr(OH)3 was observed in contrast to Pr6O11 films

  20. Characterisation of TiO 2 deposited by photo-induced chemical vapour deposition

    Science.gov (United States)

    Kaliwoh, Never; Zhang, Jun-Ying; Boyd, Ian W.

    2002-01-01

    We report the deposition of thin TiO 2 films on crystalline Si and quartz by photo-induced chemical vapour deposition (CVD) using UV excimer lamps employing a dielectric barrier discharge in krypton chloride (KrCl ∗) to provide intense narrow band radiation at λ=222 nm. The precursor used was titanium isopropoxide (TTIP). Films from around 20-510 nm in thickness with refractive indices from 2.20 to 2.54 were grown at temperatures between 50 and 350 °C. The higher refractive index values compare favourably with the value of 2.58 recorded for the bulk material. The measured deposition rate was around 50 nm/min at 350 °C. Fourier transform infrared spectroscopy (FTIR) revealed the presence of TiO 2 through the observation of a Ti-O absorption peak and the absence of OH in films deposited at 250-350 °C indicated relatively good quality films. The phase of films deposited at 200-350 °C was anatase as determined by X-ray diffraction.

  1. Chemical Vapour Deposition Graphene Radio-Frequency Field-Effect Transistors

    International Nuclear Information System (INIS)

    We report the dc and rf performance of graphene rf field-effect transistors, where the graphene films are grown on copper by using the chemical vapour deposition (CVD) method and transferred to SiO2/Si substrates. Composite materials, benzocyclobutene and atomic layer deposition Al2O3 are used as the gate dielectrics. The observation of n- and p-type transitions verifies the ambipolar characteristics in the graphene layers. While the intrinsic carrier mobility of CVD graphene is extracted to be 1200 cm2/V·s, the parasitic series resistances are demonstrated to have a serious impact on device performance. With a gate length of 1 μm and an extrinsic transconductance of 72 mS/mm, a cutoff frequency of 6.6 GHz and a maximum oscillation frequency of 8.8 GHz are measured for the transistors, illustrating the potential of the CVD graphene for rf applications. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  2. Chemical Vapour Deposition of Graphene with Re-useable Pt and Cu substrates for Flexible Electronics

    Science.gov (United States)

    Karamat, Shumaila; Sonusen, Selda; Celik, Umit; Uysalli, Yigit; Oral, Ahmet

    2015-03-01

    Graphene has gained the attention of scientific world due to its outstanding physical properties. The future demand of flexible electronics such as solar cells, light emitting diodes, photo-detectors and touch screen technology requires more exploration of graphene properties on flexible substrates. The most interesting application of graphene is in organic light emitting diodes (OLED) where efforts are in progress to replace brittle indium tin oxide (ITO) electrode with a flexible graphene electrode because ITO raw materials are becoming increasingly expensive, and its brittle nature makes it unsuitable for flexible devices. In this work, we grow graphene on Pt and Cu substrates using chemical vapour deposition (CVD) and transferred it to a polymer material (PVA) using lamination technique. We used hydrogen bubbling method for separating graphene from Pt and Cu catalyst to reuse the substrates many times. After successful transfer of graphene on polymer samples, we checked the resistivity values of the graphene sheet which varies with growth conditions. Furthermore, Raman, atomic force microscopy (AFM), I-V and Force-displacement measurements will be presented for these samples.

  3. Excimer laser recrystallization of nanocrystalline-Si films deposited by inductively coupled plasma chemical vapour deposition at 150 deg. C

    International Nuclear Information System (INIS)

    Polycrystalline silicon thin film transistors (poly-Si TFTs) fabricated at low temperature (under 200 deg. C) have been widely investigated for flexible substrate applications such as a transparent plastic substrate. Unlike the conventional TFT process using glass substrate, the maximum process temperature should be kept less than 200 deg. C in order to avoid thermal damage on flexible substrates. We report the characteristics of nanocrystalline silicon (nc-Si) irradiated by an excimer laser. Nc-Si precursors were deposited on various buffer layers by inductively coupled plasma chemical vapour deposition (ICP-CVD) at 150 deg. C. We employed various buffer layers, such as silicon nitride (SiNX) and silicon dioxide (SiO2), in order to report recrystallization characteristics in connection with a buffer layer of a different thermal conductivity. The dehydrogenation and recrystallization was performed by step-by-step excimer laser annealing (ELA) (XeCl,λ=308 nm) in order to prevent the explosive release of hydrogen atoms. The grain size of the poly-Si film, which was recrystallized on the various buffer layers, was measured by scanning electron microscopy (SEM) at each laser energy density. The process margin of step-by-step ELA employing the SiNX buffer layer is wider than SiO2 and the maximum grain size slightly increased

  4. Excimer laser recrystallization of nanocrystalline-Si films deposited by inductively coupled plasma chemical vapour deposition at 150 deg. C

    Energy Technology Data Exchange (ETDEWEB)

    Park, Joong-Hyun [School of Electrical Engineering (50), Seoul National University, Shinlim-Dong, Gwanak-Gu, Seoul (Korea, Republic of); Han, Sang-Myeon [School of Electrical Engineering (50), Seoul National University, Shinlim-Dong, Gwanak-Gu, Seoul (Korea, Republic of); Park, Sang-Geun [School of Electrical Engineering (50), Seoul National University, Shinlim-Dong, Gwanak-Gu, Seoul (Korea, Republic of); Han, Min-Koo [School of Electrical Engineering (50), Seoul National University, Shinlim-Dong, Gwanak-Gu, Seoul (Korea, Republic of); Shin, Moon-Young [LTPS Team, AMLCD Business, Samsung Electronics Co., Giheung, Yongin City (Korea, Republic of)

    2006-09-01

    Polycrystalline silicon thin film transistors (poly-Si TFTs) fabricated at low temperature (under 200 deg. C) have been widely investigated for flexible substrate applications such as a transparent plastic substrate. Unlike the conventional TFT process using glass substrate, the maximum process temperature should be kept less than 200 deg. C in order to avoid thermal damage on flexible substrates. We report the characteristics of nanocrystalline silicon (nc-Si) irradiated by an excimer laser. Nc-Si precursors were deposited on various buffer layers by inductively coupled plasma chemical vapour deposition (ICP-CVD) at 150 deg. C. We employed various buffer layers, such as silicon nitride (SiN{sub X}) and silicon dioxide (SiO{sub 2}), in order to report recrystallization characteristics in connection with a buffer layer of a different thermal conductivity. The dehydrogenation and recrystallization was performed by step-by-step excimer laser annealing (ELA) (XeCl,{lambda}=308 nm) in order to prevent the explosive release of hydrogen atoms. The grain size of the poly-Si film, which was recrystallized on the various buffer layers, was measured by scanning electron microscopy (SEM) at each laser energy density. The process margin of step-by-step ELA employing the SiN{sub X} buffer layer is wider than SiO{sub 2} and the maximum grain size slightly increased.

  5. An Investigative and Concise Review on Evaporation and Condensation Processes Using Vapour Adsorption Technique

    Directory of Open Access Journals (Sweden)

    Dim Dim Kumar

    2014-10-01

    Full Text Available The vapour adsorption refrigeration is based on the evaporation and condensation of a refrigerant combined with adsorption or chemical reaction. The towering fossil fuel price and the responsiveness of environmental problems offer many potential applications to thermal powered adsorption cooling. However, the adsorption cooling machines still have some disadvantages that hinder their wide application. The patents surveyed are classified into four main groups: adsorption system development, adsorbent bed innovation, adsorbent/adsorbate material development and novel application of adsorption cooling system. The adsorption refrigeration is based on the evaporation and condensation of a refrigerant combined with adsorption or chemical reaction. Important targets are to reach a high efficiency through optimization measures at various components and the control system. On the other hand measures are to verify to simplify the construction with regard to a low-cost manufacturing, as well as to reach long periods with maintenance-free operation. This review paper gives a comprehensive review on the work carried out on vapour adsorption refrigeration for cryogenic applications.

  6. Atmospheric pressure chemical vapour deposition of thermochromic tungsten doped vanadium dioxide thin films for use in architectural glazing

    OpenAIRE

    Blackman, C. S.; Piccirillo, C.; Binions, R.; Parkin, I. P.

    2009-01-01

    Atmospheric pressure chemical vapour deposition of VCl4, WCl6 and water at 550 degrees C lead to the production of high quality tungsten doped vanadium dioxide thin films. Careful control of the gas phase precursors allowed for tungsten doping up to 8 at.%. The transition temperature of the thermochromic switch was tunable in the range 55 degrees C to - 23 degrees C. The films were analysed using X-ray diffraction, scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spect...

  7. Structural and Compositional Study of Graphene grown on SrTiO3 by Chemical Vapour Deposition

    Science.gov (United States)

    Karamat, Shumaila; Celik, Umit; Oral, Ahmet

    Graphene, a monolayer of sp2 bonded carbon atom, is considered as one of the most promising candidate materials for future electronics. The most critical step in graphene research is its transfer from the growth catalyst to the dielectric substrate, many unavoidable issues in the transfer process are: contamination from etchants, photoresist residues, wrinkles, and mechanical breakage. The direct growth of graphene on the substrates without using catalyst offer new opportunities in device fabrication without any transfer process. But till now, the field of direct graphene growth on dielectrics or insulating substrates is not mature like growth on metallic catalysts using CVD. We used chemical vapour deposition to grow graphene on SrTiO3 (110) substrates. The growth was carried out in presence of methane, argon and hydrogen. Raman Spectrum clearly showed the D and G peaks which were absent in bare substrate. XPS was used to get information about the presence of necessary elements, their bonding with STO substrates. AFM imaging clearly showed graphene island formation on substrates.

  8. Role of Duty Ratio in Diamond Growth by Pulsed DC-Bias Enhanced Hot Filament Chemical Vapour Deposition

    Institute of Scientific and Technical Information of China (English)

    MENG Liang; ZHOU Haiyang; ZHU Xiaodong

    2007-01-01

    In this study, the role of the pulse duty ratio was investigated during the deposition of diamond films in a hot filament chemical vapour deposition reactor with a pulsed-dc biased substrate positively relative to the hot filaments. The voltage-current characteristics showed that the discharge current rose with the increase of biasing voltage, which was modified by the duty ratio. Before deposition, two approaches were adopted for the pre-treatment of the silicon substrates, respectively, and the substrates were scratched by diamond paste or seeded by diamond powders using the so-called 'soft dry polished' technique. Diamond films were deposited under a fixed discharge power by changing the duty ratios. In the first group with scratched substrates, it was found that under a high duty ratio the diamond grew slowly with quite poor nucleation, while in the second case a high duty ratio induced a high deposition rate and good diamond quality. Reactive hydrocarbon species with high energy are essential for the initial nucleation process, which is more effectively achieved at a high biasing voltage in the condition of a low duty ratio. In the film growth process, the large discharge current at a high duty ratio represents an increased concentration of electrons and reactive species as well, promoting the growth of diamond films.

  9. PENGARUH KATALIS Co DAN Fe TERHADAP KARAKTERISTIK CARBON NANOTUBES DARI GAS ASETILENA DENGAN MENGGUNAKAN PROSES CATALYTIC CHEMICAL VAPOUR DEPOSITION (CCVD

    Directory of Open Access Journals (Sweden)

    Tutuk Djoko Kusworo

    2013-11-01

    Full Text Available EFFECT OF Co AND Fe ON CARBON NANOTUBES CHARACTERISTICS FROM ACETYLENE USING CATALYTIC CHEMICAL VAPOUR DEPOSITION (CCVD PROCESS. Carbon Nanotubes (CNTs is one of the most well known nano-technology applications which the most of attracting the attention of researchers, because it has more advantages than other materials. The application of the CNT has extended into various aspects, such as electronics, materials, biology and chemistry. This research uses a system of Catalytic Chemical Vapour Deposition (CCVD, which aims to determine the influence of Co and Fe as a catalyst and zeolite 4A as a support catalyst with acetylene gas (C2H2 as carbon source in the synthesis of Carbon Nanotubes (CNTs. In this experiment, used the ratio of acetylene gas and flow rate of N2 gas is 1:1 by weight of the catalyst Co/Zeolite and Fe/Zeolite amounted to 0.5 grams at the operating temperature of 700oC for 20 minutes. N2 gas serves to minimize the occurrence of oxidation reaction (explosion when operating. From analysis result by Scanning Electron Microscopy (SEM shows the CNTs formed a type of MWNT with different of diameter size and product weight, depending on the size of the active component concentration on the catalyst. The larger of active components produced CNTs with larger diameter, whereas product weight syntheses result smaller. Use of the catalyst Fe/Zeolite produce CNTs with a diameter larger than the catalyst Co/Zeolite.  Carbon Nanotubes (CNTs merupakan salah satu aplikasi nanoteknologi yang paling terkenal dan banyak menarik perhatian para peneliti, karena memiliki beberapa kelebihan daripada material lainnya. Aplikasi dari CNT telah merambah ke berbagai aspek, seperti bidang elektronika, material, biologi dan kimia. Penelitian ini menggunakan sistem Catalytic Chemical Vapour Deposition (CCVD yang bertujuan untuk mengetahui pengaruh variasi Cobalt (Co dan Ferrum (Fe sebagai katalis dan zeolit tipe 4A sebagai penyangga katalis dengan gas

  10. Low-pressure Chemical Vapour Deposition of Silicon Nanoparticles:Synthesis and Characterisation

    Directory of Open Access Journals (Sweden)

    A. Kumar

    2008-07-01

    Full Text Available emiconductor nanostructures such as quantum wells, quantum wires or quantum dots exhibit superior properties in comparison to their bulk forms. Quantum dots are described aszero-dimensional electron gas system, as carriers are confined in all the three directions. Densityof states is discrete function of energy. Allowed energy spectrum is discrete like in an atom.Energy band gap is broadened due to carriers confinement. Semiconductor quantum dots exhibittypical coulomb blockade characteristic which is exploited for development of new generationof nanoelectronic devices namely single-electron transistor, memories, etc, whose operationdepends on quantum mechanical tunneling of carriers through energy barriers. Thesesemiconductor nanostructures emit light in visible range upon excitation by optical means. Inrecent years,  research  has been focused on different nano-scale materials; metals (Au, Ag, Fe,Mn, Ni, metal oxides (SnO2, ZnO2, compound semiconductors (GaAs, GaAlAs, CdSe, CdS,GaN, and elemental semiconductors (silicon and germanium. As silicon is the most favouredmaterial in the established integrated circuits manufacturing technology, research is being donefor controlled synthesis and characterisation of Si nanoparticles. The Si nanoparticles havebeen synthesised on oxide and nitride layers over  Si substrate by IC technology compatiblelow-pressure chemical vapour deposition technique. Atomic force microscopy (AFMcharacterisation has been extensively carried out on the samples. It is shown that the tip radiusand shape of tip lead to less accurate estimate of the actual size. The AFM images have been evaluated based on the real surface topography and shape of the tip. Photolumine scence (PL studies have been performed to characterise the samples. The PL measurements showed visiblelight emission from synthesised silicon nanoparticles.Defence Science Journal, 2008, 58(4, pp.550-558, DOI:http://dx.doi.org/10.14429/dsj.58.1676

  11. Temporal Stability of Metal-Chloride-Doped Chemical-Vapour-Deposited Graphene.

    Science.gov (United States)

    Kang, Moon H; Milne, William I; Cole, Matthew T

    2016-08-18

    Graphene has proven to be a promising material for transparent flexible electronics. In this study, we report the development of a transfer and doping scheme of large-area chemical vapour deposited (CVD) graphene. A technique to transfer the as-grown material onto mechanically flexible and optically transparent polymeric substrates using an ultraviolet adhesive (UVA) is outlined, along with the temporal stability of the sheet resistance and optical transparency following chemical doping with various metal chlorides (Mx Cly The sheet resistance (RS ) and 550 nm optical transparency (%T550 ) of the transferred un-doped graphene was 3.5 kΩ sq(-1) (±0.2 kΩ sq(-1) ) and 84.1 % (±2.9 %), respectively. Doping with AuCl3 showed a notable reduction in RS by some 71.4 % (to 0.93 kΩ sq(-1) ) with a corresponding %T550 of 77.0 %. After 200 h exposure to air at standard temperature and pressure, the increase in RS was found to be negligible (ΔRS AuCl3 =0.06 kΩ sq(-1) ), indicating that, of the considered Mx Cly species, AuCl3 doping offered the highest degree of time stability under ambient conditions. There appears a tendency of increasing RS with time for the remaining metal chlorides studied. We attribute the observed temporal shift to desorption of molecular dopants. We find that desorption was most significant in RhCl3 -doped samples whereas, in contrast, after 200 h in ambient conditions, AuCl3 -doped graphene showed only marginal desorption. The results of this study demonstrate that chemical doping of UVA-transferred graphene is a promising means for enhancing large-area CVD graphene in order to realise a viable platform for next-generation optically transparent and mechanically flexible electronics. PMID:27165783

  12. Surface and Compositional Study of Graphene grown on Lithium Niobate (LiNbO3) substrates by Chemical Vapour Deposition

    Science.gov (United States)

    Karamat, Shumaila; Celik, Umit; Oral, Ahmet

    The diversity required in the designing of electronic devices motivated the community to always attempt for new functional materials and device structures. Graphene is considered as one of the most promising candidate materials for future electronics and carbon based devices. It is very exciting to combine graphene with new dielectric materials which exhibit multifunctional properties. Lithium Niobate exhibits ferro-, pyro-, and piezoelectric properties with large electro-optic, acousto-optic, and photoelastic coefficients as well as strong photorefractive and photovoltaic effects which made it one of the most extensively studied materials over the last 50 years. We used ambient pressure chemical vapour deposition to grow graphene on LiNbO3 substrates without any catalyst. The growth was carried out in presence of methane, argon and hydrogen. AFM imaging showed very unique structures on the surface which contains triangular domains. X-ray photoelectron spectroscopy (XPS) was used to get information about the presence of necessary elements, their bonding with LiNbO3 substrates. Detailed characterization is under process which will be presented later.

  13. Influence of hydrogen on chemical vapour synthesis of different carbon nanostructures using propane as precursor and nickel as catalyst

    Indian Academy of Sciences (India)

    R K Sahoo; H Mamgain; C Jacob

    2014-10-01

    The role of hydrogen in the catalytic chemical vapour deposition of carbon nanotubes using sputtered nickel thin film as a catalyst is explained in this work. The growth of different carbon nanostructures with the variation in the precursor gas content was studied by keeping all other process parameters constant and using sputtered Ni thin film as a catalyst. The catalyst granule size, its external morphology and the resulting products were analysed. Carbon nanotubes (CNTs), carbon nanofibres (CNFs) and carbon nanoribbons (CNRs) were observed under different growth conditions. The different conditions of growth leading to form tubes, fibres or ribbons were analysed by varying the flow ratio of propane and hydrogen gas during the high temperature growth. Scanning and transmission electron microscopies confirmed the above structures under different growth conditions. The role of hydrogen on the surface passivation behaviour of the Ni catalyst and its correlative effect on the growth of carbon nanostructures is analysed. This direct approach can, in principle, be used to synthesize different types of carbon nanostructures by tailoring the hydrogen concentration.

  14. Aerosol assisted chemical vapour deposition of gas sensitive SnO2 and Au-functionalised SnO2 nanorods via a non-catalysed vapour solid (VS) mechanism

    Science.gov (United States)

    Vallejos, Stella; Selina, Soultana; Annanouch, Fatima Ezahra; Gràcia, Isabel; Llobet, Eduard; Blackman, Chris

    2016-06-01

    Tin oxide nanorods (NRs) are vapour synthesised at relatively lower temperatures than previously reported and without the need for substrate pre-treatment, via a vapour-solid mechanism enabled using an aerosol-assisted chemical vapour deposition method. Results demonstrate that the growth of SnO2 NRs is promoted by a compression of the nucleation rate parallel to the substrate and a decrease of the energy barrier for growth perpendicular to the substrate, which are controlled via the deposition conditions. This method provides both single-step formation of the SnO2 NRs and their integration with silicon micromachined platforms, but also allows for in-situ functionalization of the NRs with gold nanoparticles via co-deposition with a gold precursor. The functional properties are demonstrated for gas sensing, with microsensors using functionalised NRs demonstrating enhanced sensing properties towards H2 compared to those based on non-functionalised NRs.

  15. Investigation of optical and electronic properties of hafnium aluminate films deposited by Metal-Organic Chemical Vapour Deposition

    International Nuclear Information System (INIS)

    Alloying elemental high-k metal oxides (such as HfO2) with other metals is seen as an effective method of controlling the properties of the dielectric based on the concentration of cations in the mixture; in particular, mixing HfO2 with Al2O3, and forming hafnium aluminate layers which will still have a relatively high dielectric constant (typically k ∼ 15) and remain amorphous up to high processing temperatures. This paper summarizes the results of physical and electrical characterisation of hafnium aluminate (HfAl xO y) films prepared by Metal-Organic Chemical Vapour Deposition. We show how, using ultraviolet-visible, single angle ellipsometry, the thickness and composition of the deposited and of the transition/interfacial layers can be extracted, and further used for the estimation of the relative dielectric constant. Moreover, a methodology for extracting the band gap of these materials and its dependence on the aluminium concentration is presented. This has been achieved by using a simple parameterization model (Wemple-Di Domenico) to account for the optical dispersion of the films. Preparing thin films with a relatively high dielectric constant and with an amorphous structure even at high processing temperatures, are not the only requirements to be achieved when such layers are to be used as gate dielectrics. The electrical characteristics - such as leakage current, density of interface states, fixed charge in the oxide - are extremely important. The results obtained through capacitance-voltage and current-voltage measurements show the possibility of adjusting the relative dielectric constant of the layers in a wide range (9-16), when the aluminium concentration varies between 4% and 38%. The minimum leakage current occurs for Al concentrations up to 9%. The thinner films show Fowler-Nordheim conduction even at higher concentrations of Al into the film, while thicker films show a higher hysteresis due to an increased number of slow trapping centres in the

  16. Growth of AlGaN Epitaxial Film with High Al Content by Metalorganic Chemical Vapour Deposition

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-Lan; ZHAO De-Gang; YANG Hui; LIANG Jun-Wu

    2007-01-01

    A high-Al-content AlCaN epilayer is grown on a low-temperature-deposited AlN buffer on (0001) sapphire bylow pressure metalorganic chemical vapour deposition. The dependence of surface roughness, tilted mosaicity,and twisted mosaicity on the conditions of the AlCaN epilayer deposition is evaluated. An AlCaN epilayer withfavourable surface morphology and crystal quality is deposited on a 20nm low-temperature-deposited AlN buffer at a low Ⅴ/Ⅲ flow ratio of 783 and at a low reactor pressure of 100 Torr, and the adduct reaction between trimethylaluminium and NH3 is considered.

  17. Morphology of carbon nanotubes prepared via chemical vapour deposition technique using acetylene: A small angle neutron scattering investigation

    Indian Academy of Sciences (India)

    D Sen; K Dasgupta; J Bahadur; S Mazumder; D Sathiyamoorthy

    2008-11-01

    Small angle neutron scattering (SANS) has been utilized to study the morphology of the multi-walled carbon nanotubes prepared by chemical vapour deposition of acetylene. The effects of various synthesis parameters like temperature, catalyst concentration and catalyst support on the size distribution of the nanotubes are investigated. Distribution of nanotube radii in two length scales has been observed. The number density of the smaller diameter tubes was found more in number compared to the bigger one for all the cases studied. No prominent scaling of the structure factor was observed for the different synthesis conditions.

  18. Nitrogen-Doped Chemical Vapour Deposited Diamond: a New Material for Room-Temperature Solid State Maser

    Institute of Scientific and Technical Information of China (English)

    N. A. Poklonski; N. M. Lapchuk; A. V. Khomich; LU Fan-Xiu; TANG Wei-Zhong; V. G. Ralchenko; I. I. Vlasov; M. V. Chukichev; Sambuu Munkhtsetseg

    2007-01-01

    Electron spin resonance (ESR) in polycrystalline diamond films grown by dc arc-jet and microwave plasma chemical vapour deposition is studied. The films with nitrogen impurity concentration up to 8 × 1018 cm-3 are also characterized by Raman, cathodoluminescence and optical absorption spectra. The ESR signal from P1 centre with g-factor of 2.0024 (nitrogen impurity atom occupying C site in diamond lattice) is found to exhibit an inversion with increasing the microwave power in an H102 resonator. The spin inversion effect could be of interest for further consideration of N-doped diamonds as a medium for masers operated at room temperature.

  19. Nanoparticulate cerium dioxide and cerium dioxide-titanium dioxide composite thin films on glass by aerosol assisted chemical vapour deposition

    International Nuclear Information System (INIS)

    Two series of composite thin films were deposited on glass by aerosol assisted chemical vapour deposition (AACVD)-nanoparticulate cerium dioxide and nanoparticulate cerium dioxide embedded in a titanium dioxide matrix. The films were analysed by a range of techniques including UV-visible absorption spectroscopy, X-ray diffraction, scanning electron microscopy and energy dispersive analysis by X-rays. The AACVD prepared films showed the functional properties of photocatalysis and super-hydrophilicity. The CeO2 nanoparticle thin films displaying photocatalysis and photo-induced hydrophilicity almost comparable to that of anatase titania.

  20. Review of analytical techniques to determine the chemical forms of vapours and aerosols released from overheated fuel

    International Nuclear Information System (INIS)

    A comprehensive review has been undertaken of appropriate analytical techniques to monitor and measure the chemical effects that occur in large-scale tests designed to study severe reactor accidents. Various methods have been developed to determine the chemical forms of the vapours, aerosols and deposits generated during and after such integral experiments. Other specific techniques have the long-term potential to provide some of the desired data in greater detail, although considerable efforts are still required to apply these techniques to the study of radioactive debris. Such in-situ and post-test methods of analysis have been also assessed in terms of their applicability to the analysis of samples from the Phebus-FP tests. The recommended in-situ methods of analysis are gamma-ray spectroscopy, potentiometry, mass spectrometry, and Raman/UV-visible absorption spectroscopy. Vapour/aerosol and deposition samples should also be obtained at well-defined time intervals during each experiment for subsequent post-test analysis. No single technique can provide all the necessary chemical data from these samples, and the most appropriate method of analysis involves a complementary combination of autoradiography, AES, IR, MRS, SEMS/EDS, SIMS/LMIS, XPS and XRD

  1. Chemical process hazards analysis

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-02-01

    The Office of Worker Health and Safety (EH-5) under the Assistant Secretary for the Environment, Safety and Health of the US Department (DOE) has published two handbooks for use by DOE contractors managing facilities and processes covered by the Occupational Safety and Health Administration (OSHA) Rule for Process Safety Management of Highly Hazardous Chemicals (29 CFR 1910.119), herein referred to as the PSM Rule. The PSM Rule contains an integrated set of chemical process safety management elements designed to prevent chemical releases that can lead to catastrophic fires, explosions, or toxic exposures. The purpose of the two handbooks, ``Process Safety Management for Highly Hazardous Chemicals`` and ``Chemical Process Hazards Analysis,`` is to facilitate implementation of the provisions of the PSM Rule within the DOE. The purpose of this handbook ``Chemical Process Hazards Analysis,`` is to facilitate, within the DOE, the performance of chemical process hazards analyses (PrHAs) as required under the PSM Rule. It provides basic information for the performance of PrHAs, and should not be considered a complete resource on PrHA methods. Likewise, to determine if a facility is covered by the PSM rule, the reader should refer to the handbook, ``Process Safety Management for Highly Hazardous Chemicals`` (DOE- HDBK-1101-96). Promulgation of the PSM Rule has heightened the awareness of chemical safety management issues within the DOE. This handbook is intended for use by DOE facilities and processes covered by the PSM rule to facilitate contractor implementation of the PrHA element of the PSM Rule. However, contractors whose facilities and processes not covered by the PSM Rule may also use this handbook as a basis for conducting process hazards analyses as part of their good management practices. This handbook explains the minimum requirements for PrHAs outlined in the PSM Rule. Nowhere have requirements been added beyond what is specifically required by the rule.

  2. Ge-rich islands grown on patterned Si substrates by low-energy plasma-enhanced chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Bollani, M; Fedorov, A [CNISM and L-NESS, Dipartimento di Fisica del Politecnico di Milano, Polo Regionale di Como, Via Anzani 42, I-22100 Como (Italy); Chrastina, D; Sordan, R [L-NESS, Dipartimento di Fisica del Politecnico di Milano, Polo Regionale di Como, Via Anzani 42, I-22100 Como (Italy); Picco, A; Bonera, E, E-mail: monica.bollani@mater.unimib.it [Dipartimento di Scienza dei Materiali, and L-NESS, Universita degli Studi di Milano-Bicocca, via Cozzi 53, I-20125 Milano (Italy)

    2010-11-26

    Si{sub 1-x}Ge{sub x} islands grown on Si patterned substrates have received considerable attention during the last decade for potential applications in microelectronics and optoelectronics. In this work we propose a new methodology to grow Ge-rich islands using a chemical vapour deposition technique. Electron-beam lithography is used to pre-pattern Si substrates, creating material traps. Epitaxial deposition of thin Ge films by low-energy plasma-enhanced chemical vapour deposition then leads to the formation of Ge-rich Si{sub 1-x}Ge{sub x} islands (x > 0.8) with a homogeneous size distribution, precisely positioned with respect to the substrate pattern. The island morphology was characterized by atomic force microscopy, and the Ge content and strain in the islands was studied by {mu}Raman spectroscopy. This characterization indicates a uniform distribution of islands with high Ge content and low strain: this suggests that the relatively high growth rate (0.1 nm s{sup -1}) and low temperature (650 deg. C) used is able to limit Si intermixing, while maintaining a long enough adatom diffusion length to prevent nucleation of islands outside pits. This offers the novel possibility of using these Ge-rich islands to induce strain in a Si cap.

  3. Inline atmospheric pressure metal-organic chemical vapour deposition for thin film CdTe solar cells

    International Nuclear Information System (INIS)

    A detailed study has been undertaken to assess the deposition of CdTe for thin film devices via an inline atmospheric pressure metal-organic chemical vapour deposition (AP-MOCVD) reactor. The precursors for CdTe synthesis were released from a showerhead assembly normal to a transparent conductive oxide (TCO)/glass substrate, previously coated with a CdZnS window layer using a conventional batch AP-MOCVD reactor with horizontal flow delivery. Under a simulated illumination with air mass coefficient 1.5 (AM1.5), the initial best cell conversion efficiency (11.2%) for such hybrid cells was comparable to a reference device efficiency (∼ 13%), grown entirely in the AP-MOCVD batch reactor. The performance and structure of the hybrid and conventional devices are compared for spectral response, CdTe grain morphology and crystal structure. These preliminary results reported on the transfer from a batch to an inline AP-MOCVD reactor which holds a good potential for the large-scale production of thin film photovoltaics devices and related materials. - Highlights: • Inline metal-organic chemical vapour deposition (MOCVD) used to grow CdTe films • Desired dopant profiles in CdTe:As achieved with inline MOCVD reactor • Initial conversion efficiency of 11.2% was comparable to batch devices (∼ 13%). • Inline MOCVD holds a good potential for large-scale thin film photovoltaics production

  4. RDF gasification with water vapour: influence of process temperature on yield and products composition

    International Nuclear Information System (INIS)

    The opportunity of using RDF (Refused Derived Fuel) to produce fuel gas seems to be promising and particular attention has been focused on alternative process technologies such as pyrolysis and gasification. Within this frame, present work relates to experimental tests and obtained results of a series of experimental surveys on RDF gasification with water vapour, carried out by means of a bench scale rotary kiln plant at different process temperature, using thermogravimetry (TG) and infrared spectrometry (FTIR), in order to characterize the incoming material, and online gas chromatography to qualify the gaseous stream. Experimental data show that gas yield rise with temperature and, with respect to the gas composition, hydrogen content grows up mainly at the expense of the other gaseous compound, pointing out the major extension of secondary cracking reactions into the gaseous fraction at higher temperature. Syngas obtained at process temperature of 950oC or higher seems to be suitable for fuel cells applications; at lower process temperature, gas composition suggest a final utilisation for feedstock recycling. The low organic content of solid residue does not suggest any other exploitation of the char apart from the land filling

  5. Diagnosis of processes controlling water vapour in the tropical tropopause layer by a Lagrangian cirrus model

    Directory of Open Access Journals (Sweden)

    C. Ren

    2007-04-01

    Full Text Available We have developed a Lagrangian air-parcel cirrus model (LACM, to diagnose the processes controlling water in the tropical tropopause layer (TTL. LACM applies parameterised microphysics to air parcel trajectories. The parameterisation includes the homogeneous freezing of aerosol droplets, the growth/sublimation of ice particles, and sedimentation of ice particles, so capturing the main dehydration mechanism for air in the TTL. Rehydration is also considered by resetting the water vapour mixing ratio in an air parcel to the value at the point in the 4-D analysis/forecast data used to generate the trajectories, but only when certain conditions, indicative of convection, are satisfied. These conditions are imposed to confine what processes contribute to rehydration. The conditions act to restrict rehydration of the Lagrangian air parcels to regions where convective transport of water vapour from below is significant, at least to the extent that the analysis/forecast captures this process. The inclusion of hydration and dehydration mechanisms in LACM results in total water fields near tropical convection that have more of the "stripey" character of satellite observations of high cloud, than do either the ECMWF analysis or trajectories without microphysics.

    The mixing ratios of total water in the TTL, measured by a high-altitude aircraft over Brazil (during the TROCCINOX campaign, have been reconstructed by LACM using trajectories generated from ECMWF analysis. Two other Lagrangian reconstructions are also tested: linear interpolation of ECMWF analysed specific humidity onto the aircraft flight track, and instantaneous dehydration to the saturation vapour pressure over ice along trajectories. The reconstructed total water mixing ratios along aircraft flight tracks are compared with observations from the FISH total water hygrometer. Process-oriented analysis shows that modelled cirrus cloud events are responsible for dehydrating the air

  6. Diagnosis of processes controlling water vapour in the tropical tropopause layer by a Lagrangian cirrus model

    Directory of Open Access Journals (Sweden)

    C. Ren

    2007-10-01

    Full Text Available We have developed a Lagrangian air-parcel cirrus model (LACM, to diagnose the processes controlling water in the tropical tropopause layer (TTL. LACM applies parameterised microphysics to air parcel trajectories. The parameterisation includes the homogeneous freezing of aerosol droplets, the growth/sublimation of ice particles, and sedimentation of ice particles, so capturing the main dehydration mechanism for air in the TTL. Rehydration is also considered by resetting the water vapour mixing ratio in an air parcel to the value at the point in the 4-D analysis/forecast data used to generate the trajectories, but only when certain conditions, indicative of convection, are satisfied. The conditions act to restrict rehydration of the Lagrangian air parcels to regions where convective transport of water vapour from below is significant, at least to the extent that the analysis/forecast captures this process. The inclusion of hydration and dehydration mechanisms in LACM results in total water fields near tropical convection that have more of the "stripy" character of satellite observations of high cloud, than do either the ECMWF analysis or trajectories without microphysics.

    The mixing ratios of total water in the TTL, measured by a high-altitude aircraft over Brazil (during the TROCCINOX campaign, have been reconstructed by LACM using trajectories generated from ECMWF analysis. Two other Lagrangian reconstructions are also tested: linear interpolation of ECMWF analysed specific humidity onto the aircraft flight track, and instantaneous dehydration to the saturation vapour pressure over ice along trajectories. The reconstructed total water mixing ratios along aircraft flight tracks are compared with observations from the FISH total water hygrometer. Process-oriented analysis shows that modelled cirrus cloud events are responsible for dehydrating the air parcels coming from lower levels, resulting in total water mixing ratios as low as 2

  7. Recent decadal trends in Iberian water vapour: GPS analysis and WRF process study

    Science.gov (United States)

    Miranda, Pedro M. A.; Nogueira, Miguel; Semedo, Alvaro; Benevides, Pedro; Catalao, Joao; Costa, Vera

    2016-04-01

    A 24-year simulation of the recent Iberian climate, using the WRF model at 9km resolution forced by ERA-Interim reanalysis (1989-2012), is analysed for the decadal evolution of the upwelling forcing coastal wind and for column integrated Precipitable water vapour (PWV). Results indicate that, unlike what was found by Bakun et al. (2009) for the Peruvian region, a statistically significant trend in the upwelling favourable (northerly) wind has been accompanied by a corresponding decrease in PWV, not only inland but also over the coastal waters. Such increase is consistent with a reinforced northerly coastal jet in the maritime boundary layer contributing to atmospheric Ekman pumping of dry continental air into the coastal region. Diagnostics of the prevalence of the Iberian thermal low following Hoinka and Castro (2003) also show a positive trend in its frequency during an extended summer period (April to September). These results are consistent with recent studies indicating an upward trend in the frequency of upwelling in SW Iberia (Alves and Miranda 2013), and may be relevant for climate change applications as an increase in coastal upwelling (Miranda et al 2013) may lead to substantial regional impacts in the subtropics. The same analysis with ERA-Interim reanalysis data, which was used to force the WRF simulations, does not reveal the same signal in PWV, and indeed correlates poorly with the GPS observations, indicating that the data assimilation process makes the water vapour data in reanalysis unusable for climate change purposes. The good correlation between the WRF simulated data and GPS observations allow for a detailed analysis of the processes involved in the evolution of the PWV field. Akcnowledgements: Study done within FCT Grant RECI/GEO-MET/0380/2012, financially supported by FCT Grant UID/ GEO/50019/2013-IDL Alves JMR, Miranda PMA (2013) Variability of Iberian upwelling implied by ERA-40 and ERA-Interim reanalyses, Tellus A 2013, http

  8. Grafting 4f and 3d metal complexes into mesoporous MCM-41 silica by wet impregnation and by chemical vapour infiltration

    International Nuclear Information System (INIS)

    Hybrid organic/inorganic materials have been prepared by reacting mesoporous MCM-41 silica with transition metal β-diketonates, either by wet impregnation (WI) or by chemical vapour infiltration (CVI). Compounds obtained from Eu(III) or Gd(III) β-diketonates, both by wet impregnation and by CVI, contain chemisorbed metalorganic species with strong Si-O-Ln bonding. Compounds prepared (by CVI only) from Cu(II) or Mn(III) β-diketonates show a more complex absorption process than the lanthanides, since upon heating under dynamic vacuum they release part of the absorbed metal complex. Eu(thd)3 was more specifically used to prepare luminescent materials. It was used either alone, or with phenanthroline as an additional ligand in order to promote the so called 'antenna effect'

  9. Asphaltene precipitation and its effects on the vapour extraction (VAPEX) heavy oil recovery process

    Energy Technology Data Exchange (ETDEWEB)

    Luo, P.; Wang, X.; Gu, Y. [Society of Petroleum Engineers, Canadian Section, Calgary, AB (Canada)]|[Regina Univ., SK (Canada). Petroleum Technology Research Centre; Zhang, H. [Society of Petroleum Engineers, Canadian Section, Calgary, AB (Canada)]|[Core Laboratories Canada Ltd., Calgary, AB (Canada); Moghadam, L. [Fekete Associates Inc., Calgary, AB (Canada)

    2008-10-15

    One of the most important physical phenomena during the solvent vapour extraction (VAPEX) of heavy oil recovery is asphaltene precipitation. After the asphaltene precipitation occurs, the produced heavy oil is deasphalted in-situ, resulting in a lower viscosity and better quality. However, precipitated asphaltenes may plug some small pores of the reservoir formation, thus reducing its permeability. This paper examined the effects of three operating factors on the asphaltene precipitation during the VAPEX process, notably solvent type; operating pressure; and sand-pack permeability. Eight VAPEX tests were conducted to recover two different Lloydminster heavy oil samples from a rectangular sand-packed physical model with a butane mixture and propane as the respective solvents. The accumulative heavy oil and solvent production from the physical model were measured in the entire VAPEX process. The paper described the materials, experimental set-up, and experimental preparation. The VAPEX test was also explained. Results were presented for sand consolidation; solvent effect; pressure effect; and permeability effect. It was concluded that when the extracting solvent is in a liquid-gas state, asphaltene precipitation occurs and leads to in-situ deasphalting. 15 refs., 3 tabs., 6 figs.

  10. Liquid and vapour-phase antifungal activities of selected essential oils against candida albicans: microscopic observations and chemical characterization of cymbopogon citratus

    Directory of Open Access Journals (Sweden)

    Malik Anushree

    2010-11-01

    Full Text Available Abstract Background Use of essential oils for controlling Candida albicans growth has gained significance due to the resistance acquired by pathogens towards a number of widely-used drugs. The aim of this study was to test the antifungal activity of selected essential oils against Candida albicans in liquid and vapour phase and to determine the chemical composition and mechanism of action of most potent essential oil. Methods Minimum Inhibitory concentration (MIC of different essential oils in liquid phase, assayed through agar plate dilution, broth dilution & 96-well micro plate dilution method and vapour phase activity evaluated through disc volatilization method. Reduction of C. albicans cells with vapour exposure was estimated by kill time assay. Morphological alteration in treated/untreated C. albicans cells was observed by the Scanning electron microscopy (SEM/Atomic force microscopy (AFM and chemical analysis of the strongest antifungal agent/essential oil has been done by GC, GC-MS. Results Lemon grass (Cymbopogon citratus essential oil exhibited the strongest antifungal effect followed by mentha (Mentha piperita and eucalyptus (Eucalyptus globulus essential oil. The MIC of lemon grass essential oil in liquid phase (288 mg/l was significantly higher than that in the vapour phase (32.7 mg/l and a 4 h exposure was sufficient to cause 100% loss in viability of C. albicans cells. SEM/AFM of C. albicans cells treated with lemon grass essential oil at MIC level in liquid and vapour phase showed prominent shrinkage and partial degradation, respectively, confirming higher efficacy of vapour phase. GC-MS analysis revealed that lemon grass essential oil was dominated by oxygenated monoterpenes (78.2%; α-citral or geranial (36.2% and β-citral or neral (26.5%, monoterpene hydrocarbons (7.9% and sesquiterpene hydrocarbons (3.8%. Conclusion Lemon grass essential oil is highly effective in vapour phase against C. albicans, leading to deleterious

  11. a Study of Volatile Precursors for the Growth of Cadmium Sulphide and Cadmium Selenide by Metal Organic Chemical Vapour Deposition.

    Science.gov (United States)

    Beer, Michael P.

    Available from UMI in association with The British Library. The wide-band-gap semiconductors, cadmium sulphide and cadmium selenide, may be grown by Metal Organic Chemical Vapour Deposition (MOCVD). This method typically involves the reaction of gaseous streams of Me_2 Cd and H_2Y (Y = S, Se) over a heated substrate (usually gallium arsenide) on which the desired compound is grown as an epitaxial layer. Unfortunately, the precursors start to react in the cold zone of the reactor, that is before they reach the heated substrate. This problem is known as prereaction. The problem of prereaction is partially reduced by the use of adducts of dimethyl cadmium in place of the free dialkyl compound although the mechanism by which such adducts block prereaction is unknown. Accordingly, a study of adducts of dimethyl cadmium was undertaken with a view to determining their properties in all phases. The adduct of Me_2Cd with 2,2^ '-bipyridyl was found to be monomeric in the solid state while that with 1,4-dioxane, a volatile compound used for prereaction reduction, was found to be polymeric. A study of adducts in the gas phase using mass spectrometry and gas phase Fourier transform infrared spectroscopy gave no evidence to suggest there is any gas phase association between 1,4-dioxane and dimethyl cadmium. With the 2,2 ^'-bipyridyl adduct some evidence for partial retention of coordinate bonds upon sublimation was obtained. The solid adduct of Me _2Cd with N,N,N^' ,N^'-tetramethylethylenediamine (TMEDA) was prepared as it was hoped that the flexibility of the aliphatic Lewis base would permit the formation of an adduct containing strong co-ordinate bonds which would remain intact upon sublimation. Using gas phase electron diffraction, the structure of the adduct of Me_2Cd and TMEDA was determined. It was shown to exist in the gas phase purely as the associated monomeric species. The adduct was then employed for the growth of CdS and CdSe in an industrial MOCVD apparatus. The

  12. Growth of aligned single-walled carbon nanotubes under ac electric fields through floating catalyst chemical vapour deposition

    Institute of Scientific and Technical Information of China (English)

    Dou Xin-Yuan; Luo Shu-Dong; Zhang Zeng-Xing; Liu Dong-Fang; Wang Jian-Xiong; Gao Yan; Zhou Wei-Ya; Wang Gang; Zhou Zhen-Ping; Tan Ping-Heng; Zhou Jian-Jun; Song Li; Sun Lian-Feng; Jiang Peng; Liu Li-Feng; Zhao Xiao-Wei

    2005-01-01

    Through floating catalyst chemical vapour deposition(CVD) method, well-aligned isolated single-walled carbon nanotubes (SWCNTs) and their bundles were deposited on the metal electrodes patterned on the SiO2/Si surface under ac electric fields at relatively low temperature(280℃). It was indicated that SWCNTs were effectively aligned under ac electric fields after they had just grown in the furnace. The time for a SWCNT to be aligned in the electric field and the effect of gas flow were estimated. Polarized Raman scattering was performed to characterize the aligned structure of SWCNTs. This method would be very useful for the controlled fabrication and preparation of SWCNTs in practical applications.

  13. Properties of MgB{sub 2} films grown at various temperatures by hybrid physical-chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Ke; Veldhorst, Menno; Li, Qi; Xi, X X [Department of Physics, Pennsylvania State University, University Park, PA 16802 (United States); Lee, Che-Hui; Lamborn, Daniel R; DeFrain, Raymond; Redwing, Joan M [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 (United States)

    2008-09-15

    A hybrid physical-chemical vapour deposition (HPCVD) system consisting of separately controlled Mg-source heater and substrate heater is used to grow MgB{sub 2} thin films and thick films at various temperatures. We are able to grow superconducting MgB{sub 2} thin films at temperatures as low as 350 deg. C with a T{sub c0} of 35.5 K. MgB{sub 2} films up to 4 {mu}m in thickness grown at 550 deg. C have J{sub c} over 10{sup 6} A cm{sup -2} at 5 K and zero applied field. The low deposition temperature of MgB{sub 2} films is desirable for all-MgB{sub 2} tunnel junctions and MgB{sub 2} thick films are important for applications in coated conductors.

  14. Growth of large size diamond single crystals by plasma assisted chemical vapour deposition: Recent achievements and remaining challenges

    Science.gov (United States)

    Tallaire, Alexandre; Achard, Jocelyn; Silva, François; Brinza, Ovidiu; Gicquel, Alix

    2013-02-01

    Diamond is a material with outstanding properties making it particularly suited for high added-value applications such as optical windows, power electronics, radiation detection, quantum information, bio-sensing and many others. Tremendous progresses in its synthesis by microwave plasma assisted chemical vapour deposition have allowed obtaining single crystal optical-grade material with thicknesses of up to a few millimetres. However the requirements in terms of size, purity and crystalline quality are getting more and more difficult to achieve with respect to the forecasted applications, thus pushing the synthesis method to its scientific and technological limits. In this paper, after a short description of the operating principles of the growth technique, the challenges of increasing crystal dimensions both laterally and vertically, decreasing and controlling point and extended defects as well as modulating crystal conductivity by an efficient doping will be detailed before offering some insights into ways to overcome them.

  15. The properties of GaMnN films grown by metalorganic chemical vapour deposition using Raman spectroscopy

    Institute of Scientific and Technical Information of China (English)

    Xing Hai-Ying; Niu Ping-Juan; Xie Yu-Xin

    2012-01-01

    An investigation of room-temperature Raman scattering is carried out on ferromagnetic semiconductor GaMnN films grown by metalorganic chemical vapour deposition with different Mn content values.New bands around 300 and 669 cm-1,that are not observed in undoped GaN,are found.They are assigned to disorder-activated mode and local vibration mode (LVM),respectively.After annealing,the intensity ratio between the LVM and E2(high) mode,i.e.,ILVM/IE2(high),increases.The LO phonon-plasmon coupled (LOPC) mode is found in GaMnN,and the frequency of the LOPC mode of GaMnN shifting toward higher side is observed with the increase in the Mn doping in GaN.The ferromagnetic character and the carrier density of our GaMnN sample are discussed.

  16. Room-Temperature Ferromagnetic ZnMnO Thin Films Synthesized by Plasma Enhanced Chemical Vapour Deposition Method

    Institute of Scientific and Technical Information of China (English)

    LIN Ying-Bin; ZHANG Feng-Ming; DU You-Wei; HUANG Zhi-Gao; ZHENG Jian-Guo; LU Zhi-Hai; ZOU Wen-Qin; LU Zhong-Lin; XU Jian-Ping; JI Jian-Ti; LIU Xing-Chong; WANG Jian-Feng; LV Li-Ya

    2007-01-01

    Room-temperature ferromagnetic Mn-doped ZnO films are grown on Si (001) substrates by plasma enhanced chemical vapour deposition (PECVD). X-ray diffraction measurements reveal that the Zn1-xMnxO films have the single-phase wurtzite structure. X-ray photoelectron spectroscopy indicates the existence of Mn2+ ions in Mndoped ZnO films. Furthermore, the decreasing additional Raman peak with increasing Mn-doping is considered to relate to the substitution of Mn ions for the Zn ions in ZnO lattice. Superconducting quantum interference device (SQUID) measurements demonstrate that Mn-doped ZnO films have ferromagnetic behaviour at room temperature.

  17. Aerosol assisted chemical vapour deposition of germanium thin films using organogermanium carboxylates as precursors and formation of germania films

    Indian Academy of Sciences (India)

    Alpa Y Shah; Amey Wadawale; Vijaykumar S Sagoria; Vimal K Jain; C A Betty; S Bhattacharya

    2012-06-01

    Diethyl germanium bis-picolinate, [Et2Ge(O2CC5H4N)2], and trimethyl germanium quinaldate, [Me3Ge(O2CC9H6N)], have been used as precursors for deposition of thin films of germanium by aerosol assisted chemical vapour deposition (AACVD). The thermogravimetric analysis revealed complete volatilization of complexes under nitrogen atmosphere. Germanium thin films were deposited on silicon wafers at 700°C employing AACVD method. These films on oxidation under an oxygen atmosphere at 600°C yield GeO2. Both Ge and GeO2 films were characterized by XRD, SEM and EDS measurements. Their electrical properties were assessed by current–voltage (–) characterization.

  18. Structural and Luminescent Properties of ZnO Thin Films Deposited by Atmospheric Pressure Chemical Vapour Deposition

    Institute of Scientific and Technical Information of China (English)

    ZHAO Guo-Liang; LIN Bi-Xia; HONG Liang; MENG Xiang-Dong; FU Zhu-Xi

    2004-01-01

    ZnO thin films were successfully deposited on Si (100) substrates by chemical vapour deposition (CVD) at atmospheric pressure (1 atm). The only solid source used here is zinc acetate, (CHsCOO)2Zn, and the carrier gas is nitrogen. The sample, which was prepared at 550℃ during growth and then annealed in air at 900℃ , has only a ZnO (002) diffraction peak at 34.6° with its FWHM of 0.23° in the XRD pattern. The room-temperature PL spectrum shows a strong ultraviolet emission with the peak centred at 380nm. We analysed the effects of many factors, such as the source, substrates, growth and annealing temperatures, and annealing ambience, on the structural and optical properties of our prepared ZnO films.

  19. Atmospheric pressure chemical vapour deposition of NbSe2-TiSe2 composite thin films

    International Nuclear Information System (INIS)

    Atmospheric pressure chemical vapour deposition of titanium tetrachloride and niobium pentachloride with di-tert-butyl selenide at 550 deg. C was investigated for different precursors' flow rates. Scanning electron microscopy of the films showed that they were composed of two different kinds of plate-like crystallites. Point wavelength dispersive X-ray (WDX) analyses of the crystallites revealed that they either had the NbSe2 or the TiSe2 composition. The presence of the two phases was confirmed by X-ray diffraction (XRD) and the calculated cell parameters indicate that niobium or titanium was not incorporated into each others' lattice. WDX and XRD analyses highlighted how the NbSe2:TiSe2 ratio in the composite films could be controlled by precursor flow rate.

