Showing papers by "Energy Conversion Devices published in 2001"

Development of high catalytic activity disordered hydrogen-storage alloys for electrochemical application in nickel–metal hydride batterie

Abstract: Multi-element, multiphase disordered metal hydride alloys have enabled the widespread commercialization of nickel–metal hydride (NiMH) batteries by allowing high capacity and good kinetics while overcoming the crucial barrier of unstable oxidation/corrosion behavior to obtain long cycle life. Alloy-formula optimization and advanced materials processing have been used to promote a high concentration of active hydrogen-storage sites vital for raising NiMH specific energy. New commercial applications demand fundamentally higher specific power and discharge-rate kinetics. Disorder at the metal/electrolyte interface has enabled a surface oxide with less than 70 A metallic nickel alloy inclusions suspended within the oxide, which provide exceptional catalytic activity to the metal hydride electrode surface.

Heterogeneity in hydrogenated silicon: Evidence for intermediately ordered chainlike objects

Abstract: Hydrogen $({\mathrm{H}}_{2})$ dilution of the source gas is known to be a key factor in producing hydrogenated amorphous silicon films that demonstrate a high degree of optoelectronic stability. In this work, we investigate, using Raman spectroscopy and high-resolution transmission electron microscopy (TEM), whether microstructural differences exist between such films and those made with no ${\mathrm{H}}_{2}$ dilution (i.e., that have greater instabilities). The key variable is the ${\mathrm{H}}_{2}$ dilution, which ranges from none to very high levels, producing amorphous and microcrystalline silicon films. The TEM results show that embedded within the amorphous matrix are chainlike objects (CLO's) having \ensuremath{\sim}3 nm widths, \ensuremath{\sim}30 nm lengths, and showing a high degree of order along their length. Such order implies vanishing levels of bond-angle distortion (BAD). These CLO's are present in all samples investigated, but their density increases with the level of ${\mathrm{H}}_{2}$ dilution. The Raman spectra show a TO band centered at $490 {\mathrm{cm}}^{\ensuremath{-}1}$ $(37\ifmmode\pm\else\textpm\fi{}3{\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ full width). Quantitative analysis shows this band to exist in all samples investigated, but increases in magnitude with increasing ${\mathrm{H}}_{2}$ dilution. In the highest dilutions when microcrystallites are observed, the band is distinctly evident. Its position and width are also consistent with very low (crystallinelike) levels of BAD \ensuremath{\sim}0\ifmmode^\circ\else\textdegree\fi{}. It is thus likely the $490 {\mathrm{cm}}^{\ensuremath{-}1}$ Raman band is a signature of the intermediate ordered CLO's.

Semiconductor with coordinatively irregular structures

Abstract: A non-single crystalline semiconductor material includes coordinatively irregular structures characterized by distorted chemical bonding, reduced dimensionality and novel electronic properties. A process for forming the material permits variation of the size, concentration and spatial distribution of coordinatively irregular structures. The electronic properties of the material can be changed by controlling the characteristics of the coordinatively irregular structures.

Non-contacting capacitive diagnostic device

Abstract: A non-contacting capacitive diagnostic device includes a pulsed light source for producing an electric field in a semiconductor or photovoltaic device or material to be evaluated (PV substrate) and a circuit responsive to the electric field. The circuit is not in physical contact with the device or material being evaluated (PV substrate) and produces an electrical signal (Vpv) characteristic of the electric field produced in the device or material (PV substrate). The diagnostic device permits quality control and evaluation of semiconductor or photovoltaic device properties in continuous manufacturing process.________________________________

Fuel cell hydrogen supply systems using secondary fuel to release stored hydrogen

Abstract: Hydrogen propelled fuel cell vehicle system designs that reduce the relative cost of releasing hydrogen from hydrogen storage alloys by providing and/or utilizing secondary sources of heat to supply the heat of desorption of stored hydrogen The secondary source can include combusting conventional secondary (non-hydrogen) fuels The fuel supply system uses fundamentally new magnesium-based hydrogen storage alloy materials which for the first time make it feasible and practical to use solid state storage and delivery of hydrogen storage capacity of over 7 weight % coupled with extraordinary absorption kinetics such that the alloy powder absorbs 80 % of its total capacity within 15 minutes at 300C and a cycle life of at least 2000 cycles (see figure 4) without loss of capacity or kinetics

