Showing papers on "Inert gas published in 1998"

Production of carbon nanotubes

Abstract: Carbon nanostructures such as single-walled and multi-walled nanotubes (SWNTs and MWNTs) or graphitic polyhedral nanoparticles can be produced using various methods. Most of them are based on the sublimation of carbon under an inert atmosphere, such as the electric arc discharge process, the laser ablation method, or the solar tech- nique. But chemical methods can also be used to synthesize these kinds of carbon materials: the catalytic decomposi- tion of hydrocarbons, the production by electrolysis, the heat treatment of a polymer, the low temperature solid pyrolysis, or the in situ catalysis.

Very high aspect ratio gapfill using HDP

Abstract: A process for filling high aspect ratio gaps on substrates uses conventional high density plasma deposition processes, with an efficient sputtering inert gas, such as Ar, replaced or reduced with an He inefficient sputtering inert gas such as He. By reducing the sputtering component, sidewall deposition from the sputtered material is reduced. Consequently, gaps with aspect ratios of 6.0:1 and higher can be filled without the formation of voids and without damaging circuit elements.

Organic electroluminescent display device, and method and system for making the same

Abstract: In an organic EL display device, an organic EL multilayer structure is disposed in a gastight space defined between a substrate and a shield member and filled with an inert gas. The organic EL multilayer structure includes organic materials having a Tg of at most 140° C. The shield member is a continuous member free of a filling port. The shield member is joined to the substrate with a UV-curing epoxy resin adhesive of the cationic curing type. The inert gas in the space has a water content of at most 100 ppm. The steps of forming layers on substrates to form organic EL multilayer structures and the steps of adhesively joining shield members to the substrates are carried out in inert gas atmospheres.

Method for improved cleaning of substrate processing systems

Abstract: A method for a multiple-stage microwave plasma cleaning technique for efficiently cleaning a substrate processing chamber. In a specific embodiment, a two-stage cleaning process is described. The first stage begins by flowing a reactive gas from a gas source (7) into a processing chamber (15) where microwaves ignite and maintain a plasma from the reactive gas. Reactive radicals generated which react with residues on the interior surfaces of the processing chamber. In the second stage, an inert gas is flowed into the processing chamber in addition to the reactive gas. Microwaves then ignite and maintain a plasma from the reactive gas and optionally, the inert gas as well. Optionally, an inert gas can be flowed into the processing chamber prior to the first stage to remove loose particles from the processing chamber. The reactive gas in such embodiments is preferably NF3, but other fluorine-containing gases such as carbon tetrafluoride (CF4) or sulfurhexafluoride (SF6) may also be used. Moreover, chlorine- or other halogen-containing gases may also be used as the reactive gas in other embodiments in place of fluorine-containing gases.

Evidence of spin disorder at the surface–core interface of oxygen passivated Fe nanoparticles

Abstract: Hysteresis, thermal dependence of magnetization, and coercivity of oxide coated ultrafine Fe particles prepared by inert gas condensation and oxygen passivation have been studied in the 5–300 K range. The results are found to be consistent with a spin-glasslike state of the oxide layer inducing, through exchange interaction with the ferromagnetic core, a shift of the field cooled hysteresis loops at temperatures below the freezing at approximately 50 K.

Kinetics of thermal degradation of thermotropic poly(p-oxybenzoate-co-ethylene terephthalate) by single heating rate methods

