Table of contents

Ti‐Zr‐Mn‐V‐Ni alloys have high discharge capacities in KOH electrolyte. The rapid degradation of their capacities, however, makes them unsuitable for use as the negative electrode material in a Ni‐metal hydride battery. In this work, Mn was partially substituted by Cr in the Ti‐Zr‐Mn‐V‐Nio alloys to improve their cycle life. The microstructure, hydrogenation properties, and the cycle life of these Cr‐substituted alloys were investigated. The Cr‐substitution was very effective in improving the cyclic durability of alloys in spite of decreasing the discharge capacity. The surface oxidation and pulverization rate of the alloys decreased with an increasing amount of Cr. © 2000 The Electrochemical Society. All rights reserved.

To improve the water electrolysis performance of unitized regenerative fuel cells, ultrafine powder was synthesized from colloidal precursors, and an active electrode for oxygen evolution and reduction was prepared by mixing the powder and Pt black. Analysis showed that the surface area of the synthesized was higher than that of high‐surface‐area Pt black. During fuel cell operation, increased the overpotential slightly; however during water electrolysis, the mixed electrocatalyst had a considerably higher activity for oxygen evolution. The addition of only a small amount of to the oxygen electrode was sufficient for the unitized regenerative fuel cell. © 2000 The Electrochemical Society. All rights reserved.

powders were synthesized at 800°C using acrylic acid as a chelating agent. The comparison between local structure refinements of and during the charging and cycling process was carried out by Co K‐edge X‐ray absorption spectroscopy (XAS). Al addition was found to cause a larger local structure distortion during Li deintercalation compared to that of . Extended X‐ray absorption fine structure refinements during Li deintercalation showed that the degree of structural disorder around Co atoms in becomes higher than that of . XAS analysis for and during cycling revealed that the large capacity fading of the electrode could be explained by the remaining ions and local structure distortion. © 2000 The Electrochemical Society. All rights reserved.

The higher reversible discharge capacity exhibited by (bc: badly crystalline)‐nickel hydroxide compared to that of β‐nickel hydroxide can be attributed to the presence of regions characterized by turbostratic disorder in the former. These regions comprise the α‐modification of nickel hydroxide existing in an interstratified form within the sample. The α‐motifs in the are anion‐free, but hydrated, by virtue of which hydroxide exhibits a higher water content (11% by weight) compared to the β‐form (<1%). © 2000 The Electrochemical Society. All rights reserved.

Lithium intercalated graphites have taken the place of metallic lithium as anodes for secondary lithium batteries. Controlling the anode‐electrolyte interface has been a major technical challenge in the development of lithium‐ion battery technologies. The interfacial characteristics can be greatly affected by the kinetics of intercalation. However, the kinetics of the electrochemical intercalation of lithium into graphites has not been well analyzed yet. Very few kinetic and interfacial parameters have been reported. In this work, the electrochemical impedance spectroscopy, constant charge step, and galvanostatic pulse polarization techniques were applied to study the kinetics of the intercalation and deintercalation processes of graphite electrodes in a few important lithium battery electrolyte solutions. Based on the proposed equivalent circuit model, we determined the kinetic and interfacial parameters of the intercalation and deintercalation processes. The measured intercalation charge‐transfer resistance, exchange current densities, and intercalation capacitance range between 11 and , 1.0 and , and 1.0 and , respectively, depending on the electrolyte solution compositions. The dependence of these kinetic and interfacial parameters on solvent composition, electrolyte concentration, storage time, and intercalated state is discussed. In addition, the transfer coefficients have been determined. The results suggest that the intercalation/deintercalation process is electrochemically reversible. © 2000 The Electrochemical Society. All rights reserved.