New developments in optical phase-change memory

Abstract: Phase change technology has progressed from the original invention of Ovshinsky to become the leading choice for rewritable optical disks. ECD's early work in phase change materials and methods for operating in a direct overwrite fashion were crucial to the successes that have been achieved. Since the introduction of the first rewritable phase change products in 1991, the market has expanded from CD-RW into rewritable DVD with creative work going on worldwide. Phase change technology is ideally suited to address the continuous demand for increased storage capacity. First, laser beams can be focused to ever-smaller spot sizes using shorter wavelength lasers and higher performance optics. Blue lasers are now commercially viable and high numerical aperture and near field lenses have been demonstrated. Second, multilevel approaches can be used to increase capacity by a factor of three or more with concomitant increases in data transfer rate. In addition, ECD has decreased manufacturing costs through the use of innovative production technology. These factors combine to accelerate the widespread use of phase change technology. As in all our technologies, such as thin film photovoltaics, nickel metal hydride batteries, hydrogen storage systems, fuel cells, electrical memory, etc., we have invented the materials, the products, the production machines and the production processes for high rate, low-cost manufacture.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

High storage capacity, fast kinetics, long cycle-life, hydrogen storage alloys

Abstract: Hydrogen propelled vehicles and fundamentally new magnesium-based hydrogen storage alloy materials (12) which for the first time make it feasible and practical to use solid state storage and delivery of hydrogen to power internal combustion engine or fuel cell vehicles These exceptional alloys have remarkable hydrogen storage capacity of well over 6 weight % coupled with extraordinary absorption kinetics such that the alloy powder absorbs 80 % of its total capacity within 10 minutes at 300C and a cycle life of at least 500 cycles without loss of capacity or kinetics

Fuel cell cathodes and their fuel cells

Abstract: Fuel cell cathodes and instant startup fuel cells employing the cathodes. The cathodes operate through the valency change mechanism of redox couples which uniquely provide multiple degrees of freedom in selecting the operating voltages available for such fuel cells. Such cathodes provide the fuel cells in which they are used a “buffer” or “charge” of oxidizer available within the cathode at all times.

Safe, economical transport of hydrogen in pelletized form

Abstract: A magnesium hydrogen storage alloy that has been hydrided and compacted into highly dense pellets for shipment and use, a method for making said magnesium alloy (see Fig. 7) and a method for the safe, economical shipment of said hydrided magnesium hydrogen storage material.

Electrochemical hydrogen storage alloys for nickel metal, hydride batteries, fuel cells, and methods of manufacturing same

Abstract: Practice of this invention provides, at least, a method of making a hydrogen storage material comprising the steps of: 1. forming a molten mixture comprising nickel and at least one other transition metal element, the combination of which will form a TiNi-type alloy and including in said molten mixture from about 0.1 at. % to about 10 at. % of one or more elements which will form an alloy which is immiscible in the TiNi-type alloy; and (b) cooling said molten mixture to form a solid alloy-system material by rapid solidification of said molten mixture at a cooling rate of at least 103 °C per second.

Assessment of the Use of Microcrystalline Silicon Materials Grown at Rates Near 15 Å/s as i-layer Material for Single and Multi-Junction Solar Cells

Abstract: A microwave-based technique has been used to prepare microcrystalline Si (µc-Si) materials rates near 15 A/s. The use of these materials as intrinsic layers (i-layers) for single and multi-junction devices has been assessed. Since the high deposition rates allow for fabrication of the required thicker µc-Si i-layers in a similar amount of time to that used for high quality a-SiGe i-layers (rates of 1-3 A/s), the materials are attractive, low cost replacements for a-SiGe bottom cell i-layers in a-Si/a-SiGe and a-Si/a-SiGe/a-SiGe multi-junction cells. Single-junction nip, a-Si/µc-Si and a-Si/a-SiGe/µc-Si devices have been fabricated. For these devices, the doped and amorphous layers were deposited using conventional rf glow discharge processes and deposition equipment separate from that used to fabricate the µc-Si materials. 7.0% efficiencies have been achieved for single-junction devices while pre-light soaked 9.8 and 11.4% efficiencies have been achieved for the tandem and triple-junction devices, respectively. The single-junction devices exhibit a degradation of only 0-2% after long term (1000 hrs.) of light soaking demonstrating a high degree of stability. Based on the present status, the µc-Si material prepared at high rates qualifies as a reasonable candidate for the i-layer of a bottom cell of a triple-junction device. Improvements in the performance, particularly the FF, will be needed before use in single-junction and tandem devices can be considered.