  20. Perfluorodecyltrichlorosilane-based seed-layer for improved chemical vapour deposition of ultrathin hafnium dioxide films on graphene

    Science.gov (United States)

    Kitzmann, Julia; Göritz, Alexander; Fraschke, Mirko; Lukosius, Mindaugas; Wenger, Christian; Wolff, Andre; Lupina, Grzegorz

    2016-01-01

    We investigate the use of perfluorodecyltrichlorosilane-based self-assembled monolayer as seeding layer for chemical vapour deposition of HfO2 on large area CVD graphene. The deposition and evolution of the FDTS-based seed layer is investigated by X-ray photoelectron spectroscopy, Auger electron spectroscopy, and transmission electron microscopy. Crystalline quality of graphene transferred from Cu is monitored during formation of the seed layer as well as the HfO2 growth using Raman spectroscopy. We demonstrate that FDTS-based seed layer significantly improves nucleation of HfO2 layers so that graphene can be coated in a conformal way with HfO2 layers as thin as 10 nm. Proof-of-concept experiments on 200 mm wafers presented here validate applicability of the proposed approach to wafer scale graphene device fabrication. PMID:27381715

  1. Perfluorodecyltrichlorosilane-based seed-layer for improved chemical vapour deposition of ultrathin hafnium dioxide films on graphene.

    Science.gov (United States)

    Kitzmann, Julia; Göritz, Alexander; Fraschke, Mirko; Lukosius, Mindaugas; Wenger, Christian; Wolff, Andre; Lupina, Grzegorz

    2016-01-01

    We investigate the use of perfluorodecyltrichlorosilane-based self-assembled monolayer as seeding layer for chemical vapour deposition of HfO2 on large area CVD graphene. The deposition and evolution of the FDTS-based seed layer is investigated by X-ray photoelectron spectroscopy, Auger electron spectroscopy, and transmission electron microscopy. Crystalline quality of graphene transferred from Cu is monitored during formation of the seed layer as well as the HfO2 growth using Raman spectroscopy. We demonstrate that FDTS-based seed layer significantly improves nucleation of HfO2 layers so that graphene can be coated in a conformal way with HfO2 layers as thin as 10 nm. Proof-of-concept experiments on 200 mm wafers presented here validate applicability of the proposed approach to wafer scale graphene device fabrication. PMID:27381715

  2. Low Density Self-Assembled InAs/GaAs Quantum Dots Grown by Metal Organic Chemical Vapour Deposition

    Institute of Scientific and Technical Information of China (English)

    LI Lin; LIU Guo-Jun; WANG Xiao-Hua; LI Mei; LI Zhan-Guo; WAN Chun-Ming

    2008-01-01

    The serf-assembled InAs quantum dots (QDs) on GaAs substrates with low density (5×108cm-2) are achieved using relatively higher growth temperature and low InAs coverage by low-pressure metal-organic chemical vapour deposition.The macro-PL spectra exhibit three emission peaks at 1361,1280 and 1204nm,corresponding to the ground level (GS),the first excited state (ES1) and the second excited state (ES2) of the QDs,respectively,which are obtained when the GaAs capping layer/s grown using triethylgallium and tertiallybutylarsine.As a result of micro-PL,only a few peaks from individual dots have been observed.The exciton-biexciton behaviour was clearly observed at low temperature.

  3. Monte Carlo simulation of the behaviour of electrons during electron-assisted chemical vapour deposition of diamond

    Institute of Scientific and Technical Information of China (English)

    董丽芳; 陈俊英; 董国义; 尚勇

    2002-01-01

    The behaviour of electrons during electron-assisted chemical vapour deposition of diamond is investigated using Monte Carlo simulation. The electron energy distribution and velocity distribution are obtained over a wide range of reduced field E/N (the ratio of the electric field to gas molecule density) from 100 to 2000 in units of 1Td=10-17Vcm2.Their effects on the diamond growth are also discussed. Themain results obtained are as follows. (1) The velocity profile is asymmetric for the component parallel to the field.Ihe velocity distribution has a peak shift in the field direction. Most electrons possess non-zero velocity parallel to the substrate. (2) The number of atomic H is a function of E/N. (3) High-quality diamond can be obtained under the condition of E/N from 50 to 800Td due to sufficient atomic H and electron bombardment.

  4. Electron field emission characteristics of nano-catkin carbon films deposited by electron cyclotron resonance microwave plasma chemical vapour deposition

    Institute of Scientific and Technical Information of China (English)

    Gu Guang-Rui; Wu Bao-Jia; Jin Zhe; Ito Toshimichi

    2008-01-01

    This paper reported that the nano-catkin carbon films were prepared on Si substrates by means of electron cyclotron resonance microwave plasma chemical vapour deposition in a hydrogen and methane mixture.The surface morphology and the structure of the fabricated films were characterized by using scanning electron microscopes and Raman spectroscopy,respectively.The stable field emission properties with a low threshold field of 5V/μm corresponding to a current density of about 1μA/cm2 and a current density of 3.2mA/cm2 at an electric field of 10V/μm were obtained from the carbon film deposited at CH4 concentration of 8%.The mechanism that the threshold field decreased with the increase of the CH4 concentration and the high emission current appeared at the high CH4 concentration was explained by using the Fowler-Nordheim theory.

  5. Electron field emission characteristics of nano-catkin carbon films deposited by electron cyclotron resonance microwave plasma chemical vapour deposition

    Science.gov (United States)

    Gu, Guang-Rui; Wu, Bao-Jia; Jin, Zhe; Ito, Toshimichi

    2008-02-01

    This paper reported that the nano-catkin carbon films were prepared on Si substrates by means of electron cyclotron resonance microwave plasma chemical vapour deposition in a hydrogen and methane mixture. The surface morphology and the structure of the fabricated films were characterized by using scanning electron microscopes and Raman spectroscopy, respectively. The stable field emission properties with a low threshold field of 5V/μm corresponding to a current density of about 1μA/cm2 and a current density of 3.2mA/cm2 at an electric field of 10V/μm were obtained from the carbon film deposited at CH4 concentration of 8%. The mechanism that the threshold field decreased with the increase of the CH4 concentration and the high emission current appeared at the high CH4 concentration was explained by using the Fowler-Nordheim theory.

  6. Growth of a Novel Periodic Structure of SiC/AlN Multilayers by Low Pressure Chemical Vapour Deposition

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yong-Mei; SUN Guo-Sheng; LI Jia-Ye; LIU Xing-Fang; WANG Lei; ZHAO Wan-Shun; LI Jin-Min

    2007-01-01

    A novel 10-period SiC/AlN multilayered structure with a SiC cap layer is prepared by low pressure chemical vapour deposition (LPCVD). The structure with total Sim thickness of about 1.45μm is deposited on a Si (111) substrate and shows good surface morphology with a smaller rms surface roughness of 5.3 nm. According to the secondary ion mass spectroscopy results, good interface of the 10 period SiC/AlN structure and periodic changes of depth profiles of C, Si, Al, N components are obtained by controlling the growth procedure. The structure exhibits the peak reflectivity close to 30% near the wavelength of 322 nm. To the best of our knowledge, this is the first report of growth of the SiC/AlN periodic structure using the home-made LPCVD system.

  7. Multi-wavelength copper vapour lasers for novel materials processing application

    International Nuclear Information System (INIS)

    The copper vapour laser (CVL) is a high average power, short pulse laser with a multi-kilohertz pulse repetition rate. The CVL laser lines (511 nm and 578 nm) combined with the good beam quality and high peak power available from these lasers allow it to operate in a unique parameter space. Consequently, it has demonstrated many unique and advantageous machining characteristics. We have also demonstrated efficient conversion of CVL radiation to other wavelengths using non-linear frequency conversion, dye lasers and Ti:AL2O3. Output powers of up to 4 W at 255 nm have been achieved by frequency doubling. The frequency doubled CVL is inherently narrow linewidth and frequency locked making it a suitable source for UV photolithography. Slope efficiencies in excess of 25 % have been achieved with CVL pumped Ti:Al2O3 and dye lasers. These laser extend the wavelengths options into the red and infrared regions of the spectrum. The near diffraction limited beams from these tunable lasers can be efficiently frequency doubled into the blue and near UV. The wide range of wavelength options from the CVL enable a wide variety of materials processing and material interactions to be explored. A European consortium for Copper Laser Applications in Manufacture and Production (CLAMP) has been set up under the EUREKA scheme to coordinate the commercial and technical expertise currently available in Europe. (author)

  8. Lasers in chemical processing

    International Nuclear Information System (INIS)

    The high cost of laser energy is the crucial issue in any potential laser-processing application. It is expensive relative to other forms of energy and to most bulk chemicals. We show those factors that have previously frustrated attempts to find commercially viable laser-induced processes for the production of materials. Having identified the general criteria to be satisfied by an economically successful laser process and shown how these imply the laser-system requirements, we present a status report on the uranium laser isotope separation (LIS) program at the Lawrence Livermore National Laboratory

  9. Chemical-vapour-deposition growth and electrical characterization of intrinsic silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Salem, B. [Laboratoire des Technologies de la Microelectronique (LTM)-UMR 5129 CNRS, CEA-Grenoble, 17 Rue des Martyrs, F-38054 Grenoble (France)], E-mail: bassem.salem@cea.fr; Dhalluin, F.; Baron, T. [Laboratoire des Technologies de la Microelectronique (LTM)-UMR 5129 CNRS, CEA-Grenoble, 17 Rue des Martyrs, F-38054 Grenoble (France); Jamgotchian, H.; Bedu, F.; Dallaporta, H. [CRMC-N, Faculte des Sciences de Luminy, Case 913, 13288 Marseille Cedex 09 (France); Gentile, P.; Pauc, N. [CEA-DRFMC/SiNaPS, 17 Rue des Martyrs, F-38054 Grenoble (France); Hertog, M.I. den; Rouviere, J.L. [CEA-DRFMC/SP2M/LEMMA GEM-minatec, 17 Rue des Martyrs, F-38054 Grenoble (France); Ferret, P. [CEA-Leti, DOPT, 17 Rue des Martyrs, F-38054 Grenoble (France)

    2009-03-15

    In this work, we present the elaboration and the electrical characterisation of undoped silicon nanowires (SiNWs) which are grown via vapour-liquid-solid mechanism using Au nucleation catalyst and SiH{sub 4} as the silicon source. The nanowires were investigated by high-resolution transmission electron microscopy. An electrical test structure was realized by a dispersion of the nanowires on SiO{sub 2}/Si substrate with photolithography pre-patterned Au/Ti microelectrodes. The connexion is made on a single nanowire using a cross beam plate form allowing scanning electron microscopy imaging and the deposition of tungsten wiring by focussed ion beam deposition. The current-voltage characteristics of the nanowires are linear which indicates an ohmic contact between tungsten allow and SiNWs. The total resistance of the nanowires increases from 135 M{omega} to 5 G{omega} when the diameter decreases from 190 to 130 nm. This effect is may be due to the reduction of the conductive inner volume of the nanowires and to charged defects at the Si-SiO{sub 2} interface if we assume that the contact resistance is constant. Moreover, gate-dependent current versus bias voltage measurement show that the nanowires exhibit a field effect response characteristic of a p-type semiconductor.

  10. The effect of thermal annealing on the properties of alumina films prepared by metal organic chemical vapour deposition at atmospheric pressure

    NARCIS (Netherlands)

    Haanappel, V.A.C.; Corbach, van H.D.; Fransen, T.; Gellings, P.J.

    1994-01-01

    Thin films deposited at 330°C by metal organic chemical vapour deposition on stainless steel, type AISI 304, were annealed in a nitrogen atmosphere for 1, 2 and 4 h at 600, 700 and 800°C. The film properties, including the protection of the underlying substrate against high temperature corrosion, th

  11. The protective properties of thin alumina films deposited by metal organic chemical vapour deposition against high-temperature corrosion of stainless steels

    NARCIS (Netherlands)

    Morssinkhof, R.W.J.; Fransen, T.; Heusinkveld, M.M.D.; Gellings, P.J.

    1989-01-01

    Coatings of Al2O3 were deposited on Incoloy 800H and AISI 304 by means of metal organic chemical vapour deposition. Diffusion limitation was the rate-determining step above 420 °C. Below this temperature, the activation energy of the reaction appeared to be 30 kJ mol−1. Coating with Al2O3 increases

  12. Charge effect of superparamagnetic iron oxide nanoparticles on their surface functionalization by photo-initiated chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Javanbakht, Taraneh [Ecole Polytechnique of Montreal, Department of Chemical Engineering (Canada); Laurent, Sophie; Stanicki, Dimitri [University of Mons, Laboratory of NMR and Molecular Imaging (Belgium); Raphael, Wendell; Tavares, Jason Robert, E-mail: jason.tavares@polymtl.ca [Ecole Polytechnique of Montreal, Department of Chemical Engineering (Canada)

    2015-12-15

    Diverse applications of superparamagnetic iron oxide nanoparticles (SPIONs) in the chemical and biomedical industry depend on their surface properties. In this paper, we investigate the effect of initial surface charge (bare, positively and negatively charged SPIONs) on the resulting physicochemical properties of the particles following treatment through photo-initiated chemical vapour deposition (PICVD). Transmission electron microscopy shows a nanometric polymer coating on the SPIONs and contact angle measurements with water demonstrate that their surface became non-polar following functionalization using PICVD. FTIR and XPS data confirm the change in the chemical composition of the treated SPIONs. Indeed, XPS data reveal an initial charge-dependent increase in the surface oxygen content in the case of treated SPIONs. The O/C percentage ratios of the bare SPIONs increase from 1.7 to 1.9 after PICVD treatment, and decrease from 1.7 to 0.7 in the case of negatively charged SPIONs. The ratio remains unchanged for positively charged SPIONs (1.7). This indicates that bare and negatively charged SPIONs showed opposite preference for the oxygen or carbon attachment to their surface during their surface treatment. These results reveal that both the surface charge and stereochemical effects have determinant roles in the polymeric coating of SPIONs with PICVD. Our findings suggest that this technique is appropriate for the treatment of nanoparticles.Graphical Abstract.

  13. Charge effect of superparamagnetic iron oxide nanoparticles on their surface functionalization by photo-initiated chemical vapour deposition

    International Nuclear Information System (INIS)

    Diverse applications of superparamagnetic iron oxide nanoparticles (SPIONs) in the chemical and biomedical industry depend on their surface properties. In this paper, we investigate the effect of initial surface charge (bare, positively and negatively charged SPIONs) on the resulting physicochemical properties of the particles following treatment through photo-initiated chemical vapour deposition (PICVD). Transmission electron microscopy shows a nanometric polymer coating on the SPIONs and contact angle measurements with water demonstrate that their surface became non-polar following functionalization using PICVD. FTIR and XPS data confirm the change in the chemical composition of the treated SPIONs. Indeed, XPS data reveal an initial charge-dependent increase in the surface oxygen content in the case of treated SPIONs. The O/C percentage ratios of the bare SPIONs increase from 1.7 to 1.9 after PICVD treatment, and decrease from 1.7 to 0.7 in the case of negatively charged SPIONs. The ratio remains unchanged for positively charged SPIONs (1.7). This indicates that bare and negatively charged SPIONs showed opposite preference for the oxygen or carbon attachment to their surface during their surface treatment. These results reveal that both the surface charge and stereochemical effects have determinant roles in the polymeric coating of SPIONs with PICVD. Our findings suggest that this technique is appropriate for the treatment of nanoparticles.Graphical Abstract

  14. The influence of substrate orientation on the density of silicon nanowires grown on multicrystalline and single crystal substrates by electron cyclotron resonance chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Ball, J., E-mail: balljb@lsbu.ac.uk; Reehal, H.S.

    2012-01-31

    The Au catalysed, vapour-liquid-solid growth of Si nanowires on Si substrates of different orientations has been studied using electron cyclotron resonance plasma-assisted chemical vapour deposition (ECRCVD). ECRCVD plasma excitation is found to strongly promote wire growth rate and density with wire diameters in excess of 200 nm under the conditions used. Substrate orientation and nanowire density are strongly correlated. This has been studied using multicrystalline as well as single crystal Si substrates. It is suggested that the Gibbs-Thomson effect can account for the behaviour of wire density with orientation. The application of an RF generated, DC self-bias of - 5 V on the substrate during growth strongly enhances wire density without affecting growth rate or diameter. A tentative model for wire growth has been proposed which is based on an initial incubation/crystallisation step, followed by silicon incorporation at the vapour-liquid interface being rate-limiting.

  15. A novel three-jet microreactor for localized metal-organic chemical vapour deposition of gallium arsenide: design and simulation

    Science.gov (United States)

    Konakov, S. A.; Krzhizhanovskaya, V. V.

    2016-08-01

    We present a novel three-jet microreactor design for localized deposition of gallium arsenide (GaAs) by low-pressure Metal-Organic Chemical Vapour Deposition (MOCVD) for semiconductor devices, microelectronics and solar cells. Our approach is advantageous compared to the standard lithography and etching technology, since it preserves the nanostructure of the deposited material, it is less time-consuming and less expensive. We designed two versions of reactor geometry with a 10-micron central microchannel for precursor supply and with two side jets of a dilutant to control the deposition area. To aid future experiments, we performed computational modeling of a simplified-geometry (twodimensional axisymmetric) microreactor, based on Navier-Stokes equations for a laminar flow of chemically reacting gas mixture of Ga(CH3)3-AsH3-H2. Simulation results show that we can achieve a high-rate deposition (over 0.3 μm/min) on a small area (less than 30 μm diameter). This technology can be used in material production for microelectronics, optoelectronics, photovoltaics, solar cells, etc.

  16. Detection of chemical substances in water using an oxide nanowire transistor covered with a hydrophobic nanoparticle thin film as a liquid-vapour separation filter

    Science.gov (United States)

    Lim, Taekyung; Lee, Jonghun; Ju, Sanghyun

    2016-08-01

    We have developed a method to detect the presence of small amounts of chemical substances in water, using a Al2O3 nanoparticle thin film covered with phosphonic acid (HDF-PA) self-assembled monolayer. The HDF-PA self-assembled Al2O3 nanoparticle thin film acts as a liquid-vapour separation filter, allowing the passage of chemical vapour while blocking liquids. Prevention of the liquid from contacting the SnO2 nanowire and source-drain electrodes is required in order to avoid abnormal operation. Using this characteristic, the concentration of chemical substances in water could be evaluated by measuring the current changes in the SnO2 nanowire transistor covered with the HDF-PA self-assembled Al2O3 nanoparticle thin film.

  17. Optical and electrical properties of ZrSe3 single crystals grown by chemical vapour transport technique

    Indian Academy of Sciences (India)

    Kaushik Patel; Jagdish Prajapati; Rajiv Vaidya; S G Patel

    2005-08-01

    Single crystals of the lamellar compound, ZrSe3, were grown by chemical vapour transport technique using iodine as a transporting agent. The grown crystals were characterized with the help of energy dispersive analysis by X-ray (EDAX), which gave confirmation about the stoichiometry. The optical band gap measurement of as grown crystals was carried out with the help of optical absorption spectra in the range 700–1450 nm. The indirect as well as direct band gap of ZrSe3 were found to be 1.1 eV and 1.47 eV, respectively. The resistivity of the as grown crystals was measured using van der Pauw method. The Hall parameters of the grown crystals were determined at room temperature from Hall effect measurements. Electrical resistivity measurements were performed on this crystal in the temperature range 303–423 K. The crystals were found to exhibit semiconducting nature in this range. The activation energy and anisotropy measurements were carried out for this crystal. Pressure dependence of electrical resistance was studied using Bridgman opposed anvils set up up to 8 GPa. The semiconducting nature of ZrSe3 single crystal was inferred from the graph of resistance vs pressure. The results obtained are discussed in detail.

  18. Evaluation of freestanding boron-doped diamond grown by chemical vapour deposition as substrates for vertical power electronic devices

    Energy Technology Data Exchange (ETDEWEB)

    Issaoui, R.; Achard, J.; Tallaire, A.; Silva, F.; Gicquel, A. [LSPM-CNRS (formerly LIMHP), Universite Paris 13, 99, Avenue Jean-Baptiste Clement, 93430 Villetaneuse (France); Bisaro, R.; Servet, B.; Garry, G. [Thales Research and Technology France, Campus de Polytechnique, 1 Avenue Augustin Fresnel, F-91767 Palaiseau Cedex (France); Barjon, J. [GEMaC-CNRS, Universite de Versailles Saint Quentin Batiment Fermat, 45 Avenue des Etats-Unis, 78035 Versailles Cedex (France)

    2012-03-19

    In this study, 4 x 4 mm{sup 2} freestanding boron-doped diamond single crystals with thickness up to 260 {mu}m have been fabricated by plasma assisted chemical vapour deposition. The boron concentrations measured by secondary ion mass spectroscopy were 10{sup 18} to 10{sup 20} cm{sup -3} which is in a good agreement with the values calculated from Fourier transform infrared spectroscopy analysis, thus indicating that almost all incorporated boron is electrically active. The dependence of lattice parameters and crystal mosaicity on boron concentrations have also been extracted from high resolution x-ray diffraction experiments on (004) planes. The widths of x-ray rocking curves have globally shown the high quality of the material despite a substantial broadening of the peak, indicating a decrease of structural quality with increasing boron doping levels. Finally, the suitability of these crystals for the development of vertical power electronic devices has been confirmed by four-point probe measurements from which electrical resistivities as low as 0.26 {Omega} cm have been obtained.

  19. InGa1−N fibres grown on Au/SiO2 by chemical vapour deposition

    Indian Academy of Sciences (India)

    A Ramos-Carrazco; R García; M Barboza-Flores; R Rangel

    2014-12-01

    The growth of InGa1−N films ( = 0.1 and = 0.2) on a thin gold layer (Au/SiO2) by chemical vapour deposition (CVD) at 650 °C is reported. As a novelty, the use of a Ga–In metallic alloy to improve the indium incorporation in the InGa1−N is proposed. The results of high quality InGa1−N films with a thickness of three micrometres and the formation of microfibres on the surface are presented. A morphological comparison between the InGa1−N and GaN films is shown as a function of the indium incorporation. The highest crystalline InGa1−N films structure was obtained with an indium composition of = 0.20. Also, the preferential growth on the (002) plane over In0.2Ga0.8N was observed by means of X-ray diffraction. The thermoluminescence (TL) of the InGa1−N films after beta radiation exposure was measured indicating the presence of charge trapping levels responsible for a broad TL glow curve with a maximum intensity around 150 °C. The TL intensity was found to depend on composition being higher for = 0.1 and increases as radiation dose increases.

  20. Evaluation of freestanding boron-doped diamond grown by chemical vapour deposition as substrates for vertical power electronic devices

    International Nuclear Information System (INIS)

    In this study, 4 x 4 mm2 freestanding boron-doped diamond single crystals with thickness up to 260 μm have been fabricated by plasma assisted chemical vapour deposition. The boron concentrations measured by secondary ion mass spectroscopy were 1018 to 1020 cm-3 which is in a good agreement with the values calculated from Fourier transform infrared spectroscopy analysis, thus indicating that almost all incorporated boron is electrically active. The dependence of lattice parameters and crystal mosaicity on boron concentrations have also been extracted from high resolution x-ray diffraction experiments on (004) planes. The widths of x-ray rocking curves have globally shown the high quality of the material despite a substantial broadening of the peak, indicating a decrease of structural quality with increasing boron doping levels. Finally, the suitability of these crystals for the development of vertical power electronic devices has been confirmed by four-point probe measurements from which electrical resistivities as low as 0.26 Ω cm have been obtained.

  1. Evaluation of freestanding boron-doped diamond grown by chemical vapour deposition as substrates for vertical power electronic devices

    Science.gov (United States)

    Issaoui, R.; Achard, J.; Tallaire, A.; Silva, F.; Gicquel, A.; Bisaro, R.; Servet, B.; Garry, G.; Barjon, J.

    2012-03-01

    In this study, 4 × 4 mm2 freestanding boron-doped diamond single crystals with thickness up to 260 μm have been fabricated by plasma assisted chemical vapour deposition. The boron concentrations measured by secondary ion mass spectroscopy were 1018 to 1020 cm-3 which is in a good agreement with the values calculated from Fourier transform infrared spectroscopy analysis, thus indicating that almost all incorporated boron is electrically active. The dependence of lattice parameters and crystal mosaicity on boron concentrations have also been extracted from high resolution x-ray diffraction experiments on (004) planes. The widths of x-ray rocking curves have globally shown the high quality of the material despite a substantial broadening of the peak, indicating a decrease of structural quality with increasing boron doping levels. Finally, the suitability of these crystals for the development of vertical power electronic devices has been confirmed by four-point probe measurements from which electrical resistivities as low as 0.26 Ω cm have been obtained.

  2. In situ high temperature XRD studies of ZnO nanopowder prepared via cost effective ultrasonic mist chemical vapour deposition

    Indian Academy of Sciences (India)

    Preetam Singh; Ashvani Kumar; Ajay Kaushal; Davinder Kaur; Ashish Pandey; R N Goyal

    2008-06-01

    Ultrasonic mist chemical vapour deposition (UM–CVD) system has been developed to prepare ZnO nanopowder. This is a promising method for large area deposition at low temperature inspite of being simple, inexpensive and safe. The particle size, lattice parameters and crystal structure of ZnO nanopowder are characterized by in situ high temperature X-ray diffraction (XRD). Surface morphology of powder was studied using transmission electron microscopy (TEM) and field emission electron microscope (FESEM). The optical properties are observed using UV-visible spectrophotometer. The influence of high temperature vacuum annealing on XRD pattern is systematically studied. Results of high temperature XRD showed prominent 100, 002 and 101 reflections among which 101 is of highest intensity. With increase in temperature, a systematic shift in peak positions towards lower 2 values has been observed, which may be due to change in lattice parameters. Temperature dependence of lattice constants under vacuum shows linear increase in their values. Diffraction patterns obtained from TEM are also in agreement with the XRD data. The synthesized powder exhibited the estimated direct bandgap (g) of 3.43 eV. The optical bandgap calculated from Tauc’s relation and the bandgap calculated from the particle size inferred from XRD were in agreement with each other.

  3. Temperature-dependent Hall effect studies of ZnO thin films grown by metalorganic chemical vapour deposition

    International Nuclear Information System (INIS)

    The electrical properties of zinc oxide (ZnO) thin films of various thicknesses (0.3–4.4 µm) grown by metalorganic chemical vapour deposition on glass substrates have been studied by using temperature-dependent Hall-effect (TDH) measurements in the 18–300 K range. The high quality of the layers has been confirmed with x-ray diffraction, transmission electron microscopy, scanning electron microscopy and photoluminescence techniques. TDH measurements indicate the presence of a degenerate layer which significantly influences the low-temperature data. It is found that the measured mobility generally increases with increasing layer thickness, reaching a value of 120 cm2 V−1 s−1 at room temperature for the 4.4 µm thick sample. The lateral grain size of the layers is also found to increase with thickness indicating a clear correlation between the size of the surface grains and the electrical properties of corresponding films. Theoretical fits to the Hall data suggest that the bulk conduction of the layers is dominated by a weakly compensated donor with activation energy in the 33–41 meV range and concentration of the order of 1017 cm−3, as well as a total acceptor concentration of mid-1015 cm−3. Grain boundary scattering is found to be an important limiting factor of the mobility throughout the temperature range considered

  4. Atmospheric pressure chemical vapour deposition of SnSe and SnSe{sub 2} thin films on glass

    Energy Technology Data Exchange (ETDEWEB)

    Boscher, Nicolas D.; Carmalt, Claire J.; Palgrave, Robert G. [Department of Chemistry, University College London, 20 Gordon Street, London, WC1H OAJ (United Kingdom); Parkin, Ivan P. [Department of Chemistry, University College London, 20 Gordon Street, London, WC1H OAJ (United Kingdom)], E-mail: i.p.parkin@ucl.ac.uk

    2008-06-02

    Atmospheric pressure chemical vapour deposition of tin monoselenide and tin diselenide films on glass substrate was achieved by reaction of diethyl selenide with tin tetrachloride at 350-650 {sup o}C. X-ray diffraction showed that all the films were crystalline and matched the reported pattern for SnSe and/or SnSe{sub 2}. Wavelength dispersive analysis by X-rays show a variable Sn:Se ratio from 1:1 to 1:2 depending on conditions. The deposition temperature, flow rates and position on the substrate determined whether mixed SnSe-SnSe{sub 2}, pure SnSe or pure SnSe{sub 2} thin films could be obtained. SnSe films were obtained at 650 {sup o}C with a SnCl{sub 4} to Et{sub 2}Se ratio greater than 10. The SnSe films were silver-black in appearance and adhesive. SnSe{sub 2} films were obtained at 600-650 {sup o}C they had a black appearance and were composed of 10 to 80 {mu}m sized adherent crystals. Films of SnSe only 100 nm thick showed complete absorbtion at 300-1100 nm.

  5. Growth mechanism of planar or nanorod structured tungsten oxide thin films deposited via aerosol assisted chemical vapour deposition (AACVD)

    Energy Technology Data Exchange (ETDEWEB)

    Ling, Min; Blackman, Chris [Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom)

    2015-07-15

    Aerosol assisted chemical vapour deposition (AACVD) is used to deposit tungsten oxide thin films from tungsten hexacarbonyl (W(CO){sub 6}) at 339 to 358 C on quartz substrate. The morphologies of as-deposited thin films, which are comprised of two phases (W{sub 25}O{sub 73} and W{sub 17}O{sub 47}), vary from planar to nanorod (NR) structures as the distance from the inlet towards the outlet of the reactor is traversed. This is related to variation of the actual temperature on the substrate surface (ΔT = 19 C), which result in a change in growth mode due to competition between growth rate (perpendicular to substrate) and nucleation rate (parallel to substrate). When the ratio of perpendicular growth rate to growth rate contributed by nucleation is higher than 7.1, the as-deposited tungsten oxide thin film forms as NR. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Photoluminescence and lasing properties of InAs/GaAs quantum dots grown by metal-organic chemical vapour deposition

    Institute of Scientific and Technical Information of China (English)

    Liang Song; Wang Wei; Zhu Hong-Liang; Pan Jiao-Qing; Zhao Ling-Juan; Wang Lu-Feng; Zhou Fan; Shu Hui-Yun; Bian Jing; An Xin

    2008-01-01

    Photoluminescence (PL) and lasing properties of InAs/GaAs quantum dots (QDs) with different growth procedures prepared by metalorganic chemical vapour deposition are studied.PL measurements show that the low growth rate QD sample has a larger PL intensity and a narrower PL line width than the high growth rate sample.During rapid thermal annealing,however,the low growth rate sample shows a greater blueshift of PL peak wavelength.This is caused by the larger InAs layer thickness which results from the larger 2-3 dimensional transition critical layer thickness for the QDs in the low-growth-rate sample.A growth technique including growth interruption and in-situ annealing,named indium flush method,is used during the growth of GaAs cap layer,which can flatten the GaAs surface effectively.Though the method results in a blueshift of PL peak wavelength and a broadening of PL line width,it is essential for the fabrication of room temperature working QD lasers.

  7. Metal organic chemical vapour deposition of SrRuO3 thin films on SrTiO3

    International Nuclear Information System (INIS)

    SrRuO3 with pseudo-cubic crystalline structure (a=0.393 nm) appears to be one of the most suitable conductive oxides to be used as bottom electrode for the oxide-based electronic devices, due to its high conductivity and low lattice misfit with many functional perovskite transition metal oxides. Furthermore, this electrode has a lower density of defects (oxygen vacancies, dislocations, dead layer) compared with metal electrodes (Pt,Ru,Ir). A vertical liquid-delivery metal-organic chemical vapour deposition (MO-CVD) reactor was used to deposit (100)-oriented SrRuO3 films on vicinal SrTiO3(100) substrates. In order to grow epitaxial thin films with low defect density and high electrical conductivity and to optimise the deposition parameters, the influence of deposition temperature (500-700 C), argon/oxygen ratio (1.6-3.3), total gas flow (4875-8125 sccm) and reactor pressure (12 mbar-40 mbar) was investigated. Composition of the films was identified by GDOES technique. Raman and XRD were used to determine film orientation and the surface morphology and roughness was analysed by AFM and SEM microscopy

  8. Osteoconductive Potential of Barrier NanoSiO2 PLGA Membranes Functionalized by Plasma Enhanced Chemical Vapour Deposition

    Directory of Open Access Journals (Sweden)

    Antonia Terriza

    2014-01-01

    Full Text Available The possibility of tailoring membrane surfaces with osteoconductive potential, in particular in biodegradable devices, to create modified biomaterials that stimulate osteoblast response should make them more suitable for clinical use, hopefully enhancing bone regeneration. Bioactive inorganic materials, such as silica, have been suggested to improve the bioactivity of synthetic biopolymers. An in vitro study on HOB human osteoblasts was performed to assess biocompatibility and bioactivity of SiO2 functionalized poly(lactide-co-glycolide (PLGA membranes, prior to clinical use. A 15 nm SiO2 layer was deposited by plasma enhanced chemical vapour deposition (PECVD, onto a resorbable PLGA membrane. Samples were characterized by X-ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy, and infrared spectroscopy (FT-IR. HOB cells were seeded on sterilized test surfaces where cell morphology, spreading, actin cytoskeletal organization, and focal adhesion expression were assessed. As proved by the FT-IR analysis of samples, the deposition by PECVD of the SiO2 onto the PLGA membrane did not alter the composition and other characteristics of the organic membrane. A temporal and spatial reorganization of cytoskeleton and focal adhesions and morphological changes in response to SiO2 nanolayer were identified in our model. The novedous SiO2 deposition method is compatible with the standard sterilization protocols and reveals as a valuable tool to increase bioactivity of resorbable PLGA membranes.

  9. Deposition and characterization of diamond-like nanocomposite coatings grown by plasma enhanced chemical vapour deposition over different substrate materials

    Indian Academy of Sciences (India)

    Awadesh Kr Mallik; Nanadadulal Dandapat; Prajit Ghosh; Utpal Ganguly; Sukhendu Jana; Sayan Das; Kaustav Guha; Garfield Rebello; Samir Kumar Lahiri; Someswar Datta

    2013-04-01

    Diamond-like nanocomposite (DLN) coatings have been deposited over different substrates used for biomedical applications by plasma-enhanced chemical vapour deposition (PECVD). DLN has an interconnecting network of amorphous hydrogenated carbon and quartz-like oxygenated silicon. Raman spectroscopy, Fourier transform–infra red (FT–IR) spectroscopy, transmission electron microscopy (TEM) and X-ray diffraction (XRD) have been used for structural characterization. Typical DLN growth rate is about 1 m/h, measured by stylus profilometer. Due to the presence of quartz-like Si:O in the structure, it is found to have very good adhesive property with all the substrates. The adhesion strength found to be as high as 0.6 N on SS 316 L steel substrates by scratch testing method. The Young’s modulus and hardness have found to be 132 GPa and 14.4 GPa, respectively. DLN coatings have wear factor in the order of 1 × 10-7 mm3/N-m. This coating has found to be compatible with all important biomedical substrate materials and has successfully been deposited over Co–Cr alloy based knee implant of complex shape.

  10. Metal-organic chemical vapour deposition of lithium manganese oxide thin films via single solid source precursor

    Directory of Open Access Journals (Sweden)

    Oyedotun K.O.

    2015-12-01

    Full Text Available Lithium manganese oxide thin films were deposited on sodalime glass substrates by metal organic chemical vapour deposition (MOCVD technique. The films were prepared by pyrolysis of lithium manganese acetylacetonate precursor at a temperature of 420 °C with a flow rate of 2.5 dm3/min for two-hour deposition period. Rutherford backscattering spectroscopy (RBS, UV-Vis spectrophotometry, X-ray diffraction (XRD spectroscopy, atomic force microscopy (AFM and van der Pauw four point probe method were used for characterizations of the film samples. RBS studies of the films revealed fair thickness of 1112.311 (1015 atoms/cm2 and effective stoichiometric relationship of Li0.47Mn0.27O0.26. The films exhibited relatively high transmission (50 % T in the visible and NIR range, with the bandgap energy of 2.55 eV. Broad and diffused X-ray diffraction patterns obtained showed that the film was amorphous in nature, while microstructural studies indicated dense and uniformly distributed layer across the substrate. Resistivity value of 4.9 Ω·cm was obtained for the thin film. Compared with Mn0.2O0.8 thin film, a significant lattice absorption edge shift was observed in the Li0.47Mn0.27O0.26 film.

  11. Titania Coated Mica via Chemical Vapour Deposition, Post N-doped by Liquid Ammonia Treatment

    Science.gov (United States)

    Powell, Michael J.; Parkin, Ivan P.

    TiO2 films were successfully grown on synthetic mica powders via Chemical Vapor Deposition (CVD). The CVD rig is a cold-walled design that allows surface coverage of a powder to be successfully achieved. The TiO2 was produced by the reaction between TiCl4 and Ethyl Acetate. The powder produced could be successfully N-doped using post liquid ammonia treatment. The TiO2 powder produced could have potential applications in self-cleaning surfaces or antimicrobial paints.

  12. A Passively Mode-Locked Diode-End-Pumped Nd:YAG Laser with a Semiconductor Saturable Absorber Mirror Grown by Metal Organic Chemical Vapour Deposition

    Institute of Scientific and Technical Information of China (English)

    王勇刚; 马骁宇; 李春勇; 张治国; 张丙元; 张志刚

    2003-01-01

    We report the experimental results of a mode-locked diode-end-pumped Nd:YAG laser with a semiconductor saturable absorber mirror(SESAM)from which we achieved a 10ps pulse duration at 150MHz repetition rate.The SESAM was grown by metal organic chemical vapour deposition at low temperature.The recovery time was measured to be 0.5 ps,indicating the potential pulse compression to sub-picoseconds.

  13. Fabrication and gas sensing properties of pure and au-functionalised W03 nanoneedle-like structures, synthesised via aerosol assisted chemical vapour deposition method

    OpenAIRE

    Stoycheva, Toni

    2011-01-01

    In this doctoral thesis, it has been investigated and developed the Aerosol Assisted Chemical Vapour Deposition (AACVD) method for direct in-situ growth of intrinsic and Au-functionalised nanostructured WO3, as well as SnO2-based devices for gas sensing applications. The nanostructured material synthesis, device fabrication and their gas sensing properties have been studied. AACVD method was used for synthesis and direct deposition of sensing films onto classical alumina and microhotplat...

  14. Substrate and material transfer effects on the surface chemistry and texture of diamond-like carbon deposited by plasma-enhanced chemical vapour deposition

    OpenAIRE

    Jones, Benjamin; Ojeda, J. J.

    2012-01-01

    Diamond-like carbon (DLC), a thin amorphous carbon film, has many uses in tribological systems. Exploiting alternative substrates and interlayers can enable the control of the hardness and modulus of the multilayer system and improve wear or friction properties. We used XPS and atomic force microscopy to examine DLC that had been concurrently coated on an epoxy interlayer and a steel substrate by plasma-enhanced chemical vapour deposition. sp2/sp3 ratios were calculated both by the deconvolut...

  15. Modified DLC coatings prepared in a large-scale reactor by dual microwave/pulsed-DC plasma-activated chemical vapour deposition

    International Nuclear Information System (INIS)

    Diamond-Like Carbon (DLC) films find abundant applications as hard and protective coatings due to their excellent mechanical and tribological performances. The addition of new elements to the amorphous DLC matrix tunes the properties of this material, leading to an extension of its scope of applications. In order to scale up their production to a large plasma reactor, DLC films modified by silicon and oxygen additions have been grown in an industrial plant of 1m3 by means of pulsed-DC plasma-activated chemical vapour deposition (PACVD). The use of an additional microwave (MW) source has intensified the glow discharge, partly by electron cyclotron resonance (ECR), accelerating therefore the deposition process. Hence, acetylene, tetramethylsilane (TMS) and hexamethyldisiloxane (HMDSO) constituted the respective gas precursors for the deposition of a-C:H (DLC), a-C:H:Si and a-C:H:Si:O films by dual MW/pulsed-DC PACVD. This work presents systematic studies of the deposition rate, hardness, adhesion, abrasive wear and water contact angle aimed to optimize the technological parameters of deposition: gas pressure, relative gas flow of the monomers and input power. This study has been completed with measures of the atomic composition of the samples. Deposition rates around 1 μm/h, typical for standard processes held in the large reactor, were increased about by a factor 10 when the ionization source has been operated in ECR mode

  16. Investigation of the growth process of Si nanowires using the vapour-liquid-solid mechanism

    Institute of Scientific and Technical Information of China (English)

    邢英杰; 俞大鹏; 奚中和; 薛增泉

    2002-01-01

    Silicon nanowires have been grown by the thermal decomposition of silane via the vapour-liquid-solid (VLS)mechanism. Three different stages of VLS growth (eutectic alloy formation, crystal nucleation and unidirectional growth)were studied separately using a scanning electron microscope and a high-resolution transmission electron microscope.Very short silicon nanowires prepared under particular conditions provide direct evidence of the VLS mechanism on a nanometre scale. Our results will be very helpful for the controllable synthesis of Si nanowires.

  17. Growth of AlGaSb Compound Semiconductors on GaAs Substrate by Metalorganic Chemical Vapour Deposition

    Directory of Open Access Journals (Sweden)

    A. H. Ramelan

    2010-01-01

    Full Text Available Epitaxial AlxGa1-xSb layers on GaAs substrate have been grown by atmospheric pressure metalorganic chemical vapour deposition using TMAl, TMGa, and TMSb. We report the effect of V/III flux ratio and growth temperature on growth rate, surface morphology, electrical properties, and composition analysis. A growth rate activation energy of 0.73 eV was found. For layers grown on GaAs at 580∘C and 600∘C with a V/III ratio of 3 a high quality surface morphology is typical, with a mirror-like surface and good composition control. It was found that a suitable growth temperature and V/III flux ratio was beneficial for producing good AlGaSb layers. Undoped AlGaSb grown at 580∘C with a V/III flux ratio of 3 at the rate of 3.5 μm/hour shows p-type conductivity with smooth surface morphology and its hole mobility and carrier concentration are equal to 237 cm2/V.s and 4.6 × 1017 cm-3, respectively, at 77 K. The net hole concentration of unintentionally doped AlGaSb was found to be significantly decreased with the increased of aluminium concentration. All samples investigated show oxide layers (Al2O3, Sb2O3, and Ga2O5 on their surfaces. In particular the percentage of aluminium-oxide was very high compared with a small percentage of AlSb. Carbon content on the surface was also very high.

  18. Remote plasma-enhanced chemical vapour deposition of silicon nitride at atmospheric pressure

    International Nuclear Information System (INIS)

    Silicon nitride films were deposited using an atmospheric pressure plasma source. The discharge was produced by flowing nitrogen and helium through two perforated metal electrodes that were driven by 13.56 MHz radio frequency power. Deposition occurred by mixing the plasma effluent with silane and directing the flow onto a rotating silicon wafer heated to between 100 deg. C and 500 deg. C. Film growth rates ranged from 90±10 to 1300±130 A min-1. Varying the N2/SiH4 feed ratio from 55.0 to 5.5 caused the film stoichiometry to shift from SiN1.45 to SiN1.2. Minimum impurity concentrations of 0.04% carbon, 3.6% oxygen and 13.6% hydrogen were achieved at 500 deg. C, and an N2/SiH4 feed ratio of 22.0. The growth rate increased with increasing silane and nitrogen partial pressures, but was invariant with respect to substrate temperature and rotational speed. The deposition rate also decreased sharply with distance from the plasma. These results combined with emission spectra taken of the afterglow suggest that gas-phase reactions between nitrogen atoms and silane play an important role in this process

  19. SiC fibre by chemical vapour deposition on tungsten filament

    Indian Academy of Sciences (India)

    R V Krishnarao; J Subrahmanyam; S Subbarao

    2001-06-01

    A CVD system for the production of continuous SiC fibre was set up. The process of SiC coating on 19 m diameter tungsten substrate was studied. Methyl trichloro silane (CH3SiCl3) and hydrogen reactants were used. Effect of substrate temperature (1300–1500°C) and concentration of reactants on the formation of SiC coating were studied. SiC coatings of negligible thickness were formed at very low flow rates of hydrogen (5 × 10–5 m3/min) and CH3SiCl3 (1.0 × 10–4 m3/min of Ar). Uneven coatings and brittle fibres were formed at very high concentrations of CH3SiCl3 (6 × 10–4 m3/min of Ar). The flow rates of CH3SiCl3 and hydrogen were adjusted to get SiC fibre with smooth surface. The structure and morphology of SiC fibres were evaluated.

  20. Biocidal Silver and Silver/Titania Composite Films Grown by Chemical Vapour Deposition

    Directory of Open Access Journals (Sweden)

    D. W. Sheel

    2008-01-01

    Full Text Available This paper describes the growth and testing of highly active biocidal films based on photocatalytically active films of TiO2, grown by thermal CVD, functionally and structurally modified by deposition of nanostructured silver via a novel flame assisted combination CVD process. The resulting composite films are shown to be highly durable, highly photocatalytically active and are also shown to possess strong antibacterial behaviour. The deposition control, arising from the described approach, offers the potential to control the film nanostructure, which is proposed to be crucial in determining the photo and bioactivity of the combined film structure, and the transparency of the composite films. Furthermore, we show that the resultant films are active to a range of organisms, including Gram-negative and Gram-positive bacteria, and viruses. The very high-biocidal activity is above that expected from the concentrations of silver present, and this is discussed in terms of nanostructure of the titania/silver surface. These properties are especially significant when combined with the well-known durability of CVD deposited thin films, offering new opportunities for enhanced application in areas where biocidal surface functionality is sought.

  1. Effect of gas flow rates on the anatase-rutile transformation temperature of nanocrystalline TiO2 synthesised by chemical vapour synthesis.

    Science.gov (United States)

    Ahmad, Md Imteyaz; Bhattacharya, S S; Fasel, Claudia; Hahn, Horst

    2009-09-01

    Of the three crystallographic allotropes of nanocrystalline titania (rutile, anatase and brookite), anatase exhibits the greatest potential for a variety of applications, especially in the area of catalysis and sensors. However, with rutile being thermodynamically the most stable phase, anatase tends to transform into rutile on heating to temperatures in the range of 500 degrees C to 700 degrees C. Efforts made to stabilize the anatase phase at higher temperatures by doping with metal oxides suffer from the problems of having a large amorphous content on synthesis as well as the formation of secondary impurity phases on doping. Recent studies have suggested that the as-synthesised phase composition, crystallite size, initial surface area and processing conditions greatly influence the anatase to rutile transformation temperature. In this study nanocrystalline titania was synthesised in the anatase form bya chemical vapour synthesis (CVS) method using titanium tetra iso-propoxide (TTIP) as a precursor under varying flow rates of oxygen and helium. The anatase to rutile transformation was studied using high temperature X-ray diffraction (HTXRD) and simultaneous thermogravimetric analysis (STA), followed by transmission electron microscopy (TEM). It was demonstrated that the anatase-rutile transformation temperatures were dependent on the oxygen to helium flow rate ratio during CVS and the results are presented and discussed. PMID:19928267

  2. Physical and tribological properties of a-Si1-xCx:H coatings prepared by r.f. plama-assisted chemical vapour deposition

    International Nuclear Information System (INIS)

    A-Si1-xCx:H films deposited by r.f. plasma-assisted chemical vapour deposition were studied as a function of their composition. The friction and wear properties were investigated with the help of a conventional ball-on-disc apparatus. These results are correlated with chemical (Si/C atomic ratio) and structural (Raman and infrared spectroscopy) properties. The friction coefficient in a humid ambient atmosphere changes markedly with the carbon fraction and reaches a value as low as 0.05 for coatings with 70 to 90 at.% C. The carbon-rich films consist of diamond-like carbon with silicon. (orig.)

  3. Modelling and optimization of seawater desalination process using mechanical vapour compression

    Directory of Open Access Journals (Sweden)

    V.P. Kravchenko

    2016-09-01

    Full Text Available In the conditions of global climate changes shortage of fresh water becomes an urgent problem for an increasing number of the countries. One of the most perspective technologies of a desalting of sea water is the mechanical vapour compression (MVC providing low energy consumption due to the principle of a heat pump. Aim: The aim of this research is to identify the reserves of efficiency increasing of the desalination systems based on mechanical vapour compression by optimization of the scheme and parameters of installations with MVC. Materials and Methods: The new type of desalination installation is offered which main element is the heat exchanger of the latent heat. Sea water after preliminary heating in heat exchangers comes to the evaporator-condenser where receives the main amount of heat from the condensed steam. A part of sea water evaporates, and the strong solution of salt (brine goes out of the evaporator, and after cooling is dumped back in the sea. The formed steam is compressed by the compressor and comes to the condenser. An essential singularity of this scheme is that condensation happens at higher temperature, than evaporation. Thanks to this the heat, which is comes out at devaporation, is used for evaporation of sea water. Thereby, in this class of desalination installations the principle of a heat pump is implemented. Results: For achievement of a goal the following tasks were solved: the mathematical model of installations with MVC is modified and supplemented; the scheme of heat exchangers switching is modified; influence of design data of desalination installation on the cost of an inventory and the electric power is investigated. The detailed analysis of the main schemes of installation and mathematical model allowed defining ways of decrease in energy consumption and the possible merit value. Influence of two key parameters - a specific power of the compressor and a specific surface area of the evaporator-condenser - on a

  4. Behaviour of the iron vapour core in the arc of a controlled short-arc GMAW process with different shielding gases

    Science.gov (United States)

    Wilhelm, G.; Kozakov, R.; Gött, G.; Schöpp, H.; Uhrlandt, D.

    2012-02-01

    The controlled metal transfer process (CMT) is a variation of the gas metal arc welding (GMAW) process which periodically varies wire feeding speed. Using a short-arc burning phase to melt the wire tip before the short circuit, heat input to the workpiece is reduced. Using a steel wire and a steel workpiece, iron vapour is produced in the arc, its maximum concentration lying centrally. The interaction of metal vapour and welding gas considerably impacts the arc profile and, consequently, the heat transfer to the weldpool. Optical emission spectroscopy has been applied to determine the radial profiles of the plasma temperature and iron vapour concentration, as well as their temporal behaviour in the arc period for different mixtures of Ar, O2 and CO2 as shielding gases. Both the absolute iron vapour density and the temporal expansion of the iron core differ considerably for the gases Ar + 8%O2, Ar + 18% CO2 and 100% CO2 respectively. Pronounced minimum in the radial temperature profile is found in the arc centre in gas mixtures with high Ar content under the presence of metal vapour. This minimum disappears in pure CO2 gas. Consequently, the temperature and electrical and thermal conductivity in the arc when CO2 is used as a shielding gas are considerably lower.

  5. Effect of surfactants on the morphology of FeSe films fabricated from a single source precursor by aerosol assisted chemical vapour deposition

    Indian Academy of Sciences (India)

    Raja Azadar Hussain; Amin Badshah; Naghma Haider; Malik Dilshad Khan; Bhajan Lal

    2015-03-01

    This article presents the fabrication of FeSe thin films from a single source precursor namely (1-(2-fluorobenzoyl)-3-(4-ferrocenyl-3-methylphenyl)selenourea (MeP2F)) by aerosol assisted chemical vapour deposition (AACVD). All the films were prepared via similar experimental conditions (temperature, flow rate, concentration, solvent system and reactor type) except the use of three different concentrations of two different surfactants i.e., triton and span. Seven thin films were characterized with PXRD, SEM, AFM, EDS and EDS mapping. The mechanism of the interaction of surfactant with MeP2F was determined with cyclic voltammetry (CV) and UV-Vis spectroscopy.

  6. Mechanical alloying and sintering of aluminum reinforced with SiC nanopowders produced by plasma-enhanced chemical-vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Costa, J.; Fort, J.; Roura, P. [GRM, Dept. de Enginyeria Industrial, Universitat de Girona (Spain); Froyen, L. [MTM Katholieke Universiteit Leuven (Belgium); Viera, G.; Bertran, E. [FEMAN, Dept. Fisica Aplicada i Optica, Universitat de Barcelona (Spain)

    2000-07-01

    Nanometric powders of stoichiometric SiC have been synthesised by plasma-enhanced chemical-vapour deposition. These are constituted by amorphous particles with diameters ranging from 10 to 100 nm. Due to their high hydrogen content, a heat treatment at 900 C was needed to prevent spontaneous oxidation. The stabilized SiC powder was mechanically alloyed with aluminum particles of 40 {mu}m in diameter and the alloy was formed by hot isostatic sintering. The SiC content ranged from 0 to 5% in weight. A detailed analysis of the alloyed powder microstructure is presented as well as preliminary results concerning the mechanical properties after sintering. (orig.)

  7. Evolution of Structural Defects in SiOx Films Fabricated by Electron Cyclotron Resonance Plasma Chemical Vapour Deposition upon Annealing Treatment

    Institute of Scientific and Technical Information of China (English)

    HAO Xiao-Peng; WANG Bao-Yi; Yu Run-Sheng; WEI Long; WANG Hui; ZHAO De-Gang; HAO Wei-Chang

    2008-01-01

    @@ We study the structural defects in the SiOx film prepared by electron cyclotron resonance plasma chemical vapour deposition and annealing recovery evolution.The photoluminescence property is observed in the as-deposited and annealed samples.[-SiO3]2- defects are the luminescence centres of the ultraviolet photoluminescence(PL)from the Fourier transform infrared spectroscopy and PL measurements.[-SiO3]2- is observed by positron annihilation spectroscopy,and this defect can make the S parameters increase.After 1000℃ annealing,[-SiO3]2- defects still exist in the films.