Lithium salts, such as , , and , were added to the "single‐ion" solid polymer electrolyte poly[lithium bis{endomethyl‐oligo(oxyethylene)oxy}oligo(oxyethylene)oxyaluminate] in which is the only mobile ion, to adjust the transport number from to . When was used, the average transport number was found to deviate little over a wide salt concentration range. This characteristic meets a requirement for batteries in which the salt concentration fluctuates with the ingress/egress of and during the charging/discharging processes. A cell using this transport‐number‐adjusted electrolyte exhibited a distinct discharge plateau at a reasonably high voltage and excellent cycle stability. © 2000 The Electrochemical Society. All rights reserved.

Nanostructured electrodes consisting of nanotubules that protrude from a current collector surface like the bristles of a brush were prepared using the template method. The rate capabilities of these nanostructured electrodes were investigated at the 4 V (vs. ) potential plateau in aqueous electrolyte. Rate capability improved with decreasing wall thickness of the tubules which formed the electrode. This result is in agreement with our prior investigations of template‐synthesized electrode materials which showed that rate capabilities improve with decreasing distance for transport in the solid state. The rate capabilities of electrodes prepared from the smallest‐wall‐thickness tubules are extraordinary; these electrodes can be cycled at C rates as high as 109 C. In addition, these investigations suggest that the poor cycling performance observed in prior studies of this electrode/electrolyte system results from unwanted oxidation of water during the charging process. By controlling the charge rate and the dimensions of the nanotubules making up the template‐synthesized cathodes, this unwanted side reaction can be eliminated and good cycle life is observed. These data show that the nanostructured electrodes offer a unique advantage to this particular electrode/electrolyte system. © 2000 The Electrochemical Society. All rights reserved.

We have used a lithiated , , with ordered alternating one‐dimensional [1 × 2] and [1 × 1] channels as a cathode material in solid‐state lithium/polymer cells. An optimized cell can operate at moderate temperatures (40–80°C). delivers a rechargeable capacity of 160 mAh/g with a flat potential plateau at ca. 3.0 V vs. at the C/3 rate and 65°C, corresponding to a specific energy of 450 Wh/kg of the pure oxide. Cells show good rate capability and excellent cyclability when cycled between 2.7 and 3.5 V at 80% depth of discharge, whereas a capacity decline was observed when cycled between 2.0 and 3.5 V. Capacity fading upon cycling is believed to be due to the formation of a thin layer of spinel phase (transformation to from ) on the particle surfaces, as well as to increased cell resistance during charge/discharge cycling. The cell self‐discharge at high temperature and the thermal stability of in contact with the polymer electrolyte are also discussed. © 2000 The Electrochemical Society. All rights reserved.

Electrochemical properties of a film in 1 M solution was studied by means of the electrochemical quartz crystal microbalance (QCM) at an elevated temperature (50°C). The film preparation was conducted by an electrostatic spray deposition, which enabled us to obtain a uniform and dense film of on a QCM electrode at low temperature (400°C) to avoid the thermal damage of the quartz. During the galvanostatic charge‐discharge experiment, the mass of electrode specimen increased, most likely due to the formation of a passivation film. If an as‐prepared electrode was only immersed in the solution at 50°C, the mass of electrode decreased steadily, resulting eventually in extinction of the manganese film. Such manganese dissolution was attended by a shift of open circuit voltage from 3.8 to 4.3 V vs. Li, suggesting a formation for as an intermediate in the dissolution reaction. © 2000 The Electrochemical Society. All rights reserved.

New layered oxides were synthesized by a coprecipitation method followed by a high‐temperature thermal treatment. Rietveld refinements of their X‐ray diffraction patterns showed that they exhibit a quasi‐two‐dimensional structure, isostructural to , for small substitution amounts (y ≤ 0.10). For larger amounts (y = 0.15, 0.20), the Li/(Ni + Mg) ratio is significantly lower than unity. In all cases, the extra ions located in the inter‐slab space for lithium deficiency compensation are preferentially ions. A magnetic study confirmed the cationic distributions which result from the size difference between and ions. An electrochemical study showed reversible behavior for all materials. A high capacity was found for phases (y ≤ 0.02), which decreased when y increased. The presence of cations in the inter‐slab space, which cannot be oxidized and have a size close to , prevents the local collapses of the structure which occurs for the system; therefore good cycling stability is observed. © 2000 The Electrochemical Society. All rights reserved.