Abstract: The kinetics of decomposition of thermotropic liquid crystalline poly(p-oxybenzoate-co-ethylene terephthalate) (poly(B-co-E), BE polymer) with different monomer ratios in both nitrogen and air were studied by dynamic thermogravimetry (TG) from ambient temperature to 800°C. The kinetic parameters, including the activation energy E′, the reaction order n, and the pre-exponential factor Z, of the degradation of the BE polymers were evaluated by the single heating rate methods of Friedman, Freeman–Carroll and Chang. The BE polymers which degraded in two distinct stages in nitrogen and air, were stable under nitrogen, while almost completely burned in air. The weight losses in the first stage in nitrogen and air were dominated by the thermal degradation of both B and E segments, but the weight losses in the second stage were governed by the thermal degradation of B segment in nitrogen and by the oxidative degradation of both B and E segments in air. The maximum rate of weight loss increased linearly with the increase of E content and heating rate, but as E content increased, the char yield at 800°C in nitrogen decreased linearly. The E′, n and ln Z values of the BE polymers in the first stage of thermal pyrolysis are higher in nitrogen than in air, indicating that the degradation rate is slower in an inert atmosphere. The E′ value increased with increasing heating rate but varied irregularly with the variations of B/E ratios and molecular weight. The n and ln Z values for the BE polymers in nitrogen were found to be in the wide ranges 1·5–5·6 and 12–48min-1, respectively, suggesting a complex degradation process. The estimated lifetimes of the BE polymers at 250°C were calculated to be at least 33 days in nitrogen and 3h in air. © 1998 SCI.

Thermodynamic Analysis of Hydride Vapor Phase Epitaxy of GaN

Abstract: A thermodynamic analysis of hydride vapor phase epitaxy (HVPE) is described for GaN. The partial pressures of gaseous species in equilibrium with GaN are calculated for temperatures, input GaCl partial pressures, input V/III ratios and mole fractions of hydrogen relative to the inert gas atoms. It is shown that the deposition of GaN is significantly influenced by the hydrogen mole fraction in the carrier gas. The growth rate is discussed in comparison with the experimental data reported in the literature. It is shown that the growth rate of GaN grown using HVPE is thermodynamically controlled.

Vaporizer for inhalation and method for extraction of active ingredients from a crude natural product or other matrix

Abstract: The present invention is a vaporizer apparatus (1) and method for uniformly extracting active ingredients of specimen of crude natural product, or inert particulate matrix impregnated with volatile substances without pyrolysis which uses hot air (2), or a heated inert gas stream to volatilize the specimen. The heated air or gas in introduced from below (from either a hot air gun or a high-pressure tank connected to a heat exchanger), and ascends through in most embodiments through a permeable support structure (4) (e.g., fritted glass disk, etc.) subsequently causing specimen particules disposed on the permeable support structure to be suspended within the confines of an isolation chamber (5).

Thermal Decomposition of Copper(I) Thiocarbamide Chloride Hemihydrate

Abstract: Two combinations of simultaneous thermoanalytical techniques (TG+DTA and TG+EGA) were used to study the thermal decomposition of the title compound in order to gain a better insight into the spray pyrolytic processes leading to Cu2-xS and CuInS2 thin films. After dehydration a complex sequence of reactions starts above 220°C leading through several intermediates to the formation of CuO in air at 1000°C. In an inert atmosphere Cu2S is formed which in helium above 800°C partly decomposes to Cu. XRD and FTIR were used to identify the intermediate solid phases which in air included CuCl, Cu2OSO4, Cu2OCl2 and CuSO4. EGA-FTIR confirmed the complex reaction mechanism with NH3, HCl, H2O, COS, CO2 and some HCN as main gaseous products under oxidative conditions.

Process for rapid activation of double metal cyanide catalysts

Abstract: A process for activating double metal cyanide catalysts is disclosed. A polyol starter or starter/catalyst mixture is heated under vacuum under conditions effective to achieve improved stripping compared with that which can be achieved through conventional vacuum stripping. Coupling vacuum stripping with inert gas sparging or stripping in the presence of an organic solvent gives a starter/catalyst mixture that activates rapidly in an epoxide polymerization process. Rapid activation makes process start-ups reliable and reduces cycle time. The process gives polyols with lower viscosity, lower polydispersity, and lower unsaturation for better polyurethanes.

Chemistry for etching organic low-k materials

Abstract: A process for plasma etching of contact and via openings in low-k organic polymer dielectric layers is described which overcomes problems of sidewall bowing and hardmask pattern deterioration by etching the organic layer in a high density plasma etcher with a chlorine/inert gas plasma. By adding chlorine to the oxygen/inert gas plasma, the development of an angular aspect or faceting of the hardmask pattern edges by ion bombardment is abated. Essentially vertical sidewalls are obtained in the openings etched in the organic polymer layer while hardmask pattern integrity is maintained. The addition of a passivating agent such as nitrogen, BCl3, or CHF3 to the etchant gas mixture further improves the sidewall profile by reducing bowing through protective polymer formation.