  8. The study and the realization of radiation detectors made from polycrystalline diamond films grown by microwave plasma enhanced chemical vapour deposition technique

    International Nuclear Information System (INIS)

    The aim of this work was to develop radiation detectors made from polycrystalline diamond films grown by microwave plasma enhanced chemical vapour deposition technique. The influence of surface treatments, contact technology and diamond growth parameters on the diamond detectors characteristics was investigated in order to optimise the detector response to alpha particles. The first part of the study focused on the electrical behaviour of as-deposited diamond surface, showing a p type conduction and its influence on the leakage current of the device. A surface preparation process was established in order to reduce the leakage current of the device by surface dehydrogenation using an oxidising step. Several methods to form and treat electrical contacts were also investigated showing that the collection efficiency of the device decreases after contact annealing. In the second part, we reported the influence of the diamond deposition parameters on the characteristics of the detectors. The increase of the deposition temperature and/or methane concentration was shown to lead η to decrease. In contrast, η was found to increase with the micro-wave power. The evolution of the diamond detector characteristics results from the variation in sp2 phases incorporation and in the crystallography quality of the films. These defects increase the leakage current and reduce the carrier mobility and lifetime. Measurements carried out on detectors with different thicknesses showed that the physical properties varies along the growth direction, improving with the film thickness. Finally, the addition of nitrogen (> 10 ppm) in the gas mixture during diamond deposition was found to strongly reduce the collection efficiency of the detectors. To conclude the study, we fabricated and characterised diamond devices which were used for thermal neutron detection and for the intensity and shape measurement of VUV and soft X-ray pulses. (author)

  9. Polycyclic organic material (POM) in urban air. Fractionation, chemical analysis and genotoxicity of particulate and vapour phases in an industrial town in Finland

    Science.gov (United States)

    Pyysalo, Heikki; Tuominen, Jari; Wickström, Kim; Skyttä, Eija; Tikkanen, Leena; Salomaa, Sisko; Sorsa, Marja; Nurmela, Tuomo; Mattila, Tiina; Pohjola, Veijo

    Polycyclic organic material (POM) was collected by high-volume sampling on filter and on XAD-2 resin from the air of a small industrial town in Finland. Concurrent chemical analysis and the assays for genotoxic activity were performed on the particulate and the vapour phases of ambient air POM and their chemical fractions. Furthermore, correlations between seasonal meteorological parameters and POM concentrations were studied to reveal characteristic POM profiles for various emission sources. The range of total POM concentrations varied from 115 to 380 ng m -3 in late spring and from 17 to 83 ng m -3 in early winter. No direct correlation of ambient POM was seen with the temperature, but rather with the wind direction from various emission sources. Especially the low molecular weight compounds were associated with wind direction from industrial sources. Genotoxic activity, as detected by the Ames Salmonella/microsome test and the SCE assay in CHO cells, was found not only in the paniculate phase samples but also in the vapour phase. The polar fractions of some of the samples showed genotoxic activity, and also direct mutagenicity was observed with both the assay systems; these facts support the significance of compounds other than conventional polycyclic aromatic hydrocarbons (PAH) in the samples.

  10. Atmospheric pressure chemical vapour deposition of vanadium arsenide thin films via the reaction of VCl4 or VOCl3 with tBuAsH2

    International Nuclear Information System (INIS)

    Thin films of vanadium arsenide were deposited via the dual-source atmospheric pressure chemical vapour deposition reactions of VCl4 or VOCl3 with tBuAsH2. Using the vanadium precursor VCl4, films were deposited at substrate temperatures of 550–600 °C, which were black-gold in appearance and were found to be metal-rich with high levels of chlorine incorporation. The use of VOCl3 as the vanadium source resulted in films being deposited between 450 and 600 °C and, unlike when using VCl4, were silver in appearance. The films deposited using VOCl3 demonstrated vanadium to arsenic ratios close to 1:1, and negligible chlorine incorporation. Films deposited using either vanadium precursor were identified as VAs using powder X-ray diffraction and possessed borderline metallic/semiconductor resistivities. - Highlights: • Formation of VAs films via atmospheric pressure chemical vapour deposition. • Films formed using VCl4 or VOCl3 and tBuAsH2. • Powder X-ray diffraction showed that crystalline VAs films were deposited. • Films from VOCl3 had a V:As ratio close to 1 with negligible Cl incorporation. • Films were silver and possessed borderline metallic/semiconductor resistivities

  11. Solvent purification using a current of water vapour. A continuous process applicable to chemical plants treating irradiated fuels; Purification des solvants par entrainement a la vapeur d'eau. Procede continu applicable aux usines chimiques de traitement des combustibles irradies

    Energy Technology Data Exchange (ETDEWEB)

    Auchapt, P.R.; Sautray, R.R.; Girard, B.R. [Commissariat a l' Energie Atomique, Centre de Production de Plutonium, Marcoule (France). Centre d' Etudes Nucleaires

    1964-07-01

    The pilot plant described in this report is intended for the continuous purification of the solvent used in the plutonium extraction plant at Marcoule, by separating the impurities (fission products). This physical separation is operated by carrying over in a water vapour stream. The contaminating products, only slightly volatile, remain in the form of the droplets and are separated; the vaporised solvent and the water vapour used are condensed and then separated. The originality of the installation resides in the system for pulverising the liquid and in the operating conditions: low working pressure and temperature. The systematic analysis of the various parameters (percentage of residue; flow, pressure and temperature ratios etc...) has shown their influence on the decontamination. The activity due to the zirconium-niobium is undetectable after treatment, and it is easy to obtain decontamination factors of 300 for the ruthenium. The, presence of uranium is favorable for the decontamination. As a conclusion, some extra-technical considerations are given concerning in particular the approximate cost price of the treated solvent per litre. (authors) [French] L'installation pilote decrite dans ce rapport est destinee a purifier, en continu, le solvant utilise a l'usine d'extraction du plutonium de Marcoule, en separant les impuretes (produits de fission). Cette separation physique est realisee par entrainement a la vapeur d'eau. Les produits contaminants, peu volatils, restant sous forme de gouttelettes, sont separes; le solvant vaporise ainsi que la vapeur d'entrainement sont condenses puis separes. L'originalite de l'installation reside dans le systeme de pulverisation du liquide et dans les conditions operatoires: faible pression et basse temperature de fonctionnement. L'analyse systematique des differents parametres (pourcentage de residus, rapport de debits, pression et temperature, etc...) a mis en evidence leur influence

  12. Vapour Treatment Method Against Other Pyro- and Hydrometallurgical Processes Applied to Recover Platinum From Used Auto Catalytic Converters

    Institute of Scientific and Technical Information of China (English)

    Agnieszka FORNALCZYK; Mariola SATERNUS

    2013-01-01

    Today more and more cars are produced every year.All of them have to be equipped with catalytic converters,the main role of which is to obtain substances harmless to the environment instead of exhausted gases.Catalytic converters contain platinum group metals (PGM) especially platinum,palladium and rhodium.The price of these metals and their increasing demand are the reasons why today it is necessary to recycle used auto catalytic converters.There are many available methods of recovering PGM metals from them,especially platinum.These methods used mainly hydrometallurgical processes; however pyrometallurgical ones become more and more popular.The article presents results of the research mainly concerning pyrometallurgical processes.Two groups of research were carried out.In the first one different metals such as lead,magnesium and copper were used as a metal collector.During the tests,platinum went to those metals forming an alloy.In other research metal vapours were blown through catalytic converter carrier (grinded or whole).In the tests metals such as calcium,magnesium,cadmium and zinc were applied.As a result white or grey powder (metal plus platinum) was obtained.The tables present results of the research.Processing parameters and conclusions are also shown.To compare efficiency of pyrometallurgical and hydrometallurgical methods catalytic converter carrier and samples of copper with platinum obtained from pyrometallurgical method were solved in aqua regia,mixture of aqua regia and fluoric acid.

  13. Room-Temperature Ferromagnetism of Ga1-xMnxN Grown by Low-Pressure Metalorganic Chemical Vapour Deposition

    Institute of Scientific and Technical Information of China (English)

    CHEN Zhi-Tao; ZHANG Guo-Yi; SU Yue-Yong; YANG Zhi-Jian; ZHANG Yan; ZHANG Bin; GUO Li-Ping; XU Ke; PAN Yao-Bao; ZHANG Han

    2006-01-01

    @@ Epitaxial films of Ga1-xMnxN have been grown on c-sapphire substrates by low-pressure metal-organic vapour phase epitaxy. The samples show ferromagnetic behaviour up to a temperature of T = 380 K with hysteresis curves showing a coercivity of 50-100Oe. No ferromagnetic second phases and no significant deterioration in crystal quality with the incorporation of Mn can be detected by high-resolution x-ray diffraction. The result of x-ray absorption near-edge structures indicates that Mn atoms substitute for Ga atoms. The Mn concentrations of the layers are determined to reach x = 0.038 by proton-induced x-ray emission.

  14. Characterization of thin TiO{sub 2} films prepared by plasma enhanced chemical vapour deposition for optical and photocatalytic applications

    Energy Technology Data Exchange (ETDEWEB)

    Sobczyk-Guzenda, A., E-mail: asobczyk@p.lodz.p [Institute of Materials Science and Engineering, Technical University of Lodz, Stefanowskiego 1, 90-924 Lodz (Poland); Gazicki-Lipman, M.; Szymanowski, H.; Kowalski, J. [Institute of Materials Science and Engineering, Technical University of Lodz, Stefanowskiego 1, 90-924 Lodz (Poland); Wojciechowski, P.; Halamus, T. [Department of Molecular Physics, Technical University of Lodz, Stefanowskiego 1, 90-924 Lodz (Poland); Tracz, A. [Centre for Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363 Lodz (Poland)

    2009-07-31

    Thin titanium oxide films were deposited using a radio frequency (RF) plasma enhanced chemical vapour deposition method. Their optical properties and thickness were determined by means of ultraviolet-visible absorption spectrophotometry. Films of the optical parameters very close to those of titanium dioxide have been obtained at the high RF power input. Their optical quality is high enough to allow for their use in a construction of stack interference optical filters. At the same time, these materials exhibit strong photocatalytic effects. The results of structural analysis, carried out by Raman Shift Spectroscopy, show that the coatings posses amorphous structure. However, Raman spectra of the same films subjected to thermal annealing at 450 {sup o}C disclose an appearance of a crystalline form, namely that of anatase. Surface morphology of the films has also been characterized by Atomic Force Microscopy revealing granular, broccoli-like topography of the films.

  15. Thin films of tin(II) sulphide (SnS) by aerosol-assisted chemical vapour deposition (AACVD) using tin(II) dithiocarbamates as single-source precursors

    Science.gov (United States)

    Kevin, Punarja; Lewis, David J.; Raftery, James; Azad Malik, M.; O'Brien, Paul

    2015-04-01

    The synthesis of the asymmetric dithiocarbamates of tin(II) with the formula [Sn(S2CNRR')2] (where R=Et, R'=n-Bu (1); R=Me, R'=n-Bu (2); R=R'=Et (3)) and their use for the deposition of SnS thin films by aerosol-assisted chemical vapour deposition (AACVD) is described. The effects of temperature and the concentration of the precursors on deposition were investigated. The stoichiometry of SnS was best at higher concentrations of precursors (250 mM) and at 450 °C. The direct electronic band gap of the SnS produced by this method was estimated from optical absorbance measurements as 1.2 eV. The composition of films was confirmed by powder X-ray diffraction (p-XRD) and energy dispersive analysis of X-rays (EDAX) spectroscopy.

  16. An investigation into the optimum thickness of titanium dioxide thin films synthesized by using atmospheric pressure chemical vapour deposition for use in photocatalytic water oxidation.

    Science.gov (United States)

    Hyett, Geoffrey; Darr, Jawwad A; Mills, Andrew; Parkin, Ivan P

    2010-09-10

    Twenty eight films of titanium dioxide of varying thickness were synthesised by using atmospheric pressure chemical vapour deposition (CVD) of titanium(IV) chloride and ethyl acetate onto glass and titanium substrates. Fixed reaction conditions at a substrate temperature of 660 °C were used for all depositions, with varying deposition times of 5-60 seconds used to control the thickness of the samples. A sacrificial electron acceptor system composed of alkaline sodium persulfate was used to determine the rate at which these films could photo-oxidise water in the presence of 365 nm light. The results of this work showed that the optimum thickness for CVD films on titanium substrates for the purposes of water oxidation was ≈200 nm, and that a platinum coating on the reverse of such samples leads to a five-fold increase in the observed rate of water oxidation. PMID:20645333

  17. Preparation of high-quality hydrogenated amorphous silicon film with a new microwave electron cyclotron resonance chemical vapour deposition system assisted with hot wire

    Institute of Scientific and Technical Information of China (English)

    Zhu Xiu-Hong; Chen Guang-Hua; Yin Sheng-Yi; Rong Yan-Dong; Zhang Wen-Li; Hu Yue-Hui

    2005-01-01

    The preparation of high-quality hydrogenated amorphous silicon (a-Si:H) film with a new microwave electron cyclotron resonance-chemical vapour deposition (MWECR-CVD) system assisted with hot wire is presented. In this system the hot wire plays an important role in perfecting the microstructure as well as improving the stability and the optoelectronic properties of the a-Si:H film. The experimental results indicate that in the microstructure of the a-Si:H film, the concentration of dihydride is decreased and a trace of microcrystalline occurs, which is useful to improve its stability, and that in the optoelectronic properties of the a-Si:H film, the deposition rate reaches above 2.0nm/s and the photosensitivity increases up to 4.71× 105.

  18. Growth of MgB2 Thin Films by Chemical Vapour Deposition Using B2H6 as a boron Source

    Institute of Scientific and Technical Information of China (English)

    王淑芳; 朱亚彬; 刘震; 周岳亮; 张芹; 陈正豪; 吕惠宾; 杨国桢

    2003-01-01

    Superconducting MgB2 thin films were grown on single crystal Al2O3 (0001) by chemical vapour deposition using B2H6 as a boron source. MgB2 film was then accomplished by annealing the boron precursor films in the presence of high-purity magnesium bulk at 890℃ in vacuum. The as-grown MgB2 films are smooth and c-axis-oriented.The films exhibit a zero-resistance transition of about 38K with a narrow transition width of 0.2 K. Magnetic hysteresis measurements yield the critical current density of 1.9 × 107 A/cm2 at 10 K in zero field.

  19. Influence of double AlN buffer layers on the qualities of GaN films prepared by metal-organic chemical vapour deposition

    Institute of Scientific and Technical Information of China (English)

    Lin Zhi-Yu; Hao Yue; Zhang Jin-Cheng; Zhou Hao; Li Xiao-Gang; Meng Fan-Na; Zhang Lin-Xia; Ai Shan; Xu Sheng-Rui; Zhao Yi

    2012-01-01

    In this paper we report that the GaN thin film is grown by metal-organic chemical vapour deposition on a sapphire (0001) substrate with double AlN buffer layers.The buffer layer consists of a low-temperature (LT) AlN layer and a high-temperature (HT) AlN layer that are grown at 600 ℃ and 1000 ℃,respectively.It is observed that the thickness of the LT-AlN layer drastically influences the quality of GaN thin film,and that the optimized 4.25-min-LT-AlN layer minimizes the dislocation density of GaN thin film.The reason for the improved properties is discussed in this paper.

  20. Ellipsometric and Rutherford Back scattering Spectrometry studies of SiO(X)N(Y) films elaborated by plasma-enhanced chemical vapour deposition technique.

    Science.gov (United States)

    Mahamdi, R; Boulesbaa, M; Saci, L; Mansour, F; Molliet, C; Collet, M; Temple-Boyer, P

    2011-10-01

    Silicon oxynitride (SiO(X)N(Y)) thin films were deposited by plasma-enhanced chemical vapour deposition technique (PECVD) from silane (SiH4), nitrous oxide (N2O), ammonia (NH3) and nitrogen (N2) mixture. Spectroscopic ellipsometry (SE), in the range of wavelengths 450-900 nm, was used to define the film thickness and therefore the deposition rate, as well as the refractive index as a function of the N2O gaseous flow. While considering the (Si3N4, SiO2, H2 or void) heterogeneous mixture, Maxwell Garnett (MG) theory allows to fit the SE measurements and to define the volume fraction of the different phases. Finally, Rutherford Backscattering Spectrometry (RBS) results showed that x = O/Si ratio increases gradually with increasing the N2O flow, allowing the correlation of the SiO(X)N(Y) films main parameters. PMID:22400311

  1. Effect of Al Doping in the InGaN/GaN Multiple Quantum Well Light Emitting Diodes Grown by Metalorganic Chemical Vapour Deposition

    Institute of Scientific and Technical Information of China (English)

    LU Yu; YANG Zhi-Jian; PAN Yao-Bo; XU Ke; HU Xiao-Dong; ZHANG Bei; ZHANG Guo-Yi

    2006-01-01

    The effect of Al doping in the GaN layer of InGaN/GaN multiple quantum-well light emitting diodes (LEDs) grown by metalorganic chemical vapour deposition is investigated by using photoluminescence (PL) and high-resolution x-ray diffraction. The full width at half maximum of PL of Al doped LEDs is measured to be about 12nm. The band edge photoluminescence emission intensity is enhanced significantly. In addition, the in-plane compressive strain in the Al-doped LEDs is improved significantly and measured by reciprocal space map. The output power of Al-doped LEDs is 130mW in the case of the induced current of 200mA.

  2. The physics of plasma-enhanced chemical vapour deposition for large-area coating: industrial application to flat panel displays and solar cells

    International Nuclear Information System (INIS)

    Designing plasma-enhanced chemical vapour deposition (PECVD) reactors to coat large-area glass plates (∼1 m2) for flat panel display or solar cell manufacturing raises challenging issues in physics and chemistry as well as mechanical, thermal, and electrical engineering, and material science. In such reactive glow discharge plasma slabs, excited at RF frequency (from 13.56 MHz up to ∼100 MHz), the thin-film deposition uniformity is determined by the gas flow distribution, as well as the RF voltage distribution along the electrodes, and by local plasma perturbations at the reactor boundaries. All these aspects can be approached by analytical and numerical modelling. Moreover, the film properties are largely determined by the plasma chemistry involving the neutral radicals contributing to film growth, the effect of ion bombardment, and the formation and trapping of dust triggered by homogeneous nucleation. This paper will review progress in this field, with particular emphasis on modelling developments. (author)

  3. Vapour-liquid equilibrium in the monoethylene glycol - methane system at elevated pressures

    OpenAIRE

    Bersås, Anita

    2012-01-01

    A range of different chemicals are used in natural gas processing. The systems operate in closed loops, but a small amount of the chemicals are lost due to the solubility of the chemical in the gas phase. This leads to increased operational costs, it may cause HSE related problems, and it can lead to operational difficulties and contamination of downstream processes and products. A limited number of vapour-liquid equilibrium, VLE, data for processing chemicals in methane are available in...

  4. Determination and characterization of phytochelatins by liquid chromatography coupled with on line chemical vapour generation and atomic fluorescence spectrometric detection.

    Science.gov (United States)

    Bramanti, Emilia; Toncelli, Daniel; Morelli, Elisabetta; Lampugnani, Leonardo; Zamboni, Roberto; Miller, Keith E; Zemetra, Joseph; D'Ulivo, Alessandro

    2006-11-10

    Liquid chromatography (LC) coupled on line with UV/visible diode array detector (DAD) and cold vapour generation atomic fluorescence spectrometry (CVGAFS) has been developed for the speciation, determination and characterization of phytochelatins (PCs). The method is based on a bidimensional approach, e.g. on the analysis of synthetic PC solutions (apo-PCs and Cd(2+)-complexed PCs) (i) by size exclusion chromatography coupled to UV diode array detector (SEC-DAD); (ii) by the derivatization of PC -SH groups in SEC fractions by p-hydroxymercurybenzoate (PHMB) and the indirect detection of PC-PHMB complexes by reversed phase liquid chromatography coupled to atomic fluorescence detector (RPLC-CVGAFS). MALDI-TOF/MS (matrix assisted laser desorption ionization time of flight mass spectrometry) analysis of underivatized synthetic PC samples was performed in order have a qualitative information of their composition. Quantitative analysis of synthetic PC solutions has been performed on the basis of peak area of PC-PHMB complexes of the mercury specific chromatogram and calibration curve of standard solution of glutathione (GSH) complexed to PHMB (GS-PHMB). The limit of quantitation (LOQ) in terms of GS-PHMB complex was 90 nM (CV 5%) with an injection volume of 35 microL, corresponding to 3.2 pmol (0.97 ng) of GSH. The method has been applied to analysis of extracts of cell cultures from Phaeodactylum tricornutum grown in Cd-containing nutrient solutions, analysed by SEC-DAD-CVGAFS and RPLC-DAD-CVGAFS.

  5. Idaho Chemical Processing Plant Process Efficiency improvements

    Energy Technology Data Exchange (ETDEWEB)

    Griebenow, B.

    1996-03-01

    In response to decreasing funding levels available to support activities at the Idaho Chemical Processing Plant (ICPP) and a desire to be cost competitive, the Department of Energy Idaho Operations Office (DOE-ID) and Lockheed Idaho Technologies Company have increased their emphasis on cost-saving measures. The ICPP Effectiveness Improvement Initiative involves many activities to improve cost effectiveness and competitiveness. This report documents the methodology and results of one of those cost cutting measures, the Process Efficiency Improvement Activity. The Process Efficiency Improvement Activity performed a systematic review of major work processes at the ICPP to increase productivity and to identify nonvalue-added requirements. A two-phase approach was selected for the activity to allow for near-term implementation of relatively easy process modifications in the first phase while obtaining long-term continuous improvement in the second phase and beyond. Phase I of the initiative included a concentrated review of processes that had a high potential for cost savings with the intent of realizing savings in Fiscal Year 1996 (FY-96.) Phase II consists of implementing long-term strategies too complex for Phase I implementation and evaluation of processes not targeted for Phase I review. The Phase II effort is targeted for realizing cost savings in FY-97 and beyond.

  6. Idaho Chemical Processing Plant Process Efficiency improvements

    International Nuclear Information System (INIS)

    In response to decreasing funding levels available to support activities at the Idaho Chemical Processing Plant (ICPP) and a desire to be cost competitive, the Department of Energy Idaho Operations Office (DOE-ID) and Lockheed Idaho Technologies Company have increased their emphasis on cost-saving measures. The ICPP Effectiveness Improvement Initiative involves many activities to improve cost effectiveness and competitiveness. This report documents the methodology and results of one of those cost cutting measures, the Process Efficiency Improvement Activity. The Process Efficiency Improvement Activity performed a systematic review of major work processes at the ICPP to increase productivity and to identify nonvalue-added requirements. A two-phase approach was selected for the activity to allow for near-term implementation of relatively easy process modifications in the first phase while obtaining long-term continuous improvement in the second phase and beyond. Phase I of the initiative included a concentrated review of processes that had a high potential for cost savings with the intent of realizing savings in Fiscal Year 1996 (FY-96.) Phase II consists of implementing long-term strategies too complex for Phase I implementation and evaluation of processes not targeted for Phase I review. The Phase II effort is targeted for realizing cost savings in FY-97 and beyond

  7. Surface transformations of carbon (graphene, graphite, diamond, carbide), deposited on polycrystalline nickel by hot filaments chemical vapour deposition

    International Nuclear Information System (INIS)

    The deposition of carbon has been studied at high temperature on polycrystalline nickel by hot filaments activated chemical vapor deposition (HFCVD). The sequences of carbon deposition are studied by surface analyses: Auger electron spectroscopy (AES), electron loss spectroscopy (ELS), X-ray photoelectron spectroscopy (XPS) in a chamber directly connected to the growth chamber. A general scale law of the (C/Ni) intensity lines is obtained with a reduced time. Both, shape analysis of the AES C KVV line and the C1s relative intensity suggest a three-step process: first formation of graphene and a highly graphitic layer, then multiphase formation with graphitic, carbidic and diamond-like carbon and finally at a critical temperature that strongly depends on the pretreatment of the polycrystalline nickel surface, a rapid transition to diamond island formation. Whatever the substrate diamond is always the final product and some graphene layers the initial product. Moreover it is possible to stabilize a few graphene layers at the initial sequences of carbon deposition. The duration of this stabilization step is strongly depending however on the pre-treatment of the Ni surface.

  8. Personal Simulator of Chemical Process

    Institute of Scientific and Technical Information of China (English)

    吴重光

    2002-01-01

    The Personal Simulator of chemical process (PS) means that fully simulationsoftware can be run on one personal computer. This paper describes the kinds of PSprograms, its features, the graphic functions and three examples. PS programs are allbased on one object-oriented and real-time simulation software environment. Authordevelops this simulation software environment. An example of the batch reaction kineticsmodel is also described. Up to now a lot of students in technical schools and universitieshave trained on PS. The training results are very successful.

  9. Evaluation of water vapour assimilation in the tropical upper troposphere and lower stratosphere by a chemical transport model

    Science.gov (United States)

    Payra, Swagata; Ricaud, Philippe; Abida, Rachid; El Amraoui, Laaziz; Attié, Jean-Luc; Rivière, Emmanuel; Carminati, Fabien; von Clarmann, Thomas

    2016-09-01

    The present analysis deals with one of the most debated aspects of the studies on the upper troposphere/lower stratosphere (UTLS), namely the budget of water vapour (H2O) at the tropical tropopause. Within the French project "Multiscale water budget in the upper troposphere and lower stratosphere in the TROpics" (TRO-pico), a global-scale analysis has been set up based on space-borne observations, models and assimilation techniques. The MOCAGE-VALENTINA assimilation tool has been used to assimilate the Aura Microwave Limb Sounder (MLS) version 3.3 H2O measurements within the 316-5 hPa range from August 2011 to March 2013 with an assimilation window of 1 h. Diagnostics based on observations minus analysis and forecast are developed to assess the quality of the assimilated H2O fields. Comparison with an independent source of H2O measurements in the UTLS based on the space-borne Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) observations and with meteorological ARPEGE analyses is also shown. Sensitivity studies of the analysed fields have been performed by (1) considering periods when no MLS measurements are available and (2) using H2O data from another MLS version (4.2). The studies have been performed within three different spaces in time and space coincidences with MLS (hereafter referred to as MLS space) and MIPAS (MIPAS space) observations and with the model (model space) outputs and at three different levels: 121 hPa (upper troposphere), 100 hPa (tropopause) and 68 hPa (lower stratosphere) in January and February 2012. In the MLS space, the analyses behave consistently with the MLS observations from the upper troposphere to the lower stratosphere. In the model space, the analyses are wetter than the reference atmosphere as represented by ARPEGE and MLS in the upper troposphere (121 hPa) and around the tropopause (100 hPa), but are consistent with MLS and MIPAS in the lower stratosphere (68 hPa). In the MIPAS space, the sensitivity and the

  10. Optical and passivating properties of hydrogenated amorphous silicon nitride deposited by plasma enhanced chemical vapour deposition for application on silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wight, Daniel Nilsen

    2008-07-01

    Within this thesis, several important subjects related to the use of amorphous silicon nitride made by plasma enhanced chemical vapour deposition as an anti-reflective coating on silicon solar cells are presented. The first part of the thesis covers optical simulations to optimise single and double layer anti-reflective coatings with respect to optical performance when situated on a silicon solar cell. The second part investigates the relationship between important physical properties of silicon nitride films when deposited under different conditions. The optical simulations were either based on minimising the reflectance off a silicon nitride/silicon wafer stack or maximising the transmittance through the silicon nitride into the silicon wafer. The former method allowed consideration of the reflectance off the back surface of the wafer, which occurs typically at wavelengths above 1000 nm due to the transparency of silicon at these wavelengths. However, this method does not take into consideration the absorption occurring in the silicon nitride, which is negligible at low refractive indexes but quite significant when the refractive index increases above 2.1. For high-index silicon nitride films, the latter method is more accurate as it considers both reflectance and absorbance in the film to calculate the transmittance into the Si wafer. Both methods reach similar values for film thickness and refractive index for optimised single layer anti-reflective coatings, due to the negligible absorption occurring in these films. For double layer coatings, though, the reflectance based simulations overestimated the optimum refractive index for the bottom layer, which would have lead to excessive absorption if applied to real anti-reflective coatings. The experimental study on physical properties for silicon nitride films deposited under varying conditions concentrated on the estimation of properties important for its applications, such as optical properties, passivation

  11. ZT thin films produced by metal organic-chemical vapour deposition to be used as high-k dielectrics

    International Nuclear Information System (INIS)

    In this work the synthesis and characterisation of ZrxTi1-xO2 (ZT) grown via a non conventional MOCVD apparatus on both silicon and platinum coated substrates are described. The samples have been chemically, morphologically and structurally characterised by AFM, XRD, SEM + FEG and XPS. Also high and low frequencies electrical characterisation has been performed to evaluate a possible application of such materials as high-k dielectrics

  12. Hydrogen production by ethanol partial oxidation over nano-iron oxide catalysts produced by chemical vapour synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Wael Ahmed Abou Taleb Sayed

    2011-01-13

    This work presents the experimental results of the synthesis of unsupported and supported SiC iron oxide nanoparticles and their catalytic activity towards ethanol partial oxidation. For comparison, further unsupported iron oxide phases were investigated towards the ethanol partial oxidation. These {gamma}-Fe{sub 2}O{sub 3} and {alpha}/{gamma}-Fe{sub 2}O{sub 3} phase catalysts were prepared by the CVS method using Fe(CO){sub 5} as precursor, supplied by another author. The {alpha}-Fe{sub 2}O{sub 3} and SiC nanoparticles were prepared by the CVS method using a home made hot wall reactor technique at atmospheric pressure. Ferrocene and tetramethylsilane were used as precursor for the production process. Process parameters of precursor evaporation temperature, precursor concentration, gas mixture velocity and gas mixture dilution were investigated and optimised to produce particle sizes in a range of 10 nm. For Fe{sub 2}O{sub 3}/SiC catalyst series production, a new hot wall reactor setup was used. The particles were produced by simultaneous thermal decomposition of ferrocene and tetramethylsilane in one reactor from both sides. The production parameters of inlet tube distance inside the reactor, precursor evaporation temperature and carrier gas flow were investigated to produce a series of samples with different iron oxide content. The prepared catalysts composition, physical and chemical properties were characterized by XRD, EDX, SEM, BET surface area, FTIR, XPS and dynamic light scattering (DLS) techniques. The catalytic activity for the ethanol gas-phase oxidation was investigated in a temperature range from 260 C to 290 C. The product distributions obtained over all catalysts were analysed with mass spectrometry analysis tool. The activity of bulk Fe{sub 2}O{sub 3} and SiC nanoparticles was compared with prepared nano-iron oxide phase catalysts. The reaction parameters, such as reaction temperature and O{sub 2}/ethanol ratio were investigated. The catalysts

  13. Effect of Postdeposition Heat Treatment on the Crystallinity, Size, and Photocatalytic Activity of TiO2 Nanoparticles Produced via Chemical Vapour Deposition

    Directory of Open Access Journals (Sweden)

    Siti Hajar Othman

    2010-01-01

    Full Text Available Titanium dioxide (TiO2 nanoparticles were produced using chemical vapour deposition (CVD at different deposition temperatures (300–700°C. All the samples were heat treated at their respective deposition temperatures and at a fixed temperature of 400°C. A scanning electron microscope (SEM, a transmission electron microscope (TEM, and X-ray diffraction (XRD were used to characterize the nanoparticles in terms of size and crystallinity. The photocatalytic activity was investigated via degradation of methylene blue under UV light. The effects of post deposition heat treatment are discussed in terms of crystallinity, nanoparticle size as well as photocatalytic activity. Crystallinity was found to have a much larger impact on photocatalytic activity compared to nanoparticle size. Samples having a higher degree of crystallinity were more photocatalytically active despite being relatively larger in size. Surprisingly, the photocatalytic activity of the samples reduced when heat treated at temperatures lower than the deposition temperature despite showing an improvement in crystallinity.

  14. Growth and characterization of germanium epitaxial film on silicon (001 with germane precursor in metal organic chemical vapour deposition (MOCVD chamber

    Directory of Open Access Journals (Sweden)

    Kwang Hong Lee

    2013-09-01

    Full Text Available The quality of germanium (Ge epitaxial film grown directly on a silicon (Si (001 substrate with 6° off-cut using conventional germane precursor in a metal organic chemical vapour deposition (MOCVD system is studied. The growth sequence consists of several steps at low temperature (LT at 400 °C, intermediate temperature ramp (LT-HT of ∼10 °C/min and high temperature (HT at 600 °C. This is followed by post-growth annealing in hydrogen at temperature ranging from 650 to 825 °C. The Ge epitaxial film of thickness ∼ 1 μm experiences thermally induced tensile strain of 0.11 % with a treading dislocation density (TDD of ∼107/cm2 and the root-mean-square (RMS roughness of ∼ 0.75 nm. The benefit of growing Ge epitaxial film using MOCVD is that the subsequent III-V materials can be grown in-situ without the need of breaking the vacuum hence it is manufacturing worthy.

  15. Polyethylene Oxide Films Polymerized by Radio Frequency Plasma-Enhanced Chemical Vapour Phase Deposition and Its Adsorption Behaviour of Platelet-Rich Plasma

    Institute of Scientific and Technical Information of China (English)

    HU Wen-Juan; XIE Fen-Yan; CHEN Qiang; WENG Jing

    2008-01-01

    We present polyethylene oxide (PEO) functional films polymerized by rf plasma-enhanced vapour chemical deposition (rf-PECVD) on p-Si (100) surface with precursor ethylene glycol dimethyl ether (EGDME) and diluted Ar in pulsed plasma mode. The influences of discharge parameters on the film properties and compounds are investigated. The film structure is analysed by Fourier transform infrared (FTIR) spectroscopy. The water contact angle measurement and atomic force microscope (AFM) are employed to examine the surface polarity and to detect surface morphology, respectively. It is concluded that the smaller duty cycle in pulsed plasma mode contributes to the rich C-O-C (EO) group on the surfaces. As an application, the adsorption behaviour of platelet-rich plasma on plasma polymerization films performed in-vitro is explored. The shapes of attached cells are studied in detail by an optic invert microscope, which clarifies that high-density C-O-C groups on surfaces are responsible for non-fouling adsorption behaviour of the PEO films.

  16. Pengaruh Temperatur, Massa Zink, Substrat Dan Waktu Tahan Terhadap Struktur Dan Morfologi Zno Hasil Sintesis Dengan Metode Chemical Vapour Transport (CVT

    Directory of Open Access Journals (Sweden)

    Arisela Distyawan

    2013-09-01

    Full Text Available Normal 0 false false false MicrosoftInternetExplorer4 Material Zink Oksida (ZnO telah berhasil disintesis menggunakan metode Chemical Vapour Transport dengan bahan dasar prekursor berupa serbuk Zn yang dipanaskan hingga mencapai temperatur uap dalam furnace horisontal. Adapun variasi yang diberikan dalam penelitian adalah berupa temperatur pemanasan (850, 900, dan 950oC, massa prekursor Zn (0,15, 0,25, dan 0,35g, lama waktu sputtering substrat (90 dan 180 detik, dan waktu tahan khusus untuk mengetahui initial growth ZnO (10, 20, 30, 40, 50, dan 60 menit. Pembentukan Zink Oksida (ZnO dikonfirmasi melalui data X-RD, dimana telah terbentuk material ZnO dengan struktur hexagonal wurtzite. Berdarsarkan data XRD juga diketahui ukuran kristal pada sampel sputtering 90 detik mengalami penurunan bersamaan penambahan massa Zn. Dari hasil pengamatan SEM didapatkan bahwa morfologi permukaan lapisan tipis ZnO terdiri dari berbagai macam bentuk berupa nanoparticle, nanowires, nanorods, dan nanotetrapod. Lapisan Zno paling tebal sebesar ±350 nm pada sampel 950oC-0,15g sputter 90 detik. Semakin tinggi temperatur operasi berdampak peningkatan ukuran partikel. Pengujian FTIR turut menguatkan terbentuknya lapisan tipis di permukaan substrat Alumina. Hal ini didasarkan terjadinya penyerapan vibrasi yang membentuk lekukan pada kisaran area 509 cm-1 dari masing-masing sampel.

  17. A chemical assessment of the suitability of allyl- iso-propyltelluride as a Te precursor for metal organic vapour phase epitaxy

    Science.gov (United States)

    Hails, Janet E.; Cole-Hamilton, David J.; Stevenson, John; Bell, William; Foster, Douglas F.; Ellis, David

    2001-04-01

    The chemical studies, which led to the testing of allyl- iso-propyltelluride (allylTePr i) as a Te precursor in metal organic vapour phase epitaxy are presented. The pyrolysis in hydrogen of allylTePr i gave products including 1,5-hexadiene, propane and propene. Co-pyrolysis of dimethylcadmium (Me 2Cd) and allylTePr i gave the hydrocarbons expected from the pyrolysis of the individual precursors plus additional hydrocarbons including 2-methylpropane and 1-butene. Plots of percentage decomposition versus temperature, which proved extremely useful in determining the likely growth temperatures for both CdTe and HgTe, showed that allylTePr i is less stable than both Pr 2iTe (di- iso-propyltelluride) and Me 2Cd. The possible role of Hg in the growth of CdTe is also discussed. The chemistry of allylTePr i is well suited for use as an efficient precursor for epitaxial growth of tellurium containing semiconductors since there is very little formation of other organotellurium compounds on pyrolysis.

  18. Structural and optical investigation of nonpolar a-plane GaN grown by metal-organic chemical vapour deposition on r-plane sapphire by neutron irradiation

    Institute of Scientific and Technical Information of China (English)

    Xu Sheng-Rui; Zhang Jin-Feng; Gu Wen-Ping; Hao Yue; Zhang Jin-Cheng; Zhou Xiao-Wei; Lin Zhi-Yu; Mao Wei

    2012-01-01

    Nonpolar (11(2)0) a-plane GaN films are grown by metal-organic chemical vapour deposition (MOCVD) on r-plane (1(1)02) sapphire.The samples are irradiated with neutrons under a dose of 1 × 1015 cm-2.The surface morphology,the crystal defects and the optical properties of the samples before and after irradiation are analysed using atomic force microscopy (AFM),high resolution X-ray diffraction (HRXRD) and photoluminescence (PL).The AFM result shows deteriorated sample surface after the irradiation.Careful fitting of the XRD rocking curve is carried out to obtain the Lorentzian weight fraction.Broadening due to Lorentzian type is more obvious in the as-grown sample compared with that of the irradiated sample,indicating that more point defects appear in the irradiated sample.The variations of line width and intensity of the PL band edge emission peak are consistent with the XRD results.The activation energy decreases from 82.5 meV to 29.9 meV after irradiation by neutron.

  19. Effect of oxygen plasma on field emission characteristics of single-wall carbon nanotubes grown by plasma enhanced chemical vapour deposition system

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Avshish; Parveen, Shama; Husain, Samina; Ali, Javid; Zulfequar, Mohammad [Department of Physics, Jamia Millia Islamia (A Central University), New Delhi 110025 (India); Harsh [Centre for Nanoscience and Nanotechnology, Jamia Millia Islamia, New Delhi 110025 (India); Husain, Mushahid, E-mail: mush-reslab@rediffmail.com [Department of Physics, Jamia Millia Islamia (A Central University), New Delhi 110025 (India); Centre for Nanoscience and Nanotechnology, Jamia Millia Islamia, New Delhi 110025 (India)

    2014-02-28

    Field emission properties of single wall carbon nanotubes (SWCNTs) grown on iron catalyst film by plasma enhanced chemical vapour deposition system were studied in diode configuration. The results were analysed in the framework of Fowler-Nordheim theory. The grown SWCNTs were found to be excellent field emitters, having emission current density higher than 20 mA/cm{sup 2} at a turn-on field of 1.3 V/μm. The as grown SWCNTs were further treated with Oxygen (O{sub 2}) plasma for 5 min and again field emission characteristics were measured. The O{sub 2} plasma treated SWCNTs have shown dramatic improvement in their field emission properties with emission current density of 111 mA/cm{sup 2} at a much lower turn on field of 0.8 V/μm. The as grown as well as plasma treated SWCNTs were also characterized by various techniques, such as scanning electron microscopy, high resolution transmission electron microscopy, Raman spectroscopy, and Fourier transform infrared spectroscopy before and after O{sub 2} plasma treatment and the findings are being reported in this paper.

  20. Effect of oxygen plasma on field emission characteristics of single-wall carbon nanotubes grown by plasma enhanced chemical vapour deposition system

    Science.gov (United States)

    Kumar, Avshish; Parveen, Shama; Husain, Samina; Ali, Javid; Zulfequar, Mohammad; Harsh; Husain, Mushahid

    2014-02-01

    Field emission properties of single wall carbon nanotubes (SWCNTs) grown on iron catalyst film by plasma enhanced chemical vapour deposition system were studied in diode configuration. The results were analysed in the framework of Fowler-Nordheim theory. The grown SWCNTs were found to be excellent field emitters, having emission current density higher than 20 mA/cm2 at a turn-on field of 1.3 V/μm. The as grown SWCNTs were further treated with Oxygen (O2) plasma for 5 min and again field emission characteristics were measured. The O2 plasma treated SWCNTs have shown dramatic improvement in their field emission properties with emission current density of 111 mA/cm2 at a much lower turn on field of 0.8 V/μm. The as grown as well as plasma treated SWCNTs were also characterized by various techniques, such as scanning electron microscopy, high resolution transmission electron microscopy, Raman spectroscopy, and Fourier transform infrared spectroscopy before and after O2 plasma treatment and the findings are being reported in this paper.

  1. Effects of Surface Modification of Nanodiamond Particles for Nucleation Enhancement during Its Film Growth by Microwave Plasma Jet Chemical Vapour Deposition Technique

    Directory of Open Access Journals (Sweden)

    Chii-Ruey Lin

    2014-01-01

    Full Text Available The seedings of the substrate with a suspension of nanodiamond particles (NDPs were widely used as nucleation seeds to enhance the growth of nanostructured diamond films. The formation of agglomerates in the suspension of NDPs, however, may have adverse impact on the initial growth period. Therefore, this paper was aimed at the surface modification of the NDPs to enhance the diamond nucleation for the growth of nanocrystalline diamond films which could be used in photovoltaic applications. Hydrogen plasma, thermal, and surfactant treatment techniques were employed to improve the dispersion characteristics of detonation nanodiamond particles in aqueous media. The seeding of silicon substrate was then carried out with an optimized spin-coating method. The results of both Fourier transform infrared spectroscopy and dynamic light scattering measurements demonstrated that plasma treated diamond nanoparticles possessed polar surface functional groups and attained high dispersion in methanol. The nanocrystalline diamond films deposited by microwave plasma jet chemical vapour deposition exhibited extremely fine grain and high smooth surfaces (~6.4 nm rms on the whole film. These results indeed open up a prospect of nanocrystalline diamond films in solar cell applications.

  2. A Simple Route of Morphology Control and Structural and Optical Properties of ZnO Grown by Metal-Organic Chemical Vapour Deposition

    Institute of Scientific and Technical Information of China (English)

    FAN Hai-Bo; YANG Shao-Yan; ZHANG Pan-Feng; WEI Hong-Yuan; LIU Xiang-Lin; JIAO Chun-Mei; ZHU Qin-Sheng; CHEN Yong-Hai; WANG Zhan-Guo

    2008-01-01

    @@ Employing the metal-organic chemical vapour deposition (MOCVD) technique, we prepare ZnO samples with different morphologies from the film to nanorods through conveniently changing the bubbled diethylzinc flux (BDF) and the carrier gas flux of oxygen (OCGF). The scanning electron microscope images indicate that small BDF and OCGF induce two-dimensional growth while the large ones avail quasi-one-dimensional growth. X-ray diffraction (XRD) and Raman scattering analyses show that all of the morphology-dependent ZnO samples are of high crystal quality with a c-axis orientation. From the precise shifts of the 20 locations of ZnO (002) face in the XRD patterns and the E2 (high) locations in the Raman spectra, we deduce that the compressive stress forms in the ZnO samples and is strengthened with the increasing BDF and OCGF. Photoluminescence spectroscopyresults show all the samples have a sharp ultraviolet luminescent band without any defects-related emission.Upon the experiments a possible growth mechanism is proposed.

  3. Thermal Modification of a-SiC:H Films Deposited by Plasma Enhanced Chemical Vapour Deposition from CH4+SiH4 Mixtures

    Institute of Scientific and Technical Information of China (English)

    刘玉学; 王宁会; 刘益春; 申德振; 范希武; 李灵燮

    2001-01-01

    The effects of thermal annealing on photoluminescence (PL) and structural properties of a-Si1-xCx :H films deposited by plasma enhanced chemical vapour deposition from CH4+SiH4 mixtures are studied by using infrared, PL and transmittance-reflectance spectra. In a-SiC:H network, high-temperature annealing gives rise to the effusion of hydrogen from strongly bonded hydrogen in SiH, SiH2, (SiH2)n, SiCHn and CHn configurations and the break of weak C-C, Si-Si and C-Si bonds. A structural rearrangement will occur, which causes a significant correlation of the position and intensity of the PL signal with the annealing temperature. The redshift of the PL peak is related to the destruction of the confining power of barriers. However, the PL intensity does not have a significant correlation with the annealing temperature for a C-rich a-SiC:H network, which refers to the formation of π-bond cluster as increasing carbon content. It is indicated that the thermal stability of C-rich a-Si1-xCx:H films is better than that of Si-like a-Si1-xCx :H films.

  4. Effects of annealing temperature on crystallisation kinetics and properties of polycrystalline Si thin films and solar cells on glass fabricated by plasma enhanced chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Tao Yuguo, E-mail: yuguo.tao@hotmail.com [Photovoltaics Centre of Excellence, University of New South Wales, Sydney NSW 2052 (Australia); Varlamov, Sergey; Jin, Guangyao [Photovoltaics Centre of Excellence, University of New South Wales, Sydney NSW 2052 (Australia); Wolf, Michael; Egan, Renate [CSG Solar Pty Ltd, Sydney, NSW (Australia)

    2011-10-31

    Solid-phase crystallisation of Si thin films on glass fabricated by plasma enhanced chemical vapour deposition is compared at different annealing temperatures. Four independent techniques, optical transmission microscopy, Raman and UV reflectance spectroscopy, and X-ray diffraction, are used to characterise the crystallisation kinetics and film properties. The 1.5 {mu}m thick films with the n+/p-/p+ solar cell structure have incubation times of about 300, 53, and 14 min and full crystallisation times of about 855, 128, and 30 min at 600 deg. C, 640 deg. C, and 680 deg. C respectively. Estimated activation energies for incubation and crystal growth are 2.7 and 3.2 eV respectively. The average grain size in the resulting polycrystalline Si films measured from scanning electron microscopy images gradually decreases with a higher annealing temperature and the crystal quality becomes poorer according to the Raman, UV reflection, and X-ray diffraction results. The dopant activation and majority carrier mobilities in heavily doped n+ and p+ layers are similar for all crystallisation temperatures. Both the open-circuit voltage and the spectral response are lower for the cells crystallised at higher temperatures and the minority carrier diffusion lengths are shorter accordingly although they are still longer than the cell thickness for all annealing temperatures. The results indicate that shortening the crystallisation time by merely increasing the crystallisation temperature offers little or no merits for PECVD polycrystalline Si thin-film solar cells on glass.

  5. Characterization of GaN/AlGaN epitaxial layers grown by metalorganic chemical vapour deposition for high electron mobility transistor applications

    Indian Academy of Sciences (India)

    Bhubesh Chander Joshi; Manish Mathew; B C Joshi; D Kumar; C Dhanavantri

    2010-01-01

    GaN and AlGaN epitaxial layers are grown by a metalorganic chemical vapour deposition (MOCVD) system. The crystalline quality of these epitaxially grown layers is studied by different characterization techniques. PL measurements indicate band edge emission peak at 363.8 nm and 312 nm for GaN and AlGaN layers respectively. High resolution XRD (HRXRD) peaks show FWHM of 272 and 296 arcsec for the (0 0 0 2) plane of GaN and GaN in GaN/AlGaN respectively. For GaN buffer layer, the Hall mobility is 346 cm2/V-s and carrier concentration is 4.5 × 1016 /cm3. AFM studies on GaN buffer layer show a dislocation density of 2 × 108/cm2 by wet etching in hot phosphoric acid. The refractive indices of GaN buffer layer on sapphire at 633 nm are 2.3544 and 2.1515 for TE and TM modes respectively.

  6. Fabrication of 160-nm T-gate metamorphic AlInAs/GaInAs HEMTs on GaAs substrates by metal organic chemical vapour deposition

    Institute of Scientific and Technical Information of China (English)

    Li Hai-Ou; Huang Wei; Tang Chak Wah; Deng Xiao-Fang; Lau Kei May

    2011-01-01

    The fabrication and performance of 160-nm gate-length metamorphic AlInAs/GaInAs high electron mobility transistors (mHEMTs) grown on GaAs substrate by metal organic chemical vapour deposition (MOCVD) are reported.By using a novel combined optical and e-beam photolithography technology, submicron mHEMTs devices have been achieved. The devices exhibit good DC and RF performance. The maximum current density was 817 mA/mm and the maximum transconductance was 828 mS/mm. The non-alloyed Ohmic contact resistance Rc was as low as 0.02 Ω-mm. The unity current gain cut-off frequency (fT) and the maximum oscillation frequency (fmax) were 146 GHz and 189 GHz, respectively. This device has the highest fT yet reported for a 160-nm gate-length HEMTs grown by MOCVD.The output conductance is 28.9 mS/mm, which results in a large voltage gain of 28.6. Also, an input capacitance to gate-drain feedback capacitance ratio, Cgs/Cgd, of 4.3 is obtained in the device.

  7. Stochastic processes in chemical physics

    CERN Document Server

    Shuler, K E

    2009-01-01

    The Advances in Chemical Physics series provides the chemical physics and physical chemistry fields with a forum for critical, authoritative evaluations of advances in every area of the discipline. Filled with cutting-edge research reported in a cohesive manner not found elsewhere in the literature, each volume of the Advances in Chemical Physics series serves as the perfect supplement to any advanced graduate class devoted to the study of chemical physics.

  8. Large-scale synthesis of single-crystal molybdenum trioxide nanobelts by hot-wire chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jianjun, E-mail: chen@zstu.edu.cn [Department of Materials Forming and Control Engineering, College of Machinery and Automation, Zhejiang Sci-Tech University, Hangzhou 310018 (China); State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Wang, Mingming; Liao, Xin; Liu, Zhaoxiang; Zhang, Judong; Ding, Lijuan [Department of Materials Engineering, College of Materials and Textile, Zhejiang Sci-Tech University, Hangzhou 310018 (China); Gao, Li [Department of Materials Forming and Control Engineering, College of Machinery and Automation, Zhejiang Sci-Tech University, Hangzhou 310018 (China); Li, Ye [Department of Materials Engineering, College of Materials and Textile, Zhejiang Sci-Tech University, Hangzhou 310018 (China)

    2015-01-15

    Graphical abstract: Bulk quantities of α-MoO{sub 3} nanobelts were synthesized by a simple hot wire chemical vapor deposition on the surface of commercial U shape MoSi{sub 2} rod electric heater. - Highlights: • The hot-wire CVD technique is introduced for the preparation of α-MoO{sub 3} nanobelts. • The MoO{sub 3} nanobelts grown on each commercial MoSi{sub 2} rod were up to 20 g in weight. • The possible vapor–solid growth mechanism of MoO{sub 3} nanobelts was discussed. • This technique also provides valuable information for high-capacity Li-ion battery. - Abstract: Bulk quantities of molybdenum trioxide (α-MoO{sub 3}) nanobelts were synthesized via hot wire chemical vapor deposition on the surface of the MoSi{sub 2} rod electric heater at 600 °C under air atmosphere. The MoO{sub 3} nanobelts grown on each MoSi{sub 2} rod were up to 20 g in weight. The possible vapor–solid growth mechanism was discussed. Before the growth of MoO{sub 3} nanobelts, SiO{sub 2} protective layers of MoSi{sub 2} rod electric heater were deoxidized by the carbothermal reduction reaction, and Mo{sub 2}C was formed on the surface of the MoSi{sub 2} rods. When Mo{sub 2}C was oxidized under air atmosphere, Mo-O vapor was deposited on the hot MoSi{sub 2} rod surface to form yellow MoO{sub 3} nanobelts. The hot wire chemical vapor deposition technique is desirable for the large-scale production of MoO{sub 3} nanomaterials.