The irreversible consumption of lithium during deposition and dissolution in nonaqueous electrolytes with a small amount of hydrofluoric acid was studied by an electrochemical in situ quartz crystal microbalance technique. It was found that lithium is not only consumed by chemical reactions with the electrolyte during deposition, but is also lost during dissolution. This result is strongly related to breakdown of the surface film formed on lithium during the deposition process. From the experimental data, it is concluded that the stability of the surface film on lithium metal during dissolution is a key requirement for high coulombic efficiency of lithium metal deposition and dissolution. © 2000 The Electrochemical Society. All rights reserved.

The overpotential of Ni/yttria‐stabilized zirconia cermet anodes used in solid oxide fuel cells (SOFCs) was studied. We measured the current‐density dependence of the anodic overpotential at 85°C operating temperature using the inlet fuel gases with compositions of , , and . It was found that the overpotential was lower under wet‐anode conditions than under dry conditions. We also showed that under wet‐anode conditions the overpotential gradually increased with the increase of the current density, whereas under dry‐anode conditions, the overpotential increased steeply with the increase of the current density up to and then showed a gradual increase with the current density. We related the overpotential of SOFCs to the reaction rate constants and to the operating conditions by using a reaction model and found that the surface reaction model can successfully explain the experimental results. © 2000 The Electrochemical Society. All rights reserved.

Electrochemical impedance and self‐discharge studies were carried out to investigate lithium intercalation into bare and Ni‐coated KS10 graphite. Values of the charge‐transfer resistances, exchange current densities, surface film resistances, and lithium‐ion diffusion coefficients as functions of the state of charge (SOC) all favored the 10 wt % Ni composite KS10 graphite over bare KS10 graphite when these materials were used as the negative electrode in a Li‐ion cell with mixed organic electrolyte. The charge‐transfer resistances were always lower and gave rise to between 26 and 27% larger exchange current densities, which increased from 137 to 614 mA/g as the SOC increased. The surface film resistances for Ni composite KS10 were between 0.02 and 0.05 Ω g, slightly smaller than those of 0.03 to 0.08 Ω g for bare KS10, and both surface film resistances decreased with increasing SOC. The lithium‐ion diffusion coefficients were always slightly larger, ranging between and . Results from the self‐discharge study also favored the 10 wt % Ni composite KS10, which exhibited less capacity loss over a 10 day period compared to bare KS10. © 2000 The Electrochemical Society. All rights reserved.

A mathematical model has been developed to study heat transfer and thermal management of lithium polymer batteries. Temperature dependent parameters including the diffusion coefficient of lithium ions, ionic conductivity of lithium ions, transference number of lithium ions, etc., have been added to a previously developed electrochemical model to more completely characterize the thermal behavior of the lithium polymer system. In addition, experimental studies of the discharge behavior and heat generation rate of lithium polymer cells have been conducted. Comparisons between experimental and mathematical results are presented. Finally different thermal management approaches are discussed. © 2000 The Electrochemical Society. All rights reserved.

For performance purposes, the electrochemically active positive electrode in Ni‐based rechargeable alkaline batteries consists of particles coated with CoOOH. The positive attributes of the CoOOH coating, however, vanish upon cycling because it transforms into or even through dissolution‐crystallization processes. The benefit of adding Bi‐based salts or bismuth oxide to prevent these phase transformations is presented. From chemical and electrochemical studies, coupled with potentiometric titration and ultraviolet‐visible spectroscopy, we demonstrate that the positive effect of Bi additives is twofold. First, Bi adsorption onto the Co surface modifies the CoOOH chemical reactivity and thereby its dissolution. Second, since bismuth forms Bi‐Co‐oxohydroxo complexes in solution, as experimentally proved, it delays precipitation of the and phases during cycling. Finally, an implementation of these findings toward the most efficient use of nickel positive electrodes containing Co‐based additives is shown. © 2000 The Electrochemical Society. All rights reserved.