Novel alkaline fuel cell

Abstract: A fuel cell (7) which has the ability to start up instantly and can accept recaptured energy such as that of regenerative braking by operating in reverse as an electrolyzer. The instant startup fuel cells (7) have increased efficiency and power availability (higher voltage and current) and a dramatic improvement in operating temperature range of about -20 to 150 °C.

Method of recording memory

Abstract: Methods of writing information to an optical memory device (10). The methods comprise the step of writing a mark (28, 30, 32,) to the active material of the optical memory device by irradiating the material with an applied energy source. In one embodiment, the applied energy source provides a plurality of energy pulses. In another embodiment, energy in excess of that required to form a mark (28, 30, 32) is released and dissipated in a manner that minimizes mark enlargement, spurious mark formation, recrystallization and back crystallization. The methods are effective to provide better cooling characteristics through enhancement of the capacitive cooling contribution.

Method for intializing a data storage device

Abstract: A method for initializing a phase change information storage device. The method includes the steps of: providing a data storage device having a phase change data storage medium (12), and exposing the phase change data storage medium with a first energy exposure for about 1 νsec (14) or less. The first exposure is then followed by at least one additional energy exposure to complete initialization (16).

The Effects of Acid Passivation, Tricresyl Phosphate Presoak, and UV/Ozone Treatment on the Tribology of Perfluoropolyether-Lubricated 440C Stainless Steel Couples

Abstract: The boundary-lubrication performance of two perfluoropolyether (PFPE) thin films in the presence of passivated 440C stainless steel is presented. The study used a standard ball on disk (BoD) tribometer in dry nitrogen and a vacuum spiral orbit tribometer (SOT). Stainless steel surfaces were passivated with one of four techniques: high and low temperature chromic acid bath, a tricresyl phosphate (TCP) soak, or UV/Ozone treated for 15 min. After passivation, each BoD disk had a 400A film of Krytox 16256 (PFPE) applied to it. The lifetimes of these films were quantified by measuring the number of sliding cycles before an increase in friction occurred. The lubricated lifetime of the 440C couple was not altered as a result of the various passivation techniques. The resulting surface chemistry of each passivation technique was examined using X-ray photoelectron spectroscopy (XPS). The SOT was used to examine the effects of the TCP treatment on the lubricated lifetime of another PFPE, Brayco 815Z, under rolling conditions. None of the passivation techniques were found to dramatically increase the oxide film thickness or lubricated lifetimes.

Recording mark formation in a phase change memory material via a predominately capacitive cooling process

Abstract: Methods of writing information to an optical memory device. The methods comprise the step of writing a mark to the active material of the optical memory device by irradiating the material with an applied energy source. In one embodiment, the applied energy source provides a plurality of energy pulses. In another embodiment, energy in excess of that required to form a mark is released and dissipated in a manner that minimizes mark enlargement, spurious mark formation, recrystallization and back crystallization. The methods are effective to provide better cooling characteristics through enhancement of the capacitive cooling contribution.

Formation of a Co3O4 Top Layer in SiO2 Cobalt Containing Coatings Sol-gel Obtained

Abstract: SiO 2 coatings containing cobalt were prepared on glass substrates using the sol-gel method. It has been found that in coatings with a Si to Co ratio of 1.3, a layer of Co 3 O 4 is formed at the free surface of the coating upon thermal annealings in air. The properties of the coatings were studied using optical, x-ray and Auger depth profile measurements. The thermal annealings in the temperature range of 300 to 500 o C, in steps of 50 o C, were performed for 10 min. Some samples were subjected to an isothermal annealing at 400 °C for different times from 10 to 210 min. From the x-ray diffraction patterns the cubic spinel structure of Co 3 O 4 was detected after the thermal treatments. The optical reflection and transmission spectra for each annealing temperature and annealing time, are described with an air-Co 3 O 4 -SiO 2 :Co 2+ -substrate system. From this, the cobalt oxide thickness was obtained as a function of the annealing temperature and annealing time. From the Arrhenius plots, in the temperature range studied, it was found that the activation energy for the growth of the cobalt oxide layer is 0.41 eV. The layer thickness follows a parabolic behavior with time, which suggests a diffusion-controlled process. The Auger depth profiles obtained from a sample annealed at 500 °C confirm the optical model used.