  9. Raman Spectroscopic Study of Carbon Nanotubes Prepared Using Fe/ZnO-Palm Olein-Chemical Vapour Deposition

    Directory of Open Access Journals (Sweden)

    Syazwan Afif Mohd Zobir

    2012-01-01

    Full Text Available Multiwalled carbon nanotubes (MWCNTs were synthesized using Fe/ZnO catalyst by a dual-furnace thermal chemical vapor deposition (CVD method at 800–1000°C using nitrogen gas with a constant flow rate of 150 sccm/min as a gas carrier. Palm olein (PO, ferrocene in the presence of 0.05 M zinc nitrate, and a p-type silicon wafer were used as carbon source, catalyst precursor, and sample target, respectively. D, G, and G′ bands were observed at 1336–1364, 1559–1680, and 2667–2682 cm-1, respectively. Carbon nanotubes (CNTs with the highest degree of crystallinity were obtained at around 8000°C, and the smallest diameter of about 2 nm was deposited on the silicon substrate at 1000°C.

  10. The Liquid Vapour Interface

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage

    1985-01-01

    In this short review we are concerned with the density variation across the liquid-vapour interface, i.e. from the bulk density of the liquid to the essentially zero density of the vapour phase. This density variation can in principle be determined from the deviation of the reflectivity from...

  11. Experiments To Demonstrate Chemical Process Safety Principles.

    Science.gov (United States)

    Dorathy, Brian D.; Mooers, Jamisue A.; Warren, Matthew M.; Mich, Jennifer L.; Murhammer, David W.

    2001-01-01

    Points out the need to educate undergraduate chemical engineering students on chemical process safety and introduces the content of a chemical process safety course offered at the University of Iowa. Presents laboratory experiments demonstrating flammability limits, flash points, electrostatic, runaway reactions, explosions, and relief design.…

  12. Chemical reagent and process for refuse disposal

    International Nuclear Information System (INIS)

    A process for treating refuse by mixing them with a reactive chemical and a puzzolana-type material. Said chemical includes a retarding agent which modifies the viscosity and an accelerating agent. (author)

  13. A dilute Cu(Ni) alloy for synthesis of large-area Bernal stacked bilayer graphene using atmospheric pressure chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Madito, M. J.; Bello, A.; Dangbegnon, J. K.; Momodu, D. Y.; Masikhwa, T. M.; Barzegar, F.; Manyala, N., E-mail: ncholu.manyala@up.ac.za [Department of Physics, Institute of Applied Materials, SARCHI Chair in Carbon Technology and Materials, University of Pretoria, Pretoria 0028 (South Africa); Oliphant, C. J.; Jordaan, W. A. [National Metrology Institute of South Africa, Private Bag X34, Lynwood Ridge, Pretoria 0040 (South Africa); Fabiane, M. [Department of Physics, Institute of Applied Materials, SARCHI Chair in Carbon Technology and Materials, University of Pretoria, Pretoria 0028 (South Africa); Department of Physics, National University of Lesotho, P.O. Roma 180 (Lesotho)

    2016-01-07

    A bilayer graphene film obtained on copper (Cu) foil is known to have a significant fraction of non-Bernal (AB) stacking and on copper/nickel (Cu/Ni) thin films is known to grow over a large-area with AB stacking. In this study, annealed Cu foils for graphene growth were doped with small concentrations of Ni to obtain dilute Cu(Ni) alloys in which the hydrocarbon decomposition rate of Cu will be enhanced by Ni during synthesis of large-area AB-stacked bilayer graphene using atmospheric pressure chemical vapour deposition. The Ni doped concentration and the Ni homogeneous distribution in Cu foil were confirmed with inductively coupled plasma optical emission spectrometry and proton-induced X-ray emission. An electron backscatter diffraction map showed that Cu foils have a single (001) surface orientation which leads to a uniform growth rate on Cu surface in early stages of graphene growth and also leads to a uniform Ni surface concentration distribution through segregation kinetics. The increase in Ni surface concentration in foils was investigated with time-of-flight secondary ion mass spectrometry. The quality of graphene, the number of graphene layers, and the layers stacking order in synthesized bilayer graphene films were confirmed by Raman and electron diffraction measurements. A four point probe station was used to measure the sheet resistance of graphene films. As compared to Cu foil, the prepared dilute Cu(Ni) alloy demonstrated the good capability of growing large-area AB-stacked bilayer graphene film by increasing Ni content in Cu surface layer.

  14. A dilute Cu(Ni) alloy for synthesis of large-area Bernal stacked bilayer graphene using atmospheric pressure chemical vapour deposition

    International Nuclear Information System (INIS)

    A bilayer graphene film obtained on copper (Cu) foil is known to have a significant fraction of non-Bernal (AB) stacking and on copper/nickel (Cu/Ni) thin films is known to grow over a large-area with AB stacking. In this study, annealed Cu foils for graphene growth were doped with small concentrations of Ni to obtain dilute Cu(Ni) alloys in which the hydrocarbon decomposition rate of Cu will be enhanced by Ni during synthesis of large-area AB-stacked bilayer graphene using atmospheric pressure chemical vapour deposition. The Ni doped concentration and the Ni homogeneous distribution in Cu foil were confirmed with inductively coupled plasma optical emission spectrometry and proton-induced X-ray emission. An electron backscatter diffraction map showed that Cu foils have a single (001) surface orientation which leads to a uniform growth rate on Cu surface in early stages of graphene growth and also leads to a uniform Ni surface concentration distribution through segregation kinetics. The increase in Ni surface concentration in foils was investigated with time-of-flight secondary ion mass spectrometry. The quality of graphene, the number of graphene layers, and the layers stacking order in synthesized bilayer graphene films were confirmed by Raman and electron diffraction measurements. A four point probe station was used to measure the sheet resistance of graphene films. As compared to Cu foil, the prepared dilute Cu(Ni) alloy demonstrated the good capability of growing large-area AB-stacked bilayer graphene film by increasing Ni content in Cu surface layer

  15. A dilute Cu(Ni) alloy for synthesis of large-area Bernal stacked bilayer graphene using atmospheric pressure chemical vapour deposition

    Science.gov (United States)

    Madito, M. J.; Bello, A.; Dangbegnon, J. K.; Oliphant, C. J.; Jordaan, W. A.; Momodu, D. Y.; Masikhwa, T. M.; Barzegar, F.; Fabiane, M.; Manyala, N.

    2016-01-01

    A bilayer graphene film obtained on copper (Cu) foil is known to have a significant fraction of non-Bernal (AB) stacking and on copper/nickel (Cu/Ni) thin films is known to grow over a large-area with AB stacking. In this study, annealed Cu foils for graphene growth were doped with small concentrations of Ni to obtain dilute Cu(Ni) alloys in which the hydrocarbon decomposition rate of Cu will be enhanced by Ni during synthesis of large-area AB-stacked bilayer graphene using atmospheric pressure chemical vapour deposition. The Ni doped concentration and the Ni homogeneous distribution in Cu foil were confirmed with inductively coupled plasma optical emission spectrometry and proton-induced X-ray emission. An electron backscatter diffraction map showed that Cu foils have a single (001) surface orientation which leads to a uniform growth rate on Cu surface in early stages of graphene growth and also leads to a uniform Ni surface concentration distribution through segregation kinetics. The increase in Ni surface concentration in foils was investigated with time-of-flight secondary ion mass spectrometry. The quality of graphene, the number of graphene layers, and the layers stacking order in synthesized bilayer graphene films were confirmed by Raman and electron diffraction measurements. A four point probe station was used to measure the sheet resistance of graphene films. As compared to Cu foil, the prepared dilute Cu(Ni) alloy demonstrated the good capability of growing large-area AB-stacked bilayer graphene film by increasing Ni content in Cu surface layer.

  16. Comparison of the Er,Cr:YSGG laser with a chemical vapour deposition bur and conventional techniques for cavity preparation: a microleakage study.

    Science.gov (United States)

    Yazici, A Rüya; Yıldırım, Zeren; Antonson, Sibel A; Kilinc, Evren; Koch, Daniele; Antonson, Donald E; Dayangaç, Berrin; Ozgünaltay, Gül

    2012-01-01

    The aim of this study was to compare the effects of the Er,Cr:YSGG laser using chemical vapour deposition (CVD) bur cavity preparation with conventional preparation methods including a diamond bur and a carbide bur on the microleakage with two different adhesive systems. A total of 40 extracted human premolars were randomly assigned to four experimental groups according to the cavity preparation technique: group I diamond bur (Diatech); group II carbide bur (Diatech); group III Er,Cr:YSGG laser (Biolase Millennium II); and group IV CVD bur (CVDentUS). Using the different preparation techniques, Class V standardized preparations were performed on the buccal and lingual surfaces with gingival margins on the dentin and occlusal margins on the enamel. Each preparation group was randomly assigned to two subgroups (five teeth, ten preparations) according to the type of adhesive: an etch-and-rinse adhesive (Adper Single Bond), and a single-step self-etch adhesive (AdheSE One). All preparations were restored with a nanohybrid composite resin in a single increment. Following thermocycling (×500; 5-55°C), the teeth were immersed in basic fuchsin and sectioned in the orovestibular direction. Dye penetration was evaluated under a light microscope by two blinded examiners. Data were statistically analysed with the Kruskal-Wallis and Wilcoxon tests (p0.05). Comparing the enamel and dentin leakage scores within each group, no statistically significant differences were found (p>0.05). The Er,Cr:YSGG laser cavity preparation did not differ from preparation with CVD, diamond or carbide bur in terms of microleakage with the different adhesive systems.

  17. Determination of the optical parameters of a-Si:H thin films deposited by hot wire–chemical vapour deposition technique using transmission spectrum only

    Indian Academy of Sciences (India)

    Nabeel A Bakr; A M Funde; V S Waman; M M Kamble; R R Hawaldar; D P Amalnerkar; S W Gosavi; S R Jadkar

    2011-03-01

    Three demonstration samples of intrinsic hydrogenated amorphous silicon (a-Si:H) films were deposited using hot wire–chemical vapour deposition (HW–CVD) technique. The optical parameters and the thickness were determined from the extremes of the interference fringes of transmission spectrum in the range of 400–2500 nm using the envelope method. The calculated values of the refractive index () were fitted using the two-term Cauchy dispersion relation and the static refractive index values (0) obtained were 2.799, 2.629 and 3.043 which were in the range of the reported values. The calculated thicknesses for all samples were cross-checked with Taly-Step profilometer and found to be almost equal. Detailed analysis was carried out to obtain the optical band gap (g) using Tauc’s method and the estimated values were 1.99, 2.01 and 1.75 eV. The optical band gap values were correlated with the hydrogen content (H) in the samples calculated from Fourier transform infrared (FTIR) analysis. An attempt was made to apply Wemple–DiDomenico single-effective oscillator model to the a-Si:H samples to calculate the optical parameters. The optical band gap obtained by Tauc’s method and the static refractive index calculated from Cauchy fitting are in good agreement with those obtained by the single-effective oscillator model. The real and the imaginary parts of dielectric constant (r, ), and the optical conductivity () were also calculated.

  18. Simulation of the isotopic composition of stratospheric water vapour - Part 2: Investigation of HDO / H2O variations

    Science.gov (United States)

    Eichinger, R.; Jöckel, P.; Lossow, S.

    2015-06-01

    Studying the isotopic composition of water vapour in the lower stratosphere can reveal the driving mechanisms of changes in the stratospheric water vapour budget and therefore help to explain the trends and variations of stratospheric water vapour during recent decades. We equipped a global chemistry climate model with a description of the water isotopologue HDO, comprising its physical and chemical fractionation effects throughout the hydrological cycle. We use this model to improve our understanding of the processes which determine the patterns in the stratospheric water isotope composition and in the water vapour budget itself. The link between the water vapour budget and its isotopic composition in the tropical stratosphere is presented through their correlation in a simulated 21-year time series. The two quantities depend on the same processes; however, they are influenced with different strengths. A sensitivity experiment shows that fractionation effects during the oxidation of methane have a damping effect on the stratospheric tape recorder signal in the water isotope ratio. Moreover, the chemically produced high water isotope ratios overshadow the tape recorder in the upper stratosphere. Investigating the origin of the boreal-summer signal of isotopically enriched water vapour reveals that in-mixing of old stratospheric air from the extratropics and the intrusion of tropospheric water vapour into the stratosphere complement each other in order to create the stratospheric isotope ratio tape recorder signal. For this, the effect of ice lofting in monsoon systems is shown to play a crucial role. Furthermore, we describe a possible pathway of isotopically enriched water vapour through the tropopause into the tropical stratosphere.

  19. TPR system: a powerful technique to monitor carbon nanotube formation during chemical vapour deposition; Sistema RTP: uma tecnica poderosa para o monitoramento da formacao de nanotubos de carbono durante o processo por deposicao de vapor quimico

    Energy Technology Data Exchange (ETDEWEB)

    Tristao, Juliana Cristina; Moura, Flavia Cristina Camilo; Lago, Rochel Montero, E-mail: rochel@ufmg.b [Universidade Federal de Minas Gerais (DQ/UFMG), Belo Horizonte, MG (Brazil). Dept. de Quimica; Sapag, Karim [Universidade Nacional de San Luis (Argentina). Lab. de Ciencias de Superficies y Medios Porosos

    2010-07-01

    In this work, a TPR (Temperature Programmed Reduction) system is used as a powerful tool to monitor carbon nanotubes production during CVD (Chemical Vapour Deposition), The experiments were carried out using catalyst precursors based on Fe-Mo supported on Al{sub 2}O{sub 3} and methane as carbon source. As methane reacts on the Fe metal surface, carbon is deposited and H2 is produced. TPR is very sensitive to the presence of H2 and affords information on the temperature where catalyst is active to form different forms of carbon, the reaction kinetics, the catalyst deactivation and carbon yields. (author)

  20. Chemical production processes and systems

    Science.gov (United States)

    Holladay, Johnathan E.; Muzatko, Danielle S.; White, James F.; Zacher, Alan H.

    2014-06-17

    Hydrogenolysis systems are provided that can include a reactor housing an Ru-comprising hydrogenolysis catalyst and wherein the contents of the reactor is maintained at a neutral or acidic pH. Reactant reservoirs within the system can include a polyhydric alcohol compound and a base, wherein a weight ratio of the base to the compound is less than 0.05. Systems also include the product reservoir comprising a hydrogenolyzed polyhydric alcohol compound and salts of organic acids, and wherein the moles of base are substantially equivalent to the moles of salts or organic acids. Processes are provided that can include an Ru-comprising catalyst within a mixture having a neutral or acidic pH. A weight ratio of the base to the compound can be between 0.01 and 0.05 during exposing.

  1. Chemical Processing Department monthly report, October 1965

    Energy Technology Data Exchange (ETDEWEB)

    1965-11-22

    This report, from the Chemical Processing Department at HAPO, discusses the following: production operation; purex and redox operation; finished products operation; maintenance; financial operations; facilities engineering; research; and employee relations.

  2. Chemical Processing Department monthly report, February 1963

    Energy Technology Data Exchange (ETDEWEB)

    1963-03-21

    This report, for February 1963 from the Chemical Processing Department at HAPO, discusses the following: Production operation; Purex and Redox operation; Finished products operation; maintenance; Financial operations; facilities engineering; research; employee relations; weapons manufacturing operation; and safety and security.

  3. Chemical Processing Department monthly report, December 1963

    Energy Technology Data Exchange (ETDEWEB)

    1964-01-22

    This report, for December 1963 from the Chemical Processing Department at HAPO, discusses the following: Production operation; Purex and Redox operation; Financial operations; facilities engineering; research; and employee relations. Weapons manufacturing operation; and safety and security.

  4. Chemical Processing Department monthly report, June 1958

    Energy Technology Data Exchange (ETDEWEB)

    1958-07-22

    This report for June 1958, from the Chemical Processing Department at HAPO, discusses the following: Production operation; Purex and Redox operation; Finished products operation; maintenance; Financial operations; facilities engineering; research; and employee relations.

  5. Chemical Processing Department monthly report, October 1962

    Energy Technology Data Exchange (ETDEWEB)

    1962-11-21

    This report, from the Chemical Processing Department at HAPO, for October, 1962 discusses the following: Production operation; Purex and Redox operation; Finished products operation; maintenance; Financial operations; facilities engineering; research; employee relations; and weapons manufacturing operation.

  6. Chemical Processing Division monthly report, September 1966

    Energy Technology Data Exchange (ETDEWEB)

    Warren, J.H.

    1966-10-21

    This report, from the Chemical Processing Department at HAPO for September 1966, discusses the following: Production operation; Purex and Redox operation; Finished products operation; maintenance; Financial operations; facilities engineering; research; and employee-relations, and waste management.

  7. Chemical Processing Department monthly report, October 1963

    Energy Technology Data Exchange (ETDEWEB)

    Young, J. F.; Johnson, W. E.; Reinker, P. H.; Warren, J. H.; McCullugh, R. W.; Harmon, M. K.; Gartin, W. J.; LaFollette, T. G.; Shaw, H. P.; Frank, W. S.; Grim, K. G.; Warren, J. H.

    1963-11-21

    This report, for October 1963 from the Chemical Processing Department at HAPO, discusses the following: Production operation; Purex and Redox operation; Finished products operation; maintenance; Financial operations; facilities engineering; research; employee relations; weapons manufacturing operation; and safety and security.

  8. Modeling heterogeneous chemical processes on aerosol surface

    Institute of Scientific and Technical Information of China (English)

    Junjun Deng; Tijian Wang; Li Liu; Fei Jiang

    2010-01-01

    To explore the possible impact of heterogeneous chemical processes on atmospheric trace components,a coupled box model including gas-phase chemical processes,aerosol thermodynamic equilibrium processes,and heterogeneous chemical processes on the surface of dust,black carbon(BC)and sea salt is set up to simulate the effects of heterogeneous chemistry on the aerosol surface,and analyze the primary factors affecting the heterogeneous processes.Results indicate that heterogeneous chemical processes on the aerosol surface in the atmosphere will affect the concentrations of trace gases such as H2O2,HO2,O3,NO2,NO3,HNO3 and SO2,and aerosols such as SO42-,NO3-and NH4+.Sensitivity tests suggest that the magnitude of the impact of heterogeneous processes strongly depends on aerosol concentration and the surface uptake coefficients used in the box model.However,the impact of temperature on heterogeneous chemical processes is considerably less.The"renoxification"of HNO3 will affect the components of the troposphere such as nitrogen oxide and ozone.

  9. Preparation of Ru/HSAG Catalysts for Ammonia Synthesis via Metal-Organic Chemical Vapour Deposition Technology%MOCVD法制备Ru/HSAG氨合成催化剂

    Institute of Scientific and Technical Information of China (English)

    严海宇; 黄仕良; 韩文锋; 刘化章

    2014-01-01

    Ruthenium catalysts supported on high surface area graphite (HSAG), impregnated with KNO3 and Ba(NO3)2,was prepared via metal-organic chemical vapour deposition technology(MOCVD) with tri-ruthenium dodecacarbonyl as the Ru precursor. The catalysts were characterized by X-ray diffraction, N2 physical adsorption and transmission electron microscope. The activity of the Ru catalyst for ammonia synthesis was evaluated. The results showed that the sublimation rate of tri-ruthenium dodecacarbony depends on temperature under vacuum and dark conditions. It is confirmed that uniform dispersion can be achieved via MOCVD route with Ru nanoparticle sizes around 2 nm. As Ru3(CO)12 commences to decompose at 130℃ and reach maximum decomposition rate at 175℃, the sublimation temperature is suggested to be 110-130℃. With the increase in Ru loading from 3.2% to 6.0%, as evidenced by TEM experiments, Ru nanoparticle size keeps unchanged (around 2 nm), while the activity for ammonia synthesis is enhanced dramatically, especially at low temperature (375℃).%采用金属有机物化学气相沉积技术(MOCVD)将羰基钌升华至已浸渍 KNO3和 Ba(NO3)2的高比表面石墨(HSAG)上,制备了一系列Ru/HSAG催化剂。采用X射线衍射、透射电镜(TEM)和N2物理吸附等表征手段,考察了催化剂的物相和表面结构性质及氨合成催化活性。结果表明,以化学气相沉积技术制备的催化剂,能使钌均匀地分散于载体中,形成较小的钌粒子,从而得到高活性的氨合成催化剂。羰基钌的加热温度对升华速率有很大影响,但对沉积效果和催化活性没有明显影响,负载的羰基钌含量对催化剂活性有显著影响。羰基钌在130℃开始分解,并在175℃达到最大分解速率,因此合适的升华温度为110~130℃。催化剂的钌负载量(质量分数)从3.2%增至6.0%时,低反应温度(375℃)下,氨合成活性明显提高。在实验负载量范围内

  10. Loading conditions of nuclear power plant structures by vapour cloud explosions in consideration of nuclear process heat supply

    International Nuclear Information System (INIS)

    During the last decades there were great explosion accidents in the chemical industry. The analyses of the damage isn't exactly correct neither with a constant nor a variable TNT-equivalent. Another explanation of the damages are the excessive pressure mechanisms such as partial confinement, turbulence acceleration and pressure - sustained combustion which produce a higher pressure maximum than mere combustion. (orig./HP)

  11. Chemical Processing Department monthly report, November 1956

    Energy Technology Data Exchange (ETDEWEB)

    1956-12-21

    The November 1956 monthly report for the Chemical Processing Department of Hanford Atomic Products Operation includes information regarding research and engineering efforts with respect to the Purex and Redox process technology. Also discussed was the production operation, finished product operation, power and general maintenance, financial operation, engineering and research operations, and employee operations. (MB)

  12. Chemical Processing Department monthly report, July 1958

    Energy Technology Data Exchange (ETDEWEB)

    1958-08-22

    The July, 1958 monthly report for the Chemical Processing Department of the Hanford Atomic Products Operation includes information regarding research and engineering efforts with respect to the Purex and Redox process technology. Also discussed is the production operation, finished product operation, power and general maintenance, financial operation, engineering and research operations, and employee operation. (MB)

  13. Chemical Processing Department monthly report, May 1958

    Energy Technology Data Exchange (ETDEWEB)

    1958-06-20

    The May, 1956 monthly report for the Chemical Processing Department of Hanford Atomic Products Operation includes information regarding research and engineering efforts with respect to the Purex and Redox process technology. Also discussed is the production operation, finished products operation, power and general maintenance, financial operation, engineering and research operations, and employee operations. (MB)

  14. Chemical Processing Department monthly report, February 1958

    Energy Technology Data Exchange (ETDEWEB)

    1958-03-21

    The February, 1958 monthly report for the Chemical Processing Department of the Hanford Atomic Products Operation includes information regarding research and engineering efforts with respect to the Purex and Redox process technology. Also discussed is the production operation, finished product operation, power and general maintenance, financial operation, engineering and research operations, and employee operation. (MB)

  15. Chemical Processing Department monthly report, May 1957

    Energy Technology Data Exchange (ETDEWEB)

    1957-06-21

    The May, 1957 monthly report for the Chemical Processing Department of the Hanford Atomic Products Operation includes information regarding research and engineering efforts with respect to the Purex and Redox process technology. Also discussed is the production operation, finished product operation, power and general maintenance, financial operation, engineering and research operations, and employee operation.(MB)

  16. Process safety management for highly hazardous chemicals

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-02-01

    Purpose of this document is to assist US DOE contractors who work with threshold quantities of highly hazardous chemicals (HHCs), flammable liquids or gases, or explosives in successfully implementing the requirements of OSHA Rule for Process Safety Management of Highly Hazardous Chemicals (29 CFR 1910.119). Purpose of this rule is to prevent releases of HHCs that have the potential to cause catastrophic fires, explosions, or toxic exposures.

  17. Chemicals Industry New Process Chemistry Roadmap

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2000-08-01

    The Materials Technology I workshop was held in November 1998 to address future research needs for materials technology that will support the chemical industry. Areas covered included disassembly, recovery, reuse and renewable technology; new materials; and materials measurement and characterization. The Materials Technology II workshop was held in September 1999 and covered additives, modeling and prediction and an additional segment on new materials. Materials Technology Institute (MTI) for the Chemical Process Industries, Inc. and Air Products & Chemicals lead the workshops. The Materials Technology Roadmap presents the results from both workshops.

  18. Numerical simulation of complete liquid-vapour phase change process inside porous media using smoothing of diffusion coefficient

    International Nuclear Information System (INIS)

    The present paper deals with numerical simulations of complete phase change process inside porous media, based on the two-phase mixture model, using finite volume method for discretization. The investigation proposes a successful remedy in order to eliminate the occurrence of 'jump' in predicted properties, by introducing an efficient smoothing algorithm for the effective diffusion coefficient. A thorough parametric study also indicates that the adoption of proposed remedy does not alter the true or expected solution. All tested cases, covering applicable ranges of parametric variations, could be physically interpreted. The methodology is, therefore, recommended for future simulations of complete phase change processes within porous media. (authors)

  19. Safety Considerations in the Chemical Process Industries

    Science.gov (United States)

    Englund, Stanley M.

    There is an increased emphasis on chemical process safety as a result of highly publicized accidents. Public awareness of these accidents has provided a driving force for industry to improve its safety record. There has been an increasing amount of government regulation.

  20. A Novel Chemical Nitrate Destruction Process

    Energy Technology Data Exchange (ETDEWEB)

    Dziewinski, J.; Marczak, S.

    1999-03-01

    Nitrates represent one of the most significant pollutant discharged to the Baltic Sea by the Sliiamae hydrometallurgical plant. This article contains a brief overview of the existing nitrate destruction technologies followed by the description of a new process developed by the authors. The new chemical process for nitrate destruction is cost effective and simple to operate. It converts the nitrate to nitrogen gas which goes to the atmosphere.

  1. Synthesis and optimization of integrated chemical processes

    Energy Technology Data Exchange (ETDEWEB)

    Barton, Paul I.; Evans, Lawrence B.

    2002-04-26

    This is the final technical report for the project titled ''Synthesis and optimization of integrated chemical processes''. Progress is reported on novel algorithms for the computation of all heteroazeotropic compositions present in complex liquid mixtures; the design of novel flexible azeotropic separation processes using middle vessel batch distillation columns; and theory and algorithms for sensitivity analysis and numerical optimization of hybrid discrete/continuous dynamic systems.

  2. Desulphurization of exhaust gases in chemical processes

    Energy Technology Data Exchange (ETDEWEB)

    Asperger, K.; Wischnewski, W.

    1981-01-01

    The sulfur content of exhaust gases can be reduced by: desulphurization of fuels; modification of processes; or treatment of resultant gases. In this paper a few selected examples from the chemical industry in the German Democratic Republic are presented. Using modified processes and treating the resultant gases, the sulphuric content of exhaust gases is effectively reduced. Methods to reduce the sulfur content of exhaust gases are described in the field of production of: sulphuric acid; viscose; fertilizers; and paraffin.

  3. Investigations into the application of a combination of bioventing and biotrickling filter technologies for soil decontamination processes--a transition regime between bioventing and soil vapour extraction.

    Science.gov (United States)

    Magalhães, S M C; Ferreira Jorge, R M; Castro, P M L

    2009-10-30

    Bioventing has emerged as one of the most cost-effective in situ technologies available to address petroleum light-hydrocarbon spills, one of the most common sources of soil pollution. However, the major drawback associated with this technology is the extended treatment time often required. The present study aimed to illustrate how an intended air-injection bioventing technology can be transformed into a soil vapour extraction effort when the air flow rates are pushed to a stripping mode, thus leading to the treatment of the off-gas resulting from volatilisation. As such, a combination of an air-injection bioventing system and a biotrickling filter was applied for the treatment of contaminated soil, the latter aiming at the treatment of the emissions resulting from the bioventing process. With a moisture content of 10%, soil contaminated with toluene at two different concentrations, namely 2 and 14 mg g soil(-1), were treated successfully using an air-injection bioventing system at a constant air flow rate of ca. 0.13 dm(3) min(-1), which led to the removal of ca. 99% toluene, after a period of ca. 5 days of treatment. A biotrickling filter was simultaneously used to treat the outlet gas emissions, which presented average removal efficiencies of ca. 86%. The proposed combination of biotechnologies proved to be an efficient solution for the decontamination process, when an excessive air flow rate was applied, reducing both the soil contamination and the outlet gas emissions, whilst being able to reduce the treatment time required by bioventing only.

  4. Chemical computing with reaction-diffusion processes.

    Science.gov (United States)

    Gorecki, J; Gizynski, K; Guzowski, J; Gorecka, J N; Garstecki, P; Gruenert, G; Dittrich, P

    2015-07-28

    Chemical reactions are responsible for information processing in living organisms. It is believed that the basic features of biological computing activity are reflected by a reaction-diffusion medium. We illustrate the ideas of chemical information processing considering the Belousov-Zhabotinsky (BZ) reaction and its photosensitive variant. The computational universality of information processing is demonstrated. For different methods of information coding constructions of the simplest signal processing devices are described. The function performed by a particular device is determined by the geometrical structure of oscillatory (or of excitable) and non-excitable regions of the medium. In a living organism, the brain is created as a self-grown structure of interacting nonlinear elements and reaches its functionality as the result of learning. We discuss whether such a strategy can be adopted for generation of chemical information processing devices. Recent studies have shown that lipid-covered droplets containing solution of reagents of BZ reaction can be transported by a flowing oil. Therefore, structures of droplets can be spontaneously formed at specific non-equilibrium conditions, for example forced by flows in a microfluidic reactor. We describe how to introduce information to a droplet structure, track the information flow inside it and optimize medium evolution to achieve the maximum reliability. Applications of droplet structures for classification tasks are discussed. PMID:26078345

  5. Rock fracture processes in chemically reactive environments

    Science.gov (United States)

    Eichhubl, P.

    2015-12-01

    Rock fracture is traditionally viewed as a brittle process involving damage nucleation and growth in a zone ahead of a larger fracture, resulting in fracture propagation once a threshold loading stress is exceeded. It is now increasingly recognized that coupled chemical-mechanical processes influence fracture growth in wide range of subsurface conditions that include igneous, metamorphic, and geothermal systems, and diagenetically reactive sedimentary systems with possible applications to hydrocarbon extraction and CO2 sequestration. Fracture processes aided or driven by chemical change can affect the onset of fracture, fracture shape and branching characteristics, and fracture network geometry, thus influencing mechanical strength and flow properties of rock systems. We are investigating two fundamental modes of chemical-mechanical interactions associated with fracture growth: 1. Fracture propagation may be aided by chemical dissolution or hydration reactions at the fracture tip allowing fracture propagation under subcritical stress loading conditions. We are evaluating effects of environmental conditions on critical (fracture toughness KIc) and subcritical (subcritical index) fracture properties using double torsion fracture mechanics tests on shale and sandstone. Depending on rock composition, the presence of reactive aqueous fluids can increase or decrease KIc and/or subcritical index. 2. Fracture may be concurrent with distributed dissolution-precipitation reactions in the hostrock beyond the immediate vicinity of the fracture tip. Reconstructing the fracture opening history recorded in crack-seal fracture cement of deeply buried sandstone we find that fracture length growth and fracture opening can be decoupled, with a phase of initial length growth followed by a phase of dominant fracture opening. This suggests that mechanical crack-tip failure processes, possibly aided by chemical crack-tip weakening, and distributed solution-precipitation creep in the

  6. Chlorine-free plasma-based vapour growth of GaN

    Energy Technology Data Exchange (ETDEWEB)

    Siche, D.; Kachel, K.; Zwierz, R.; Golka, S.; Sudhoff, P.; Gogova, D. [Leibniz-Institut fuer Kristallzuechtung, Berlin (Germany); Vodopyanov, A.; Izotov, I.; Sennikov, P.; Golubev, S. [Institute of Applied Physics, Nizhny Novgorod (Russian Federation); Franke, K.P. [Institute fuer Umwelttechnologien GmbH, Berlin (Germany)

    2012-03-15

    In pure physical vapour transport process for GaN growth, the liquid Ga source has to be kept at temperatures about 1300-1400 C to provide sufficient Ga vapour pressure for reasonably large growth rates. The growth temperature needs to be slightly lower to prevent droplet formation in the Ga vapour. At such high temperatures, however, the early ammonia decomposition prevents the favorable growth with reactive nitrogen in excess. The vapour processes under development in this study aim at overcoming the drawbacks of the reaction of physically or chemically transported Ga and ammonia. For this purpose, the reactive nitrogen will be supplied by plasma excitation of N{sub 2}. First, the results on ammonia-based GaN growth and their disadvantages are discussed. Then, the challenges in designing of a new type of plasma sources (a microwave and a dielectric barrier discharge) and the first experimental results on the ammonia-free process development are presented. The microwave approach seems to be very promising in terms of GaN growth. It has higher growth rates than the dielectric barrier discharge method and therefore it is more cost-effective. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Supporting chemical process design under uncertainty

    Directory of Open Access Journals (Sweden)

    A. Wechsung

    2010-09-01

    Full Text Available A major challenge in chemical process design is to make design decisions based on partly incomplete or imperfect design input data. Still, process engineers are expected to design safe, dependable and cost-efficient processes under these conditions. The complexity of typical process models limits intuitive engineering estimates to judge the impact of uncertain parameters on the proposed design. In this work, an approach to quantify the effect of uncertainty on a process design in order to enhance comparisons among different designs is presented. To facilitate automation, a novel relaxation-based heuristic to differentiate between numerical and physical infeasibility when simulations do not converge is introduced. It is shown how this methodology yields more details about limitations of a studied process design.

  8. Absence of the 90 K structural transition in CuV{sub 2}S{sub 4} crystals grown by chemical vapour transport using TeCl{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Crandles, D A [Department of Physics, Brock University, St Catharines, ON, L2S 3A1 (Canada); Reedyk, M [Department of Physics, Brock University, St Catharines, ON, L2S 3A1 (Canada); Wardlaw, G [Department of Physics, Brock University, St Catharines, ON, L2S 3A1 (Canada); Razavi, F S [Department of Physics, Brock University, St Catharines, ON, L2S 3A1 (Canada); Hagino, T [Department of Materials Science and Engineering, Muroran Institute of Technology, 27-1 Mizumoto-cho, Muroran, Hokkaido 050-8535 (Japan); Nagata, S [Department of Materials Science and Engineering, Muroran Institute of Technology, 27-1 Mizumoto-cho, Muroran, Hokkaido 050-8535 (Japan); Shimono, I [Hokkaido Industrial Technology Centre, 379 Kikyo-cho, Hakodate, Hokkaido 041-0801 (Japan); Kremer, R K [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-70569 Stuttgart (Germany)

    2005-08-03

    Various physical properties (magnetization, specific heat, optical reflectance, electrical resistivity) of CuV{sub 2}S{sub 4} crystals grown by chemical vapour transport using TeCl{sub 4} as the transporting agent have been measured. The data show slight differences compared to samples grown using different techniques. These differences include the absence of a sharp drop in magnetization and the absence of a peak in the heat capacity near 90 K. These differences suggest that the cubic-tetragonal phase transition near 90 K does not occur in these particular crystals. The reflectance of the same crystals has been studied from (70-20 000 cm{sup -1}) for temperatures between 40 and 300 K and the data are consistent with those for a disordered metal. A high frequency absorption, perhaps an interband transition, has been observed in addition to absorption due to strongly scattered free carriers.

  9. Energy conversion technology by chemical processes

    Energy Technology Data Exchange (ETDEWEB)

    Oh, I.W.; Yoon, K.S.; Cho, B.W. [Korea Inst. of Science and Technology, Seoul (Korea, Republic of)] [and others

    1996-12-01

    The sharp increase in energy usage according to the industry development has resulted in deficiency of energy resources and severe pollution problems. Therefore, development of the effective way of energy usage and energy resources of low pollution is needed. Development of the energy conversion technology by chemical processes is also indispensable, which will replace the pollutant-producing and inefficient mechanical energy conversion technologies. Energy conversion technology by chemical processes directly converts chemical energy to electrical one, or converts heat energy to chemical one followed by heat storage. The technology includes batteries, fuel cells, and energy storage system. The are still many problems on performance, safety, and manufacturing of the secondary battery which is highly demanded in electronics, communication, and computer industries. To overcome these problems, key components such as carbon electrode, metal oxide electrode, and solid polymer electrolyte are developed in this study, followed by the fabrication of the lithium secondary battery. Polymer electrolyte fuel cell, as an advanced power generating apparatus with high efficiency, no pollution, and no noise, has many applications such as zero-emission vehicles, on-site power plants, and military purposes. After fabricating the cell components and operating the single cells, the fundamental technologies in polymer electrolyte fuel cell are established in this study. Energy storage technology provides the safe and regular heat energy, irrespective of the change of the heat energy sources, adjusts time gap between consumption and supply, and upgrades and concentrates low grade heat energy. In this study, useful chemical reactions for efficient storage and transport are investigated and the chemical heat storage technology are developed. (author) 41 refs., 90 figs., 20 tabs.

  10. Utilization of chemical looping strategy in coal gasification processes

    Institute of Scientific and Technical Information of China (English)

    Liangshih Fan; Fanxing Li; Shwetha Ramkumar

    2008-01-01

    Three chemical looping gasification processes, i. e. Syngas Chemical Looping (SCL) process, Coal Direct Chemical Looping (CDCL) process, and Calcium Looping process (CLP), are being developed at the Ohio State University (OSU). These processes utilize simple reaction schemes to convert carbonaceous fuels into products such as hydrogen, electricity, and synthetic fuels through the transformation of a highly reactive, highly recyclable chemical intermediate. In this paper, these novel chemical looping gasification processes are described and their advantages and potential challenges for commercialization are discussed.

  11. Porous Silicon & Titanium Dioxide Coatings Prepared by Atmospheric Pressure Plasma Jet Chemical Vapour Deposition Technique-A Novel Coating Technology for Photovoltaic Modules

    Directory of Open Access Journals (Sweden)

    S. Bhatt

    2011-01-01

    Full Text Available Atmospheric Pressure Plasma Jet (APPJ is an alternative for wet processes used to make anti reflection coatings and smooth substrate surface for the PV module. It is also an attractive technique because of it’s high growth rate, low power consumption, lower cost and absence of high cost vacuum systems. This work deals with the deposition of silicon oxide from hexamethyldisiloxane (HMDSO thin films and titanium dioxide from tetraisopropyl ortho titanate using an atmospheric pressure plasma jet (APPJ system in open air conditions. A sinusoidal high voltage with a frequency between 19-23 kHz at power up to 1000 W was applied between two tubular electrodes separated by a dielectric material. The jet, characterized by Tg ~ 600-800 K, was mostly laminar (Re ~ 1200 at the nozzle exit and became partially turbulent along the jet axis (Re ~ 3300. The spatially resolved emission spectra showed OH, N2, N2+ and CN molecular bands and O, H, N, Cu and Cr lines as well as the NO2 chemiluminescence continuum (450-800 nm. Thin films with good uniformity on the substrate were obtained at high deposition rate, between 800 -1000 nm.s-1, and AFM results revealed that coatings are relatively smooth (Ra ~ 2 nm. The FTIR and SEM analyses were better used to monitor the chemical composition and the morphology of the films in function of the different experimental conditions.

  12. Deposition of cobalt and nickel sulfide thin films from thio- and alkylthio-urea complexes as precursors via the aerosol assisted chemical vapour deposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Mgabi, L.P.; Dladla, B.S. [Department of Chemistry, University of Zululand, Private bag X1001 KwaDlangezwa, 3880 (South Africa); Malik, M.A. [School of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom); Garje, Shivram S. [Department of Chemistry, University of Mumbai, Vidyanagari, Santacruz (East), Mumbai 400098 (India); Akhtar, J. [Nanoscience and Materials Synthesis Lab, Department of Physics, COMSATS, Institute of Information Technology (CIIT), Chak shahzad, Islamabad (Pakistan); Revaprasadu, N., E-mail: RevaprasaduN@unizulu.ac.za [Department of Chemistry, University of Zululand, Private bag X1001 KwaDlangezwa, 3880 (South Africa)

    2014-08-01

    We report the synthesis of Co(II) and Ni(II) thiourea and alkylthiourea complexes by reacting the metal salts (CoCl{sub 2} and NiCl{sub 2}) with the thiourea, phenylthiourea and dicyclohexylthiourea ligands in a 1:2 ratio. The complexes, [CoCl{sub 2}(CS(NH{sub 2}){sub 2}){sub 2}] (I), [CoCl{sub 2}(CSNHC{sub 6}H{sub 5}NH{sub 2}){sub 2} (II) and [CoCI{sub 2}(SC(NHC{sub 6}H{sub 11}){sub 2}){sub 2}] (III), [NiCl{sub 2}(CS(NH{sub 2}){sub 2}){sub 2}] (IV), [NiCl{sub 2}(CSNHC{sub 6}H{sub 5}NH{sub 2}){sub 2}] (V) and [NiCl{sub 2}(SC(NHC{sub 6}H{sub 11}){sub 2}){sub 2}] (VI) were characterized by C, H, N analysis and Fourier transform infrared spectroscopy. Thermogravimetric analysis shows that all complexes undergo a two step decomposition process except for [NiCl{sub 2}(CSNHC{sub 6}H{sub 5}NH{sub 2}){sub 2}] (V) which decomposes in a single step. The complexes were used as single-source precursors for the deposition of cobalt sulfide and nickel sulfide thin films by aerosol assisted chemical vapor deposition at temperatures between 350 an 500 °C. The crystallinity of the films was determined by X-ray diffraction and their morphology was determined by scanning electron microscopy. The morphology of the cobalt sulfide thin films varies from randomly oriented platelets, to granulated spheres and cubes as the precursor and deposition conditions are changed. For nickel sulfide, the [NiCl{sub 2}(CS(NH{sub 2}){sub 2}){sub 2}] (IV) complex gave rods whereas the [NiCl{sub 2}(CSNHC{sub 6}H{sub 5}NH{sub 2}){sub 2}] (V) produced spherical particles. - Highlights: • We report the synthesis of Co(II) and Ni(II) thiourea and alkylthiourea complexes. • C, H, N analysis and Fourier transform infrared spectroscopy characterization • NiS and CoS thin films deposited by aerosol assisted chemical vapor deposition • X-ray diffraction characterization of the phase of the films • Film morphology determined by scanning electron microscopy.

  13. SAPHYR: A new chemical stabilisation process

    Energy Technology Data Exchange (ETDEWEB)

    Baratto, Gilles; Fernandes, Paulo; Patria; Lucie; Cretenot, Didier

    2003-07-01

    Odour control and dewaterability are the key criteria during biosolids storage either for use on land or incineration. In the case of use on land, stabilisation/sanitisation are also part of the key criteria. Vivendi Water Systems developed the SAPHYR process to answer those three requirements. The SAPHYR process principle is based on an acidification of biosolids associated to the addition of nitrite. The main results are a noticeable odour control lasting other periods of 6 to 9 months, an improved dewaterability (2 to 4 points of dryness) and depending on chemical dosages a stabilisation or a sanitisation of biosolids. Another characteristic is that biosolids conditioned with the Saphyr process can be used both on land or for incineration. After several demonstrations on more than 5 different plants throughout France on a 10 000 p.e. unit, the first industrial reference of the process was installed on a 50 000 population equivalent wastewater treatment plant in 2002 and has been in operation since december 2002. A close monitoring of the process operation, the biosolids quality and its storage and spreading on land is planned from November 2002 to spring 2003. A comparison with lime addition will take place on the same plant. The present paper will produce a presentation of the SAPHYR process, its operation on a 50 000 pe WWTP and its different applications for biosolids storage.

  14. Intelligent Controller Design for a Chemical Process

    Directory of Open Access Journals (Sweden)

    Mr. Glan Devadhas G

    2010-12-01

    Full Text Available Chemical process control is a challenging problem due to the strong on*line non*linearity and extreme sensitivity to disturbances of the process. Ziegler – Nichols tuned PI and PID controllers are found to provide poor performances for higher*order and non–linear systems. This paper presents an application of one*step*ahead fuzzy as well as ANFIS (adaptive*network*based fuzzy inference system tuning scheme for an Continuous Stirred Tank Reactor CSTR process. The controller is designed based on a Mamdani type and Sugeno type fuzzy system constructed to model the dynamics of the process. The fuzzy system model can take advantage of both a priori linguistic human knowledge through parameter initialization, and process measurements through on* line parameter adjustment. The ANFIS, which is a fuzzy inference system, is implemented in the framework of adaptive networks. The proposed ANFIS can construct an input*output mapping based on both human knowledge (in the form of fuzzy if*then rules and stipulated input*output data pairs. In this method, a novel approach based on tuning of fuzzy logic control as well as ANFIS for a CSTR process, capable of providing an optimal performance over the entire operating range of process are given. Here Fuzzy logic control as well as ANFIS for obtaining the optimal design of the CSTR process is explained. In this approach, the development of rule based and the formation of the membership function are evolved simultaneously. The performance of the algorithm in obtaining the optimal tuning values has been analyzed in CSTR process through computer simulation.

  15. An example of transition from a corrosion process in gaseous phase to corrosion in aqueous environment: the case of Z2CN18-10 stainless steel by iodine and water in vapour phase

    International Nuclear Information System (INIS)

    This research thesis addresses an example of transition of a corrosion process in gaseous phase towards corrosion in aqueous environment, specifically in the case of the corrosion of the Z2CN18-10 stainless steel by gaseous iodine in presence of water vapour (and possibly nitrogen dioxide). This transition occurs in two steps: initiation in gaseous phase and growth in aqueous environment. This transition is due to hygroscopic properties of mostly chromium iodides and, to a lesser extent, iron iodides. Morphological, electrochemical and thermogravimetry studies have been performed by varying different parameters governing corrosion processes: corrosion temperature, iodine concentration, relative humidity, and reaction time

  16. Idaho Chemical Processing Plant Site Development Plan

    International Nuclear Information System (INIS)

    The Idaho Chemical Processing Plant (ICPP) mission is to receive and store spent nuclear fuels and radioactive wastes for disposition for Department of Energy (DOE) in a cost-effective manner that protects the safety of Idaho National Engineering Laboratory (INEL) employees, the public, and the environment by: Developing advanced technologies to process spent nuclear fuel for permanent offsite disposition and to achieve waste minimization. Receiving and storing Navy and other DOE assigned spent nuclear fuels. Managing all wastes in compliance with applicable laws and regulations. Identifying and conducting site remediation consistent with facility transition activities. Seeking out and implementing private sector technology transfer and cooperative development agreements. Prior to April 1992, the ICPP mission included fuel reprocessing. With the recent phaseout of fuel reprocessing, some parts of the ICPP mission have changed. Others have remained the same or increased in scope

  17. Generation and spectroscopic investigation of an atmospheric pressure water vapour plasma jet

    International Nuclear Information System (INIS)

    Water vapour plasma technologies could be used for the conversion of biomass to hydrogen rich synthetic gas and for the neutralization and utilization of hazardous wastes. Formation of water vapour plasma has been investigated using a linear direct current plasma torch with stair stepped anode. A new device with a unique structure, operating at atmospheric pressure has been designed and tested at Lithuanian Energy Institute, Plasma Processing Laboratory for the innovative and environmental friendly plasma treatment of organic materials. The main operating conditions of plasma torch and main parameters of water vapour plasma jet were investigated. The power of plasma torch was 25–45kW; arc current was 140–180 A, the arc voltage was 172–231 V, the efficiency was 0.5–0.78. The average temperature of water vapour plasma jet in exhaust nozzle was 2600–3500 K, and the plasma jet velocity was 200–310 m/s. Emission lines, registered by the optical emission spectrometer AOS4-1, are analysed to observe the chemical composition of water vapour plasma jet. The optical emission spectrum measurement shows that the water molecule in the plasma is decomposed into H, OH and O radicals. Hydrogen is very desirable in the formation of high caloric synthetic gas (CO+H2) during thermal plasma gasification of organic materials. The summarized results can help to calculate and design gasification systems of biomass, to establish optimal parameters for stable operation of plasma generator and regulate the process parameters. (author)

  18. 21 CFR 170.19 - Pesticide chemicals in processed foods.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Pesticide chemicals in processed foods. 170.19... chemicals in processed foods. When pesticide chemical residues occur in processed foods due to the use of... exemption granted or a tolerance prescribed under section 408 of the Act, the processed food will not...

  19. 21 CFR 570.19 - Pesticide chemicals in processed foods.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Pesticide chemicals in processed foods. 570.19... chemicals in processed foods. When pesticide chemical residues occur in processed foods due to the use of... exemption granted or a tolerance prescribed under section 408 of the act, the processed food will not...

  20. SOSA – a new model to simulate the concentrations of organic vapours and sulphuric acid inside the ABL – Part 1: Model description and initial evaluation

    DEFF Research Database (Denmark)

    Boy, M.; Sogachev, Andrey; Lauros, J.;

    2011-01-01

    Chemistry in the atmospheric boundary layer (ABL) is controlled by complex processes of surface fluxes, flow, turbulent transport, and chemical reactions. We present a new model SOSA (model to simulate the concentration of organic vapours and sulphuric acid) and attempt to reconstruct the emissions...

  1. SOSA – a new model to simulate the concentrations of organic vapours and sulphuric acid inside the ABL – Part 1: Model description and initial evaluation

    DEFF Research Database (Denmark)

    Boy, M.; Sogachev, Andrey; Lauros, J.;

    2010-01-01

    Chemistry in the atmospheric boundary layer (ABL) is controlled by complex processes of surface fluxes, flow, turbulent transport, and chemical reactions. We present a new model SOSA (model to simulate the concentration of organic vapours and sulphuric acid) and attempt to reconstruct the emissions...

  2. Thermodynamics principles characterizing physical and chemical processes

    CERN Document Server

    Honig, Jurgen M

    1999-01-01

    This book provides a concise overview of thermodynamics, and is written in a manner which makes the difficult subject matter understandable. Thermodynamics is systematic in its presentation and covers many subjects that are generally not dealt with in competing books such as: Carathéodory''s approach to the Second Law, the general theory of phase transitions, the origin of phase diagrams, the treatment of matter subjected to a variety of external fields, and the subject of irreversible thermodynamics.The book provides a first-principles, postulational, self-contained description of physical and chemical processes. Designed both as a textbook and as a monograph, the book stresses the fundamental principles, the logical development of the subject matter, and the applications in a variety of disciplines. This revised edition is based on teaching experience in the classroom, and incorporates many exercises in varying degrees of sophistication. The stress laid on a didactic, logical presentation, and on the relat...

  3. Variability of winter-time middle atmospheric water vapour over the Arctic as observed with a ground-based microwave radiometer

    Science.gov (United States)

    Tschanz, Brigitte; Kivi, Rigel; Rüfenacht, Rolf; Kämpfer, Niklaus

    2014-05-01

    Middle atmospheric water vapour has a long chemical lifetime and can therefore be used as a tracer for dynamics. The ground-based microwave radiometer MIAWARA-C is designed for the use on campaigns and measures profiles of water vapour in the upper stratosphere and mesosphere and thus provides valuable data for the investigation of atmospheric processes. It has been operational for five years and has successfully participated in measurement campaigns under various climatic conditions in Germany, Switzerland, California, Finland and on la Réunion. The temporal resolution of the obtained water vapour profiles approximately 2 hours depending on tropospheric conditions. During two campaigns from January to June 2010 and from July 2011 to April 2013 in Sodankylä, Finland, MIAWARA-C monitored time series of polar middle atmospheric water vapour for three winters with three Sudden Stratospheric Warmings (SSW) occurring in early 2010, 2012 and 2013. The obtained time series are used to study the effects of the three SSWs on middle-atmospheric water vapour. During an SSW, humid mid- to low-latitude air is transported towards the polar region resulting in a fast increase in water vapour. The descent of water vapour after the SSW allows the estimation of the descent rate over the polar region as the normal wintertime circulation reforms. Results from the three SSWs are compared. The ground-based water vapour data is combined with sonde data of the Finnish Meteorological Institute and ground-based microwave wind measurements for one winter in order to obtain a more complete picture of the dynamics in the polar winter atmosphere.

  4. Preparation and Properties of N-Doped p-Type ZnO Films by Solid-Source Chemical Vapour Deposition with the c-Axis Parallel to the Substrate

    Institute of Scientific and Technical Information of China (English)

    吕建国; 叶志镇; 汪雷; 赵炳辉; 黄靖云

    2002-01-01

    We report on N-doped p-type ZnO films with the c-axis parallel to the substrate. ZnO films were prepared onan α-A12O3 (0001) substrate by solid-source chemical vapour deposition (CVD). Zn( CH3COO)2.2H2O was usedas the precursor and CH3COONH4 as the nitrogen source. The growth temperature was varied from 300℃ C to600℃ C. The as-grown ZnO film deposited at 500° C showed p-type conduction with its resistivity of 42 Ωcrm, carrierdensity 3.7 × 1017 cm-3 and Hall mobility 1.26cm2V-1.s-1 at room temperature, which are the best propertiesfor p-type ZnO deposited by CVD. The p-type ZnO film possesses a transmittance of about 85% in the visibleregion and a bandgap of 3.21 eV at room temperature.