The activation of Mg in GaN by annealing with minority-carrier injection

Abstract: The activation of a Mg acceptor in GaN, by means of annealing under minority-carrier injection, is observed at a temperature above 300 °C. This activation is carried on with hydrogen left in the layer. The p-type GaN layers activated by this treatment are repassivated by additional annealing in an open-circuit configuration even in inert gas, and then reactivated by annealing under minority-carrier injection. Hydrogen remaining in the layer seems to play a major role in this reversible phenomenon.

Rapid Evaporative Cooling Suppresses Fragmentation in Mass Spectrometry: Synthesis of ``Unprotonated'' Water Cluster Ions

Abstract: Hydrogen-bonded water clusters were formed with inert gases adsorbed to them in a strong molecular beam expansion. Upon single-photon ionization of such mixed clusters using VUV light, fragmentation of the substrate water cluster ion is markedly suppressed. Experimental evidence is presented, showing that the rapid evaporation of the inert gas from the newly formed water cluster ion efficiently removes internal energy on a time scale much faster than the usual fragmentation reactions present in pure water clusters, i.e., rates of fragmentation that are normally >109 s-1. This phenomenon is exploited to produce “unprotonated” water clusters, formally (H2O)n+. Using post source decay reflectron time-of-flight mass spectrometry, the structure of the “unprotonated” water cluster ions is experimentally determined for the first time. The structure determined, H3O+(H2O)k·OH where the hydroxyl radical is found outside the first solvation shell of the charge, is consistent with recent ab initio calculations. This ...

Comparison of four combustion models for simulating the premixed combustion in inert porous media

Abstract: This work reports one-dimensional predictions of methane/air fuel combustion in inert porous media using four combustion models: full mechanism (FM, 49 species and 227 elemental reactions), skeletal mechanism (SM, 26 species and 77 elemental reactions), 4-step reduced mechanism (4RM, 9 species) and 1-step global mechanism (1GM). The effects of these models on temperature, species, burning speeds and pollutant emissions are examined. The calculations are compared with available experimental data. It is concluded that the already known limitation of the 1-step global mechanism can be partially eliminated by the present 4-step reduced mechanism. This 4RM model compares very satisfactorily with the full mechanism in the simulation of combustion in porous media. This conclusion is encouraging for the simulation of practical porous media burners because the 4RM model improves the stability of the calculation process and can be used with reduced computational resources and cost.

Production of Carbon Nanotubes

Abstract: Carbon nanostructures such as single-walled and multi-walled nanotubes (SWNTs and MWNTs) or graphitic polyhedral nanoparticles can be produced using various methods. Most of them are based on the sublimation of carbon under an inert atmosphere, such as the electric arc discharge process, the laser ablation method, or the solar tech- nique. But chemical methods can also be used to synthesize these kinds of carbon materials: the catalytic decomposi- tion of hydrocarbons, the production by electrolysis, the heat treatment of a polymer, the low temperature solid pyrolysis, or the in situ catalysis.

Anisotropic etching of organic-containing insulating layers

Abstract: A method for forming an opening in an organic insulating layer by covering the insulating layer with a bilayer containing a resist hard mask layer and a resist layer on top of the resist hard mask layer. The bilayer is patterned, and an opening is created by plasma etching the insulating layer in a reaction chamber containing a gas mixture. The plasma etching is controlled so that virtually no etch residues are deposited and so that the side walls of the opening are fluorinated to enhance the anisotropy of the etching. The gas mixture can be a mixture of a fluorine-containing gas and an inert gas, a mixture of an oxygen-containing gas and an inert gas, or a mixture of hydrogen bromide and an additive.