  5. A catalyst-free synthesis of germanium nanowires obtained by combined X-ray chemical vapour deposition of GeH$_4$ and low-temperature thermal treatment techniques

    Indian Academy of Sciences (India)

    CHIARA DEMARIA; ALDO ARRAIS; PAOLA BENZI; ENRICO BOCCALERI; PAOLA ANTONIOTTI; ROBERTO RABEZZANA; LORENZA OPERTI

    2016-04-01

    A catalyst-free innovative synthesis, by combined X-ray chemical vapour deposition and lowtemperature thermal treatments, which has not been applied since so far to the growth of germanium nanowires (Ge-NWs), produced high yields of the nanoproducts with theGeH4 reactant gas. Nanowires were grown on both surfaces of a conventional deposition quartz substrate. They were featured with high purity and very large aspect ratios (ranging from 100 to 500). Products were characterized by scanning electron microscopy with energy-dispersiveatomic X-ray fluorescence and transmission electron microscopies, X-ray powder diffraction diffractometry, thermogravimetric analysis with differential scanning calorimetry, vibrational infrared and Raman and ultraviolet–visible–near infrared spectroscopies. A quantitative nanowire bundles formation was observed in the lower surface of the quartz substrate positioned over a heating support, whilst spots of nanoflowers constituted by Ge-NWs emerged from a bulk amorphous germanium film matter, deposited on the upper surface of the substrate. Thenanoproducts were characterized by crystalline core morphology, providing semiconductive features and optical band gap of about 0.67 eV. The possible interpretative base-growth mechanisms of the nanowires, stimulated bythe concomitant application of radiant and thermal conditions with no specific added metal catalyst, are hereafter investigated and presented.

  6. On-line speciation of inorganic and methyl mercury in waters and fish tissues using polyaniline micro-column and flow injection-chemical vapour generation-inductively coupled plasma mass spectrometry (FI-CVG-ICPMS).

    Science.gov (United States)

    Krishna, M V Balarama; Chandrasekaran, K; Karunasagar, D

    2010-04-15

    A simple and efficient method for the determination of ultra-trace amounts of inorganic mercury (iHg) and methylmercury (MeHg) in waters and fish tissues was developed using a micro-column filled with polyaniline (PANI) coupled online to flow injection-chemical vapour generation-inductively coupled plasma mass spectrometry (FI-CVG-ICPMS) system. Preliminary studies indicated that inorganic and methyl mercury species could be separated on PANI column in two different speciation approaches. At pH extraction of the mercury species from biological samples, was used directly to separate MeHg from iHg in the fish tissues (tuna fish ERM-CE 463, ERM-CE 464 and IAEA-350) by PANI column using speciation procedure 1. The determined values were in good agreement with certified values. Under optimal conditions, the limits of detection (LODs) were 2.52 pg and 3.24 pg for iHg and MeHg (as Hg) respectively. The developed method was applied successfully to the direct determination of iHg and MeHg in various waters (tap water, lake water, ground water and sea-water) and the recoveries for the spiked samples were in the range of 96-102% for both the Hg species.

  7. Comparative Study of Properties of ZnO/GaN/Al2O3 and ZnO/Al2O3 Films Grown by Low-Pressure Metal Organic Chemical Vapour Deposition

    Institute of Scientific and Technical Information of China (English)

    赵佰军; 杨洪军; 杜国同; 缪国庆; 杨天鹏; 张源涛; 高仲民; 王金忠; 方秀军; 刘大力; 李万成; 马燕; 杨晓天; 刘博阳

    2003-01-01

    ZnO films were deposited by low-pressure metal organic chemical vapour deposition on epi-GaN/Al2O3 films and c-Al2O3 substrates.The structure and optical properties of the ZnO/GaN/Al2O3 and ZnO/Al2O3 films have been investigated to determine the differences between the two substrates.ZnO films on GaN/Al2O3 show very strong emission features associated with exciton transitions,just as ZnO films on Al2O3,while the crystalline structural qualities for ZnO films on GaN/Al2O3 are much better than those for ZnO films directly grown on Al2O3 substrates.Zn and O elements in the deposited ZnO/GaN/Al2O3 and ZnO/Al2O3 films are investigated and compared by x-ray photoelectron spectroscopy.According to the statistical results,the Zn/O ratio changes from Zn-rich for ZnO/Al2O3 films to O-rich for ZnO/GaN/Al2O3 films.

  8. Studying chemical vapor deposition processes with theoretical chemistry

    OpenAIRE

    Pedersen, Henrik; Elliott, Simon D.

    2014-01-01

    In a chemical vapor deposition (CVD) process, a thin film of some material is deposited onto a surface via the chemical reactions of gaseous molecules that contain the atoms needed for the film material. These chemical reactions take place on the surface and in many cases also in the gas phase. To fully understand the chemistry in the process and thereby also have the best starting point for optimizing the process, theoretical chemical modeling is an invaluable tool for providing atomic-scale...

  9. Epitaxial growth of antiphase boundary free GaAs layer on 300 mm Si(001) substrate by metalorganic chemical vapour deposition with high mobility

    Science.gov (United States)

    Alcotte, R.; Martin, M.; Moeyaert, J.; Cipro, R.; David, S.; Bassani, F.; Ducroquet, F.; Bogumilowicz, Y.; Sanchez, E.; Ye, Z.; Bao, X. Y.; Pin, J. B.; Baron, T.

    2016-04-01

    Metal organic chemical vapor deposition of GaAs on standard nominal 300 mm Si(001) wafers was studied. Antiphase boundary (APB) free epitaxial GaAs films as thin as 150 nm were obtained. The APB-free films exhibit an improvement of the room temperature photoluminescence signal with an increase of the intensity of almost a factor 2.5. Hall effect measurements show an electron mobility enhancement from 200 to 2000 cm2/V s. The GaAs layers directly grown on industrial platform with no APBs are perfect candidates for being integrated as active layers for nanoelectronic as well as optoelectronic devices in a CMOS environment.

  10. Epitaxial growth of antiphase boundary free GaAs layer on 300 mm Si(001 substrate by metalorganic chemical vapour deposition with high mobility

    Directory of Open Access Journals (Sweden)

    R. Alcotte

    2016-04-01

    Full Text Available Metal organic chemical vapor deposition of GaAs on standard nominal 300 mm Si(001 wafers was studied. Antiphase boundary (APB free epitaxial GaAs films as thin as 150 nm were obtained. The APB-free films exhibit an improvement of the room temperature photoluminescence signal with an increase of the intensity of almost a factor 2.5. Hall effect measurements show an electron mobility enhancement from 200 to 2000 cm2/V s. The GaAs layers directly grown on industrial platform with no APBs are perfect candidates for being integrated as active layers for nanoelectronic as well as optoelectronic devices in a CMOS environment.

  11. Interactions of fission product vapours with aerosols

    Energy Technology Data Exchange (ETDEWEB)

    Benson, C.G.; Newland, M.S. [AEA Technology, Winfrith (United Kingdom)

    1996-12-01

    Reactions between structural and reactor materials aerosols and fission product vapours released during a severe accident in a light water reactor (LWR) will influence the magnitude of the radiological source term ultimately released to the environment. The interaction of cadmium aerosol with iodine vapour at different temperatures has been examined in a programme of experiments designed to characterise the kinetics of the system. Laser induced fluorescence (LIF) is a technique that is particularly amenable to the study of systems involving elemental iodine because of the high intensity of the fluorescence lines. Therefore this technique was used in the experiments to measure the decrease in the concentration of iodine vapour as the reaction with cadmium proceeded. Experiments were conducted over the range of temperatures (20-350{sup o}C), using calibrated iodine vapour and cadmium aerosol generators that gave well-quantified sources. The LIF results provided information on the kinetics of the process, whilst examination of filter samples gave data on the composition and morphology of the aerosol particles that were formed. The results showed that the reaction of cadmium with iodine was relatively fast, giving reaction half-lives of approximately 0.3 s. This suggests that the assumption used by primary circuit codes such as VICTORIA that reaction rates are mass-transfer limited, is justified for the cadmium-iodine reaction. The reaction was first order with respect to both cadmium and iodine, and was assigned as pseudo second order overall. However, there appeared to be a dependence of aerosol surface area on the overall rate constant, making the precise order of the reaction difficult to assign. The relatively high volatility of the cadmium iodide formed in the reaction played an important role in determining the composition of the particles. (author) 23 figs., 7 tabs., 22 refs.

  12. ADVANCED OXIDATION PROCESSES (AOP'S FOR THE TREATMENT OF CCL CHEMICALS

    Science.gov (United States)

    Research on treatment of Contaminant Candidate List (CCL) chemicals is being conducted. Specific groups of contaminants on the CCL will be evaluated using numerous advanced oxidation processes (AOPs). Initially, these CCL contaminants will be evaluated in groups based on chemical...

  13. Chemical vapour deposition of graphene on Nk(111) and Co(0001) and intercalation with Au to study Dirac Cone Formation and Rashba splitting

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Barriga, J.; Vescovo, E.; Varykhalov, A.; Scholz, M.R.; Rader, O.; Marchenko, D.; Rybkin, A.

    2010-01-01

    We show in detail monitoring by photoelectron spectroscopy how graphene can be grown by chemical vapor deposition on the transition-metal surfaces Ni(111) and Co(0001) and intercalated by a monoatomic layer of Au. For both systems, a linear E(k) dispersion of massless Dirac fermions appears in the graphene {pi}-band in the vicinity of the Fermi energy. In order to study ferromagnetism and spin-orbit effects by spin- and angle-resolved photoelectron spectroscopy, the sample must be magnetized in remanence. To this end, a W(110) substrate is prepared, its cleanliness verified by photoemission from W(110) surface states and surface core levels, and epitaxial Ni(111) and Co(0001) thin films are grown on top. Spin-resolved photoemission from the {pi}-band shows that the ferromagnetic polarization of graphene/Ni(111) and graphene/Co(0001) is negligible and that graphene on Ni(111) is after intercalation of Au spin-orbit split by the Rashba effect.

  14. Resonant and nonresonant vibrational excitation of ammonia molecules in the growth of gallium nitride using laser-assisted metal organic chemical vapour deposition

    Science.gov (United States)

    Golgir, Hossein Rabiee; Zhou, Yun Shen; Li, Dawei; Keramatnejad, Kamran; Xiong, Wei; Wang, Mengmeng; Jiang, Li Jia; Huang, Xi; Jiang, Lan; Silvain, Jean Francois; Lu, Yong Feng

    2016-09-01

    The influence of exciting ammonia (NH3) molecular vibration in the growth of gallium nitride (GaN) was investigated by using an infrared laser-assisted metal organic chemical vapor deposition method. A wavelength tunable CO2 laser was used to selectively excite the individual vibrational modes. Resonantly exciting the NH-wagging mode (v2) of NH3 molecules at 9.219 μm led to a GaN growth rate of 84 μm/h, which is much higher than the reported results. The difference between the resonantly excited and conventional thermally populated vibrational states was studied via resonant and nonresonant vibrational excitations of NH3 molecules. Resonant excitation of various vibrational modes was achieved at 9.219, 10.35, and 10.719 μm, respectively. Nonresonant excitation was conducted at 9.201 and 10.591 μm, similar to conventional thermal heating. Compared to nonresonant excitation, resonant excitation noticeably promotes the GaN growth rate and crystalline quality. The full width at half maximum value of the XRD rocking curves of the GaN (0002) and GaN (10-12) diffraction peaks decreased at resonant depositions and reached its minimum value of 45 and 53 arcmin, respectively, at the laser wavelength of 9.219 μm. According to the optical emission spectroscopic studies, resonantly exciting the NH3 v2 mode leads to NH3 decomposition at room temperature, reduces the formation of the TMGa:NH3 adduct, promotes the supply of active species in GaN formation, and, therefore, results in the increased GaN growth rate.

  15. Influence of hydrogen dilution on structural, electrical and optical properties of hydrogenated nanocrystalline silicon (nc-Si:H) thin films prepared by plasma enhanced chemical vapour deposition (PE-CVD)

    Energy Technology Data Exchange (ETDEWEB)

    Funde, A.M.; Bakr, Nabeel Ali; Kamble, D.K. [School of Energy Studies, University of Pune, Pune 411 007 (India); Hawaldar, R.R.; Amalnerkar, D.P. [Center for Materials for Electronics Technology (C-MET), Panchawati, Pune 411 008 (India); Jadkar, S.R. [Department of Physics, University of Pune, Ganeshkhind Road, Pune 411 007 (India)

    2008-10-15

    Hydrogenated nanocrystalline silicon (nc-Si:H) thin films were deposited from pure silane (SiH{sub 4}) and hydrogen (H{sub 2}) gas mixture by conventional plasma enhanced chemical vapour deposition (PE-CVD) method at low temperature (200 C) using high rf power. The structural, optical and electrical properties of these films are carefully and systematically investigated as a function of hydrogen dilution of silane (R). Characterization of these films with low angle X-ray diffraction and Raman spectroscopy revealed that the crystallite size in the films tends to decrease and at same time the volume fraction of crystallites increases with increase in R. The Fourier transform infrared (FTIR) spectroscopic analysis showed at low values of R, the hydrogen is predominantly incorporated in the nc-Si:H films in the mono-hydrogen (Si-H) bonding configuration. However, with increasing R the hydrogen bonding in nc-Si:H films shifts from mono-hydrogen (Si-H) to di-hydrogen (Si-H{sub 2}) and (Si-H{sub 2}){sub n} complexes. The hydrogen content in the nc-Si:H films decreases with increase in R and was found less than 10 at% over the entire studied range of R. On the other hand, the Tauc's optical band gap remains as high as 2 eV or much higher. The quantum size effect may responsible for higher band gap in nc-Si:H films. A correlation between electrical and structural properties has been found. For optimized deposition conditions, nc-Si:H films with crystallite size {proportional_to}7.67 nm having good degree of crystallinity ({proportional_to}84%) and high band gap (2.25 eV) were obtained with a low hydrogen content (6.5 at%). However, for these optimized conditions, the deposition rate was quite small (1.6 Aa/s). (author)

  16. Comparison between conventional chemical processes and bioprocesses in cotton fabrics

    OpenAIRE

    Mojsov, Kiro

    2015-01-01

    Textile processing is a growing industry that traditionally has used a lot of water, energy and harsh chemicals. They are also not easily biodegradable. Biotechnology in textiles is one of the revolutionary ways to promote the textile field. Bio-processing were accompanied by a significant lower demand of energy, water, chemicals, time and costs. Due to the ever growing costs for water and energy worldwide investigations are carried out to substitute conventional chemical textile processes by...

  17. Total chemical management in photographic processing

    Science.gov (United States)

    Luden, Charles; Schultz, Ronald

    1985-01-01

    The mission of the U. S. Geological Survey's Earth Resources Observation Systems (EROS) Data Center is to produce high-quality photographs of the earth taken from aircraft and Landsat satellite. In order to meet the criteria of producing research-quality photographs, while at the same time meeting strict environmental restrictions, a total photographic chemical management system was installed. This involved a three-part operation consisting of the design of a modern chemical analysis laboratory, the implementation of a chemical regeneration system, and the installation of a waste treatment system, including in-plant pretreatment and outside secondary waste treatment. Over the last ten years the result of this program has yielded high-quality photographs while saving approximately 30,000 per year and meeting all Environmental Protection Agency (EPA) restrictions.

  18. Estimation of vapour pressure and partial pressure of subliming compounds by low-pressure thermogravimetry

    Indian Academy of Sciences (India)

    G V Kunte; Ujwala Ail; P K Ajikumar; A K Tyagi; S A Shivashankar; A M Umarji

    2011-12-01

    A method for the estimation of vapour pressure and partial pressure of subliming compounds under reduced pressure, using rising temperature thermogravimetry, is described in this paper. The method is based on our recently developed procedure to estimate the vapour pressure from ambient pressure thermogravimetric data using Langmuir equation. Using benzoic acid as the calibration standard, vapour pressure–temperature curves are calculated at 80, 160 and 1000 mbar for salicylic acid and vanadyl bis-2,4-pentanedionate, a precursor used for chemical vapour deposition of vanadium oxides. Using a modification of the Langmuir equation, the partial pressure of these materials at different total pressures is also determined as a function of temperature. Such data can be useful for the deposition of multi-metal oxide thin films or doped thin films by chemical vapour deposition (CVD).

  19. Metal Vapour Lasers: Physics, Engineering and Applications

    Science.gov (United States)

    Little, Christopher E.

    1999-03-01

    Metal Vapour Lasers Christopher E. Little University of St Andrews, St Andrews, Scotland Since the first successful demonstration of a metal vapour laser (MVL) in 1962, this class of laser has become widely used in a broad range of fields including precision materials processing, isotope separation and medicine. The MVLs that are used today have a range of impressive characteristics that are not readily available using other technologies. In particular, the combination of high average output powers, pulse recurrence frequencies and beam quality available from green/yellow Cu vapour lasers (CVLs) and Cu bromide lasers, coupled with the high-quality, multiwatt ultraviolet (265-289 nm) radiation that can be produced using simple nonlinear optical techniques, means that Cu lasers will continue to be important for many years. Metal Vapour Lasers covers all the most commercially important and scientifically interesting pulsed and continuous wave (CW) gas-discharge MVLs, and includes device histories, operating characteristics, engineering, kinetics, commercial exploitation and applications. Short descriptions of gas discharges and excitation techniques make this volume self-consistent. A comprehensive bibliography is also provided. The greater part of this book is devoted to CVLs and their variants, including new sealed-off, high-power 'kinetically enhanced' CVLs and Cu bromide lasers. However, many other self-terminating MVLs are also discussed, including the red AuVL, green/infrared MnVL and infrared BaVL. Pulsed, high-gain, high average power lasers in the UV/violet (373.7, 430.5 nm) spectral regions are represented by Sr¯+ and Ca¯+ discharge-afterglow recombination lasers. The most commercially successful of the MVLs - the CW, UV/blue cataphoretic He-Cd¯+ ion laser - is described. Hollow cathode lasers are represented in two guises: 'white light' (blue/green/red) He-Cd¯+ ion lasers and UV/infrared Ne/He-Cu¯+ ion lasers. This unique volume is an

  20. Stereodynamics: From elementary processes to macroscopic chemical reactions

    Energy Technology Data Exchange (ETDEWEB)

    Kasai, Toshio [Department of Chemistry, National Taiwan University, Taipei 106, Taiwan (China); Graduate School of Science, Department of Chemistry, Osaka University, Toyonaka, 560-0043 Osaka (Japan); Che, Dock-Chil [Graduate School of Science, Department of Chemistry, Osaka University, Toyonaka, 560-0043 Osaka (Japan); Tsai, Po-Yu [Department of Chemistry, National Taiwan University, Taipei 106, Taiwan (China); Department of Chemistry, National Chung Hsing University, Taichung 402, Taiwan (China); Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan (China); Lin, King-Chuen [Department of Chemistry, National Taiwan University, Taipei 106, Taiwan (China); Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan (China); Palazzetti, Federico [Scuola Normale Superiore, Pisa (Italy); Dipartimento di Chimica Biologia e Biotecnologie, Università di Perugia, 06123 Perugia (Italy); Aquilanti, Vincenzo [Dipartimento di Chimica Biologia e Biotecnologie, Università di Perugia, 06123 Perugia (Italy); Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Roma (Italy); Instituto de Fisica, Universidade Federal da Bahia, Salvador (Brazil)

    2015-12-31

    This paper aims at discussing new facets on stereodynamical behaviors in chemical reactions, i.e. the effects of molecular orientation and alignment on reactive processes. Further topics on macroscopic processes involving deviations from Arrhenius behavior in the temperature dependence of chemical reactions and chirality effects in collisions are also discussed.

  1. Chemical reactions during sintering of Fe-Cr-Mn-Si-Ni-Mo-C-steels with special reference to processing in semi-closed containers

    Directory of Open Access Journals (Sweden)

    Cias A.

    2015-01-01

    Full Text Available Sintering of Cr, Mn and Si bearing steels has recently attracted both experimental and theoretical attention and processing in semiclosed containers has been reproposed. This paper brings together relevant thermodynamic data and considers the kinetics of some relevant chemical reactions. These involve iron and carbon, water vapour, carbon monoxide and dioxide, hydrogen and nitrogen of the sintering atmospheres and the alloying elements Cr, Mn, Mo and Si. The paper concludes by presenting mechanical properties data for three steels sintered in local microatmosphere with nitrogen, hydrogen, nitrogen-5% hydrogen and air as the furnace gas.

  2. News: Good chemical manufacturing process criteria

    Science.gov (United States)

    This news column covers topics relating to manufacturing criteria, machine to machine technology, novel process windows, green chemistry indices, business resilience, immobilized enzymes, and Bt crops.

  3. Fluid flow for chemical and process engineers

    CERN Document Server

    Holland, F

    1995-01-01

    This major new edition of a popular undergraduate text covers topics of interest to chemical engineers taking courses on fluid flow. These topics include non-Newtonian flow, gas-liquid two-phase flow, pumping and mixing. It expands on the explanations of principles given in the first edition and is more self-contained. Two strong features of the first edition were the extensive derivation of equations and worked examples to illustrate calculation procedures. These have been retained. A new extended introductory chapter has been provided to give the student a thorough basis to understand the methods covered in subsequent chapters.

  4. Chemical Sensing for Buried Landmines - Fundamental Processes Influencing Trace Chemical Detection

    Energy Technology Data Exchange (ETDEWEB)

    PHELAN, JAMES M.

    2002-05-01

    Mine detection dogs have a demonstrated capability to locate hidden objects by trace chemical detection. Because of this capability, demining activities frequently employ mine detection dogs to locate individual buried landmines or for area reduction. The conditions appropriate for use of mine detection dogs are only beginning to emerge through diligent research that combines dog selection/training, the environmental conditions that impact landmine signature chemical vapors, and vapor sensing performance capability and reliability. This report seeks to address the fundamental soil-chemical interactions, driven by local weather history, that influence the availability of chemical for trace chemical detection. The processes evaluated include: landmine chemical emissions to the soil, chemical distribution in soils, chemical degradation in soils, and weather and chemical transport in soils. Simulation modeling is presented as a method to evaluate the complex interdependencies among these various processes and to establish conditions appropriate for trace chemical detection. Results from chemical analyses on soil samples obtained adjacent to landmines are presented and demonstrate the ultra-trace nature of these residues. Lastly, initial measurements of the vapor sensing performance of mine detection dogs demonstrates the extreme sensitivity of dogs in sensing landmine signature chemicals; however, reliability at these ultra-trace vapor concentrations still needs to be determined. Through this compilation, additional work is suggested that will fill in data gaps to improve the utility of trace chemical detection.

  5. BEHAVIOR OF MERCURY DURING DWPF CHEMICAL PROCESS CELL PROCESSING

    Energy Technology Data Exchange (ETDEWEB)

    Zamecnik, J.; Koopman, D.

    2012-04-09

    The Defense Waste Processing Facility has experienced significant issues with the stripping and recovery of mercury in the Chemical Processing Cell (CPC). The stripping rate has been inconsistent, often resulting in extended processing times to remove mercury to the required endpoint concentration. The recovery of mercury in the Mercury Water Wash Tank has never been high, and has decreased significantly since the Mercury Water Wash Tank was replaced after the seventh batch of Sludge Batch 5. Since this time, essentially no recovery of mercury has been seen. Pertinent literature was reviewed, previous lab-scale data on mercury stripping and recovery was examined, and new lab-scale CPC Sludge Receipt and Adjustment Tank (SRAT) runs were conducted. For previous lab-scale data, many of the runs with sufficient mercury recovery data were examined to determine what factors affect the stripping and recovery of mercury and to improve closure of the mercury material balance. Ten new lab-scale SRAT runs (HG runs) were performed to examine the effects of acid stoichiometry, sludge solids concentration, antifoam concentration, form of mercury added to simulant, presence of a SRAT heel, operation of the SRAT condenser at higher than prototypic temperature, varying noble metals from none to very high concentrations, and higher agitation rate. Data from simulant runs from SB6, SB7a, glycolic/formic, and the HG tests showed that a significant amount of Hg metal was found on the vessel bottom at the end of tests. Material balance closure improved from 12-71% to 48-93% when this segregated Hg was considered. The amount of Hg segregated as elemental Hg on the vessel bottom was 4-77% of the amount added. The highest recovery of mercury in the offgas system generally correlated with the highest retention of Hg in the slurry. Low retention in the slurry (high segregation on the vessel bottom) resulted in low recovery in the offgas system. High agitation rates appear to result in lower

  6. BEHAVIOR OF MERCURY DURING DWPF CHEMICAL PROCESS CELL PROCESSING

    Energy Technology Data Exchange (ETDEWEB)

    Zamecnik, J.; Koopman, D.

    2012-04-09

    The Defense Waste Processing Facility has experienced significant issues with the stripping and recovery of mercury in the Chemical Processing Cell (CPC). The stripping rate has been inconsistent, often resulting in extended processing times to remove mercury to the required endpoint concentration. The recovery of mercury in the Mercury Water Wash Tank has never been high, and has decreased significantly since the Mercury Water Wash Tank was replaced after the seventh batch of Sludge Batch 5. Since this time, essentially no recovery of mercury has been seen. Pertinent literature was reviewed, previous lab-scale data on mercury stripping and recovery was examined, and new lab-scale CPC Sludge Receipt and Adjustment Tank (SRAT) runs were conducted. For previous lab-scale data, many of the runs with sufficient mercury recovery data were examined to determine what factors affect the stripping and recovery of mercury and to improve closure of the mercury material balance. Ten new lab-scale SRAT runs (HG runs) were performed to examine the effects of acid stoichiometry, sludge solids concentration, antifoam concentration, form of mercury added to simulant, presence of a SRAT heel, operation of the SRAT condenser at higher than prototypic temperature, varying noble metals from none to very high concentrations, and higher agitation rate. Data from simulant runs from SB6, SB7a, glycolic/formic, and the HG tests showed that a significant amount of Hg metal was found on the vessel bottom at the end of tests. Material balance closure improved from 12-71% to 48-93% when this segregated Hg was considered. The amount of Hg segregated as elemental Hg on the vessel bottom was 4-77% of the amount added. The highest recovery of mercury in the offgas system generally correlated with the highest retention of Hg in the slurry. Low retention in the slurry (high segregation on the vessel bottom) resulted in low recovery in the offgas system. High agitation rates appear to result in lower

  7. Microbial production of bulk chemicals: development of anaerobic processes

    NARCIS (Netherlands)

    Weusthuis, R.A.; Lamot, I.; Oost, van der J.; Sanders, J.P.M.

    2011-01-01

    nnovative fermentation processes are necessary for the cost-effective production of bulk chemicals from renewable resources. Current microbial processes are either anaerobic processes, with high yield and productivity, or less-efficient aerobic processes. Oxygen utilization plays an important role i

  8. Low Temperature Growth of In2O3and InN Nanocrystals on Si(111 via Chemical Vapour Deposition Based on the Sublimation of NH4Cl in In

    Directory of Open Access Journals (Sweden)

    Tsokkou Demetra

    2009-01-01

    Full Text Available Abstract Indium oxide (In2O3 nanocrystals (NCs have been obtained via atmospheric pressure, chemical vapour deposition (APCVD on Si(111 via the direct oxidation of In with Ar:10% O2at 1000 °C but also at temperatures as low as 500 °C by the sublimation of ammonium chloride (NH4Cl which is incorporated into the In under a gas flow of nitrogen (N2. Similarly InN NCs have also been obtained using sublimation of NH4Cl in a gas flow of NH3. During oxidation of In under a flow of O2the transfer of In into the gas stream is inhibited by the formation of In2O3around the In powder which breaks up only at high temperatures, i.e.T > 900 °C, thereby releasing In into the gas stream which can then react with O2leading to a high yield formation of isolated 500 nm In2O3octahedrons but also chains of these nanostructures. No such NCs were obtained by direct oxidation forT G < 900 °C. The incorporation of NH4Cl in the In leads to the sublimation of NH4Cl into NH3and HCl at around 338 °C which in turn produces an efficient dispersion and transfer of the whole In into the gas stream of N2where it reacts with HCl forming primarily InCl. The latter adsorbs onto the Si(111 where it reacts with H2O and O2leading to the formation of In2O3nanopyramids on Si(111. The rest of the InCl is carried downstream, where it solidifies at lower temperatures, and rapidly breaks down into metallic In upon exposure to H2O in the air. Upon carrying out the reaction of In with NH4Cl at 600 °C under NH3as opposed to N2, we obtain InN nanoparticles on Si(111 with an average diameter of 300 nm.

  9. The metal-organic chemical vapour deposition and optical studies of ZnSe1-xTex and CdS1-xTex epilayers and tellurium doped ZnS/CdS superlattices

    International Nuclear Information System (INIS)

    This work sought to achieve efficient room temperature blue photoluminescence (PL) from II-VI superlattices by incorporation of tellurium (Te) exciton traps into the wells. In preparation for this, the growth and optical properties of ZnSe1-xTex and CdS1-xTex dilute alloy epilayers were first investigated. The epilayer and superlattice samples were prepared using atmospheric pressure metal-organic chemical vapour deposition (AP-MOCVD). The dependence of Te concentration (x) on the growth precursors and conditions used was investigated. This led to an understanding of the relative stabilities of the precursors used, as well as the best growth conditions required to control Te concentrations. A diffusion doping technique was also developed for growth of low Te concentration ZnSe:Te and CdS:Te epilayers. The corresponding concentration and PL results for these layers were used to confirm the expected microscopic nature of the Te centres. The low temperature (1.8K) PL emission intensities from ZnSe1-xTex and CdS1-xTex epilayers were intense, but found to decrease rapidly with increasing temperature despite the large exciton trapping energies. A theoretical capture cross section model was thus developed to explain these observations. In addition, application of this model allowed the microscopic size of Te centres to be obtained, thereby explaining the different appearance of corresponding PL bands. In view of the more persistent emissions from CdS1-xTex layers compared with those of ZnSe1-xTex, it was decided to grow Te doped ZnS/CdS:Te superlattices. The ZnS/CdS:Te superlattices were found give the intended blue emission. However, structural disruption in these superlattice samples led to quenching of this emission at room temperature. Finally, it was found that the degree of electron-phonon coupling to Te centres was less in superlattice structures compared to epilayers. (author)

  10. The Research on Atmospheric Pressure Water Vapour Plasma Generation and Application for the Destruction of Wastes

    Directory of Open Access Journals (Sweden)

    Viktorija Grigaitiene

    2013-01-01

    Full Text Available In the Lithuanian Energy Institute an experimental atmospheric pressure Ar/water vapour plasma torch has been designed and tested. The power of plasma torch was estimated 40 ÷ 69 kW, the mean temperature of plasma jet at the exhaust nozzle was 2300÷2900K. The chemical compositionof water vapour plasma was established from the emission spectrum lines at 300 ÷ 800nm range. The main species observed in Ar/water vapour plasma were: Ar, OH, H, O, Cu. The experiments on water vapour steam reforming were performed. The results confirmed that water vapour plasma has the unique properties – high enthalpy and environmentally friendly conditions. It could be employed for environmental purposes such as destruction of wastes into simple molecules or conversion to synthetic gas.

  11. The Seasonal Cycle of Water Vapour on Mars from Assimilation of Thermal Emission Spectrometer Data

    Science.gov (United States)

    Steele, Liam J.; Lewis, Stephen R.; Patel, Manish R.; Montmessin, Franck; Forget, Francois; Smith, Michael D.

    2014-01-01

    We present for the first time an assimilation of Thermal Emission Spectrometer (TES) water vapour column data into a Mars global climate model (MGCM). We discuss the seasonal cycle of water vapour, the processes responsible for the observed water vapour distribution, and the cross-hemispheric water transport. The assimilation scheme is shown to be robust in producing consistent reanalyses, and the global water vapour column error is reduced to around 2-4 pr micron depending on season. Wave activity is shown to play an important role in the water vapour distribution, with topographically steered flows around the Hellas and Argyre basins acting to increase transport in these regions in all seasons. At high northern latitudes, zonal wavenumber 1 and 2 stationary waves during northern summer are responsible for spreading the sublimed water vapour away from the pole. Transport by the zonal wavenumber 2 waves occurs primarily to the west of Tharsis and Arabia Terra and, combined with the effects of western boundary currents, this leads to peak water vapour column abundances here as observed by numerous spacecraft. A net transport of water to the northern hemisphere over the course of one Mars year is calculated, primarily because of the large northwards flux of water vapour which occurs during the local dust storm around L(sub S) = 240-260deg. Finally, outlying frost deposits that surround the north polar cap are shown to be important in creating the peak water vapour column abundances observed during northern summer.

  12. Chemical industrial wastewater treated by combined biological and chemical oxidation process.

    Science.gov (United States)

    Guomin, Cao; Guoping, Yang; Mei, Sheng; Yongjian, Wang

    2009-01-01

    Wastewaters from phenol and rubber synthesis were treated by the activated sludge process in a large-scale chemical factory in Shanghai, but the final effluent quality cannot conform with the local discharge limit without using river water for dilution. Therefore, this chemical factory had to upgrade its wastewater treatment plant. To fully use the present buildings and equipment during upgrading of the chemical factory's wastewater treatment plant and to save operation costs, a sequential biological pre-treatement, chemical oxidation, and biological post-treatment (or BCB for short) process had been proposed and investigated in a pilot trial. The pilot trial results showed that about 80% COD in the chemical wastewater could be removed through anoxic and aerobic degradation in the biological pre-treatement section, and the residual COD in the effluent of the biological pre-treatment section belongs to refractory chemicals which cannot be removed by the normal biological process. The refractory chemicals were partial oxidized using Fenton's reagent in the chemical oxidation section to improve their biodegradability; subsequently the wastewater was treated by the SBR process in the biological post-treatment section. The final effluent COD reached the first grade discharge limit (process, the operation cost of the BCB process increased by about 0.5 yuan (RMB) per cubic metre wastewater, but about 1,240,000 m(3) a(-1) dilution water could be saved and the COD emission could be cut down by 112 tonne each year.

  13. The Vapour Pressure of Plutonium

    International Nuclear Information System (INIS)

    The vapour pressure of liquid plutonium has been determined over the temperature range 1100 to 1800°K by the Knudsen effusion method. The least-squares equation which fits the data is log10p(atm) = -17 420/T(°K) + 4.913. The standard deviation corresponds to about ±10% in the pressures calculated from this equation. The heat of vaporization computed from the temperature dependence of the experimental data is ΔH0298 = 82.3 kcal/g-at. The heat computed by combining independent entropy and heat capacity data with the present measurements is ΔH0298 = 82.1 kcal/g-at. Effects of oxygen upon the volatility of liquid plutonium were sought by comparing the vapour pressures observed with the liquid in contact with tantalum, tantalum carbide, magnesia, and plutonium sesquioxide. No differences were found. In addition, the vapour pressure was measured with different degrees of vacuum in the system. No effect was found here either, except that in very poor vacuums a surface film of oxide apparently formed and reduced the volatility by about a factor of 2. (author)

  14. Property Modelling for Applications in Chemical Product and Process Design

    DEFF Research Database (Denmark)

    Gani, Rafiqul

    is missing, the atom connectivity based model is employed to predict the missing group interaction. In this way, a wide application range of the property modeling tool is ensured. Based on the property models, targeted computer-aided techniques have been developed for design and analysis of organic chemicals......, polymers, mixtures as well as separation processes. The presentation will highlight the framework (ICAS software) for property modeling, the property models and issues such as prediction accuracy, flexibility, maintenance and updating of the database. Also, application issues related to the use of property......Physical-chemical properties of pure chemicals and their mixtures play an important role in the design of chemicals based products and the processes that manufacture them. Although, the use of experimental data in design and analysis of chemicals based products and their processes is desirable...

  15. Sustainability Indicators for Chemical Processes: III. Biodiesel Case Study

    Science.gov (United States)

    The chemical industry is one of the most important business sectors, not only economically, but also societally; as it allows humanity to attain higher standards and quality of life. Simultaneously, chemical products and processes can be the origin of potential human health and ...

  16. Chemical interaction matrix between reagents in a Purex based process

    International Nuclear Information System (INIS)

    The United States Department of Energy (DOE) is the responsible entity for the disposal of the United States excess weapons grade plutonium. DOE selected a PUREX-based process to convert plutonium to low-enriched mixed oxide fuel for use in commercial nuclear power plants. To initiate this process in the United States, a Mixed Oxide (MOX) Fuel Fabrication Facility (MFFF) is under construction and will be operated by Shaw AREVA MOX Services at the Savannah River Site. This facility will be licensed and regulated by the U.S. Nuclear Regulatory Commission (NRC). A PUREX process, similar to the one used at La Hague, France, will purify plutonium feedstock through solvent extraction. MFFF employs two major process operations to manufacture MOX fuel assemblies: (1) the Aqueous Polishing (AP) process to remove gallium and other impurities from plutonium feedstock and (2) the MOX fuel fabrication process (MP), which processes the oxides into pellets and manufactures the MOX fuel assemblies. The AP process consists of three major steps, dissolution, purification, and conversion, and is the center of the primary chemical processing. A study of process hazards controls has been initiated that will provide knowledge and protection against the chemical risks associated from mixing of reagents over the life time of the process. This paper presents a comprehensive chemical interaction matrix evaluation for the reagents used in the PUREX-based process. Chemical interaction matrix supplements the process conditions by providing a checklist of any potential inadvertent chemical reactions that may take place. It also identifies the chemical compatibility/incompatibility of the reagents if mixed by failure of operations or equipment within the process itself or mixed inadvertently by a technician in the laboratories. (authors)

  17. Chemical kinetics, stochastic processes, and irreversible thermodynamics

    CERN Document Server

    Santillán, Moisés

    2014-01-01

    This book brings theories in nonlinear dynamics, stochastic processes, irreversible thermodynamics, physical chemistry, and biochemistry together in an introductory but formal and comprehensive manner.  Coupled with examples, the theories are developed stepwise, starting with the simplest concepts and building upon them into a more general framework.  Furthermore, each new mathematical derivation is immediately applied to one or more biological systems.  The last chapters focus on applying mathematical and physical techniques to study systems such as: gene regulatory networks and ion channels. The target audience of this book are mainly final year undergraduate and graduate students with a solid mathematical background (physicists, mathematicians, and engineers), as well as with basic notions of biochemistry and cellular biology.  This book can also be useful to students with a biological background who are interested in mathematical modeling, and have a working knowledge of calculus, differential equatio...

  18. Chemical Processing Department monthly report for March 1963

    Energy Technology Data Exchange (ETDEWEB)

    1963-04-22

    This report, from the Chemical Processing Department at HAPO for March 1963, discusses the following: Production operation; Purex and Redox operation; Finished products operation; maintenance; Financial operations; facilities engineering; research; employee relations; and weapons manufacturing operation.

  19. Chemical Processing Department monthly report for September 1963

    Energy Technology Data Exchange (ETDEWEB)

    1963-10-21

    This report, from the Chemical Processing Department at HAPO for September 1963, discusses the following: Production operation; Purex and Redox operation; Finished products operation; maintenance; Financial operations, facilities engineering; research; employee relations; weapons manufacturing operation; and power and crafts operation.

  20. Chemical Processing Department monthly report for February 1957

    Energy Technology Data Exchange (ETDEWEB)

    1957-03-21

    This report from the Chemical Processing Department at HAPO, discusses the following: Production operation, purex operation, redox operation, finished products operation, power and general maintenance operation, financial operation, facilities engineering operation, research and engineering operation, and employee relations operation.

  1. Chemical Processing Department monthly report for September 1962

    Energy Technology Data Exchange (ETDEWEB)

    1962-10-23

    This report, for September 1962 from the Chemical Processing Department at HAPO, discusses the following; Production operation; Purex and Redox operation; Finished products operation; maintenance; Financial operations; facilities engineering; research; and employee relations.

  2. Chemical Processing Department monthly report for February 1959

    Energy Technology Data Exchange (ETDEWEB)

    1959-03-20

    This report for February 1959, from the Chemical Processing Department at HAPO, discusses the following: Production operation; Purex and Redox operation; Finished products operation; maintenance: Financial operations; facilities engineering; research; and employee relations.

  3. Chemical Processing Department monthly report for August 1959

    Energy Technology Data Exchange (ETDEWEB)

    1959-09-21

    This report, from the Chemical Processing Department at HAPO, discusses the following: Production operation; Purex and Redox operation; Finished products operation; maintenance; Financial operations; facilities engineering; research; and employee relations.

  4. Process Design and Evaluation for Chemicals Based on Renewable Resources

    DEFF Research Database (Denmark)

    Fu, Wenjing

    One of the key steps in process design is choosing between alternative technologies, especially for processes producing bulk and commodity chemicals. Recently, driven by the increasing oil prices and diminishing reserves, the production of bulk and commodity chemicals from renewable feedstocks has...... development of chemicals based on renewable feedstocks. As an example, this thesis especially focuses on applying the methodology in process design and evaluation of the synthesis of 5-hydroxymethylfurfural (HMF) from the renewable feedstock glucose/fructose. The selected example is part of the chemoenzymatic...... gained considerable interest. Renewable feedstocks usually cannot be converted into fuels and chemicals with existing process facilities due to the molecular functionality and variety of the most common renewable feedstock (biomass). Therefore new types of catalytic methods as well as new types...

  5. Chemical Processing Department monthly report for July 1964

    Energy Technology Data Exchange (ETDEWEB)

    1964-08-21

    This report, for July 1964 from the Chemical Processing Department at HAPO, discusses the following: Production operation; Purex and Redox operation; Finished products operation; maintenance; Financial operations; facilities engineering; research; employee relations; weapons manufacturing operation; and safety and security.

  6. Chemical Processing Department monthly report for July 1957

    Energy Technology Data Exchange (ETDEWEB)

    McCune, F. K.; Johnson, W. E.; MacCready, W. K.; Warren, J. H.; Schroeder, O. C.; Groswith, C. T.; Mobley, W. N.; LaFollette, T. G.; Grim, K. G.; Shaw, H. P.; Richards, R. B.; Roberts, D. S.

    1957-08-22

    This report, for July 1957 from the Chemical Processing Department at HAPO, discusses the following; Production operation; Purex and Redox operation; Finished products operation; maintenance; Financial operations; facilities engineering; research; and employee relations.

  7. Sistema RTP: uma técnica poderosa para o monitoramento da formação de nanotubos de carbono durante o processo por deposição de vapor químico TPR system: a powerful technique to monitor carbon nanotube formation during chemical vapour deposition

    Directory of Open Access Journals (Sweden)

    Juliana Cristina Tristão

    2010-01-01

    Full Text Available In this work, a TPR (Temperature Programmed Reduction system is used as a powerful tool to monitor carbon nanotubes production during CVD (Chemical Vapour Deposition, The experiments were carried out using catalyst precursors based on Fe-Mo supported on Al2O3 and methane as carbon source. As methane reacts on the Fe metal surface, carbon is deposited and H2 is produced. TPR is very sensitive to the presence of H2 and affords information on the temperature where catalyst is active to form different forms of carbon, the reaction kinetics, the catalyst deactivation and carbon yields.

  8. Analysis of chemical coal cleaning processes. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1980-06-01

    Six chemical coal cleaning processes were examined. Conceptual designs and costs were prepared for these processes and coal preparation facilities, including physical cleaning and size reduction. Transportation of fine coal in agglomerated and unagglomerated forms was also discussed. Chemical cleaning processes were: Pittsburgh Energy Technology Center, Ledgemont, Ames Laboratory, Jet Propulsion Laboratory (two versions), and Guth Process (KVB). Three of the chemical cleaning processes are similar in concept: PETC, Ledgemont, and Ames. Each of these is based on the reaction of sulfur with pressurized oxygen, with the controlling factor being the partial pressure of oxygen in the reactor. All of the processes appear technically feasible. Economic feasibility is less certain. The recovery of process chemicals is vital to the JPL and Guth processes. All of the processes consume significant amounts of energy in the form of electric power and coal. Energy recovery and increased efficiency are potential areas for study in future more detailed designs. The Guth process (formally designed KVB) appears to be the simplest of the systems evaluated. All of the processes require future engineering to better determine methods for scaling laboratory designs/results to commercial-scale operations. A major area for future engineering is to resolve problems related to handling, feeding, and flow control of the fine and often hot coal.

  9. Chemical Processes and Thresholds in Hawaiin Soils

    Science.gov (United States)

    Chadwick, O.

    2007-12-01

    The Hawaiian Islands are a useful natural laboratory for studying soil development particularly those that can be understood using a matrix of chonosequences and climosequences. The islands are formed over a stationary mantle plume and then are carried to the northwest on the Pacific Plate. Thus the islands get older with distance from the hotspot; Kauai has remnant shield surfaces whose lavas date to about 4,000 ky. It is possible to sample soils that are developing on different age flows ranging from a few hundred years to a few million years. Additionally, individual volcanoes are impacted by differing amounts of rainfall depending on location with respect to the northeasterly trade winds. Whereas rainfall over the open ocean near Hawaii is about 700 mm, rainfall over the Islands ranges from 150 to 11,000 mm. Hawaii is minimally impacted by mineral aerosol additions compared to continental areas and this has a significant impact on soil development. More than 100 soil profiles have been sampled along the Hawaii time-climate matrix with some surprising results. For example, in arid soils might be expected to develop smectite clays, but they are rich in halloysite and allophane. Importantly, these same soils show a trend from high-Mg calcite to dolomite as carbonates accumulate within the profiles - this is one of the first documented occurrences of pedogenic dolomite that is not associated with high levels of salts. It appears that lack of smectite formation lowers the incorporation of Mg into silicate clays and increases its incorporation into carbonates. This is an unusual pedogenic process that seems to be enhanced by the lack of substantial amounts of mica in the basalt derived soils. The only mica is in surface horizons that receive dust derived from distant continents. Without mica there is no template to allow smectite clay formation under the rapid wetting and drying regimes encountered in the arid soils. At the same time that halloysite is forming, iron

  10. New Developments in Thermo-Chemical Diffusion Processes

    Institute of Scientific and Technical Information of China (English)

    Bernd Edenhofer

    2004-01-01

    Thermo-chemical diffusion processes like carburising, nitriding and boronizing play an important part in modern manufacturing technologies. They exist in many varieties depending on the type of diffusing element used and the respective process procedure. The most important industrial heat treatment process is case-hardening, which consists of thermochemical diffusion process carburising or its variation carbonitriding, followed by a subsequent quench. The latest developments of using different gaseous carburising agents and increasing the carburising temperature are one main area of this paper. The other area is the evolvement of nitriding and especially the ferritic nitrocarburising process by improved process control and newly developed process variations using carbon, nitrogen and oxygen as diffusing elements in various process steps. Also boronizing and special thermo-chemical processes for stainless steels are discussed.

  11. Chemicals in the process chain from raw material to product

    International Nuclear Information System (INIS)

    As described in this presentation, chemicals are added at various points along the physical flow from oil/gas well to sold products. They have several functions and are added in different amounts. The chemicals may have a negative impact on the environment by emission to sea. But they can also reduce the regularity of the processing equipment and the prices of the products. Therefore, Statoil has begun a research project that aims to develop improved methods and tools for the prediction of the distribution of chemicals in the process chain and the unwanted effects they might have on the environment, on downstream installations and on the products. 4 refs., 11 figs

  12. The study and the realization of radiation detectors made from polycrystalline diamond films grown by microwave plasma enhanced chemical vapour deposition technique; Etude et realisation de detecteurs de rayonnements a base de films de diamant polycristallin elabores par depot chimique en phase vapeur assiste par plasma micro-onde

    Energy Technology Data Exchange (ETDEWEB)

    Jany, Ch

    1998-10-29

    The aim of this work was to develop radiation detectors made from polycrystalline diamond films grown by microwave plasma enhanced chemical vapour deposition technique. The influence of surface treatments, contact technology and diamond growth parameters on the diamond detectors characteristics was investigated in order to optimise the detector response to alpha particles. The first part of the study focused on the electrical behaviour of as-deposited diamond surface, showing a p type conduction and its influence on the leakage current of the device. A surface preparation process was established in order to reduce the leakage current of the device by surface dehydrogenation using an oxidising step. Several methods to form and treat electrical contacts were also investigated showing that the collection efficiency of the device decreases after contact annealing. In the second part, we reported the influence of the diamond deposition parameters on the characteristics of the detectors. The increase of the deposition temperature and/or methane concentration was shown to lead {eta} to decrease. In contrast, {eta} was found to increase with the micro-wave power. The evolution of the diamond detector characteristics results from the variation in sp{sup 2} phases incorporation and in the crystallography quality of the films. These defects increase the leakage current and reduce the carrier mobility and lifetime. Measurements carried out on detectors with different thicknesses showed that the physical properties varies along the growth direction, improving with the film thickness. Finally, the addition of nitrogen (> 10 ppm) in the gas mixture during diamond deposition was found to strongly reduce the collection efficiency of the detectors. To conclude the study, we fabricated and characterised diamond devices which were used for thermal neutron detection and for the intensity and shape measurement of VUV and soft X-ray pulses. (author)

  13. Condensation of water vapour on moss-dominated biological soil crust, NW China

    Indian Academy of Sciences (India)

    Xin-Ping Wang; Yan-Xia Pan; Rui Hu; Ya-Feng Zhang; Hao Zhang

    2014-03-01

    Characteristics of water vapour condensation, including the onset, duration, and amount of water vapour condensation on moss-dominated biological soil crust (BSC) and dune sand were studied under simulated conditions with varying air temperature and relative humidity. The simulations were performed in a plant growth chamber using an electronic balance recording the weight of condensation. There was a positive linear correlation between the water vapour condensation and relative humidity while the mean temperature was negatively linearly related to amounts of water vapour condensation for both soil surfaces. The amount of water vapour condensation on BSC and dune sand can be described by the difference between air temperature and dew point with an exponential function, indicating that when the difference of air temperature and dew point exceeds a value of 35.3°C, there will be zero water vapour condensed on BSC. In contrast, when the difference of air temperature and dew point exceeds a value of 20.4°C, the water vapour condensation will be zero for dune sand. In general, when the air is fully saturated with water and the dew point is equal to the current air temperature, the water vapour condensed on BSC attained its maximum value of 0.398 mm, whereas it was 0.058 mm for dune sand. In comparison, water vapour condensed on BSC was at a relatively high temperature and low relative humidity, while we did not detect water vapour condensation on the dune sand under the similar conditions. Physical and chemical analyses of the samples pointed to a greater porosity, high content of fine particles, and high salinity for BSC compared to the dune sand. These results highlight that soil physicochemical properties are the likely factors influencing the mechanism of water vapour condensation under specific meteorological conditions, as onset was earlier and the duration was longer for water vapour condensation on BSC in comparison with that of dune sand. This contributed to

  14. Isothermal vapour flow in extremely dry soils

    Science.gov (United States)

    Todman, L. C.; Ireson, A. M.; Butler, A. P.; Templeton, M. R.

    2012-04-01

    In dry soils hydraulic connectivity within the liquid water phase decreases and vapour flow becomes a significant transport mechanism for water. The temperature or solute concentration of the liquid phase affects the vapour pressure of the surrounding air, thus temperature or solute gradients can drive vapour flows. However, in extremely dry soils where water is retained by adsorptive forces rather than capillarity, vapour flows can also occur. In such soils tiny changes in water content significantly affect the equilibrium vapour pressure in the soil, and hence small differences in water content can initiate vapour pressure gradients. In many field conditions this effect may be negligible compared to vapour flows driven by other factors. However, flows of this type are particularly significant in a new type of subsurface irrigation system which uses pervaporation, via a polymer tubing, as the mechanism for water supply. In this system, water enters the soil in vapour phase. Experiments were performed in laboratory conditions using marine sand that had previously been oven dried and cooled. This dry sand was used to represent the desert conditions in which this irrigation system is intended for use. Experimental results show that isothermal vapour flows can significantly affect the performance of such irrigation systems due to the rapid transport of water through the soil via the vapour phase. When the irrigation pipe was buried at a depth of 10cm a vapour flow from the soil surface was observed in less than 2 hours. These flows therefore affect the loss of mass into the atmosphere and thus must be considered when evaluating the availability of water for the irrigated crop. The experiments also provide a rare opportunity to observe isothermal vapour flows initiating from a subsurface source. Such experiments allow the significance of these flows to be quantified and potentially applied to other areas of arid zone hydrology.

  15. Fission product vapour - aerosol interactions in the containment: simulant fuel studies

    International Nuclear Information System (INIS)

    Experiments have been conducted in the Falcon facility to study the interaction of fission product vapours released from simulant fuel samples with control rod aerosols. The aerosols generated from both the control rod and fuel sample were chemically distinct and had different deposition characteristics. Extensive interaction was observed between the fission product vapours and the control rod aerosol. The two dominant mechanisms were condensation of the vapours onto the aerosol, and chemical reactions between the two components; sorption phenomena were believed to be only of secondary importance. The interaction of fission product vapours and reactor materials aerosols could have a major impact on the transport characteristics of the radioactive emission from a degrading core. (author)

  16. An Extended Algorithm of Flexibility Analysis in Chemical Engineering Processes

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    An extended algorithm of flexibility analysis with a local adjusting method for flexibility region of chemical processes, which is based on the active constraint strategy, is proposed, which fully exploits the flexibility region of the process system operation. The hyperrectangular flexibility region determined by the extended algorithm is larger than that calculated by the previous algorithms. The limitation of the proposed algorithm due to imperfect convexity and its corresponding verification measure are also discussed. Both numerical and actual chemical process examples are presented to demonstrate the effectiveness of the new algorithm.

  17. MICROSTRUCTURE DEVICES FOR APPLICATIONS IN THERMAL AND CHEMICAL PROCESS ENGINEERING

    OpenAIRE

    Brandner, Juergen; Anurjew, E.; Henning, T.; Schygulla, U.; Schubert, K.

    2006-01-01

    In this publication, an overview of the work dealing with thermal and chemical micro process engineering performed at the Institute for Micro Process Engineering (IMVT) of Forschungszentrum Karlsruhe will be given. The focus will be set on manufacturing of metallic microstructure devices and on microstructure heat exchangers. A brief outlook will describe possible future application fields.

  18. Chemical Processing Department monthly report for October 1956

    Energy Technology Data Exchange (ETDEWEB)

    1956-11-21

    The October, 1956 monthly report for the Chemical Processing Department of the Hanford Atomic Products Operation includes information regarding research and engineering efforts with respect to the Purex and Redox process technology. Also discussed is the production operation, finished product operation, power and general maintenance, financial operation, engineering and research operations, and employee operation. (MB)

  19. A Course in Project Evaluation in the Chemical Process Industries.

    Science.gov (United States)

    Valle-Riestra, J. Frank

    1983-01-01

    Describes a course designed to expose neophytes to methodology used in chemical process industries to evaluate commercial feasibility of proposed projects. Previously acquired disciplines are integrated to facilitate process synthesis, gain appreciation of nature of industrial projects and industrial viewpoint in managing them, and to become adept…

  20. Chemical Changes in Carbohydrates Produced by Thermal Processing.

    Science.gov (United States)

    Hoseney, R. Carl

    1984-01-01

    Discusses chemical changes that occur in the carbohydrates found in food products when these products are subjected to thermal processing. Topics considered include browning reactions, starch found in food systems, hydrolysis of carbohydrates, extrusion cooking, processing of cookies and candies, and alterations in gums. (JN)

  1. Chemical Processing Department monthly report for September 1958

    Energy Technology Data Exchange (ETDEWEB)

    1958-10-22

    The September, 1958 monthly report for the Chemical Processing Department of the Hanford Atomic Products Operation includes information regarding research and engineering efforts with respect to the Purex and Redox process technology. Also discussed is the production operation, finished product operation, power and general maintenance, financial operation, engineering and research operations, and employee operation. (MB)

  2. Dust as interstellar catalyst I. Quantifying the chemical desorption process

    CERN Document Server

    Minissale, M; Cazaux, S; Hocuk, S

    2015-01-01

    Context. The presence of dust in the interstellar medium has profound consequences on the chemical composition of regions where stars are forming. Recent observations show that many species formed onto dust are populating the gas phase, especially in cold environments where UV and CR induced photons do not account for such processes. Aims. The aim of this paper is to understand and quantify the process that releases solid species into the gas phase, the so-called chemical desorption process, so that an explicit formula can be derived that can be included into astrochemical models. Methods. We present a collection of experimental results of more than 10 reactive systems. For each reaction, different substrates such as oxidized graphite and compact amorphous water ice are used. We derive a formula to reproduce the efficiencies of the chemical desorption process, which considers the equipartition of the energy of newly formed products, followed by classical bounce on the surface. In part II we extend these resul...

  3. Laboratory study on new particle formation from the reaction OH + SO2: influence of experimental conditions, H2O vapour, NH3 and the amine tert-butylamine on the overall process

    Directory of Open Access Journals (Sweden)

    J. Curtius

    2010-08-01

    Full Text Available Nucleation experiments starting from the reaction of OH radicals with SO2 have been performed in the IfT-LFT flow tube under atmospheric conditions at 293±0.5 K for a relative humidity of 13–61%. The presence of different additives (H2, CO, 1,3,5-trimethylbenzene for adjusting the OH radical concentration and resulting OH levels in the range (4–300 ×105 molecule cm−3 did not influence the nucleation process itself. The number of detected particles as well as the threshold H2SO4 concentration needed for nucleation was found to be strongly dependent on the counting efficiency of the used counting devices. High-sensitivity particle counters allowed the measurement of freshly nucleated particles with diameters down to about 1.5 nm. A parameterization of the experimental data was developed using power law equations for H2SO4 and H2O vapour. The exponent for H2SO4 from different measurement series was in the range of 1.7–2.1 being in good agreement with those arising from analysis of nucleation events in the atmosphere. For increasing relative humidity, an increase of the particle number was observed. The exponent for H2O vapour was found to be 3.1 representing an upper limit. Addition of 1.2×1011 molecule cm−3 or 1.2×1012 molecule cm−3 of NH3 (range of atmospheric NH3 peak concentrations revealed that NH3 has a measureable, promoting effect on the nucleation rate under these conditions. The promoting effect was found to be more pronounced for relatively dry conditions, i.e. a rise of the particle number by 1–2 orders of magnitude at RH = 13% and only by a factor of 2–5 at RH = 47% (NH3 addition: 1.2×1012 molecule cm−3. Using the amine tert-butylamine instead of NH3, the enhancing impact of the base for nucleation and particle growth appears to be stronger. Tert-butylamine addition of about 1010 molecule cm−3 at RH = 13% enhances particle formation by about two orders of magnitude, while for NH3 only a small or negligible

  4. The National Toxicology Program chemical nomination selection and testing process.

    Science.gov (United States)

    Heindel, J J

    1988-01-01

    The NTP is an interagency program of the Federal Government which coordinates toxicological programs at the NIH (NIEHS), FDA (NCTR), and CDC (NIOSH) with input from NCI, NIH, OSHA, CPSC, EPA, and ATSDR. The NTP has the capability to completely characterize the toxicologic profile of a chemical, including studies of chemical disposition, genetic toxicity, immunotoxicity, teratology, reproductive toxicity, carcinogenicity, neurotoxicity, and specific organ toxicity. The NTP encourages nominations of chemicals of human health concern from all sectors of the public, including industry, labor, and the general public. The specific process of nomination, evaluation, and selection of chemicals for testing by the NTP is described. It is a multicomponent system with several evaluations and a public peer review step to assure adequate consideration of all nominated chemicals. The results of NTP studies are all peer reviewed and available to the general public as well as to the scientific community. PMID:2980357

  5. A group contribution method for estimating the vapour pressures of α-pinene oxidation products

    OpenAIRE

    J. F. Müller; Capouet, M.

    2005-01-01

    A prediction method based on group contribution principles is proposed for estimating the vapour pressure of α-pinene oxidation products. Temperature dependent contributions are provided for the following chemical groups: carbonyl, nitrate, hydroxy, hydroperoxide, acyl peroxy nitrate and acid. On the basis of observed vapour pressure differences between isomers of diols and dinitrates, a simple refinement is introduced in the method, which allows to account for the influence of the subs...

  6. A chemical process of asphaltenes dispersion : anticor DSA 700

    International Nuclear Information System (INIS)

    This work deals with asphalts dispersion chemical process. Asphaltenes are constituents of petroleum which under chemical, physical or mechanical variations effect precipitate and create deposits. In order to cope with this problem, a product : Anticor DSA 700 has been adjusted and allow to stabilize asphaltenes. This method has already been used in France and in Algeria and will be extended to others west countries. (O.L.). 2 figs

  7. Chemical sensors and gas sensors for process control in biotechnology

    International Nuclear Information System (INIS)

    This paper is concerned with the possibilities for chemical measurement of the progress of biotechnological processes which are offered by devices already developed for other demanding applications. It considers the potential use of ultrasonic instrumentation originally developed for the nuclear industry, gas measurement methods from the fields of environmental monitoring and combustion control, nuclear instruments developed for the oil, mining and chemical industries, robotic systems and advanced control techniques. (author)

  8. New Vistas in Chemical Product and Process Design

    DEFF Research Database (Denmark)

    Zhang, Lei; Babi, Deenesh Kavi; Gani, Rafiqul

    2016-01-01

    Design of chemicals-based products is broadly classified into those that are process centered and those that are product centered. In this article, the designs of both classes of products are reviewed from a process systems point of view; developments related to the design of the chemical product......, its corresponding process, and its integration are highlighted. Although significant advances have been made in the development of systematic model-based techniques for process design (also for optimization, operation, and control), much work is needed to reach the same level for product design....... Timeline diagrams illustrating key contributions in product design, process design, and integrated product-process design are presented. The search for novel, innovative, and sustainable solutions must be matched by consideration of issues related to the multidisciplinary nature of problems, the lack...

  9. Treatment Process Requirements for Waters Containing Hydraulic Fracturing Chemicals

    Science.gov (United States)

    Stringfellow, W. T.; Camarillo, M. K.; Domen, J. K.; Sandelin, W.; Varadharajan, C.; Cooley, H.; Jordan, P. D.; Heberger, M. G.; Reagan, M. T.; Houseworth, J. E.; Birkholzer, J. T.

    2015-12-01

    A wide variety of chemical additives are used as part of the hydraulic fracturing (HyF) process. There is concern that HyF chemicals will be released into the environment and contaminate drinking water, agricultural water, or other water used for beneficial purposes. There is also interest in using produced water (water extracted from the subsurface during oil and gas production) for irrigation and other beneficial purposes, especially in the arid Southwest US. Reuse of produced water is not speculative: produced water can be low in salts and is being used in California for irrigation after minimal treatment. In this study, we identified chemicals that are used for hydraulic fracturing in California and conducted an analysis to determine if those chemicals would be removed by a variety of technically available treatment processes, including oil/water separation, air stripping, a variety of sorption media, advanced oxidation, biological treatment, and a variety of membrane treatment systems. The approach taken was to establish major physiochemical properties for individual chemicals (log Koc, Henry's constant, biodegradability, etc.), group chemicals by function (e.g corrosion inhibition, biocides), and use those properties to predict the fate of chemical additives in a treatment process. Results from this analysis is interpreted in the context of what is known about existing systems for the treatment of produced water before beneficial reuse, which includes a range of treatment systems from oil/water separators (the most common treatment) to sophisticated treatment trains used for purifying produced water for groundwater recharge. The results show that most HyF chemical additives will not be removed in existing treatment systems, but that more sophisticated treatment trains can be designed to remove additives before beneficial reuse.

  10. Chemical precipitation processes for the treatment of aqueous radioactive waste

    International Nuclear Information System (INIS)

    Chemical precipitation by coagulation-flocculation and sedimentation has been commonly used for many years to treat liquid (aqueous) radioactive waste. This method allows the volume of waste to be substantially reduced for further treatment or conditioning and the bulk of the waste to de discharged. Chemical precipitation is usually applied in combination with other methods as part of a comprehensive waste management scheme. As with any other technology, chemical precipitation is constantly being improved to reduce cost to increase the effectiveness and safety on the entire waste management system. The purpose of this report is to review and update the information provided in Technical Reports Series No. 89, Chemical Treatment of Radioactive Wastes, published in 1968. In this report the chemical methods currently in use for the treatment of low and intermediate level aqueous radioactive wastes are described and illustrated. Comparisons are given of the advantages and limitations of the processes, and it is noted that good decontamination and volume reduction are not the only criteria according to which a particular process should be selected. Emphasis has been placed on the need to carefully characterize each waste stream, to examine fully the effect of segregation and the importance of looking at the entire operation and not just the treatment process when planning a liquid waste treatment facility. This general approach includes local requirements and possibilities, discharge authorization, management of the concentrates, ICRP recommendations and economics. It appears that chemical precipitation process and solid-liquid separation techniques will continue to be widely used in liquid radioactive waste treatment. Current research and development is showing that combining different processes in one treatment plant can provide higher decontamination factors and smaller secondary waste arisings. Some of these processes are already being incorporated into new and

  11. Electrochemistry and green chemical processes: electrochemical ozone production

    Directory of Open Access Journals (Sweden)

    Leonardo M. da Silva

    2003-12-01

    Full Text Available After an introductory discussion emphasising the importance of electrochemistry for the so-called Green Chemical Processes, the article presents a short discussion of the classical ozone generation technologies. Next a revision of the electrochemical ozone production technology focusing on such aspects as: fundamentals, latest advances, advantages and limitations of this technology is presented. Recent results about fundamentals of electrochemical ozone production obtained in our laboratory, using different electrode materials (e.g. boron doped diamond electrodes, lead dioxide and DSAÒ-based electrodes also are presented. Different chemical processes of interest to the solution of environmental problems involving ozone are discussed.

  12. Gas and vapour detection using polypyrrole

    NARCIS (Netherlands)

    Leur, R.H.M. van de; Waal, A. van der

    1999-01-01

    The vapours of organic solvents like toluene, butanon, and ethanol do effect the electrical conductivity of electrochemically synthesised polypyrrole. This property allows the use of polypyrrole in sensors for vapour detection. The conductivity is also a function of temperature and the history of th

  13. Intercomparison on measurement of water vapour permeability

    DEFF Research Database (Denmark)

    Hansen, Kurt Kielsgaard

    Three different materials are tested - hard woodfibre board - damp proof course - underlay for roofing The water vapour permeability has been measured according to EN ISO 12572 (2001).......Three different materials are tested - hard woodfibre board - damp proof course - underlay for roofing The water vapour permeability has been measured according to EN ISO 12572 (2001)....

  14. Breakdown and dc discharge in low-pressure water vapour

    Science.gov (United States)

    Sivoš, J.; Škoro, N.; Marić, D.; Malović, G.; Petrović, Z. Lj

    2015-10-01

    In this paper we report studies of basic properties of breakdown, low-current Townsend discharge and high-current discharge regimes in water vapour. Paschen curves and the corresponding distributions of emission intensities at low current were recorded in the range of pd (pressure x electrode gap) from 0.1 to 10 Torrcm covering the region of Paschen minimum. From the experimental profiles we obtained effective ionization coefficient of water vapour for the E/N range 650 Td-7 kTd and fitted the results by using the extended Townsend analytical formula. Using the obtained ionization coefficient, we calculated the effective yield of secondary electrons from the copper cathode. Results of the measurements of Volt-Ampere characteristics in water vapour were presented together with the images of the axial structure of the discharge in a wide range of discharge currents for two pd values. Recorded profiles showed development of the spatial structure of the discharge in different operating regimes. We were able to identify conditions where processes induced by heavy particles, probably fast hydrogen atoms, are dominant in inducing emission from the discharge. Finally, standard scaling laws were tested for low current and glow discharges in water vapour.

  15. Composition and placement process for oil field chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Cantu, L.A.; Yost, M.E.

    1991-01-22

    This patent describes a process for the continuous release of an oil field chemical within a subterranean hydrocarbon bearing formation or wellbore penetrating such formation. It comprises placing the oil field chemical in a polymeric microcapsule; dispersing such polymeric microcapsules; introducing the wellbore fluid containing the microcapsules into a well bore or subterranean formation through a wellbore; then allowing water and temperature at formation conditions to degrade; continuously releasing the chemical from the degraded microcapsules. This patent describes a composition comprising an oil field chemical incorporated in a polymeric microcapsule comprising the condensation product of hydroxyacetic acid monomer or hydroxyacetic acid co-condensed with up to 15 percent by weight of other hydroxy-, carboxylic acid-, or hydroxycarboxylic acid- containing moieties. The product has a number average molecular weight of from about 200 to about 4000.

  16. Stratospheric water vapour as tracer for Vortex filamentation in the Arctic winter 2002/2003

    Directory of Open Access Journals (Sweden)

    M. Müller

    2003-01-01

    Full Text Available Balloon-borne frost point hygrometers measured three high-resolution profiles of stratospheric water vapour above Ny-Ålesund, Spitsbergen during winter 2002/2003. The profiles obtained on 12 December 2002 and on 17 January 2003 provide an insight into the vertical distribution of water vapour in the core of the polar vortex. The water vapour sounding on 11 February 2003 was obtained within the vortex edge region of the lower stratosphere. Here, a significant reduction of water vapour mixing ratio was observed between 16 and 19 km. The stratospheric temperatures indicate that this dehydration was not caused by the presence of polar stratospheric clouds or earlier PSC particle sedimentation. Ozone observations on this day indicate a large scale movement of the polar vortex and show laminae in the same altitude range as the water vapour profile. The link between the observed water vapour reduction and filaments in the vortex edge region is indicated in the results of the semi-lagrangian advection model MIMOSA, which show that adjacent filaments of polar and mid latitude air can be identified above the Spitsbergen region. A vertical cross-section produced by the MIMOSA model reveals that the water vapour sonde flew through polar air in the lowest part of the stratosphere below 425 K, then passed through filaments of mid latitude air with lower water vapour concentrations, before it finally entered the polar vortex above 450 K. These results indicate that on 11 February 2003 the frost point hygrometer measured different water vapour concentrations as the sonde detected air with different origins. Instead of being linked to dehydration due to PSC particle sedimentation, the local reduction in the stratospheric water vapour profile was in this case caused by dynamical processes in the polar stratosphere.

  17. Removal of vapour phase PCDD/Fs in electric arc furnace steelmaking emissions by sorption using plastics.

    Science.gov (United States)

    Ooi, Tze Chean; Ewan, Bruce C R; Cliffe, Keith R; Anderson, David R; Fisher, Raymond; Thompson, Dennis

    2008-08-01

    Plastics are potentially suitable for the removal of vapour phase PCDD/Fs in emissions from the electric arc furnace (EAF) steelmaking process. Three different commercial plastics, i.e. polypropylene BE170MO (Borealis A/S, Denmark), polypropylene in the form of 5 mm spheres (The Precision Plastic Ball Co. Ltd., UK) and polyethylene LD605BA (ExxonMobil Chemical, Belgium), have been studied using a novel experimental apparatus for the removal of vapour phase PCDD/Fs. Polypropylene BE170MO was identified to be the most suitable product amongst the three plastics in terms of PCDD/F sorption and potential industrial application. The optimum temperature for PCDD/F sorption on polypropylene BE170MO was below 90 degrees C for a removal efficiency of >99% at an average vapour phase PCDD/F concentration of 3.5 ng I-TEQ/Nm(3). At 130 degrees C, 53% of the PCDD/Fs trapped on polypropylene BE170MO were desorbed.

  18. Chemical and physicochemical characteristics changes during passion fruit juice processing

    Directory of Open Access Journals (Sweden)

    Aline Gurgel Fernandes

    2011-09-01

    Full Text Available Passion fruit is widely consumed due to its pleasant flavour and aroma acidity, and it is considered very important a source of minerals and vitamins. It is used in many products such as ice-cream, mousses and, especially, juices. However, the processing of passion fruit juice may modify the composition and biodisponibility of the bioactive compounds. Investigations of the effects of processing on nutritional components in tropical juices are scarce. Frequently, only losses of vitamin C are evaluated. The objective of this paper is to investigate how some operations of passion fruit juice processing (formulation/homogeneization/thermal treatment affect this product's chemical and physicochemical characteristics. The results showed that the chemical and physicochemical characteristics are little affected by the processing although a reduction in vitamin C contents and anthocyanin, large quantities of carotenoids was verified even after the pasteurization stage.

  19. Chemical Processing Department monthly report for June 1963

    Energy Technology Data Exchange (ETDEWEB)

    1963-07-22

    This report, from the Chemical Processing Department at HAPO for June 1963, discusses the following: Production operation; Purex and Redox operation; Finished products operation; maintenance; Financial operations, facilities engineering; research; and employee relations; weapons manufacturing operation; and power and crafts operation.

  20. Portfolio Assessment on Chemical Reactor Analysis and Process Design Courses

    Science.gov (United States)

    Alha, Katariina

    2004-01-01

    Assessment determines what students regard as important: if a teacher wants to change students' learning, he/she should change the methods of assessment. This article describes the use of portfolio assessment on five courses dealing with chemical reactor and process design during the years 1999-2001. Although the use of portfolio was a new…

  1. MIMO Self-Tuning Control of Chemical Process Operation

    DEFF Research Database (Denmark)

    Hallager, L.; Jørgensen, S. B.; Goldschmidt, L.

    1984-01-01

    The problem of selecting a feasible model structure for a MIMO self-tuning controller (MIMOSC) is addressed. The dependency of the necessary structure complexity in relation to the specific process operating point is investigated. Experimental results from a fixed-bed chemical reactor are used...

  2. Fabrication of agglomerate-free nanopowders by hydrothermal chemical processing

    OpenAIRE

    Schmidt, Helmut K.; Nass, Rüdiger; Burgard, Detlef; Nonninger, Ralph

    1998-01-01

    A chemical processing technique for the fabrication of nanopowders has been developed. The route is based on precipitation processes in solutions, either within aqueous droplets in microemulsions in the presence of surface modifiers like surfactants or by direct precipitation in solutions in the presence of theses surface modifiers or small organic molecules directly bonded to the particle surface. In order to obtain well crystallized or densified particles, a continuous flow hydrothermal pro...

  3. Data reconciliation and gross error detection: application in chemical processes

    OpenAIRE

    EGHBAL AHMADİ, Mohammad Hosein

    2015-01-01

    Abstract. Measured data are normally corrupted by different kinds of errors in many chemical processes. In this work, a brief overview in data reconciliation and gross error detection believed as the most efficient technique in reducing the measurement errors and obtaining accurate information about the process is presented. In addition to defining the basic problem and a survey of recent developments in this area that is categorized in “Real Time Optimization” field, we will describe about a...

  4. Influence of surface coverage on the chemical desorption process.

    Science.gov (United States)

    Minissale, M; Dulieu, F

    2014-07-01

    In cold astrophysical environments, some molecules are observed in the gas phase whereas they should have been depleted, frozen on dust grains. In order to solve this problem, astrochemists have proposed that a fraction of molecules synthesized on the surface of dust grains could desorb just after their formation. Recently the chemical desorption process has been demonstrated experimentally, but the key parameters at play have not yet been fully understood. In this article, we propose a new procedure to analyze the ratio of di-oxygen and ozone synthesized after O atoms adsorption on oxidized graphite. We demonstrate that the chemical desorption efficiency of the two reaction paths (O+O and O+O2) is different by one order of magnitude. We show the importance of the surface coverage: for the O+O reaction, the chemical desorption efficiency is close to 80% at zero coverage and tends to zero at one monolayer coverage. The coverage dependence of O+O chemical desorption is proved by varying the amount of pre-adsorbed N2 on the substrate from 0 to 1.5 ML. Finally, we discuss the relevance of the different physical parameters that could play a role in the chemical desorption process: binding energy, enthalpy of formation, and energy transfer from the new molecule to the surface or to other adsorbates.

  5. Influence of surface coverage on the chemical desorption process

    Energy Technology Data Exchange (ETDEWEB)

    Minissale, M.; Dulieu, F., E-mail: francois.dulieu@obspm.fr [LERMA, Université de Cergy Pontoise et Observatoire de Paris, UMR 8112 du CNRS. 5, mail Gay Lussac, 95031 Cergy Pontoise (France)

    2014-07-07

    In cold astrophysical environments, some molecules are observed in the gas phase whereas they should have been depleted, frozen on dust grains. In order to solve this problem, astrochemists have proposed that a fraction of molecules synthesized on the surface of dust grains could desorb just after their formation. Recently the chemical desorption process has been demonstrated experimentally, but the key parameters at play have not yet been fully understood. In this article, we propose a new procedure to analyze the ratio of di-oxygen and ozone synthesized after O atoms adsorption on oxidized graphite. We demonstrate that the chemical desorption efficiency of the two reaction paths (O+O and O+O{sub 2}) is different by one order of magnitude. We show the importance of the surface coverage: for the O+O reaction, the chemical desorption efficiency is close to 80% at zero coverage and tends to zero at one monolayer coverage. The coverage dependence of O+O chemical desorption is proved by varying the amount of pre-adsorbed N{sub 2} on the substrate from 0 to 1.5 ML. Finally, we discuss the relevance of the different physical parameters that could play a role in the chemical desorption process: binding energy, enthalpy of formation, and energy transfer from the new molecule to the surface or to other adsorbates.

  6. Evaluating the vapour shift concept in agriculture: some aspects

    Science.gov (United States)

    Schmidt, S.; Metselaar, K.; van Dam, J. C.; Klik, A.

    2009-04-01

    Human population growth leads to an increasing pressure on freshwater resources. By 2050 Falkenmark et al. (2004) estimate a global water deficit for crop production of 5800 km3.y-1. This has important consequences for management of fresh water resources at different scales, and new strategies at different scales are required. One of the strategies suggested is that of managing crops in such a way that the use of rainfall and irrigation is shifted as much as possible from evaporation towards transpiration, a so-called vapour shift. The suggested savings are in the order of 330 km3.y-1, and are based on estimates of the magnitude of three processes: Reducing early season evaporation; increasing canopy cover; and increasing yield levels. The vapour shift concept was evaluated empirically, and in a simulation study. The empirical evaluation using results for wheat, maize, millet, cotton, and barley suggests the estimate of potential savings is 37% lower than the estimate by Falkenmark et al. (2004). The uncertainty is large and due to the limited number of experiments in which a separation of evapotranspiration in evaporation and transpiration has been made over the entire growing season. This suggests that theoretical support for the vapour shift concept should become more important. In the simulation approach two management options, mulching and planting density, are evaluated for a site in India for an irrigated wheat crop using a simulation approach for water limited crop yield. Given the simulation model used, and the management options investigated, the assumption implicit in the vapour shift concept - decreasing evaporation with increasing yield level - does not hold in irrigated areas, or in areas in which water is the most limiting factor. This suggests that vapour shift will be largest in those areas where nutrients and pests- and diseases are still limiting or reducing crop yields, and measures are taken to reduce those limitations.

  7. A Framework to Design and Optimize Chemical Flooding Processes

    Energy Technology Data Exchange (ETDEWEB)

    Mojdeh Delshad; Gary A. Pope Kamy Sepehrnoori

    2006-08-31

    The goal of this proposed research is to provide an efficient and user friendly simulation framework for screening and optimizing chemical/microbial enhanced oil recovery processes. The framework will include (1) a user friendly interface to identify the variables that have the most impact on oil recovery using the concept of experimental design and response surface maps, (2) UTCHEM reservoir simulator to perform the numerical simulations, and (3) an economic model that automatically imports the simulation production data to evaluate the profitability of a particular design. Such a reservoir simulation framework is not currently available to the oil industry. The objectives of Task 1 are to develop three primary modules representing reservoir, chemical, and well data. The modules will be interfaced with an already available experimental design model. The objective of the Task 2 is to incorporate UTCHEM reservoir simulator and the modules with the strategic variables and developing the response surface maps to identify the significant variables from each module. The objective of the Task 3 is to develop the economic model designed specifically for the chemical processes targeted in this proposal and interface the economic model with UTCHEM production output. Task 4 is on the validation of the framework and performing simulations of oil reservoirs to screen, design and optimize the chemical processes.

  8. A FRAMEWORK TO DESIGN AND OPTIMIZE CHEMICAL FLOODING PROCESSES

    Energy Technology Data Exchange (ETDEWEB)

    Mojdeh Delshad; Gary A. Pope; Kamy Sepehrnoori

    2005-07-01

    The goal of this proposed research is to provide an efficient and user friendly simulation framework for screening and optimizing chemical/microbial enhanced oil recovery processes. The framework will include (1) a user friendly interface to identify the variables that have the most impact on oil recovery using the concept of experimental design and response surface maps, (2) UTCHEM reservoir simulator to perform the numerical simulations, and (3) an economic model that automatically imports the simulation production data to evaluate the profitability of a particular design. Such a reservoir simulation framework is not currently available to the oil industry. The objectives of Task 1 are to develop three primary modules representing reservoir, chemical, and well data. The modules will be interfaced with an already available experimental design model. The objective of the Task 2 is to incorporate UTCHEM reservoir simulator and the modules with the strategic variables and developing the response surface maps to identify the significant variables from each module. The objective of the Task 3 is to develop the economic model designed specifically for the chemical processes targeted in this proposal and interface the economic model with UTCHEM production output. Task 4 is on the validation of the framework and performing simulations of oil reservoirs to screen, design and optimize the chemical processes.

  9. Laser isotope separation - a new class of chemical process

    International Nuclear Information System (INIS)

    Lasers may soon find several applications in chemical processing. The applications that have attracted the most research funding to date involve isotope separation for the nuclear industry. These isotopes have an unusually high value (≥$1000/kg) compared to bulk chemicals (∼$1/kg) and are generally required in very large quantities. In a laser isotope separation process, light is used to convert a separation that is very difficult or even impossible by conventional chemical engineering techniques to one that is readily handled by conventional separation technology. For some isotopes this can result in substantial capital and energy savings. A uranium enrichment process developed at the Lawrence Livermore National Laboratory is the closest to commercialization of the large scale laser isotope separation processes. Of particular interest to the Canadian nuclear industry are the laser separation of deuterium, tritium, zirconium-90 and carbon-14. In this paper, the basic principles behind laser isotope separation are reviewed and brief dscriptions of the more developed processes are given

  10. Methods and tools for sustainable chemical process design

    DEFF Research Database (Denmark)

    Loureiro da Costa Lira Gargalo, Carina; Chairakwongsa, Siwanat; Quaglia, Alberto;

    2015-01-01

    As the pressure on chemical and biochemical processes to achieve a more sustainable performance increases, the need to define a systematic and holistic way to accomplish this is becoming more urgent. In this chapter, a multilevel computer-aided framework for systematic design of more sustainable...... chemical processes is presented. The framework allows the use of appropriate computer-aided methods and tools in a hierarchical manner according to a developed work flow for a multilevel criteria analysis that helps generate competing and more sustainable process design options. The application...... of the framework as well as the related computer-aided methods and tools are highlighted through a case study involving the production of bioethanol from various renewable raw materials....

  11. Approaches to Chemical and Biochemical Information and Signal Processing

    Science.gov (United States)

    Privman, Vladimir

    2012-02-01

    We outline models and approaches for error control required to prevent buildup of noise when ``gates'' and other ``network elements'' based on (bio)chemical reaction processes are utilized to realize stable, scalable networks for information and signal processing. We also survey challenges and possible future research. [4pt] [1] Control of Noise in Chemical and Biochemical Information Processing, V. Privman, Israel J. Chem. 51, 118-131 (2010).[0pt] [2] Biochemical Filter with Sigmoidal Response: Increasing the Complexity of Biomolecular Logic, V. Privman, J. Halamek, M. A. Arugula, D. Melnikov, V. Bocharova and E. Katz, J. Phys. Chem. B 114, 14103-14109 (2010).[0pt] [3] Towards Biosensing Strategies Based on Biochemical Logic Systems, E. Katz, V. Privman and J. Wang, in: Proc. Conf. ICQNM 2010 (IEEE Comp. Soc. Conf. Publ. Serv., Los Alamitos, California, 2010), pages 1-9.

  12. Process/Equipment Co-Simulation on Syngas Chemical Looping Process

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Liang; Zhou, Qiang; Fan, Liang-Shih

    2012-09-30

    The chemical looping strategy for fossil energy applications promises to achieve an efficient energy conversion system for electricity, liquid fuels, hydrogen and/or chemicals generation, while economically separate CO{sub 2} by looping reaction design in the process. Chemical looping particle performance, looping reactor engineering, and process design and applications are the key drivers to the success of chemical looping process development. In order to better understand and further scale up the chemical looping process, issues such as cost, time, measurement, safety, and other uncertainties need to be examined. To address these uncertainties, advanced reaction/reactor modeling and process simulation are highly desired and the modeling efforts can accelerate the chemical looping technology development, reduce the pilot-scale facility design time and operating campaigns, as well as reduce the cost and technical risks. The purpose of this work is thus to conduct multiscale modeling and simulations on the key aspects of chemical looping technology, including particle reaction kinetics, reactor design and operation, and process synthesis and optimization.

  13. Static and dynamic properties of curved vapour-liquid interfaces by massively parallel molecular dynamics simulation

    CERN Document Server

    Horsch, Martin T; Vrabec, Jadran; Glass, Colin W; Niethammer, Christoph; Bernreuther, Martin F; Müller, Erich A; Jackson, George

    2011-01-01

    Curved fluid interfaces are investigated on the nanometre length scale by molecular dynamics simulation. Thereby, droplets surrounded by a metastable vapour phase are stabilized in the canonical ensemble. Analogous simulations are conducted for cylindrical menisci separating vapour and liquid phases under confinement in planar nanopores. Regarding the emergence of nanodroplets during nucleation, a non-equilibrium phenomenon, both the non-steady dynamics of condensation processes and stationary quantities related to supersaturated vapours are considered. Results for the truncated and shifted Lennard-Jones fluid and for mixtures of quadrupolar fluids confirm the applicability of the capillarity approximation and the classical nucleation theory.

  14. New trajectory driven aerosol and chemical process model: chemical and aerosol Lagrangian model (CALM)

    OpenAIRE

    Tunved, P.; D. G. Partridge; Korhonen, H.

    2010-01-01

    A new Chemical and Aerosol Lagrangian Model (CALM) have been developed and tested. The model incorporates all central aerosol dynamical processes, from nucleation, condensation, coagulation and deposition to cloud formation and in-cloud processing. The model is tested and evaluated against observations performed at the SMEAR II station located at Hyytiälä (61°51' N, 24°17' E) over a time period of two years, 2000–2001. The model shows good agreement with measurements thro...

  15. Chemical oxygen demand reduction in coffee wastewater through chemical flocculation and advanced oxidation processes

    Institute of Scientific and Technical Information of China (English)

    ZAYAS Pérez Teresa; GEISSLER Gunther; HERNANDEZ Fernando

    2007-01-01

    The removal of the natural organic matter present in coffee processing wastewater through chemical coagulation-flocculatio and advanced oxidation processes(AOP)had been studied.The effectiveness of the removal of natural organic matter using commercial flocculants and UV/H202,UVO3 and UV/H-H202/O3 processes was determined under acidic conditions.For each of these processes,different operational conditions were explored to optimize the treatment efficiency of the coffee wastewater.Coffee wastewater is characterized by a high chemical oxygen demand(COD)and low total suspended solids.The outcomes of coffee wastewater reeatment using coagulation-flocculation and photodegradation processes were assessed in terms of reduction of COD,color,and turbidity.It was found that a reductiOn in COD of 67%could be realized when the coffee wastewater was treated by chemical coagulation-flocculatlon witll lime and coagulant T-1.When coffee wastewater was treated by coagulation-flocculation in combination with UV/H202,a COD reduction of 86%was achieved,although only after prolonged UV irradiation.Of the three advanced oxidation processes considered,UV/H202,uv/03 and UV/H202/03,we found that the treatment with UV/H2O2/O3 was the most effective,with an efficiency of color,turbidity and further COD removal of 87%,when applied to the flocculated coffee wastewater.

  16. Chemical oxygen demand reduction in coffee wastewater through chemical flocculation and advanced oxidation processes.

    Science.gov (United States)

    Zayas Pérez, Teresa; Geissler, Gunther; Hernandez, Fernando

    2007-01-01

    The removal of the natural organic matter present in coffee processing wastewater through chemical coagulation-flocculation and advanced oxidation processes (AOP) had been studied. The effectiveness of the removal of natural organic matter using commercial flocculants and UV/H2O2, UV/O3 and UV/H2O2/O3 processes was determined under acidic conditions. For each of these processes, different operational conditions were explored to optimize the treatment efficiency of the coffee wastewater. Coffee wastewater is characterized by a high chemical oxygen demand (COD) and low total suspended solids. The outcomes of coffee wastewater treatment using coagulation-flocculation and photodegradation processes were assessed in terms of reduction of COD, color, and turbidity. It was found that a reduction in COD of 67% could be realized when the coffee wastewater was treated by chemical coagulation-flocculation with lime and coagulant T-1. When coffee wastewater was treated by coagulation-flocculation in combination with UV/H2O2, a COD reduction of 86% was achieved, although only after prolonged UV irradiation. Of the three advanced oxidation processes considered, UV/H2O2, UV/O3 and UV/H2O2/O3, we found that the treatment with UV/H2O2/O3 was the most effective, with an efficiency of color, turbidity and further COD removal of 87%, when applied to the flocculated coffee wastewater. PMID:17918591

  17. Study on microwave assisted process in chemical extraction

    International Nuclear Information System (INIS)

    The microwave assisted process is a revolutionary method of extraction that reduces the extraction time to as little as a few seconds, with up to a ten-fold decrease in the use of solvents. The target material is immersed in solvent that is transparent to microwaves, so only the target material is heated, and because of the microwaves tend to heat the inside of the material quickly, the target chemical are expelled in a few seconds. benefits from this process include significant reductions in the amount of energy required and substantial reductions in the cost and dispose of hazardous solvents. A thorough review has been displayed on: using the microwave in extraction, applications of microwave in industry, process flow diagram, mechanism of the process and comparison between microwave process and other extraction techniques (soxhlet, steam distillation and supercritical fluid). This review attempts to summarize the studies about microwave assisted process as a very promising technique. (Author)

  18. Computer-Aided Multiscale Modelling for Chemical Process Engineering

    DEFF Research Database (Denmark)

    Morales Rodriguez, Ricardo; Gani, Rafiqul

    2007-01-01

    Chemical processes are generally modeled through monoscale approaches, which, while not adequate, satisfy a useful role in product-process design. In this case, use of a multi-dimensional and multi-scale model-based approach has importance in product-process development. A computer-aided framework......T) for model translation, analysis and solution. The integration of ModDev, MoT and ICAS or any other external software or process simulator (using COM-Objects) permits the generation of different models and/or process configurations for purposes of simulation, design and analysis. Consequently, it is possible...... for model generation, analysis, solution and implementation is necessary for the development and application of the desired model-based approach for product-centric process design/analysis. This goal is achieved through the combination of a system for model development (ModDev), and a modelling tool (Mo...

  19. Material design of plasma-enhanced chemical vapour deposition SiCH films for low-k cap layers in the further scaling of ultra-large-scale integrated devices-Cu interconnects

    Directory of Open Access Journals (Sweden)

    Hideharu Shimizu, Shuji Nagano, Akira Uedono, Nobuo Tajima, Takeshi Momose and Yukihiro Shimogaki

    2013-01-01

    Full Text Available Cap layers for Cu interconnects in ultra-large-scale integrated devices (ULSIs, with a low dielectric constant (k-value and strong barrier properties against Cu and moisture diffusion, are required for the future further scaling of ULSIs. There is a trade-off, however, between reducing the k-value and maintaining strong barrier properties. Using quantum mechanical simulations and other theoretical computations, we have designed ideal dielectrics: SiCH films with Si–C2H4–Si networks. Such films were estimated to have low porosity and low k; thus they are the key to realizing a cap layer with a low k and strong barrier properties against diffusion. For fabricating these ideal SiCH films, we designed four novel precursors: isobutyl trimethylsilane, diisobutyl dimethylsilane, 1, 1-divinylsilacyclopentane and 5-silaspiro [4,4] noname, based on quantum chemical calculations, because such fabrication is difficult by controlling only the process conditions in plasma-enhanced chemical vapor deposition (PECVD using conventional precursors. We demonstrated that SiCH films prepared using these newly designed precursors had large amounts of Si–C2H4–Si networks and strong barrier properties. The pore structure of these films was then analyzed by positron annihilation spectroscopy, revealing that these SiCH films actually had low porosity, as we designed. These results validate our material and precursor design concepts for developing a PECVD process capable of fabricating a low-k cap layer.

  20. Material design of plasma-enhanced chemical vapour deposition SiCH films for low-k cap layers in the further scaling of ultra-large-scale integrated devices-Cu interconnects

    International Nuclear Information System (INIS)

    Cap layers for Cu interconnects in ultra-large-scale integrated devices (ULSIs), with a low dielectric constant (k-value) and strong barrier properties against Cu and moisture diffusion, are required for the future further scaling of ULSIs. There is a trade-off, however, between reducing the k-value and maintaining strong barrier properties. Using quantum mechanical simulations and other theoretical computations, we have designed ideal dielectrics: SiCH films with Si–C2H4–Si networks. Such films were estimated to have low porosity and low k; thus they are the key to realizing a cap layer with a low k and strong barrier properties against diffusion. For fabricating these ideal SiCH films, we designed four novel precursors: isobutyl trimethylsilane, diisobutyl dimethylsilane, 1, 1-divinylsilacyclopentane and 5-silaspiro [4,4] noname, based on quantum chemical calculations, because such fabrication is difficult by controlling only the process conditions in plasma-enhanced chemical vapor deposition (PECVD) using conventional precursors. We demonstrated that SiCH films prepared using these newly designed precursors had large amounts of Si–C2H4–Si networks and strong barrier properties. The pore structure of these films was then analyzed by positron annihilation spectroscopy, revealing that these SiCH films actually had low porosity, as we designed. These results validate our material and precursor design concepts for developing a PECVD process capable of fabricating a low-k cap layer. (paper)

  1. ROBUST TEMPERATURE CONTROLLER DESIGN FOR A CHEMICAL PROCESS

    Directory of Open Access Journals (Sweden)

    G.Glan Devadhas

    2010-10-01

    Full Text Available This paper attempts to tuning out a new PID control strategy to provide Robust Control for a Chemical process. Chemical process control is a challenging problem due to the strong on-line non-linearity and extreme sensitivity to disturbances of the process. The proposed method has the advantage that it takes into account all the parameters variations associated with the process. The variations in the process parameters are modeled as a gaussian noise and an adaptive gaussian filter is placed in the feedback path. The adaptivegaussian filter in the feedback path adapts its filter coefficients based on a kalman estimation algorithm. This adaptive filter adapts so as to maintain the mean square error a minimum. The LQG (Linear Quadratic Gaussian in Robust Control is used in designing of the proposed strategy. The analysis of a PID tuning [7] strategy and the necessity of such an adaptive strategy is also explored in this paper. The proposed strategy of Robust Control has been designed for a First Order Lag Plus Delay (FOLPD process. The proposed strategy ofRobust Control has been simulated for an FOLPD process in SIMULINK.

  2. Surface chemical studies of chemical vapour deposited diamond thin films

    CERN Document Server

    Proffitt, S

    2001-01-01

    could not easily be correlated to the bulk film properties. It is suggested that electron emission arises from the graphite component of graphite- diamond grain boundaries that are present in the nanocrystalline films. species. The adsorbed O and Cl species are more strongly bound to the K layer than they are to the diamond substrate, so thermal desorption of K from the K/CI/diamond or K/O/diamond surface results also in the simultaneous loss ofO and Cl. The phosphorus precursor trisdimethylaminophosphine (TDMAP) has a negligible reactive sticking probability on the clean diamond surface. This can be increased by thermal cracking of the gas phase precursor by a heated filament, resulting in non-activated adsorption to produce an adlayer containing a mixture of surface-bound ligands and phosphorus containing species. The ligands were readily lost upon heating, leaving P, some of which was lost from the surface at higher temperatures. Pre-hydrogenation of the diamond surface inhibited the uptake of cracked TDMA...

  3. Grand Equilibrium: vapour-liquid equilibria by a new molecular simulation method

    CERN Document Server

    Vrabec, J

    2009-01-01

    A new molecular simulation method for the calculation of vapour-liquid equilibria of mixtures is presented. In this method, the independent thermodynamic variables are temperature and liquid composition. In the first step, one isobaric isothermal simulation for the liquid phase is performed, in which the chemical potentials of all components and their derivatives with respect to the pressure, i.e., the partial molar volumes, are calculated. From these results, first order Taylor series expansions for the chemical potentials as functions of the pressure $\\mu_i(p)$ at constant liquid composition are determined. That information is needed, as the specified pressure in the liquid will generally not be equal to the equilibrium pressure, which has to be found in the course of a vapour simulation. In the second step, one pseudo grand canonical simulation for the vapour phase is performed, where the chemical potentials are set according to the instantaneous pressure $p^v$ using the previously determined function $\\mu...

  4. Microbiology and atmospheric processes: chemical interactions of primary biological aerosols

    Directory of Open Access Journals (Sweden)

    L. Deguillaume

    2008-07-01

    Full Text Available This paper discusses the influence of primary biological aerosols (PBA on atmospheric chemistry and vice versa through microbiological and chemical properties and processes. Several studies have shown that PBA represent a significant fraction of air particulate matter and hence affect the microstructure and water uptake of aerosol particles. Moreover, airborne micro-organisms, namely fungal spores and bacteria, can transform chemical constituents of the atmosphere by metabolic activity. Recent studies have emphasized the viability of bacteria and metabolic degradation of organic substances in cloud water. On the other hand, the viability and metabolic activity of airborne micro-organisms depend strongly on physical and chemical atmospheric parameters such as temperature, pressure, radiation, pH value and nutrient concentrations. In spite of recent advances, however, our knowledge of the microbiological and chemical interactions of PBA in the atmosphere is rather limited. Further targeted investigations combining laboratory experiments, field measurements, and modelling studies will be required to characterize the chemical feedbacks, microbiological activities at the air/snow/water interface supplied to the atmosphere.

  5. ENHANCED CHEMICAL CLEANING: A NEW PROCESS FOR CHEMICALLY CLEANING SAVANNAH RIVER WASTE TANKS

    Energy Technology Data Exchange (ETDEWEB)

    Ketusky, E; Neil Davis, N; Renee Spires, R

    2008-01-17

    The Savannah River Site (SRS) has 49 high level waste (HLW) tanks that must be emptied, cleaned, and closed as required by the Federal Facilities Agreement. The current method of chemical cleaning uses several hundred thousand gallons per tank of 8 weight percent (wt%) oxalic acid to partially dissolve and suspend residual waste and corrosion products such that the waste can be pumped out of the tank. This adds a significant quantity of sodium oxalate to the tanks and, if multiple tanks are cleaned, renders the waste incompatible with the downstream processing. Tank space is also insufficient to store this stream given the large number of tanks to be cleaned. Therefore, a search for a new cleaning process was initiated utilizing the TRIZ literature search approach, and Chemical Oxidation Reduction Decontamination--Ultraviolet (CORD-UV), a mature technology currently used for decontamination and cleaning of commercial nuclear reactor primary cooling water loops, was identified. CORD-UV utilizes oxalic acid for sludge dissolution, but then decomposes the oxalic acid to carbon dioxide and water by UV treatment outside the system being treated. This allows reprecipitation and subsequent deposition of the sludge into a selected container without adding significant volume to that container, and without adding any new chemicals that would impact downstream treatment processes. Bench top and demonstration loop measurements on SRS tank sludge stimulant demonstrated the feasibility of applying CORD-UV for enhanced chemical cleaning of SRS HLW tanks.

  6. Integrating chemical engineering fundamentals in the capstone process design project

    DEFF Research Database (Denmark)

    von Solms, Nicolas; Woodley, John; Johnsson, Jan Erik;

    2010-01-01

    of the CDIO standards – especially standard 3 – Integrated Curriculum - means that the course projects must draw on competences provided in other subjects which the students are taking in parallel with Process Design – specifically Process Control and Reaction Engineering. In each semester of the B.......Eng. education, one course is designated the “project” course, which should draw on material learned in parallel courses. In the 6th semester, Process Design is the project course. Process Control and Reaction Engineering are then incorporated into the final plant design project. Specifically, almost all......All B.Eng. courses offered at the Technical University of Denmark (DTU) must now follow CDIO standards. The final “capstone” course in the B.Eng. education is Process Design, which for many years has been typical of chemical engineering curricula worldwide. The course at DTU typically has about 30...

  7. New Vistas in Chemical Product and Process Design.

    Science.gov (United States)

    Zhang, Lei; Babi, Deenesh K; Gani, Rafiqul

    2016-06-01

    Design of chemicals-based products is broadly classified into those that are process centered and those that are product centered. In this article, the designs of both classes of products are reviewed from a process systems point of view; developments related to the design of the chemical product, its corresponding process, and its integration are highlighted. Although significant advances have been made in the development of systematic model-based techniques for process design (also for optimization, operation, and control), much work is needed to reach the same level for product design. Timeline diagrams illustrating key contributions in product design, process design, and integrated product-process design are presented. The search for novel, innovative, and sustainable solutions must be matched by consideration of issues related to the multidisciplinary nature of problems, the lack of data needed for model development, solution strategies that incorporate multiscale options, and reliability versus predictive power. The need for an integrated model-experiment-based design approach is discussed together with benefits of employing a systematic computer-aided framework with built-in design templates. PMID:27088667

  8. New Vistas in Chemical Product and Process Design.

    Science.gov (United States)

    Zhang, Lei; Babi, Deenesh K; Gani, Rafiqul

    2016-06-01

    Design of chemicals-based products is broadly classified into those that are process centered and those that are product centered. In this article, the designs of both classes of products are reviewed from a process systems point of view; developments related to the design of the chemical product, its corresponding process, and its integration are highlighted. Although significant advances have been made in the development of systematic model-based techniques for process design (also for optimization, operation, and control), much work is needed to reach the same level for product design. Timeline diagrams illustrating key contributions in product design, process design, and integrated product-process design are presented. The search for novel, innovative, and sustainable solutions must be matched by consideration of issues related to the multidisciplinary nature of problems, the lack of data needed for model development, solution strategies that incorporate multiscale options, and reliability versus predictive power. The need for an integrated model-experiment-based design approach is discussed together with benefits of employing a systematic computer-aided framework with built-in design templates.

  9. Process Control Systems in the Chemical Industry: Safety vs. Security

    Energy Technology Data Exchange (ETDEWEB)

    Jeffrey Hahn; Thomas Anderson

    2005-04-01

    Traditionally, the primary focus of the chemical industry has been safety and productivity. However, recent threats to our nation’s critical infrastructure have prompted a tightening of security measures across many different industry sectors. Reducing vulnerabilities of control systems against physical and cyber attack is necessary to ensure the safety, security and effective functioning of these systems. The U.S. Department of Homeland Security has developed a strategy to secure these vulnerabilities. Crucial to this strategy is the Control Systems Security and Test Center (CSSTC) established to test and analyze control systems equipment. In addition, the CSSTC promotes a proactive, collaborative approach to increase industry's awareness of standards, products and processes that can enhance the security of control systems. This paper outlines measures that can be taken to enhance the cybersecurity of process control systems in the chemical sector.

  10. EXCITATION AND IONIZATION OF LASER-PUMPED Ba VAPOUR

    OpenAIRE

    Huber, M.; Jahreiss, L.

    1985-01-01

    We describe the excitation and ionization of dense Ba vapour (1019 to 2021 m-3) by resonant (λ = 553.5 nm) laser radiation and discuss the processes responsible for the transfer of energy from the laser-excited atoms into ionization. Ionization was found to be density-dependent and this pointed to collision-dominated ionization mechanisms. It has been established that seed electrons were heated in superelastic collisions with laser-excited atoms, and that subsequent electron-impact excitation...

  11. Vibration and Stability of 3000-hp, Titanium Chemical Process Blower

    Directory of Open Access Journals (Sweden)

    Les Gutzwiller

    2003-01-01

    Full Text Available This 74-in-diameter blower had an overhung rotor design of titanium construction, operating at 50 pounds per square inch gauge in a critical chemical plant process. The shaft was supported by oil-film bearings and was directdriven by a 3000-hp electric motor through a metal disk type of coupling. The operating speed was 1780 rpm. The blower shaft and motor shaft motion was monitored by Bently Nevada proximity probes and a Model 3100 monitoring system.

  12. Quality costs and robustness criteria in chemical process design optimization

    OpenAIRE

    Bernardo, Fernando P.; Pistikopoulos, Efstratios N; Pedro M. Saraiva

    2001-01-01

    The identification and incorporation of quality costs and robustness criteria is becoming a critical issue while addressing chemical process design problems under uncertainty. This article presents a systematic design framework that includes Taguchi loss functions and other robustness criteria within a single-level stochastic optimization formulation, with expected values in the presence of uncertainty being estimated by an efficient cubature technique. The solution obtained defines an optima...