Apparatus and methods of depositing a platinum film with anti-oxidizing function over a substrate

Abstract: A platinum film, which is used as a bottom electrode for a capacitor in a DRAM cell or a non-volatile ferroelectric memory cell, is formed in two separate processes, wherein a first thickness platinum part thereof is deposited under an inert gas atmosphere, and the second thickness platinum part is deposited under an atmosphere containing oxygen, nitrogen and/or a mixture thereof as well as an inert gas. The platinum film is annealed under a vacuum atmosphere to remove the oxygen an/or nitrogen introduced during the deposition of the second thickness platinum part. The annealed platinum film prevents formation of an oxide on a functional intermediate film such as a diffusion barrier layer or an adhesion layer, which is provided below the bottom electrode of platinum film.

Dynamic characteristics of gas jets from subsonic and supersonic nozzles for high pressure gas laser cutting

Abstract: During laser cutting of stainless steels, titanium and aluminum alloys, a coaxial and high pressure inert gas jet is used to improve the cut edge quality. The process normally consumes a large amount of inert gas and has a poor tolerance to variation in process parameters. This is solely because the gas nozzles are mostly of the conical and convergent type in which the gas jets are subsonic. Based on two dimensional steady state gas dynamic theory, computer simulation and shadowgraphic techniques, the gas jet patterns from conical nozzles and the newly designed supersonic nozzles are analyzed. The distribution of pressure, momentum, gas density and existence of shock waves are predicted and mapped. Based on these characteristics, the effect of the gas jets upon the cut quality is explained. It is concluded that a supersonic gas jet offers the best flow characteristics for high pressure laser cutting.

Surface studies of plasma source ion implantation treated polystyrene

Abstract: The plasma source ion implantation (PSII) was utilized to improve the wettability and the stability of surface layer formed in the modification of polymeric materials. Polystyrene was treated with different kinds of plasma ions to render the surface more hydrophilic or hydrophobic. Hydrophobic recovery of PSII-treated polystyrene was also observed as a function of aging time, aging temperature, and treatment parameters. Treatment parameters involve kinds of gases, pressure, plasma power, pulse frequency, pulse voltage, etc. To study the effect of inert gas on hydrophobic recovery, polystyrene samples were prepared by helium, argon, or gas-mixture treatment. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) has been used to interpret the PSII-treated polystyrene surface and its hydrophobic recovery, with the assistance of x-ray photoelectron spectroscopy and water contact angle measurements. TOF-SIMS spectra of 18O2 PSII-treated samples showed the presence of 18O-containing peaks from the modified ...

Energetics of mechanism of OH‐propene reaction at low pressures in inert atmosphere

Abstract: MP2 calculations with full geometry optimizations were performed with a double‐ and a triple‐zeta basis set to obtain the energy profile for reactions of propene+OH and ethene+OH at low pressures. In these conditions, the β‐hydroxyalkyl radicals formed after OH addition to the alkene double bond may go through a rearrangement reaction to form easily identifiable aldehydes and ketones. The theoretical results obtained reproduce the available experimental data well and shed light on the mechanism of reactions characterized by negative activation energies. © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 811–819, 1998

Pitch foam products

Abstract: An improved process for the preparation of a pitch foam with a microcellular structure and a uniform pore size comprises the steps of (a) pressing a quantity of a pitch to provide a pressed article, (b) placing the pressed article in a pressure vessel, (c) introducing an inert gas into the pressure vessel under an elevated pressure of about 200 to 500 psi, (d) heating the pressed article within the pressure vessel to about 10° to 40° C. above the melting temperature of the pitch, (e) introducing additional inert gas, under pressure, to obtain a final pressure within the pressure vessel of about 1000 to 1500 psi, (f holding the pressure vessel and the compressed article under pressure for about 10 to 40 minutes, (g) venting the pressure vessel to atmospheric pressure, thereby providing a porous foam, (h) stabilizing the porous foam at an elevated temperature in an oxygen-containing environment, and (i) cooling the resulting, stabilized porous foam to ambient temperature at a cooling rate of about 0.1° to 5° C. per minute. The porous pitch foam can be converted to a porous carbon foam by heating the pitch foam in an inert atmosphere to a temperature sufficient to carbonize the pitch. The porous carbon foam can be converted to a porous graphitic foam by heating the carbon foam in an inert atmosphere to a temperature sufficient to graphitize the pitch.