  13. Deuterium excess in the atmospheric water vapour of a Mediterranean coastal wetland: regional vs. local signatures

    Science.gov (United States)

    Delattre, H.; Vallet-Coulomb, C.; Sonzogni, C.

    2015-09-01

    Stable isotopes of water vapour represent a powerful tool for tracing atmospheric vapour origin and mixing processes. Laser spectrometry recently allowed high time-resolution measurements, but despite an increasing number of experimental studies, there is still a need for a better understanding of the isotopic signal variability at different time scales. We present results of in situ measurements of δ18O and δD during 36 consecutive days in summer 2011 in atmospheric vapour of a Mediterranean coastal wetland exposed to high evaporation (Camargue, Rhône River delta, France). The mean composition of atmospheric vapour (δv) is δ18O = -14.66 ‰ and δD = - 95.4 ‰, with data plotting clearly above the local meteoric water line on a δ18O-δD plot, and an average deuterium excess (d) of 21.9 ‰. Important diurnal d variations are observed, and an hourly time scale analysis is necessary to interpret the main processes involved in its variability. After having classified the data according to air mass back trajectories, we analyse the average daily cycles relating to the two main meteorological situations, i.e. air masses originating from North Atlantic Ocean and Mediterranean Sea. In both situations, we show that diurnal fluctuations are driven by (1) the influence of local evaporation, culminating during daytime, and leading to an increase in absolute water vapour concentration associated to a δv enrichment and d increase; (2) vertical air mass redistribution when the Planetary Boundary Layer collapses in the evening, leading to a d decrease, and (3) dew formation during the night, producing a δv depletion with d remaining stable. Using a two-component mixing model, we calculate the average composition of the locally evaporated vapour (δE). We find higher d(E) under North Atlantic air mass conditions, which is consistent with lower humidity conditions. We also suggest that δv measured when the PBL collapses is the most representative of a regional signal

  14. Technical evaluation on some chemical exchange process for uranium enrichment

    International Nuclear Information System (INIS)

    In CEA in France, Asahi Chemical Industry Co., Ltd., in Japan and others, the industrialization of the uranium enrichment by chemical processes has been studied independently for ten years, using large amount of research expenses. In this study, technological examination was carried out on such processes and their separation characteristics, based on the published literatures. As the results, it was recognized that they have sufficient separation capability to aim at the industrialization, and the power required can be limited relatively low. However, very precise plant design and operation control system are required for them, and it is necessary to watch the future course to carry out the objective evaluation of the economic efficiency. The electric power has become a dominant factor in the production cost of enriched uranium. The separation of uranium isotopes with anion exchange resin being developed by Asahi Chemical Industry Co., Ltd., and the isotope separation by electron exchange using solvent extraction method being developed by CEA in France are introduced. Though the equilibrium separation factor is very small, they utilize reversible processes, and have the possibility of large power reduction and the cost reduction due to scaling-up. (Kako, I.)

  15. Numerical simulation of chemical processes in atmospheric plasmas

    Institute of Scientific and Technical Information of China (English)

    Ouyang Jian-Ming; Guo Wei; Wang Long; Shao Fu-Qiu

    2004-01-01

    A model is built to study chemical processes in atmospheric plasmas at low altitude (high pressure) and at high altitude (low pressure). The plasma lifetime and the temporal evolution of the main charged species are presented.The electron number density does not strictly obey the exponential damping law in a long period. The heavy charged species are dominant at low altitude in comparison with the light species at high altitude. Some species of small amount in natural air play an important role in the processes.

  16. Chemical Assessment of White Wine during Fermentation Process

    Directory of Open Access Journals (Sweden)

    Teodora Coldea

    2014-05-01

    Full Text Available There were investigated chemical properties of indigenous white wine varieties (Fetească albă, Fetească regală and Galbenă de Odobeşti during fermentation. The white wine making process took place at Wine Pilot Station of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca. We aimed to monitorize the evolution of fermentation process parameters (temperature, alcohol content, and real extract and the quality of the bottled white wine (total acidity, alcohol content, total sulfur dioxide, total dry extract. The results obtained were in accordance to Romanian Legislation.

  17. Supercritical Water Process for the Chemical Recycling of Waste Plastics

    Science.gov (United States)

    Goto, Motonobu

    2010-11-01

    The development of chemical recycling of waste plastics by decomposition reactions in sub- and supercritical water is reviewed. Decomposition reactions proceed rapidly and selectively using supercritical fluids compared to conventional processes. Condensation polymerization plastics such as PET, nylon, and polyurethane, are relatively easily depolymerized to their monomers in supercritical water. The monomer components are recovered in high yield. Addition polymerization plastics such as phenol resin, epoxy resin, and polyethylene, are also decomposed to monomer components with or without catalysts. Recycling process of fiber reinforced plastics has been studied. Pilot scale or commercial scale plants have been developed and are operating with sub- and supercritical fluids.

  18. ACTINIDE REMOVAL PROCESS SAMPLE ANALYSIS, CHEMICAL MODELING, AND FILTRATION EVALUATION

    Energy Technology Data Exchange (ETDEWEB)

    Martino, C.; Herman, D.; Pike, J.; Peters, T.

    2014-06-05

    Filtration within the Actinide Removal Process (ARP) currently limits the throughput in interim salt processing at the Savannah River Site. In this process, batches of salt solution with Monosodium Titanate (MST) sorbent are concentrated by crossflow filtration. The filtrate is subsequently processed to remove cesium in the Modular Caustic Side Solvent Extraction Unit (MCU) followed by disposal in saltstone grout. The concentrated MST slurry is washed and sent to the Defense Waste Processing Facility (DWPF) for vitrification. During recent ARP processing, there has been a degradation of filter performance manifested as the inability to maintain high filtrate flux throughout a multi-batch cycle. The objectives of this effort were to characterize the feed streams, to determine if solids (in addition to MST) are precipitating and causing the degraded performance of the filters, and to assess the particle size and rheological data to address potential filtration impacts. Equilibrium modelling with OLI Analyzer{sup TM} and OLI ESP{sup TM} was performed to determine chemical components at risk of precipitation and to simulate the ARP process. The performance of ARP filtration was evaluated to review potential causes of the observed filter behavior. Task activities for this study included extensive physical and chemical analysis of samples from the Late Wash Pump Tank (LWPT) and the Late Wash Hold Tank (LWHT) within ARP as well as samples of the tank farm feed from Tank 49H. The samples from the LWPT and LWHT were obtained from several stages of processing of Salt Batch 6D, Cycle 6, Batch 16.

  19. Influence of surface coverage on the chemical desorption process

    CERN Document Server

    Marco, Minissale

    2014-01-01

    In cold astrophysical environments, some molecules are observed in the gas phase whereas they should have been depleted, frozen on dust grains. In order to solve this problem, astrochemists have proposed that a fraction of molecules synthesized on the surface of dust grains could desorb just after their formation. Recently the chemical desorption process has been demonstrated experimentally, but the key parameters at play have not yet been fully understood. In this article we propose a new procedure to analyze the ratio of di-oxygen and ozone synthesized after O atoms adsorption on oxidized graphite. We demonstrate that the chemical desorption efficiency of the two reaction paths (O+O and O+O$_2$) is different by one order of magnitude. We show the importance of the surface coverage: for the O+O reaction, the chemical desorption efficiency is close to 80 $\\%$ at zero coverage and tends to zero at one monolayer coverage. The coverage dependence of O+O chemical desorption is proved by varying the amount of pre-...

  20. Application of repetitive pulsed power technology to chemical processing

    International Nuclear Information System (INIS)

    The numerous sites of soil and water contaminated with organic chemicals present an urgent environmental concern that continues to grow. Electron and x-ray irradiation have been shown to be effective methods to destroy a wide spectrum of organic chemicals, nitrates, nitrites, and cyanide in water by breaking molecules to non-toxic products or entirely mineralizing the by-products to gas, water, and salts. Sandia National Laboratories is developing Repetitive High Energy Pulsed Power (RHEPP) technology capable of producing high average power, broad area electron or x-ray beams. The 300 kW RHEPP-II facility accelerates electrons to 2.5 MeV at 25 kA over 1,000 cm2 in 60 ns pulses at repetition rates of over 100 Hz. Linking this modular treatment capability with the rapid optical-sensing diagnostics and neutral network characterization software algorithms will provide a Smart Waste Treatment (SWaT) system. Such a system would also be applicable for chemical manufacture and processing of industrial waste for reuse or disposal. This talk describes both the HREPP treatment capability and sensing technologies. Measurements of the propagated RHEPP-II beam and dose profiles are presented. Sensors and rapid detection software are discussed with application toward chemical treatment

  1. Phase Correction for ALMA with 183 GHz Water Vapour Radiometers

    CERN Document Server

    Nikolic, Bojan; Graves, Sarah F; Hills, Richard E; Richer, John S

    2013-01-01

    Fluctuating properties of the atmosphere, and in particular its water vapour content, give rise to phase fluctuations of astronomical signals which, if uncorrected, lead to rapid deterioration of performance of (sub)-mm interferometers on long baselines. The Atacama Large Millimetre/submillimeter Array (ALMA) uses a 183 GHz Water Vapour Radiometer (WVR) system to help correct these fluctuations and provide much improved performance on long baselines and at high frequencies. Here we describe the design of the overall ALMA WVR system, the choice of design parameters and the data processing strategy. We also present results of initial tests that demonstrate both the large improvement in phase stability that can be achieved and the very low contribution to phase noise from the WVRs. Finally, we describe briefly the main limiting factors to the accuracy of phase correction seen in these initial tests; namely, the degrading influence of cloud and the residual phase fluctuations that are most likely to be due to var...

  2. Slaughterhouse wastewater treatment by combined chemical coagulation and electrocoagulation process.

    Directory of Open Access Journals (Sweden)

    Edris Bazrafshan

    Full Text Available Slaughterhouse wastewater contains various and high amounts of organic matter (e.g., proteins, blood, fat and lard. In order to produce an effluent suitable for stream discharge, chemical coagulation and electrocoagulation techniques have been particularly explored at the laboratory pilot scale for organic compounds removal from slaughterhouse effluent. The purpose of this work was to investigate the feasibility of treating cattle-slaughterhouse wastewater by combined chemical coagulation and electrocoagulation process to achieve the required standards. The influence of the operating variables such as coagulant dose, electrical potential and reaction time on the removal efficiencies of major pollutants was determined. The rate of removal of pollutants linearly increased with increasing doses of PACl and applied voltage. COD and BOD(5 removal of more than 99% was obtained by adding 100 mg/L PACl and applied voltage 40 V. The experiments demonstrated the effectiveness of chemical and electrochemical techniques for the treatment of slaughterhouse wastewaters. Consequently, combined processes are inferred to be superior to electrocoagulation alone for the removal of both organic and inorganic compounds from cattle-slaughterhouse wastewater.

  3. Slaughterhouse wastewater treatment by combined chemical coagulation and electrocoagulation process.

    Science.gov (United States)

    Bazrafshan, Edris; Kord Mostafapour, Ferdos; Farzadkia, Mehdi; Ownagh, Kamal Aldin; Mahvi, Amir Hossein

    2012-01-01

    Slaughterhouse wastewater contains various and high amounts of organic matter (e.g., proteins, blood, fat and lard). In order to produce an effluent suitable for stream discharge, chemical coagulation and electrocoagulation techniques have been particularly explored at the laboratory pilot scale for organic compounds removal from slaughterhouse effluent. The purpose of this work was to investigate the feasibility of treating cattle-slaughterhouse wastewater by combined chemical coagulation and electrocoagulation process to achieve the required standards. The influence of the operating variables such as coagulant dose, electrical potential and reaction time on the removal efficiencies of major pollutants was determined. The rate of removal of pollutants linearly increased with increasing doses of PACl and applied voltage. COD and BOD(5) removal of more than 99% was obtained by adding 100 mg/L PACl and applied voltage 40 V. The experiments demonstrated the effectiveness of chemical and electrochemical techniques for the treatment of slaughterhouse wastewaters. Consequently, combined processes are inferred to be superior to electrocoagulation alone for the removal of both organic and inorganic compounds from cattle-slaughterhouse wastewater.

  4. New trajectory-driven aerosol and chemical process model Chemical and Aerosol Lagrangian Model (CALM)

    OpenAIRE

    Tunved, P.; D. G. Partridge; Korhonen, H.

    2010-01-01

    A new Chemical and Aerosol Lagrangian Model (CALM) has been developed and tested. The model incorporates all central aerosol dynamical processes, from nucleation, condensation, coagulation and deposition to cloud formation and in-cloud processing. The model is tested and evaluated against observations performed at the SMEAR II station located at Hyytiälä (61° 51' N, 24° 17' E) over a time period of two years, 2000–2001. The model shows good agreement with measurements throughout mos...

  5. Incorporation of chemical kinetic models into process control

    International Nuclear Information System (INIS)

    An important consideration in chemical process control is to determine the precise rationing of reactant streams, particularly when a large time delay exists between the mixing of the reactants and the measurement of the product. In this paper, a method is described for incorporating chemical kinetic models into the control strategy in order to achieve optimum operating conditions. The system is first characterized by determining a reaction rate surface as a function of all input reactant concentrations over a feasible range. A nonlinear constrained optimization program is then used to determine the combination of reactants which produces the specified yield at minimum cost. This operating condition is then used to establish the nominal concentrations of the reactants. The actual operation is determined through a feedback control system employing a Smith predictor. The method is demonstrated on a laboratory bench scale enzyme reactor

  6. Chemical evolution of the Earth: Equilibrium or disequilibrium process?

    Science.gov (United States)

    Sato, M.

    1985-01-01

    To explain the apparent chemical incompatibility of the Earth's core and mantle or the disequilibrium process, various core forming mechanisms have been proposed, i.e., rapid disequilibrium sinking of molten iron, an oxidized core or protocore materials, and meteorite contamination of the upper mantle after separation from the core. Adopting concepts used in steady state thermodynamics, a method is devised for evaluating how elements should distribute stable in the Earth's interior for the present gradients of temperature, pressure, and gravitational acceleration. Thermochemical modeling gives useful insights into the nature of chemical evolution of the Earth without overly speculative assumptions. Further work must be done to reconcile siderophile elements, rare gases, and possible light elements in the outer core.

  7. Mechanistic, kinetic, and processing aspects of tungsten chemical mechanical polishing

    Science.gov (United States)

    Stein, David

    This dissertation presents an investigation into tungsten chemical mechanical polishing (CMP). CMP is the industrially predominant unit operation that removes excess tungsten after non-selective chemical vapor deposition (CVD) during sub-micron integrated circuit (IC) manufacture. This work explores the CMP process from process engineering and fundamental mechanistic perspectives. The process engineering study optimized an existing CMP process to address issues of polish pad and wafer carrier life. Polish rates, post-CMP metrology of patterned wafers, electrical test data, and synergy with a thermal endpoint technique were used to determine the optimal process. The oxidation rate of tungsten during CMP is significantly lower than the removal rate under identical conditions. Tungsten polished without inhibition during cathodic potentiostatic control. Hertzian indenter model calculations preclude colloids of the size used in tungsten CMP slurries from indenting the tungsten surface. AFM surface topography maps and TEM images of post-CMP tungsten do not show evidence of plow marks or intergranular fracture. Polish rate is dependent on potassium iodate concentration; process temperature is not. The colloid species significantly affects the polish rate and process temperature. Process temperature is not a predictor of polish rate. A process energy balance indicates that the process temperature is predominantly due to shaft work, and that any heat of reaction evolved during the CMP process is negligible. Friction and adhesion between alumina and tungsten were studied using modified AFM techniques. Friction was constant with potassium iodate concentration, but varied with applied pressure. This corroborates the results from the energy balance. Adhesion between the alumina and the tungsten was proportional to the potassium iodate concentration. A heuristic mechanism, which captures the relationship between polish rate, pressure, velocity, and slurry chemistry, is presented

  8. Vapour sensitivity of an ALD hierarchical photonic structure inspired by Morpho.

    Science.gov (United States)

    Poncelet, Olivier; Tallier, Guillaume; Mouchet, Sébastien R; Crahay, André; Rasson, Jonathan; Kotipalli, Ratan; Deparis, Olivier; Francis, Laurent A

    2016-01-01

    The unique architecture of iridescent Morpho butterfly scales is known to exhibit different optical responses to various vapours. However, the mechanism behind this phenomenon is not fully quantitatively understood. This work reports on process developments in the micro-fabrication of a Morpho-inspired photonic structure in atomic layer deposited (ALD) materials in order to investigate the vapour optical sensitivity of such artificial nanostructures. By developing recipes for dry and wet etching of ALD oxides, we micro-fabricated two structures: one combining Al2O3 and TiO2, and the other combining Al2O3 and HfO2. For the first time, we report the optical response of such ALD Morpho-like structures measured under a controlled flow of either ethanol or isopropyl alcohol (IPA) vapour. In spite of the small magnitude of the effect, the results show a selective vapour response (depending on the materials used). PMID:27159922

  9. The Use of VMD Data/Model to Test Different Thermodynamic Models for Vapour-Liquid Equilibrium

    DEFF Research Database (Denmark)

    Abildskov, Jens; Azquierdo-Gil, M.A.; Jonsson, Gunnar Eigil

    2004-01-01

    Vacuum membrane distillation (VMD) has been studied as a separation process to remove volatile organic compounds from aqueous streams. A vapour pressure difference across a microporous hydrophobic membrane is the driving force for the mass transport through the membrane pores (this transport take...... place in vapour phase). The vapour pressure difference is obtained in VMD processes by applying a vacuum on one side of the membrane. The membrane acts as a mere support for the liquid-vapour equilibrium. The evaporation of the liquid stream takes place on the feed side of the membrane...... values; membrane type: PTFE/PP/PVDF; feed flow rate; feed temperature. A comparison is made between different thermodynamic models for calculating the vapour-liquid equilibrium at the membrane/pore interface. (C) 2004 Elsevier B.V. All rights reserved....

  10. A chemical cleaning process with Cerium (IV)-sulfuric acid

    International Nuclear Information System (INIS)

    A chemical cleaning process with a high decontamination factor (DF) is requested for decommissioning. Usually, the process should be qualified with the features, such as the feasibility of treating large or complicated form waste, the minimization of secondary waste. Therefore, a powerful technique of redox decontamination process with Ce+4/Ce+3 has been studied at INER. First, the redox of cerium ion with electrolytic method was developed. Two kinds of home-made electrolyzer were used. One is with an ion-exchange membrane, and the other one is with a ceramic separator. Second, factors influencing the decontamination efficiency, such as the concentration of Ce+4, regeneration current density, temperature, acidity of solution were all studied experimentally, and the optimum conditions were specified too. Third, the liquid waste recycling and treatment were developed with electrodialysis and ion-exchange absorption methods. Finally, the hot test was proceeded with the contaminated metals from DCR of nuclear facility. (author)

  11. 'Exalting Understanding without Depressing Imagination': Depicting Chemical Process

    Directory of Open Access Journals (Sweden)

    David Knight

    2003-10-01

    Full Text Available Alchemists' illustrations indicated through symbols the processes being attempted; but with Lavoisier's Elements (1789, the place of imagination and symbolic language in chemistry was much reduced. He sought to make chemistry akin to algebra and its illustrations merely careful depictions of apparatus. Although younger contemporaries sought, and found in electrochemistry, a dynamical approach based upon forces rather than weights, they found this very difficult to picture. Nevertheless, by looking at chemical illustrations in the eighty years after Lavoisier's revolutionary book, we can learn about how reactions were carried out, and interpreted, and see that there was scope for aesthetic judgement and imagination.

  12. Fundamental studies of chemical vapor deposition diamond growth processes

    International Nuclear Information System (INIS)

    We are developing laser spectroscopic techniques to foster a fundamental understanding of diamond film growth by hot filament chemical vapor deposition (CVD). Several spectroscopic techniques are under investigation to identify intermediate species present in the bulk reactor volume, the thin active volume immediately above the growing film, and the actual growing surface. Such a comprehensive examination of the overall deposition process is necessary because a combination of gas phase and surface chemistry is probably operating. Resonantly enhanced multiphoton ionization (REMPI) techniques have been emphasized. A growth rector that permits through-the-substrate gas sampling for REMPI/time-of-flight mass spectroscopy has been developed. 7 refs., 2 figs

  13. Optimization of radiation-chemical process of trichloroethylene oxidation

    International Nuclear Information System (INIS)

    Kinetics of trichloroethylene (TCE) oxidation under the effect of gamma-irradiation is investigated. It is shown that the reaction of TCE oxidation proceeds according to the chain mechanism. At the temperature of 60 deg C in the dose rate range from 1.1015 to 1.5x1016 eV(cm3xs) radiation-chemical yield changes from 1.5x104 to 5x103 molecules/100 eV. It is found that the reaction rate practically does not depend upon oxygen concentration and is directly proportional to the TCE concentration and the dose rate. The process optimization is studied

  14. Large deviations for two scale chemical kinetic processes

    CERN Document Server

    Li, Tiejun

    2015-01-01

    We formulate the large deviations for a class of two scale chemical kinetic processes motivated from biological applications. The result is successfully applied to treat a genetic switching model with positive feedbacks. The corresponding Hamiltonian is convex with respect to the momentum variable as a by-product of the large deviation theory. This property ensures its superiority in the rare event simulations compared with the result obtained by formal WKB asymptotics. The result is of general interest to understand the large deviations for multiscale problems.

  15. Relationship between snow microstructure and physical and chemical processes

    Directory of Open Access Journals (Sweden)

    T. Bartels-Rausch

    2012-11-01

    Full Text Available Ice and snow in the environment are important because they not only act as a host to rich chemistry but also provide a matrix for physical exchanges of contaminants within the ecosystem. This review discusses how the structure of snow influences both chemical reactivity and physical processes, which thereby makes snow a unique medium for study. The focus is placed on impacts of the presence of liquid and surface disorder using many experimental studies, simulations, and field observations from the molecular to the micro-scale.

  16. Integrating chemical engineering fundamentals in the capstone process design project

    OpenAIRE

    von Solms, Nicolas; Woodley, John; Johnsson, Jan Erik; Abildskov, Jens

    2010-01-01

    All B.Eng. courses offered at the Technical University of Denmark (DTU) must now follow CDIO standards. The final “capstone” course in the B.Eng. education is Process Design, which for many years has been typical of chemical engineering curricula worldwide. The course at DTU typically has about 30 students. The B.Eng. education lasts for 3½ years (seven semesters), of which the 5th semester consists of practical training with a company and the final (7th) semester consists of a research proje...

  17. Electronic dissipation processes during chemical reactions on surfaces

    CERN Document Server

    Stella, Kevin

    2012-01-01

    Hauptbeschreibung Every day in our life is larded with a huge number of chemical reactions on surfaces. Some reactions occur immediately, for others an activation energy has to be supplied. Thus it happens that though a reaction should thermodynamically run off, it is kinetically hindered. Meaning the partners react only to the thermodynamically more stable product state within a mentionable time if the activation energy of the reaction is supplied. With the help of catalysts the activation energy of a reaction can be lowered. Such catalytic processes on surfaces are widely used in industry. A

  18. Co-TPP functionalized carbon nanotube composites for detection of nitrobenzene and chlorobenzene vapours

    Indian Academy of Sciences (India)

    Swasti Saxena; G S S SAINI; A L Verma

    2015-04-01

    We report preparation of nanocomposites by non-covalent functionalization of carbon nanotubes (CNTs) with metal-tetraphenylporphyrins (M-TPP). Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM) results suggest formation of nanosized clusters of Co-TPP around the CNTs surface. X-ray diffraction studies indicate electronic charge re-distribution and strong interactions among CNTs and Co-TPP on functionalization. The films of the hybrid CNT–M-TPP nanocomposite exhibit change in conductivity on exposure to some chemical vapours. In the present work, the films prepared from the cobalt-TPP functionalized CNTs hybrid composites have been investigated for the detection of chlorobenzene (CB) and nitrobenzene (NB) vapours at room temperature. The films show response time of few seconds on exposure to both the NB and CB vapours while the recovery time for NB is significantly different compared to CB. A distinct and highly reproducible response pattern in the relative changes in resistance, recovery and response times on exposure to the vapours of NB, CB and few other chemicals at room temperature has been exploited to differentiate CB and NB vapours from one another.

  19. Chemical processes in the turbine and exhaust nozzle

    Energy Technology Data Exchange (ETDEWEB)

    Lukachko, S.P.; Waitz, I.A. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Aero-Environmental Lab.; Miake-Lye, R.C.; Brown, R.C.; Anderson, M.R. [Aerodyne Research, Inc., Billerica, MA (United States); Dawes, W.N. [University Engineering Dept., Cambridge (United Kingdom). Whittle Lab.

    1997-12-31

    The objective is to establish an understanding of primary pollutant, trace species, and aerosol chemical evolution as engine exhaust travels through the nonuniform, unsteady flow fields of the turbine and exhaust nozzle. An understanding of such processes is necessary to provide accurate inputs for plume-wake modeling efforts and is therefore a critical element in an assessment of the atmospheric effects of both current and future aircraft. To perform these studies, a numerical tool was developed combining the calculation of chemical kinetics and one-, two-, or three-dimensional (1-D, 2-D, 3-D) Reynolds-averaged flow equations. Using a chemistry model that includes HO{sub x}, NO{sub y}, SO{sub x}, and CO{sub x} reactions, several 1-D parametric analyses were conducted for the entire turbine and exhaust nozzle flow path of a typical advanced subsonic engine to understand the effects of various flow and chemistry uncertainties on a baseline 1-D result. These calculations were also used to determine parametric criteria for judging 1-D, 2-D, and 3-D modeling requirements as well as to provide information about chemical speciation at the nozzle exit plane. (author) 9 refs.

  20. Oxygen permeation and thermo-chemical stability of oxygen separation membrane materials for the oxyfuel process

    Energy Technology Data Exchange (ETDEWEB)

    Ellett, Anna Judith

    2009-07-01

    The reduction of CO{sub 2} emissions, generally held to be one of the most significant contributors to global warming, is a major technological issue. CO{sub 2} Capture and Storage (CCS) techniques applied to large stationary sources such as coal-fired power plants could efficiently contribute to the global carbon mitigation effort. The oxyfuel process, which consists in the burning of coal in an oxygen-rich atmosphere to produce a flue gas highly concentrated in CO{sub 2}, is a technology considered for zero CO{sub 2} emission coal-fired power plants. The production of this O{sub 2}-rich combustion gas from air can be carried out using high purity oxygen separation membranes. Some of the most promising materials for this application are mixed ionic-electronic conducting (MIEC) materials with perovskite and K{sub 2}NiF{sub 4} perovskite-related structures. The present work examines the selection of La{sub 0.58}Sr{sub 0.4}Co{sub 0.2}Fe{sub 0.8}O{sub 3-{delta}} (LSCF58), La{sub 2}NiO{sub 4+{delta}}, Pr{sub 0.58}Sr{sub 0.4}Co{sub 0.2}Fe{sub 0.8}O{sub 3-{delta}} (PSCF58) and Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3-{delta}} (BSCF50) as membrane materials for the separation of O{sub 2} and N{sub 2} in the framework of the oxyfuel process with flue gas recycling. Annealing experiments were carried out on pellets exposed to CO{sub 2}, water vapour, O{sub 2} and Cr{sub 2}O{sub 3} in order to determine the thermo-chemical resistance to the atmospheres and the high temperature conditions present during membrane operation in a coal-fired power plant. The degradation of their microstructure was investigated using Scanning Electron Microscopy (SEM) in combination with electron dispersive spectroscopy (EDS) as well as X-Ray Diffraction (XRD). Also, the oxygen permeation fluxes of selected membranes were investigated as a function of temperature. The membrane materials selected were characterised using thermo-analytical techniques such as precision thermogravimetric

  1. The vapour pressure of americium(III) chloride

    International Nuclear Information System (INIS)

    Based on the method described by Fischer, an ultramicro-size appratus was developed for static determination of the saturation vapour pressure of highly radioactive materials. The apparatus was tested with MgCl2, MnCl2, HoCl3 and ScF3. The vapour pressure curves of MgCl2 and MnCl2 were in good agreement with other publications and thus proved the efficiency of the apparatus in spite of its difficulties of handling. The values measured for HoCl3 and ScF3 differed from those of earlier publications. However, these deviations have been observed before and may be the result of the different measuring principles of static and dynamic methods. For AmCl3, the following vapour pressure equation was established: log psub(Torr)=-(11826/T)+10.7. The thermodynamic parameters of the evaporation process were calculated on this basis, and the values for AmBr3 and PnCl3 were determined by extrapolation. (orig.)

  2. Characterization of TiO{sub 2} thin films obtained by metal-organic chemical vapour deposition; Caracterizacao de filmes finos de TiO{sub 2} obtidos por deposicao quimica em fase vapor

    Energy Technology Data Exchange (ETDEWEB)

    Carriel, Rodrigo Crociati

    2015-07-01

    Titanium dioxide (TiO{sub 2}) thin films were grown on silicon substrate (100) by MOCVD process (chemical deposition of organometallic vapor phase). The films were grown at 400, 500, 600 and 700 ° C in a conventional horizontal equipment. Titanium tetraisopropoxide was used as source of both oxygen and titanium. Nitrogen was used as carrier and purge gas. X-ray diffraction technique was used for the characterization of the crystalline structure. Scanning electron microscopy with field emission gun was used to evaluate the morphology and thickness of the films. The films grown at 400 and 500°C presented anatase phase. The film grown at 600ºC presented rutile besides anatase phase, while the film grown at 700°C showed, in addition to anatase and rutile, brookite phase. In order to evaluate the electrochemical behavior of the films cyclic voltammetry technique was used. The tests revealed that the TiO2 films formed exclusively by the anatase phase exhibit strong capacitive character. The anodic current peak is directly proportional to the square root of the scanning rate for films grown at 500ºC, suggesting that linear diffusion is the predominant mechanism of cations transport. It was observed that in the film grown during 60 minutes the Na+ ions intercalation and deintercalation easily. The films grown in the other conditions did not present the anodic current peak, although charge was accumulated in the film. (author)

  3. Challenges in simulation of chemical processes in combustion furnaces

    Energy Technology Data Exchange (ETDEWEB)

    Hupa, M.; Kilpinen, P. [Aabo Akademi, Turku (Finland)

    1996-12-31

    The presentation gives an introduction to some of the present issues and problems in treating the complex chemical processes in combustion. The focus is in the coupling of the hydrocarbon combustion process with nitrogen oxide formation and destruction chemistry in practical furnaces or flames. Detailed kinetic modelling based on schemes of elementary reactions are shown to be a useful novel tool for identifying and studying the key reaction paths for nitrogen oxide formation and destruction in various systems. The great importance of the interaction between turbulent mixing and combustion chemistry is demonstrated by the sensitivity of both methane oxidation chemistry and fuel nitrogen conversion chemistry to the reactor and mixing pattern chosen for the kinetic calculations. The fluidized bed combustion (FBC) nitrogen chemistry involves several important heterogeneous reactions. Particularly the char in the bed plays an essential role. Recent research has advanced rapidly and the presentation proposes an overall picture of the fuel nitrogen reaction routes in circulating FBC conditions. (author)

  4. DYNSYL: a general-purpose dynamic simulator for chemical processes

    Energy Technology Data Exchange (ETDEWEB)

    Patterson, G.K.; Rozsa, R.B.

    1978-09-05

    Lawrence Livermore Laboratory is conducting a safeguards program for the Nuclear Regulatory Commission. The goal of the Material Control Project of this program is to evaluate material control and accounting (MCA) methods in plants that handle special nuclear material (SNM). To this end we designed and implemented the dynamic chemical plant simulation program DYNSYL. This program can be used to generate process data or to provide estimates of process performance; it simulates both steady-state and dynamic behavior. The MCA methods that may have to be evaluated range from sophisticated on-line material trackers such as Kalman filter estimators, to relatively simple material balance procedures. This report describes the overall structure of DYNSYL and includes some example problems. The code is still in the experimental stage and revision is continuing.

  5. Development of microforming process combined with selective chemical vapor deposition

    Directory of Open Access Journals (Sweden)

    Koshimizu Kazushi

    2015-01-01

    Full Text Available Microforming has been received much attention in the recent decades due to the wide use of microparts in electronics and medical purpose. For the further functionalization of these micro devices, high functional surface with noble metals and nanomaterials are strongly required in bio- and medical fields, such as bio-sensors. To realize the efficient manufacturing process, which can deform the submillimeter scale bulk structure and can construct the micro to nanometer scale structures in one process, the present study proposes a combined process of microforming for metal foils with a selective chemical vapor deposition (SCVD on the active surface of work materials. To clarify the availability of this proposed process, the feasibility of SCVD of functional materials to active surface of titanium (Ti was investigated. CVD of iron (Fe and carbon nanotubes (CNTs which construct CNTs on the patterned surface of active Ti and non-active oxidation layer were conducted. Ti thin films on silicon substrate and Fe were used as work materials and functional materials, respectively. CNTs were grown on only Ti surface. Consequently, the selectivity of the active surface of Ti to the synthesis of Fe particles in CVD process was confirmed.

  6. Conversion of Lignocellulosic Biomass to Nanocellulose: Structure and Chemical Process

    Science.gov (United States)

    Lee, H. V.; Hamid, S. B. A.; Zain, S. K.

    2014-01-01

    Lignocellulosic biomass is a complex biopolymer that is primary composed of cellulose, hemicellulose, and lignin. The presence of cellulose in biomass is able to depolymerise into nanodimension biomaterial, with exceptional mechanical properties for biocomposites, pharmaceutical carriers, and electronic substrate's application. However, the entangled biomass ultrastructure consists of inherent properties, such as strong lignin layers, low cellulose accessibility to chemicals, and high cellulose crystallinity, which inhibit the digestibility of the biomass for cellulose extraction. This situation offers both challenges and promises for the biomass biorefinery development to utilize the cellulose from lignocellulosic biomass. Thus, multistep biorefinery processes are necessary to ensure the deconstruction of noncellulosic content in lignocellulosic biomass, while maintaining cellulose product for further hydrolysis into nanocellulose material. In this review, we discuss the molecular structure basis for biomass recalcitrance, reengineering process of lignocellulosic biomass into nanocellulose via chemical, and novel catalytic approaches. Furthermore, review on catalyst design to overcome key barriers regarding the natural resistance of biomass will be presented herein. PMID:25247208

  7. Conversion of Lignocellulosic Biomass to Nanocellulose: Structure and Chemical Process

    Directory of Open Access Journals (Sweden)

    H. V. Lee

    2014-01-01

    Full Text Available Lignocellulosic biomass is a complex biopolymer that is primary composed of cellulose, hemicellulose, and lignin. The presence of cellulose in biomass is able to depolymerise into nanodimension biomaterial, with exceptional mechanical properties for biocomposites, pharmaceutical carriers, and electronic substrate’s application. However, the entangled biomass ultrastructure consists of inherent properties, such as strong lignin layers, low cellulose accessibility to chemicals, and high cellulose crystallinity, which inhibit the digestibility of the biomass for cellulose extraction. This situation offers both challenges and promises for the biomass biorefinery development to utilize the cellulose from lignocellulosic biomass. Thus, multistep biorefinery processes are necessary to ensure the deconstruction of noncellulosic content in lignocellulosic biomass, while maintaining cellulose product for further hydrolysis into nanocellulose material. In this review, we discuss the molecular structure basis for biomass recalcitrance, reengineering process of lignocellulosic biomass into nanocellulose via chemical, and novel catalytic approaches. Furthermore, review on catalyst design to overcome key barriers regarding the natural resistance of biomass will be presented herein.

  8. Systematic methods for synthesis and design of sustainable chemical and biochemical processes

    DEFF Research Database (Denmark)

    Gani, Rafiqul

    for process intensification, sustainable process design, identification of optimal biorefinery models as well as integrated process-control design, and chemical product design. The lecture will present the main concepts, the decomposition based solution approach, the developed methods and tools together......Chemical and biochemical process design consists of designing the process that can sustainably manufacture an identified chemical product through a chemical or biochemical route. The chemical product tree is potentially very large; starting from a set of basic raw materials (such as petroleum...... with illustrative examples covering chemical and biochemical process synthesis and design....

  9. GPS tomographic experiment on water vapour dynamics in the troposphere over Lisbon

    Science.gov (United States)

    Benevides, Pedro; Catalao, Joao; Miranda, Pedro

    2015-04-01

    Quantification of the water vapour variability on the atmosphere remains a difficult task, affecting the weather prediction. Coarse water vapour resolution measurements in space and time affect the numerical weather prediction solution models causing artifacts in the prediction of severe weather phenomena. The GNSS atmospheric processing has been developed in the past years providing integrated water vapour estimates comparable with the meteorological sensor measurements, with studies registering 1 to 2 kg/m2 bias, but lack a vertical determination of the atmospheric processes. The GNSS tomography in the troposphere is one of the most promising techniques for sensing the three-dimensional water vapour state of the atmosphere. The determination of the integrated water vapour profile by means of the widely accepted GNSS meteorology techniques, allows the reconstruction of several slant path delay rays in the satellite line of view, providing an opportunity to sense the troposphere at tree-dimensions plus time. The tomographic system can estimate an image solution of the water vapour but impositions have to be introduced to the system of equations inversion because of the non-optimal GNSS observation geometry. Application of this technique on atmospheric processes like large convective precipitation or mesoscale water vapour circulation have been able to describe its local dynamic vertical variation. A 3D tomographic experiment was developed over an area of 60x60 km2 around Lisbon (Portugal). The GNSS network available composed by 9 receivers was used for an experiment of densification of the permanent network using 8 temporarily installed GPS receivers (totalling 17 stations). This study was performed during several weeks in July 2013, where a radiosonde campaign was also held in order to validate the tomographic inversion solution. 2D integrated water vapour maps directly obtained from the GNSS processing were also evaluated and local coastal breeze circulation

  10. Integration of process design and controller design for chemical processes using model-based methodology

    DEFF Research Database (Denmark)

    Abd.Hamid, Mohd-Kamaruddin; Sin, Gürkan; Gani, Rafiqul

    2010-01-01

    In this paper, a novel systematic model-based methodology for performing integrated process design and controller design (IPDC) for chemical processes is presented. The methodology uses a decomposition method to solve the IPDC typically formulated as a mathematical programming (optimization...... that satisfy design, control and cost criteria. The advantage of the proposed methodology is that it is systematic, makes use of thermodynamic-process knowledge and provides valuable insights to the solution of IPDC problems in chemical engineering practice....... with constraints) problem. Accordingly the optimization problem is decomposed into four sub-problems: (i) pre-analysis, (ii) design analysis, (iii) controller design analysis, and (iv) final selection and verification, which are relatively easier to solve. The methodology makes use of thermodynamic-process...

  11. Solvents for CO2 capture. Structure-activity relationships combined with vapour-liquid-equilibrium measurements

    NARCIS (Netherlands)

    Mergler, Y.L.; Rumley-Van Gurp, R.; Brasser, P.; Koning, M.C. de; Goetheer, E.L.V.

    2011-01-01

    In this study a systematic approach was chosen to test and characterize amine systems for CO2 capture. Vapour-liquid-equilibrium measurements were performed on a homologue series of amines, with ethylene amine as base structure. Various functional groups were used that ranged in chemical and physica

  12. Enhanced Chemical Cleaning: A New Process for Chemically Cleaning Savannah River Waste Tanks

    Energy Technology Data Exchange (ETDEWEB)

    Ketusky, Edward; Spires, Renee; Davis, Neil

    2009-02-11

    At the Savannah River Site (SRS) there are 49 High Level Waste (HLW) tanks that eventually must be emptied, cleaned, and closed. The current method of chemically cleaning SRS HLW tanks, commonly referred to as Bulk Oxalic Acid Cleaning (BOAC), requires about a half million liters (130,000 gallons) of 8 weight percent (wt%) oxalic acid to clean a single tank. During the cleaning, the oxalic acid acts as the solvent to digest sludge solids and insoluble salt solids, such that they can be suspended and pumped out of the tank. Because of the volume and concentration of acid used, a significant quantity of oxalate is added to the HLW process. This added oxalate significantly impacts downstream processing. In addition to the oxalate, the volume of liquid added competes for the limited available tank space. A search, therefore, was initiated for a new cleaning process. Using TRIZ (Teoriya Resheniya Izobretatelskikh Zadatch or roughly translated as the Theory of Inventive Problem Solving), Chemical Oxidation Reduction Decontamination with Ultraviolet Light (CORD-UV{reg_sign}), a mature technology used in the commercial nuclear power industry was identified as an alternate technology. Similar to BOAC, CORD-UV{reg_sign} also uses oxalic acid as the solvent to dissolve the metal (hydr)oxide solids. CORD-UV{reg_sign} is different, however, since it uses photo-oxidation (via peroxide/UV or ozone/UV to form hydroxyl radicals) to decompose the spent oxalate into carbon dioxide and water. Since the oxalate is decomposed and off-gassed, CORD-UV{reg_sign} would not have the negative downstream oxalate process impacts of BOAC. With the oxalate destruction occurring physically outside the HLW tank, re-precipitation and transfer of the solids, as well as regeneration of the cleaning solution can be performed without adding additional solids, or a significant volume of liquid to the process. With a draft of the pre-conceptual Enhanced Chemical Cleaning (ECC) flowsheet, taking full

  13. Spreadsheets in chemical engineering education : a tool in process design and process integration

    OpenAIRE

    Ferreira, E. C.; Lima, Ricardo; Salcedo, Romualdo

    2004-01-01

    Recent developments in embedding numerical optimization procedures with linear and nonlinear solvers within a spreadsheet environment have greatly enhanced the use of these tools for teaching chemical process design and process integration. Student skills with respect to these topics are usually gained by complex and expensive modular simulators, e.g. ASPEN Plus® or algebraic tools such as GAMS® or AMPL®. However, modular simulators have a significant learning curve, and algebraic modeling la...

  14. Modelling vapour transport in Surtseyan bombs

    Science.gov (United States)

    McGuinness, Mark J.; Greenbank, Emma; Schipper, C. Ian

    2016-05-01

    We address questions that arise if a slurry containing liquid water is enclosed in a ball of hot viscous vesicular magma ejected as a bomb in the context of a Surtseyan eruption. We derive a mathematical model for transient changes in temperature and pressure due to flashing of liquid water to vapour inside the bomb. The magnitude of the transient pressure changes that are typically generated are calculated together with their dependence on material properties. A single criterion to determine whether the bomb will fragment as a result of the pressure changes is derived. Timescales for ejection of water vapour from a bomb that remains intact are also revealed.

  15. The condensation of sodium vapour bubbles

    International Nuclear Information System (INIS)

    This is a preliminary analytic study of the violent collapse of a vapour bubble by condensation in cold liquid. A calculation method is described and is applied to the condensation of sodium vapour bubbles such as might be formed in an overheating accident in a fast reactor. The method is not satisfactory, and a more thorough study of the problem is needed, but these preliminary results suggest that while the violent collapse is unlikely to do much mechanical damage, it produces a considerable amount of acoustic energy. (author)

  16. Leaching characteristics of Idaho Chemical Processing Plant calcines

    International Nuclear Information System (INIS)

    This report documents leaching studies conducted on two non-radioactive, pilot-plant calcines produced at the Idaho Chemical Processing Plant. The two pilot-plant calcines simulate radioactive calcine which may be produced in the New Waste Calcining Facility by blending high-level liquid waste and sodium-bearing liquid waste. The calcines were subjected to the Environmental Protection Agency's Extraction Procedure Toxicity Test and to a test based on the Materials Characterization Center's MCC-1 Static Leach Test. Following the protocol of these tests, leachates were obtained and analyzed for chemical composition to develop information about component mass loss and total mass loss. Surface analysis techniques were employed in an attempt to identify species that were leached from the calcines, but later precipitated during the MCC-1 tests. This report also documents leaching studies conducted on a radioactive fluorinel-sodium blend calcine produced in the New Waste Calcining Facility. This calcine was also subjected to a static leach test based on the MCC-1 test. The leachate was analyzed to develop information about total mass loss and leaching characteristics of radioactive species. 12 refs., 9 figs., 9 tabs

  17. Leaching characteristics of Idaho Chemical Processing Plant calcines

    Energy Technology Data Exchange (ETDEWEB)

    Chipman, N A

    1990-02-01

    This report documents leaching studies conducted on two non-radioactive, pilot-plant calcines produced at the Idaho Chemical Processing Plant. The two pilot-plant calcines simulate radioactive calcine which may be produced in the New Waste Calcining Facility by blending high-level liquid waste and sodium-bearing liquid waste. The calcines were subjected to the Environmental Protection Agency's Extraction Procedure Toxicity Test and to a test based on the Materials Characterization Center's MCC-1 Static Leach Test. Following the protocol of these tests, leachates were obtained and analyzed for chemical composition to develop information about component mass loss and total mass loss. Surface analysis techniques were employed in an attempt to identify species that were leached from the calcines, but later precipitated during the MCC-1 tests. This report also documents leaching studies conducted on a radioactive fluorinel-sodium blend calcine produced in the New Waste Calcining Facility. This calcine was also subjected to a static leach test based on the MCC-1 test. The leachate was analyzed to develop information about total mass loss and leaching characteristics of radioactive species. 12 refs., 9 figs., 9 tabs.

  18. Study of Chemical Decontamination Process for CRUD Removal

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Seongsik; Kim, Won-Seok; Kim, Jungjin; Um, Wooyong [POSTECH, Pohang (Korea, Republic of)

    2015-05-15

    Chalk River Unidentified Deposit (CRUD) is a technical term in nuclear engineering which is an accumulated material on external fuel rod cladding surfaces in nuclear power plants. It is a corrosion product which is composed of either dissolved ions or solid particles such as Ni, Fe and Co. It consists mainly of NiO and NiFe{sub 2}O{sub 4}. It can affect to reduce fuel lifetime, degrade heat transfer to the coolant, and threaten human health and environment. Therefore, decontamination process is essential for reducing occupational exposures, limiting potential releases and uptakes of radioactive materials, allowing the reuse of components, and facilitating waste management process. In this paper, we have conducted the synthesis of Cobalt ferrite as power foam to use for decontamination process. In dissolution test of Co ferrite and Ni ferrite, oxalic acid shows the most effective chemical decontamination reagent to remove the contaminants. Generally, the dissolved amount of cobalt and nickel increases at low pH condition and as the temperature goes higher, dissolved amount of cobalt and iron are much higher.

  19. Chemical Reactions in the Processing of Mosi2 + Carbon Compacts

    Science.gov (United States)

    Jacobson, Nathan S.; Lee, Kang N.; Maloy, Stuart A.; Heuer, Arthur H.

    1993-01-01

    Hot-pressing of MoSi2 powders with carbon at high temperatures reduces the siliceous grain boundary phase in the resultant compact. The chemical reactions in this process were examined using the Knudsen cell technique. A 2.3 wt pct oxygen MoSi2 powder and a 0.59 wt pct oxygen MoSi2 powder, both with additions of 2 wt pct carbon, were examined. The reduction of the siliceous grain boundary phase was examined at 1350 K and the resultant P(SiO)/P(CO) ratios interpreted in terms of the SiO(g) and CO(g) isobars on the Si-C-O predominance diagram. The MoSi2 + carbon mixtures were then heated at the hot-pressing temperature of 2100 K. Large weight losses were observed and could be correlated with the formation of a low-melting eutectic and the formation and vaporization of SiC.

  20. Linear nonequilibrium thermodynamics of periodic processes and chemical oscillations

    CERN Document Server

    Heimburg, Thomas

    2016-01-01

    Onsager's phenomenological equations successfully describe irreversible thermodynamic processes. They assume a symmetric coupling matrix between thermodynamic fluxes and forces. It is easily shown that the antisymmetric part of a coupling matrix does not contribute to dissipation. Therefore, entropy production is exclusively governed by the symmetric matrix even in the presence of antisymmetric terms. In this work we focus on the antisymmetric contributions which describe isentropic oscillations and well-defined equations of motion. The formalism contains variables that are equivalent to momenta, and coefficients that are analogous to an inertial mass. We apply this formalism to simple problems such as an oscillating piston and the oscillation in an electrical LC-circuit. We show that isentropic oscillations are possible even close to equilibrium in the linear limit and one does not require far-from equilibrium situations. One can extend this formalism to other pairs of variables, including chemical systems w...

  1. SDG-based Model Validation in Chemical Process Simulation

    Institute of Scientific and Technical Information of China (English)

    张贝克; 许欣; 马昕; 吴重光

    2013-01-01

    Signed direct graph (SDG) theory provides algorithms and methods that can be applied directly to chemical process modeling and analysis to validate simulation models, and is a basis for the development of a soft-ware environment that can automate the validation activity. This paper is concentrated on the pretreatment of the model validation. We use the validation scenarios and standard sequences generated by well-established SDG model to validate the trends fitted from the simulation model. The results are helpful to find potential problems, as-sess possible bugs in the simulation model and solve the problem effectively. A case study on a simulation model of boiler is presented to demonstrate the effectiveness of this method.

  2. Radon: Chemical and physical processes associated with its distribution

    International Nuclear Information System (INIS)

    Assessing the mechanisms which govern the distribution, fate, and pathways of entry into biological systems, as well as the ultimate hazards associated with the radon progeny and their secondary reaction products, depends on knowledge of their chemistry. Our studies are directed toward developing fundamental information which will provide a basis for modeling studies that are requisite in obtaining a complete picture of growth, attachment to aerosols, and transport to the bioreceptor and ultimate incorporation within. Our program is divided into three major areas of research. These include measurement of the determination of their mobilities, study of the role of radon progeny ions in affecting reactions, including study of the influence of the degree of solvation (clustering), and examination of the important secondary reaction products, with particular attention to processes leading to chemical conversion of either the core ions or the ligands as a function of the degree of clustering

  3. Chemical and Mechanical processes during burial diagenesis of chalk

    DEFF Research Database (Denmark)

    Borre, Mai Kirstine; Lind, Ida

    1998-01-01

    or larger influence on the textural development. In the chalk interval below, compaction is not the only porosity reducing agent but it has a larger influence on texture than concurrent recrystallization. Below 850 m grain-bridging cementation becomes important resulting in a lithified limestone below 1100......Burial diagenesis of chalk is a combination of mechanical compaction and chemical recrystallization as well as cementation. We have predicted the characteristic trends in specific surface resulting from these processes. The specific surface is normally measured by nitrogen adsorption but is here...... in the Pacific, where a > 1 km thick package of chalk facies sediments accumulated from the Cretaceous to the present. In the upper 200-300 m the sediment is unconsolidated carbonate ooze, throughout this depth interval compaction is the principal porosity reducing agent, but recrystallization has an equal...

  4. Accelerating chemical database searching using graphics processing units.

    Science.gov (United States)

    Liu, Pu; Agrafiotis, Dimitris K; Rassokhin, Dmitrii N; Yang, Eric

    2011-08-22

    The utility of chemoinformatics systems depends on the accurate computer representation and efficient manipulation of chemical compounds. In such systems, a small molecule is often digitized as a large fingerprint vector, where each element indicates the presence/absence or the number of occurrences of a particular structural feature. Since in theory the number of unique features can be exceedingly large, these fingerprint vectors are usually folded into much shorter ones using hashing and modulo operations, allowing fast "in-memory" manipulation and comparison of molecules. There is increasing evidence that lossless fingerprints can substantially improve retrieval performance in chemical database searching (substructure or similarity), which have led to the development of several lossless fingerprint compression algorithms. However, any gains in storage and retrieval afforded by compression need to be weighed against the extra computational burden required for decompression before these fingerprints can be compared. Here we demonstrate that graphics processing units (GPU) can greatly alleviate this problem, enabling the practical application of lossless fingerprints on large databases. More specifically, we show that, with the help of a ~$500 ordinary video card, the entire PubChem database of ~32 million compounds can be searched in ~0.2-2 s on average, which is 2 orders of magnitude faster than a conventional CPU. If multiple query patterns are processed in batch, the speedup is even more dramatic (less than 0.02-0.2 s/query for 1000 queries). In the present study, we use the Elias gamma compression algorithm, which results in a compression ratio as high as 0.097.

  5. Accelerating chemical database searching using graphics processing units.

    Science.gov (United States)

    Liu, Pu; Agrafiotis, Dimitris K; Rassokhin, Dmitrii N; Yang, Eric

    2011-08-22

    The utility of chemoinformatics systems depends on the accurate computer representation and efficient manipulation of chemical compounds. In such systems, a small molecule is often digitized as a large fingerprint vector, where each element indicates the presence/absence or the number of occurrences of a particular structural feature. Since in theory the number of unique features can be exceedingly large, these fingerprint vectors are usually folded into much shorter ones using hashing and modulo operations, allowing fast "in-memory" manipulation and comparison of molecules. There is increasing evidence that lossless fingerprints can substantially improve retrieval performance in chemical database searching (substructure or similarity), which have led to the development of several lossless fingerprint compression algorithms. However, any gains in storage and retrieval afforded by compression need to be weighed against the extra computational burden required for decompression before these fingerprints can be compared. Here we demonstrate that graphics processing units (GPU) can greatly alleviate this problem, enabling the practical application of lossless fingerprints on large databases. More specifically, we show that, with the help of a ~$500 ordinary video card, the entire PubChem database of ~32 million compounds can be searched in ~0.2-2 s on average, which is 2 orders of magnitude faster than a conventional CPU. If multiple query patterns are processed in batch, the speedup is even more dramatic (less than 0.02-0.2 s/query for 1000 queries). In the present study, we use the Elias gamma compression algorithm, which results in a compression ratio as high as 0.097. PMID:21696144

  6. Chemical Processing and Characterization of Fiber Reinforced Nanocomposite Silica Materials

    Science.gov (United States)

    Burnett, Steven Shannon

    Ultrasound techniques, acoustic and electroacoustic spectroscopy, are used to investigate and characterize concentrated fluid phase nanocomposites. In particular, the data obtained from ultrasound methods are used as tools to improve the understanding of the fundamental process chemistry of concentrated, multicomponent, nanomaterial dispersions. Silicon nitride nanofibers embedded in silica are particularly interesting for lightweight nanocomposites, because silicon nitride is isostructural to carbon nitride, a super hard material. However, the major challenge with processing these composites is retarding particle-particle aggregation, to maintain highly dispersed systems. Therefore, a systematic approach was developed to evaluate the affect of process parameters on particle-particle aggregation, and improving the chemical kinetics for gelation. From the acoustic analysis of the nanofibers, this thesis was able to deduce that changes in aspect ratio affects the ultrasound propagation. In particular, higher aspect ratio fibers attenuate the ultrasound wave greater than lower aspect fibers of the same material. Furthermore, our results confirm that changes in attenuation depend on the hydrodynamical interactions between particles, the aspect ratio, and the morphology of the dispersant. The results indicate that the attenuation is greater for fumed silica due to its elastic nature and its size, when compared to silica Ludox. Namely, the larger the size, the greater the attenuation. This attenuation is mostly the result of scattering loss in the higher frequency range. In addition, the silica nanofibers exhibit greater attenuation than their nanoparticle counterparts because of their aspect ratio influences their interaction with the ultrasound wave. In addition, this study observed how 3M NH 4 Cl's acoustic properties changes during the gelation process, and during that change, the frequency dependency deviates from the expected squared of the frequency, until the

  7. Collision induced photon echo in ytterbium vapour

    NARCIS (Netherlands)

    Rubtsova, N. N.; Khvorostov, E. B.; Kochubei, S. A.; Ishchenko, V. N.; Yevseyev, I. V.

    2006-01-01

    Collision induced photon echo observed in ytterbium vapour at the inter-combination transition (6s6p) P-8(1) (6s(2)) S-1(0) in the presence of Kr gas as buffer. Collision echo is generated by two unidirectional resonant dye laser pulses of linear mutually orthogonal polarizations. There is practical

  8. Water vapour loss measurements on human skin.

    NARCIS (Netherlands)

    Valk, Petrus Gerardus Maria van der

    1984-01-01

    In this thesis, the results of a series of investigations into the barrier function of human skin are presented. In these investigations, the barrier function was assessed by water vapour loss measurements of the skin using a method based on gradient estimation.... Zie: Summary and conclusions

  9. Developments in vapour cloud explosion blast modeling

    NARCIS (Netherlands)

    Mercx, W.P.M.; Berg, A.C. van den; Hayhurst, C.J.; Robertson, N.J.; Moran, K.C.

    2000-01-01

    TNT Equivalency methods are widely used for vapour cloud explosion blast modeling. Presently, however, other types of models are available which do not have the fundamental objections TNT Equivalency models have. TNO Multi-Energy method is increasingly accepted as a more reasonable alternative to be

  10. 29 CFR 1910.119 - Process safety management of highly hazardous chemicals.

    Science.gov (United States)

    2010-07-01

    .... Facility means the buildings, containers or equipment which contain a process. Highly hazardous chemical... from changes in process chemicals, technology, and equipment, and changes to facilities. The employer... “replacements in kind”) to process chemicals, technology, equipment, and procedures; and, changes to...

  11. Vapour-density determinations of Group 5 pentafluorides

    International Nuclear Information System (INIS)

    Vapour-density determinations on the saturated vapours of NbF5, TaF5, and SbF5 at temperatures above their boiling points have been made by a modified Dumas method. The average molecular weights of the vapour-phase species near the boiling points are close to those for the respective trimers. Approaching 4000C (or 3000C for SbF5), however, the major constituent of the vapour is the monomeric pentafluoride. (author)

  12. Parameter Optimization of Nitriding Process Using Chemical Kinetics

    Science.gov (United States)

    Özdemir, İ. Bedii; Akar, Firat; Lippmann, Nils

    2016-09-01

    Using the dynamics of chemical kinetics, an investigation to search for an optimum condition for a gas nitriding process is performed over the solution space spanned by the initial temperature and gas composition of the furnace. For a two-component furnace atmosphere, the results are presented in temporal variations of gas concentrations and the nitrogen coverage on the surface. It seems that the exploitation of the nitriding kinetics can provide important feedback for setting the model-based control algorithms. The present work shows that when the nitrogen gas concentration is not allowed to exceed 6 pct, the Nad coverage can attain maximum values as high as 0.97. The time evolution of the Nad coverage also reveals that, as long as the temperature is above the value where nitrogen poisoning of the surface due to the low-temperature adsorption of excess nitrogen occurs, the initial ammonia content in the furnace atmosphere is much more important in the nitriding process than is the initial temperature.

  13. The experiment on the saturation polarization of Rb vapour

    Institute of Scientific and Technical Information of China (English)

    Huang Xiang-You; You Pei-Lin; Du Wei-Min

    2004-01-01

    @@ A cylindrical capacitor containing rubidium vapour is made. The capacitance of it at. different voltages is measured under a certain Rb vapour pressure. The experimental C-V curve shows that the saturation polarization of Rb vapour is easily observed. The experiment further supports the idea that the Rb atom has a large permanent electric dipole moment.

  14. Model-Based Integrated Process Design and Controller Design of Chemical Processes

    DEFF Research Database (Denmark)

    Abd Hamid, Mohd Kamaruddin Bin

    This thesis describes the development and application of a new systematic modelbased methodology for performing integrated process design and controller design (IPDC) of chemical processes. The new methodology is simple to apply, easy to visualize and efficient to solve. Here, the IPDC problem...... and verification. Using thermodynamic and process insights, a bounded search space is first identified. This feasible solution space is further reduced to satisfy the process design and controller design constraints in sub-problems 2 and 3, respectively, until in the final sub-problem all feasible candidates...... are ordered according to the defined performance criteria (objective function). The final selected design is then verified through rigorous simulation. In the pre-analysis sub-problem, the concepts of attainable region and driving force are used to locate the optimal process-controller design solution...

  15. Applications of Process Synthesis: Moving from Conventional Chemical Processes towards Biorefinery Processes

    DEFF Research Database (Denmark)

    Yuan, Zhihong; Chen, Bingzhen; Gani, Rafiqul

    2013-01-01

    Concerns about diminishing petroleum reserves, enhanced worldwide demand for fuels and fluctuations in the global oil market, together with climate change and national security have promoted many initiatives for exploring alternative, non-petroleum based processes. Among these initiatives...... be predicted to play a significant role in the design and commercialization of sustainable and cost-effective biorefinery processes. The main objective of this perspective paper is to elucidate the potential opportunities that biorenewables processing offers to optimal synthesis; challenges and future...

  16. Chemical inhibition of PCDD/F formation in incineration processes.

    Science.gov (United States)

    Ruokojärvi, Päivi H; Asikainen, Arja H; Tuppurainen, Kari A; Ruuskanen, Juhani

    2004-06-01

    This review summarises results of our pilot-scale experiments to find suitable inhibitors for preventing the formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) during waste incineration and to specify the role of the main factors affecting the inhibition process, and is based on doctoral dissertation of Ruokojaärvi (2002). Results of previous experiments reported by other researchers are also presented and compared with ours. The detailed aims of our experiments were (1) to compare the effects of different inhibitors on PCDD/F formation during incineration in a pilot plant, (2) to investigate the role of the particle size distribution of the flue gas on the inhibition of PCDD/Fs, and (3) to find the main parameters affecting PCDD/F inhibition in waste incineration. Prevention of the formation of PCDD/Fs with chemical inhibitors and the effects of different supply points, feed temperatures and process parameters were studied in a pilot scale incinerator (50 kW) using light heating oil and refuse-derived fuel as test fuels. Various concentrations of the gaseous inhibitors (sulfur dioxide, ammonia, dimethylamine and methyl mercaptan) were sprayed into the flue gases after the furnace, in addition to which urea was dissolved in water and injected in at different concentrations. The residence time of the flue gas between the furnace and the PCDD/F sampling point was varied in the tests. In another set of urea tests, urea-water solutions at three concentrations were mixed with the RDF prior to incineration. PCDD/F and chlorophenol concentrations, together with other flue gas parameters (e.g. temperature, O2, CO, CO2 and NO), were analysed in the cooling flue gases. The gaseous and liquid inhibitors both notably reduced PCDD/F concentrations in the flue gas, the reductions achieved with the gaseous inhibitors varying from 50 to 78%, with dimethyl amine the most effective, while that produced with urea was up to 90%. The PCDD/F reductions were

  17. Chemical inhibition of PCDD/F formation in incineration processes

    International Nuclear Information System (INIS)

    This review summarises results of our pilot-scale experiments to find suitable inhibitors for preventing the formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) during waste incineration and to specify the role of the main factors affecting the inhibition process, and is based on a doctoral dissertation. Results of previous experiments reported by other researchers are also presented and compared with ours. The detailed aims of our experiments were (1) to compare the effects of different inhibitors on PCDD/F formation during incineration in a pilot plant, (2) to investigate the role of the particle size distribution of the flue gas on the inhibition of PCDD/Fs, and (3) to find the main parameters affecting PCDD/F inhibition in waste incineration. Prevention of the formation of PCDD/Fs with chemical inhibitors and the effects of different supply points, feed temperatures and process parameters were studied in a pilot scale incinerator (50 kW) using light heating oil and refuse-derived fuel as test fuels. Various concentrations of the gaseous inhibitors (sulfur dioxide, ammonia, dimethylamine and methyl mercaptan) were sprayed into the flue gases after the furnace, in addition to which urea was dissolved in water and injected in at different concentrations. The residence time of the flue gas between the furnace and the PCDD/F sampling point was varied in the tests. In another set of urea tests, urea-water solutions at three concentrations were mixed with the RDF prior to incineration. PCDD/F and chlorophenol concentrations, together with other flue gas parameters (e.g. temperature, O2, CO, CO2 and NO), were analysed in the cooling flue gases. The gaseous and liquid inhibitors both notably reduced PCDD/F concentrations in the flue gas, the reductions achieved with the gaseous inhibitors varying from 50 to 78%, with dimethyl amine the most effective, while that produced with urea was up to 90%. The PCDD/F reductions were greater at increased

  18. NATO Advanced Study Institute on Chemical Transport in Melasomatic Processes

    CERN Document Server

    1987-01-01

    As indicated on the title page, this book is an outgrowth of the NATO Advanced Study Institute (ASI) on Chemical Transport in Metasomatic Processes, which was held in Greece, June 3-16, 1985. The ASI consisted of five days of invited lectures, poster sessions, and discussion at the Club Poseidon near Loutraki, Corinthia, followed by a two-day field trip in Corinthia and Attica. The second week of the ASI consisted of an excursion aboard M/S Zeus, M/Y Dimitrios II, and the M/S Irini to four of the Cycladic Islands to visit, study, and sample outstanding exposures of metasomatic activity on Syros, Siphnos, Seriphos, and Naxos. Nine­ teen invited lectures and 10 session chairmen/discussion leaders participated in the ASI, which was attended by a total of 92 professional scientists and graduate stu­ dents from 15 countries. Seventeen of the invited lectures and the Field Excursion Guide are included in this volume, together with 10 papers and six abstracts representing contributed poster sessions. Although more...

  19. COLUMN, 1-D Migration for Various Physical Chemical Processes

    International Nuclear Information System (INIS)

    1 - Description of problem or function: COLUMN2 is designed for studies of the effects various physicochemical processes on migration in one dimension. It solves the transport equation and can take into account dispersion, sorption, ion exchange, first and second order homogeneous chemical reactions. Spatial variations of input pulses and retention factors are possible. 2 - Method of solution: The Method of solution is based on a finite difference discretion followed by the application of the method of characteristics and two separate grid systems. 3 - Restrictions on the complexity of the problem: For computational reasons the number of components has been limited to 5 and the maximum number of second order reactions is 10. However, a re-dimensioning of all relevant arrays will allow for any number of components and reactions desired. Arrays should never be dimensioned larger than needed in order to save computation time. Five components and 10 second order reactions may seem a small number. However, larger simulations are often divided into smaller sub-problems for clarification purposes. The maximum number of grid points, default value 801, may be enlarged to re-dimensioning all relevant arrays

  20. ARTIST process. A novel chemical process for treatment of spent nuclear fuel

    Energy Technology Data Exchange (ETDEWEB)

    Tachimori, Shoichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2001-10-01

    A new chemical process, ARTIST process, is proposed for the treatment of spent nuclear fuel. The main concept of the ARTIST process is to recover and stock all actinides (Ans) as two groups, uranium (U) and a mixture of transuranics (TRU), to preserve their resource value and to dispose solely fission products (FPs). The process is composed of two main steps, an U exclusive isolation and a total recovery of TRU; which copes with the nuclear non-proliferation measures, and additionally of Pu separation process and soft N-donor process if requested, and optionally of processes for separation of long-lived FPs. These An products: U-product and TRU-product, are to be solidified by calcination and allowed to the interim stockpile for future utilization. These separations are achieved by use of amidic extractants in accord with the CHON principle. The technical feasibility of the ARTIST process was explained by the performance of both the branched alkyl monoamides in extracting U and suppressing the extraction of tetravalent Ans due to the steric effect and the diglycolic amide (TODGA) in thorough extraction of all TRU by tridentate fashion. When these TRU are requested to put into reactors, LWR or FBR, for power generation or the Accelerator - Driven System (ADS) for transmutation, Pu (Np) or Am-Cm (Np) are to be extracted from the TRU-product. (author)

  1. Modelling and interpreting the isotopic composition of water vapour in convective updrafts

    Directory of Open Access Journals (Sweden)

    M. Bolot

    2013-08-01

    Full Text Available The isotopic compositions of water vapour and its condensates have long been used as tracers of the global hydrological cycle, but may also be useful for understanding processes within individual convective clouds. We review here the representation of processes that alter water isotopic compositions during processing of air in convective updrafts and present a unified model for water vapour isotopic evolution within undiluted deep convective cores, with a special focus on the out-of-equilibrium conditions of mixed-phase zones where metastable liquid water and ice coexist. We use our model to show that a combination of water isotopologue measurements can constrain critical convective parameters, including degree of supersaturation, supercooled water content and glaciation temperature. Important isotopic processes in updrafts include kinetic effects that are a consequence of diffusive growth or decay of cloud particles within a supersaturated or subsaturated environment; isotopic re-equilibration between vapour and supercooled droplets, which buffers isotopic distillation; and differing mechanisms of glaciation (droplet freezing vs. the Wegener–Bergeron–Findeisen process. As all of these processes are related to updraft strength, particle size distribution and the retention of supercooled water, isotopic measurements can serve as a probe of in-cloud conditions of importance to convective processes. We study the sensitivity of the profile of water vapour isotopic composition to differing model assumptions and show how measurements of isotopic composition at cloud base and cloud top alone may be sufficient to retrieve key cloud parameters.

  2. Chemical Processes Related to Combustion in Fluidised Bed

    Energy Technology Data Exchange (ETDEWEB)

    Steenari, Britt-Marie; Lindqvist, Oliver [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Environmental Inorganic Chemistry

    2002-12-01

    with evaluation of other biomass ash particles and, as an extension, the speciation of Cu and Zn will be studied as well. Ash fractions from combustion of MSW in a BFB boiler have been investigated regarding composition and leaching properties, i.e. environmental impact risks. The release of salts from the cyclone ash fraction can be minimised by the application of a simple washing process, thus securing that the leaching of soluble substances stays within the regulative limits. The MSW ash - water systems contain some interesting chemical issues, such as the interactions between Cr(VI) and reducing substances like Al-metal. The understanding of such chemical processes is important since it gives a possibility to predict effects of a change in ash composition. An even more detailed understanding of interactions between a solution containing ions and particle surfaces can be gained by theoretical modelling. In this project (and with additional unding from Aangpannefoereningens Forskningsstiftelse) a theoretical description of ion-ion interactions and the solid-liquid-interface has been developed. Some related issues are also included in this report. The publication of a paper on the reactions of ammonia in the presence of a calcining limestone surface is one of them. A review paper on the influence of combustion conditions on the properties of fly ash and its applicability as a cement replacement in concrete is another. The licentiate thesis describing the sampling and measurement of Cd in flue gas is also included since it was finalised during the present period. A co-operation project involving the Geology Dept. at Goeteborg Univ. and our group is briefly discussed. This project concerns the utilisation of granules produced from wood ash and dolomite as nutrient source for forest soil. Finally, the plans for our flue gas simulator facility are discussed.

  3. A water vapour monitor at Paranal Observatory

    Science.gov (United States)

    Kerber, Florian; Rose, Thomas; Chacón, Arlette; Cuevas, Omar; Czekala, Harald; Hanuschik, Reinhard; Momany, Yazan; Navarrete, Julio; Querel, Richard R.; Smette, Alain; van den Ancker, Mario E.; Cure, Michel; Naylor, David A.

    2012-09-01

    We present the performance characteristics of a water vapour monitor that has been permanently deployed at ESO's Paranal observatory as a part of the VISIR upgrade project. After a careful analysis of the requirements and an open call for tender, the Low Humidity and Temperature Profiling microwave radiometer (LHATPRO), manufactured by Radiometer Physics GmbH (RPG), has been selected. The unit measures several channels across the strong water vapour emission line at 183 GHz, necessary for resolving the low levels of precipitable water vapour (PWV) that are prevalent on Paranal (median ~2.5 mm). The unit comprises the above humidity profiler (183-191 GHz), a temperature profiler (51-58 GHz), and an infrared radiometer (~10 μm) for cloud detection. The instrument has been commissioned during a 2.5 week period in Oct/Nov 2011, by comparing its measurements of PWV and atmospheric profiles with the ones obtained by 22 radiosonde balloons. In parallel an IR radiometer (Univ. Lethbridge) has been operated, and various observations with ESO facility spectrographs have been taken. The RPG radiometer has been validated across the range 0.5 - 9 mm demonstrating an accuracy of better than 0.1 mm. The saturation limit of the radiometer is about 20 mm. Currently, the radiometer is being integrated into the Paranal infrastructure to serve as a high time-resolution monitor in support of VLT science operations. The water vapour radiometer's ability to provide high precision, high time resolution information on this important aspect of the atmosphere will be most useful for conducting IR observations with the VLT under optimal conditions.

  4. Technical safety appraisal of the Idaho Chemical Processing Plant

    International Nuclear Information System (INIS)

    On June 27, 1989, Secretary of Energy, Admiral James D. Watkins, US Navy (Retired), announced a 10-point initiative to strengthen environment, safety, and health (ES ampersand H) programs and waste management operations in the Department of Energy (DOE). One of the initiatives involved conducting independent Tiger Team Assessments (TTA) at DOE operating facilities. A TTA of the Idaho National Engineering Laboratory (INEL) was performed during June and July 1991. Technical Safety Appraisals (TSA) were conducted in conjunction with the TTA as its Safety and Health portion. However, because of operational constraints the the Idaho Chemical Processing Plant (ICPP), operated for the DOE by Westinghouse Idaho Nuclear Company, Inc. (WINCO), was not included in the Safety and Health Subteam assessment at that time. This TSA, conducted April 12 - May 8, 1992, was performed by the DOE Office of Performance Assessment to complete the normal scope of the Safety and Health portion of the Tiger Team Assessment of the Idaho National Engineering Laboratory. The purpose of TSAs is to evaluate and strengthen DOE operations by verifying contractor compliance with DOE Orders, to assure that lessons learned from commercial operations are incorporated into facility operations, and to stimulate and encourage pursuit of excellence; thus, the appraisal addresses more issues than would be addressed in a strictly compliance-oriented appraisal. A total of 139 Performance Objectives have been addressed by this appraisal in 19 subject areas. These 19 areas are: organization and administration, quality verification, operations, maintenance, training and certification, auxiliary systems, emergency preparedness, technical support, packaging and transportation, nuclear criticality safety, safety/security interface, experimental activities, site/facility safety review, radiological protection, worker safety and health compliance, personnel protection, fire protection, medical services and natural

  5. National toxicology program chemical nomination and selection process

    Energy Technology Data Exchange (ETDEWEB)

    Selkirk, J.K. [National Institute of Environmental Health Sciences, Research Triangle Park, NC (United States)

    1990-12-31

    The National Toxicology Program (NTP) was organized to support national public health programs by initiating research designed to understand the physiological, metabolic, and genetic basis for chemical toxicity. The primary mandated responsibilities of NTP were in vivo and vitro toxicity testing of potentially hazardous chemicals; broadening the spectrum of toxicological information on known hazardous chemicals; validating current toxicological assay systems as well as developing new and innovative toxicity testing technology; and rapidly communicating test results to government agencies with regulatory responsibilities and to the medical and scientific communities. 2 figs.

  6. Sensitivity of polar stratospheric cloud formation to changes in water vapour and temperature

    Science.gov (United States)

    Khosrawi, F.; Urban, J.; Lossow, S.; Stiller, G.; Weigel, K.; Braesicke, P.; Pitts, M. C.; Rozanov, A.; Burrows, J. P.; Murtagh, D.

    2016-01-01

    water vapour and particular temperature the severe denitrification observed in 2010/11 cannot be directly related to any changes in water vapour and temperature since the millennium. However, the observations indicate a clear correlation between cold winters and enhanced water vapour mixing ratios. This indicates a connection between dynamical and radiative processes that govern water vapour and temperature in the Arctic lower stratosphere.

  7. Stratospheric water vapour as tracer for vortex filamentation in the Arctic winter 2002/2003

    Directory of Open Access Journals (Sweden)

    M. Müller

    2003-08-01

    the frost point hygrometer measured strongly variable water vapour concentrations as the sonde detected air with different origins, respectively.

    Instead of being linked to dehydration due to PSC particle sedimentation, the local diminuition in the stratospheric water vapour profile of 11 February 2003 has been found to be caused by dynamical processes in the polar stratosphere.

  8. Investigation of the vapour-plasma plume in the welding of titanium by high-power ytterbium fibre laser radiation

    Science.gov (United States)

    Bykovskiy, D. P.; Petrovskii, V. N.; Uspenskiy, S. A.

    2015-03-01

    The vapour-plasma plume produced in the welding of 6-mm thick VT-23 titanium alloy plates by ytterbium fibre laser radiation of up to 10 kW power is studied in the protective Ar gas medium. High-speed video filming of the vapour-plasma plume is used to visualise the processes occurring during laser welding. The coefficient of inverse bremsstrahlung by the welding plasma plume is calculated from the data of the spectrometric study.

  9. Evaporation of a volatile organic compound in a hygroscopic soil - influence of the airflow and its VOC vapour saturation

    OpenAIRE

    Naon, Bétaboalé; Benet, Jean-Claude; Cousin, Bruno; CHERBLANC, Fabien; Chammari, Ali

    2013-01-01

    International audience; This article presents an experimental and theoretical study of VOC volatilization in soil during a decontamination process by vapour extraction or venting. A phase change law is proposed in the case of a sandy-silty soil when the convective gaseous phase is vapour-charged. A simple experimental method for analyzing the phase change is presented. Finally, an efficiency coefficient is introduced to quantify the contribution of airflow velocity on venting.

  10. Graphene composites containing chemically bonded metal oxides

    Indian Academy of Sciences (India)

    K Pramoda; S Suresh; H S S Ramakrishna Matte; A Govindaraj

    2013-08-01

    Composites of graphene involving chemically bonded nano films of metal oxides have been prepared by reacting graphene containing surface oxygen functionalities with metal halide vapours followed by exposure to water vapour. The composites have been characterized by electron microscopy, atomic force microscopy and other techniques. Magnetite particles chemically bonded to graphene dispersible in various solvents have been prepared and they exhibit fairly high magnetization.

  11. New trajectory-driven aerosol and chemical process model Chemical and Aerosol Lagrangian Model (CALM

    Directory of Open Access Journals (Sweden)

    P. Tunved

    2010-11-01

    Full Text Available A new Chemical and Aerosol Lagrangian Model (CALM has been developed and tested. The model incorporates all central aerosol dynamical processes, from nucleation, condensation, coagulation and deposition to cloud formation and in-cloud processing. The model is tested and evaluated against observations performed at the SMEAR II station located at Hyytiälä (61° 51' N, 24° 17' E over a time period of two years, 2000–2001. The model shows good agreement with measurements throughout most of the year, but fails in reproducing the aerosol properties during the winter season, resulting in poor agreement between model and measurements especially during December–January. Nevertheless, through the rest of the year both trends and magnitude of modal concentrations show good agreement with observation, as do the monthly average size distribution properties. The model is also shown to capture individual nucleation events to a certain degree. This indicates that nucleation largely is controlled by the availability of nucleating material (as prescribed by the [H2SO4], availability of condensing material (in this model 15% of primary reactions of monoterpenes (MT are assumed to produce low volatile species and the properties of the size distribution (more specifically, the condensation sink. This is further demonstrated by the fact that the model captures the annual trend in nuclei mode concentration. The model is also used, alongside sensitivity tests, to examine which processes dominate the aerosol size distribution physical properties. It is shown, in agreement with previous studies, that nucleation governs the number concentration during transport from clean areas. It is also shown that primary number emissions almost exclusively govern the CN concentration when air from Central Europe is advected north over Scandinavia. We also show that biogenic emissions have a large influence on the amount of potential CCN observed

  12. New trajectory driven aerosol and chemical process model: chemical and aerosol Lagrangian model (CALM

    Directory of Open Access Journals (Sweden)

    P. Tunved

    2010-06-01

    Full Text Available A new Chemical and Aerosol Lagrangian Model (CALM have been developed and tested. The model incorporates all central aerosol dynamical processes, from nucleation, condensation, coagulation and deposition to cloud formation and in-cloud processing. The model is tested and evaluated against observations performed at the SMEAR II station located at Hyytiälä (61°51' N, 24°17' E over a time period of two years, 2000–2001. The model shows good agreement with measurements throughout most of the year, but fails in reproducing the aerosol properties during the winter season, resulting in poor agreement between model and measurements especially during December–January. Nevertheless, through the rest of the year both trends and magnitude of modal concentrations show good agreement with observation, as do the monthly average size distribution properties. The model is also shown to capture individual nucleation events to a certain degree. This indicates that nucleation largely is controlled by the availability of nucleating material (as prescribed by the [H2SO4], availability of condensing material (in this model 15% of primary reactions of monoterpenes (MT are assumed to produce low volatile species and the properties of the size distribution (more specifically, the condensation sink. This is further demonstrated by the fact that the model captures the annual trend in nuclei mode concentration. The model is also used, alongside sensitivity tests, to examine which processes dominate the aerosol size distribution physical properties. It is shown, in agreement with previous studies, that nucleation governs the number concentration while transport from clean areas takes place. It is also shown that primary number emissions almost exclusively govern the CN concentration when air from Central Europe is advected north over Scandinavia. We also show that biogenic emissions have a large influence on the amount of potential CCN observed

  13. Effects of irrigation efficiency on chemical transport processes

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Irrigation practices greatly affect sustainable agriculture development. In this study, we investigated the effects of irrigation efficiency on water flow and chemical transport in soils, which had significant impact on the environment. Field dye staining experiments were conducted at different soils with various irrigation amount. Image analysis was conducted to study the heterogeneous flow patterns and their relationships with the irrigation efficiency. Irrigation efficiency and its environmental effects were evaluated using various indictors, including application efficiency, deep percolation ratio, storage efficiency, and uniformity. Under the same irrigation condition, soil chemical distributions were more heterogeneous than soil water distributions. The distributions were mainly affected by soil texture, initial soil water content, and irrigation amount. Storage efficiency, irrigation uniformity, and deep percolation ratio increased with irrigation amount. Since the chemical distribution uniformity was lower than the water uniformity, the amount of chemical leaching increased sharply with decrease of irrigation uniformity, which resulted in high environmental risks of groundwater pollution.

  14. Slaughterhouse Wastewater Treatment by Combined Chemical Coagulation and Electrocoagulation Process

    OpenAIRE

    Edris Bazrafshan; Ferdos Kord Mostafapour; Mehdi Farzadkia; Kamal Aldin Ownagh; Amir Hossein Mahvi

    2012-01-01

    Slaughterhouse wastewater contains various and high amounts of organic matter (e.g., proteins, blood, fat and lard). In order to produce an effluent suitable for stream discharge, chemical coagulation and electrocoagulation techniques have been particularly explored at the laboratory pilot scale for organic compounds removal from slaughterhouse effluent. The purpose of this work was to investigate the feasibility of treating cattle-slaughterhouse wastewater by combined chemical coagulation an...

  15. Microstructural development in physical vapour-deposited partially stabilized zirconia thermal barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Sohn, Y. H. (Center for Intelligent Processing of Materials, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609-2280 (United States)); Biederman, R.R. (Center for Intelligent Processing of Materials, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609-2280 (United States)); Sisson, R.D. Jr. (Center for Intelligent Processing of Materials, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609-2280 (United States))

    1994-10-01

    The effects of processing parameters of physical vapour deposition on the microstructure of partially stabilized zirconia (PSZ) thermal barrier coatings have been experimentally investigated. Emphasis has been placed on the crystallographic texture of the PSZ coatings and the microstructure of the top surface of the PSZ coatings as well as the metal-ceramic interface. The variations in the deposition chamber temperature, substrate thickness, substrate rotation and vapour incidence angle resulted in the observation of significant differences in the crystallographic texture and microstructure of the PSZ coatings. ((orig.))

  16. Formation and Yield of Multi-Walled Carbon Nanotubes Synthesized via Chemical Vapour Deposition Routes Using Different Metal-Based Catalysts of FeCoNiAl, CoNiAl and FeNiAl-LDH

    Directory of Open Access Journals (Sweden)

    Mohd Zobir Hussein

    2014-11-01

    Full Text Available Multi-walled carbon nanotubes (MWCNTs were prepared via chemical vapor deposition (CVD using a series of different catalysts, derived from FeCoNiAl, CoNiAl and FeNiAl layered double hydroxides (LDHs. Catalyst-active particles were obtained by calcination of LDHs at 800 °C for 5 h. Nitrogen and hexane were used as the carrier gas and carbon source respectively, for preparation of MWCNTs using CVD methods at 800 °C. MWCNTs were allowed to grow for 30 min on the catalyst spread on an alumina boat in a quartz tube. The materials were subsequently characterized through X-ray diffraction, Fourier transform infrared spectroscopy, surface area analysis, field emission scanning electron microscopy and transmission electron microscopy. It was determined that size and yield of MWCNTs varied depending on the type of LDH catalyst precursor that is used during synthesis. MWCNTs obtained using CoNiAl-LDH as the catalyst precursor showed smaller diameter and higher yield compared to FeCoNiAl and FeNiAl LDHs.

  17. A method for an experimental determination of the growth process of water droplets

    OpenAIRE

    Cohen, Ariel

    2011-01-01

    When condensation nuclei are injected into a chamber where supersaturation conditions prevail, water droplet, sstart to form. The growth process is then dependent on the physical and chemical characteristics of the nuclei and on the process of diffusion of water vapour (Jiusto, 1967)DOI: 10.1111/j.2153-3490.1969.tb00482.x

  18. Effects of SO2 oxidation on ambient aerosol growth in water and ethanol vapours

    Directory of Open Access Journals (Sweden)

    A. Laaksonen

    2004-11-01

    Full Text Available Hygroscopicity (i.e. water vapour affinity of atmospheric aerosol particles is one of the key factors in defining their impacts on climate. Condensation of sulphuric acid onto less hygroscopic particles is expected to increase their hygrocopicity and hence their cloud condensation nuclei formation potential. In this study, differences in the hygroscopic and ethanol uptake properties of ultrafine aerosol particles in the Arctic air masses with a different exposure to anthropogenic sulfur pollution were examined. The main discovery was that Aitken mode particles having been exposed to polluted air were more hygroscopic and less soluble to ethanol than after transport in clean air. This aging process was attributed to sulfur dioxide oxidation and subsequent condensation during the transport of these particle to our measurement site. The hygroscopicity of nucleation mode aerosol particles, on the other hand, was approximately the same in all the cases, being indicative of a relatively similar chemical composition despite the differences in air mass transport routes. These particles had also been produced closer to the observation site typically 3–8 h prior to sampling. Apparently, these particles did not have an opportunity to accumulate sulphuric acid on their way to the site, but instead their chemical composition (hygroscopicity and ethanol solubility resembled that of particles produced in the local or semi-regional ambient conditions.

  19. Survey of knowledge of hazards of chemicals potentially associated with the advanced isotope separation processes

    International Nuclear Information System (INIS)

    Hazards of chemical potentially associated with the advanced isotope separation processes are estimated based on open literature references. The tentative quantity of each chemical associated with the processes and the toxicity of the chemical are used to estimate this hazard. The chemicals thus estimated to be the most potentially hazardous to health are fluorine, nitric acid, uranium metal, uranium hexafluoride, and uranium dust. The estimated next most hazardous chemicals are bromine, hydrobromic acid, hydrochloric acid, and hydrofluoric acid. For each of these chemicals and for a number of other process-associated chemicals the following information is presented: (1) any applicable standards, recommended standards and their basis; (2) a brief discussion to toxic effects including short exposure tolerance, atmospheric concentration immediately hazardous to life, evaluation of exposures, recommended control procedures, chemical properties, and a list of any toxicology reviews; and (3) recommendations for future research

  20. Vapour Recoil Effect on a Vapour-Liquid System with a Deformable Interface

    Institute of Scientific and Technical Information of China (English)

    LIU Rong; LIU Qiu-Sheng

    2006-01-01

    @@ A new two-sided model of vapour-Iiquid layer system with a deformable interface is proposed. In this model,the vapour recoil effect on the Marangoni-Bénard instability of a thin evaporating liquid layer can be examined only when the interface deflexion is considered. The instability of a liquid layer undergoing steady evaporation induced by the coupling of vapour recoil effect and the Marangoni effect is analysed using a linear stability theory.We modify and develop the Chebyshev-Tau method to solve the instability problem of a deformable interface system by introducing a new equation at interface boundary. New instability behaviour of the system has been found and the self-amplification mechanism between the evaporation flux and the interface deflexion is discussed.

  1. Rapid neutron capture process in supernovae and chemical element formation

    NARCIS (Netherlands)

    Baruah, Rulee; Duorah, Kalpana; Duorah, H. L.

    2009-01-01

    The rapid neutron capture process (r-process) is one of the major nucleosynthesis processes responsible for the synthesis of heavy nuclei beyond iron. Isotopes beyond Fe are most exclusively formed in neutron capture processes and more heavier ones are produced by the r-process. Approximately half o

  2. 29 CFR 1926.64 - Process safety management of highly hazardous chemicals.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Process safety management of highly hazardous chemicals... Health and Environmental Controls § 1926.64 Process safety management of highly hazardous chemicals... elements of process safety management in this standard. (3) Employers shall provide to employees and...

  3. Improvement of a thermoelectric and vapour compression hybrid refrigerator

    International Nuclear Information System (INIS)

    This paper presents the improvement in the performance of a domestic hybrid refrigerator that combines vapour compression technology for the cooler and freezer compartments, and thermoelectric technology for a new compartment. The heat emitted by the Peltier modules is discharged into the freezer compartment, forming a cascade refrigeration system. This configuration leads to a significant improvement in the coefficient of operation. Thus, the electric power consumption of the modules and the refrigerator decreases by 95% and 20% respectively, with respect to those attained with a cascade refrigeration system connected with the cooler compartment. The optimization process is based on a computational model that simulates the behaviour of the whole refrigerator. Two prototypes have been built and tested. Experimental results indicate that the temperature of the new compartment is easily set up at any value between 0 and −4 °C, the oscillation of this temperature is always lower than 0.4 °C, and the electric power consumption is low enough to include this hybrid refrigerator into energy efficiency class A, according European rules and regulations. - Highlights: ► Optimization of a vapour compression and thermoelectric hybrid refrigerator. ► Two prototypes built and tested. Computational model for the whole refrigerator. ► Electric power consumption of the modules and the refrigerator 95% and 20% lower. ► New compartment refrigerated with thermoelectric technology. ► Inner temperature adjustable from 0 to −4 °C. Oscillations lower than ±0.2 °C.

  4. Laser studies of chemical reaction and collision processes

    Energy Technology Data Exchange (ETDEWEB)

    Flynn, G. [Columbia Univ., New York, NY (United States)

    1993-12-01

    This work has concentrated on several interrelated projects in the area of laser photochemistry and photophysics which impinge on a variety of questions in combustion chemistry and general chemical kinetics. Infrared diode laser probes of the quenching of molecules with {open_quotes}chemically significant{close_quotes} amounts of energy in which the energy transferred to the quencher has, for the first time, been separated into its vibrational, rotational, and translational components. Probes of quantum state distributions and velocity profiles for atomic fragments produced in photodissociation reactions have been explored for iodine chloride.

  5. The beauty of frost: nano-sulfur assembly via low pressure vapour deposition.

    Science.gov (United States)

    Wang, Yu; Chen, Lu; Scudiero, Louis; Zhong, Wei-Hong

    2015-11-14

    A low pressure vapour deposition (LPVD) technique is proposed as an environmentally friendly, cost-effective and versatile strategy for fabrication of sulfur nanomaterials. By controlling the characteristics of the deposit substrate for the LPVD, various sulfur-based nanomaterials have been obtained through a substrate-induced self-assembly process.

  6. The beauty of frost: nano-sulfur assembly via low pressure vapour deposition.

    Science.gov (United States)

    Wang, Yu; Chen, Lu; Scudiero, Louis; Zhong, Wei-Hong

    2015-11-14

    A low pressure vapour deposition (LPVD) technique is proposed as an environmentally friendly, cost-effective and versatile strategy for fabrication of sulfur nanomaterials. By controlling the characteristics of the deposit substrate for the LPVD, various sulfur-based nanomaterials have been obtained through a substrate-induced self-assembly process. PMID:26383233

  7. Kinetics and morphology of electrochemical vapour deposited thin zirconia/yttria layers on porous substrates

    NARCIS (Netherlands)

    Brinkman, H.W.; Meijerink, J.; Vries, de K.J.; Burggraaf, A.J.

    1996-01-01

    By means of electrochemical vapour deposition (EVD), it is possible to grow thin (0.5-5 µm), dense zirconia/yttria layers on porous ceramic substrates. Kinetics of the EVD process, morphology and oxygen permeation properties of the grown layers are investigated. Very thin (~ 0.5 µm) layers are grown

  8. Wagner liquid-vapour pressure equation constants from a simple methodology

    Energy Technology Data Exchange (ETDEWEB)

    Forero G, Luis A., E-mail: forerogaviria@yahoo.com [Pulp and Paper Research Group, Faculty of Chemical Engineering, Universidad Pontificia Bolivariana, Circular 1a 70-01 Medellin, Antioquia (Colombia); Velasquez J, Jorge A., E-mail: jorge.velasquezj@upb.edu.co [Pulp and Paper Research Group, Faculty of Chemical Engineering, Universidad Pontificia Bolivariana, Circular 1a 70-01 Medellin, Antioquia (Colombia)

    2011-08-15

    Highlights: > Simple methodology to estimate Wagner vapor pressure equation constants. > Full range liquid-vapor pressure predictions from limited data. > Constants satisfy the Waring criterion. - Abstract: A methodology to determine the A, B, C, and D constants from the Wagner equation is presented. The constants for 274 pure substances were determined by minimization in the sum of the squares of the relative deviation in liquid vapour pressure. For 69 chemical compounds, vapour pressures exist over the range from 1 kPa to the critical pressure and an average absolute deviation in vapour pressure of 0.039% was calculated. Using Antoine equation coefficients and initial guesses for a correlation in terms of the acentric factor, Wagner constants were estimated for substances with limited data within the range from (1 to 200) kPa. To validate the proposed methodology, vapour pressure predictions from 1 kPa to the critical pressure were made for 52 substances using Wagner parameters estimated from limited data. A value of 0.27% in average absolute deviation results for those substances. Finally the Waring criterion was applied to check the constants presented in this paper.

  9. Dynamic Processes of Conceptual Change: Analysis of Constructing Mental Models of Chemical Equilibrium.

    Science.gov (United States)

    Chiu, Mei-Hung; Chou, Chin-Cheng; Liu, Chia-Ju

    2002-01-01

    Investigates students' mental models of chemical equilibrium using dynamic science assessments. Reports that students at various levels have misconceptions about chemical equilibrium. Involves 10th grade students (n=30) in the study doing a series of hands-on chemical experiments. Focuses on the process of constructing mental models, dynamic…

  10. Ultrafast vapourization dynamics of laser-activated polymeric microcapsules

    Science.gov (United States)

    Lajoinie, Guillaume; Gelderblom, Erik; Chlon, Ceciel; Böhmer, Marcel; Steenbergen, Wiendelt; de Jong, Nico; Manohar, Srirang; Versluis, Michel

    2014-04-01

    Precision control of vapourization, both in space and time, has many potential applications; however, the physical mechanisms underlying controlled boiling are not well understood. The reason is the combined microscopic length scales and ultrashort timescales associated with the initiation and subsequent dynamical behaviour of the vapour bubbles formed. Here we study the nanoseconds vapour bubble dynamics of laser-heated single oil-filled microcapsules using coupled optical and acoustic detection. Pulsed laser excitation leads to vapour formation and collapse, and a simple physical model captures the observed radial dynamics and resulting acoustic pressures. Continuous wave laser excitation leads to a sequence of vapourization/condensation cycles, the result of absorbing microcapsule fragments moving in and out of the laser beam. A model incorporating thermal diffusion from the capsule shell into the oil core and surrounding water reveals the mechanisms behind the onset of vapourization. Excellent agreement is observed between the modelled dynamics and experiment.

  11. Chemical dehumidification and thermal regeneration: Applications in industrial processes

    Energy Technology Data Exchange (ETDEWEB)

    Lazzarin, R.; Longo, G.A.; Piccininni, F.

    1991-11-01

    Chemical dehumidification may be used in industrial dessiccation treatments operating with new air or closed cycle. The authors suggest a few schemes and analyze operation parameters and performance. Finally, comparisons are made with the most efficient systems that have been used so far: energy savings are between 25 and 40 per cent.

  12. Effects of irrigation efficiency on chemical transport processes

    Institute of Scientific and Technical Information of China (English)

    WANG Kang; ZHANG RenDuo; SHENG Feng

    2009-01-01

    Irrigation practices greatly affect sustainable agriculture development.In this study, we investigated the effects of irrigation efficiency on water flow and chemical transport in soils, which had significant impact on the environment.Field dye staining experiments were conducted at different soils with various irrigation amount.Image analysis was conducted to study the heterogeneous flow patterns and their relationships with the irrigation efficiency.Irrigation efficiency and its environmental effects were evaluated using various indictors, including application efficiency, deep percolation ratio, storage effi-ciency, and uniformity.Under the same irrigation condition, soil chemical distributions were more het-erogeneous than soil water distributions.The distributions were mainly affected by soil texture, initial soil water content, and irrigation amount.Storage efficiency, irrigation uniformity, and deep percolation ratio increased with irrigation amount.Since the chemical distribution uniformity was lower than the water uniformity, the amount of chemical leaching increased sharply with decrease of irrigation uni-formity, which resulted in high environmental risks of groundwater pollution.

  13. Flow-Injection Responses of Diffusion Processes and Chemical Reactions

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov

    2000-01-01

    The technique of Flow-injection Analysis (FIA), now aged 25 years, offers unique analytical methods that are fast, reliable and consuming an absolute minimum of chemicals. These advantages together with its inherent feasibility for automation warrant the future applications of FIA as an attractiv...

  14. Conversion of Lignocellulosic Biomass to Nanocellulose: Structure and Chemical Process

    OpenAIRE

    Lee, H. V.; S. B. A. Hamid; Zain, S. K.

    2014-01-01

    Lignocellulosic biomass is a complex biopolymer that is primary composed of cellulose, hemicellulose, and lignin. The presence of cellulose in biomass is able to depolymerise into nanodimension biomaterial, with exceptional mechanical properties for biocomposites, pharmaceutical carriers, and electronic substrate’s application. However, the entangled biomass ultrastructure consists of inherent properties, such as strong lignin layers, low cellulose accessibility to chemicals, and high cellulo...

  15. TREATMENT TANK CORROSION STUDIES FOR THE ENHANCED CHEMICAL CLEANING PROCESS

    Energy Technology Data Exchange (ETDEWEB)

    Wiersma, B.

    2011-08-24

    Radioactive waste is stored in high level waste tanks on the Savannah River Site (SRS). Savannah River Remediation (SRR) is aggressively seeking to close the non-compliant Type I and II waste tanks. The removal of sludge (i.e., metal oxide) heels from the tank is the final stage in the waste removal process. The Enhanced Chemical Cleaning (ECC) process is being developed and investigated by SRR to aid in Savannah River Site (SRS) High-Level Waste (HLW) as an option for sludge heel removal. Corrosion rate data for carbon steel exposed to the ECC treatment tank environment was obtained to evaluate the degree of corrosion that occurs. These tests were also designed to determine the effect of various environmental variables such as temperature, agitation and sludge slurry type on the corrosion behavior of carbon steel. Coupon tests were performed to estimate the corrosion rate during the ECC process, as well as determine any susceptibility to localized corrosion. Electrochemical studies were performed to develop a better understanding of the corrosion mechanism. The tests were performed in 1 wt.% and 2.5 wt.% oxalic acid with HM and PUREX sludge simulants. The following results and conclusions were made based on this testing: (1) In 1 wt.% oxalic acid with a sludge simulant, carbon steel corroded at a rate of less than 25 mpy within the temperature and agitation levels of the test. No susceptibility to localized corrosion was observed. (2) In 2.5 wt.% oxalic acid with a sludge simulant, the carbon steel corrosion rates ranged between 15 and 88 mpy. The most severe corrosion was observed at 75 C in the HM/2.5 wt.% oxalic acid simulant. Pitting and general corrosion increased with the agitation level at this condition. No pitting and lower general corrosion rates were observed with the PUREX/2.5 wt.% oxalic acid simulant. The electrochemical and coupon tests both indicated that carbon steel is more susceptible to localized corrosion in the HM/oxalic acid environment than

  16. TREATMENT TANK CORROSION STUDIES FOR THE ENHANCED CHEMICAL CLEANING PROCESS

    Energy Technology Data Exchange (ETDEWEB)

    Wiersma, B.

    2011-08-24

    Radioactive waste is stored in high level waste tanks on the Savannah River Site (SRS). Savannah River Remediation (SRR) is aggressively seeking to close the non-compliant Type I and II waste tanks. The removal of sludge (i.e., metal oxide) heels from the tank is the final stage in the waste removal process. The Enhanced Chemical Cleaning (ECC) process is being developed and investigated by SRR to aid in Savannah River Site (SRS) High-Level Waste (HLW) as an option for sludge heel removal. Corrosion rate data for carbon steel exposed to the ECC treatment tank environment was obtained to evaluate the degree of corrosion that occurs. These tests were also designed to determine the effect of various environmental variables such as temperature, agitation and sludge slurry type on the corrosion behavior of carbon steel. Coupon tests were performed to estimate the corrosion rate during the ECC process, as well as determine any susceptibility to localized corrosion. Electrochemical studies were performed to develop a better understanding of the corrosion mechanism. The tests were performed in 1 wt.% and 2.5 wt.% oxalic acid with HM and PUREX sludge simulants. The following results and conclusions were made based on this testing: (1) In 1 wt.% oxalic acid with a sludge simulant, carbon steel corroded at a rate of less than 25 mpy within the temperature and agitation levels of the test. No susceptibility to localized corrosion was observed. (2) In 2.5 wt.% oxalic acid with a sludge simulant, the carbon steel corrosion rates ranged between 15 and 88 mpy. The most severe corrosion was observed at 75 C in the HM/2.5 wt.% oxalic acid simulant. Pitting and general corrosion increased with the agitation level at this condition. No pitting and lower general corrosion rates were observed with the PUREX/2.5 wt.% oxalic acid simulant. The electrochemical and coupon tests both indicated that carbon steel is more susceptible to localized corrosion in the HM/oxalic acid environment than

  17. New insights into chemical processes within martian high latitude soils

    Science.gov (United States)

    Horgan, B.; Bell, J. F.

    2010-12-01

    Our analysis of near-infrared spectra of low albedo soils in the northern lowlands of Mars has revealed that they can be classified into three compositional groups: (1) relatively unaltered and high-calcium pyroxene-rich, (2) pervasively leached and glass-rich, and (3) gypsum-rich. Here we present results from spectral and morphologic studies, which together show that the diversity of soils observed from orbit and those observed in situ by the Phoenix lander can largely be explained by aqueous processes acting on high-calcium pyroxene-rich soils. Soils in Acidalia Planitia, parts of the north polar sand sea, and certain units within the north polar plateau exhibit spectral signatures consistent with an enrichment in iron-bearing glass, as well as signatures consistent with leached glass rinds, which form during acidic alteration of glass surfaces. As glass enrichment can be produced during acidic leaching of basaltic sand, we have proposed that these soils are the endproducts of widespread and pervasive acidic leaching. If these altered sands originally had a composition similar to the relatively unaltered high-calcium pyroxene-rich soils observed elsewhere in the northern lowlands, then we should also expect them to contain calcium-bearing secondary precipitates, primarily gypsum. While spectral analysis of Acidalia-type soils places an approximate upper limit on their gypsum concentration of 15-20 wt.%, our results suggest that the gypsum-rich (up to 40 wt.%) sands in the Olympia Undae region of the north polar sand sea could also be sourced from Acidalia-type materials within the north polar plateau. Although Olympia Undae gypsum concentrations appear too high to justify this hypothesis, our morphologic studies of the region suggest that the high concentrations are most likely surficial and do not represent the volumetric concentrations. By mapping the distribution of tensional surface cracks on sand dunes in HiRISE images, we have shown that the strength of

  18. Development of Chemical Process Design and Control for Sustainability

    Science.gov (United States)

    This contribution describes a novel process systems engineering framework that couples advanced control with sustainability evaluation and decision making for the optimization of process operations to minimize environmental impacts associated with products, materials, and energy....

  19. Water vapour measurements during POLINAT 1

    Energy Technology Data Exchange (ETDEWEB)

    Ovarlez, J.; Ovarlez, H. [Centre National de la Recherche Scientifique, 91 - Palaiseau (France). Lab. de Meteorologie Dynamique

    1997-12-31

    The POLINAT (POLlution from aircraft emissions In the North ATlantic flight corridor)1 experiment has been performed within the framework of the Environment Programme of the Commission of the European Community. It was devoted to the study of the pollution from aircraft in the North Atlantic flight corridor, in order to investigate the impact of pollutants emitted by aircraft on the concentrations of ozone and other trace gases in the upper troposphere and lower stratosphere. For that experiment the water vapour content was measured with a frost-point hygrometer on board of the DLR Falcon research aircraft. This instrument is described, and some selected results are given. (author) 19 refs.

  20. The Water Vapour Radiometer at Effelsberg

    Science.gov (United States)

    Roy, A. L.; Teuber, U.; Keller, R.

    We have installed a scanning 18 GHz to 26 GHz water vapour radiometer on the focus cabin of the Effelsberg 100 m telescope for tropospheric phase, delay and opacity correction during high-frequency VLBI observations. It is based on the design by Tahmoush & Rogers (2000) but with noise injection for calibration, weather-proof housing, and temperature stabilization. The radiometer is delivering data into an archive since July 2003, from which they are available for download. The data will be delivered automatically to PIs of EVN experiments in a calibration table attached by the EVN calibration pipeline. This paper describes the radiometer and its performance.