Apparatus and method of forming preferred orientation-controlled platinum film using oxygen

Abstract: A platinum film orientation-controlled to (111), (200) and/or (220) is provided by depositing the platinum film under an atmosphere containing an oxygen component such as O 2 , O 3 , N 2 O , N 2 +O 2 , or mixtures thereof as well as an inert gas (Ar, Ne, Kr, or Xe) on a substrate heated to a temperature ranged from room temperature to 700° C., and annealing to remove the gases introduced into the platinum film during the deposition thereof. The platinum film formed in this process has excellent electrical conductivity (resistivity is lower than 15 μΩ-cm), good enough adhesion strength to be used for electronic devices, and does not show hillocks, voids or pinholes.

Electrostatic method and means for removing contaminants from gases

Abstract: An electrical apparatus includes a reaction chamber. A stream of contaminated gasses flows through the chamber. An elongated coronating electrode is positioned in the reaction chamber for producing a corona discharge within the chamber. A multi-stage Fitch generator connected to the electrode produces a high level, rapidly pulsating voltage in the electrode. Controlled amounts of an inert gas or inert gas-air mixture are combined with the contaminated gases to provide a high concentration of inert gas in the reaction chamber. In the inert gas-enriched atmosphere, the pulsating corona discharge produces a high concentration of metastable intermediates that greatly increase the rate of chemical conversion of the contaminants. Switching circuitry allows the pulsating voltage output of the Fitch generator to be superimposed on a constant direct current voltage in the electrode, setting up an electrostatic field in the reaction chamber for removing conversion byproducts from the gas stream.

Apparatus and method for vapor reduction for a fuel storage tank

Abstract: A fuel vapor reduction apparatus comprising an inert gas receiver, pressure sensor of the vacant volume of a fuel storage tank, external pressure sensor, a non-permeable expandable member disposed inside the fuel storage tank, and an inert gas regulator that is responsive to a predetermined differential pressure between the pressure of the vacant volume inside the tank and the external fuel storage tank pressure, whereby, the expandable member is able to expandably receive and hold the inert gas to fill the vacant volume and reduce fuel vapor formation.

Solid polymer electrolyte electrochemical oxygen control system with integral reactor feedback sensing

Abstract: Disclosed is a novel proton-exchange membrane (PEM) based solid polymer electrolyte electrochemical oxygen control (EOC) system that can deplete and control the oxygen from a closed container to levels sufficient for both disinfestation and preservation. With the use of this electrochemical process, many insects that infest raw agricultural products and other produce can be exterminated, without detriment to the quality of the produce and without deposition of harmful residue, by reducing the ambient oxygen to a controlled low level for several days. The electrochemical process features the use of a bipolar stack comprised of a selected number of PEM cells connected electrically in series and separated by an electrically conductive bipolar plate. Each cell contains a membrane and electrode assembly, consisting of an anode structure and cathode structure in intimate contact with a PEM. When DC power is applied to the cell stack, electrons are supplied to the cathode, supporting reduction of oxygen at the cathode with the formation of water, and electrons removed from the anode, supporting oxygen evolution by the decomposition of water at the anode. The anode and cathode compartments are separated by the solid ionomer PEM, which transports protons generated at the anode through the PEM to the cathode to complete the electrical circuit internally. Oxygen is depleted by recirculating the gas in the dosed container over the cathode, and expelling the oxygen evolved at the anode by separating the oxygen from the recirculating anode water stream and venting it to the outside of the closed container. Nitrogen or other inert gas is added as makeup gas to avoid creating a negative pressure in the container. A unique feature of this process is that at a low oxygen concentration, the cell and stack cathode current becomes rate-limited in direct proportion to the oxygen level in the recirculating gas and can therefore be used as a measure of the container oxygen level. In the sensing/control scheme developed as part of this invention, the current is periodically allowed to rise to the diffusion limit in a “measure mode” and then reset according to the desired oxygen level, determined from a slope-intercept “measure mode” calibration curve, for a longer “control mode” period.