In situ X‐ray absorption spectroscopy study of phases shows that the Ni K edge continuously shifts to higher energies with a decrease in Li content in a manner consistent with oxidation of Ni(III) to Ni(IV) The Ni K‐edge energy for is consistent with that observed for chemically prepared quadrivalent Ni in . Variations in the coordination numbers, bond lengths, and disorders as a function of state of charge (i.e., the value of x) are consistent with the following facts: (i) a Jahn‐Teller distortion for Ni(III), (ii) an undistorted environment for Ni(IV), and (iii) an electrochemical oxidation of Ni(III) to Ni(IV). © 2000 The Electrochemical Society. All rights reserved.

Electrolyte decomposition and irreversible capacity loss (ICL) occur on carbon electrodes in Li‐ion cells. The nature of the surface sites and their role in the amount of electrolyte decomposition on carbon electrodes is not fully understood. Therefore, a study was undertaken to analyze the relationship between the ICL and the active sites on natural graphite of prismatic structure. The ICL was measured on natural graphite of predominantly two‐dimensional platelets of average particle size varying from 2 to 40 μm. The fraction of edge and basal plane sites was determined for ideal prismatic structures of different particle size and used as a model for the natural graphite particles. This analysis permitted an analysis of the relationship between the electrolyte decomposition and the distribution of surface sites. From this analysis we conclude that these sites play an important role in the magnitude of the irreversible capacity loss on natural graphite. © 2000 The Electrochemical Society. All rights reserved.

A new spinel material, oxysulfide , has been synthesized using a sol‐gel method. The cathode fabricated using the material shows the capacities of 89.5, 125, and 196 mAh/g in the 4 V (4.3 to 3.0 V), 3 V (2.4 to 3.5 V) and both the 3 and 4 V regions (4.3 to 2.4 V), respectively. This material exhibits no capacity loss after 30 cycles in both the 3 and 4 V regions during cycling. It was found that S doping was very effective in suppressing the formation of the tetragonal phase of in potential ranges of 2.4 to 4.3 V. © 2000 The Electrochemical Society. All rights reserved.

concentration relaxation experiments in a 52/48 mol % Li/Na molten carbonate melt saturated with NiO were performed. The was added to act as a probe for the concentration. The dynamic behavior of the and concentration during the relaxation of the melt back to the initial equilibrium was studied by recording square wave voltammograms. Our experiments show clearly that dissolution is the slowest step in the relaxation. Consequently the values for the recombination reaction rate obtained in other studies are not correct, since in them a fast dissolution was assumed. A gas dissolution rate of and Henry's constant for of at 650°C could be determined. Our numbers were used in simple calculations of the performance of the porous molten carbonate fuel cell cathode, and indicate that the dissolution rate determines the lower limit for of 0.05 atm at for proper cathode operation. © 2000 The Electrochemical Society. All rights reserved.

Aluminum foils with two different surface topographic textures were anodically oxidized at constant current in a phosphoric acid bath. In situ atomic force microscopy (AFM) was used to follow the initial development of surface topography on a 1 μm scale, during the early stages of porous oxide film formation. Microscopic convex features such as ridges on both foils begin to increase in height and width when the anodic film thickness exceeds the initial feature height. Equations of a mathematical model are presented incorporating established interfacial reactions and oxide conduction behavior. The model indicates that the film‐solution interface recedes into the metal during anodizing, since the current efficiency for oxide formation is smaller than the oxygen ion transport number in the film. Ridge surfaces increase in height due to the higher local conduction resistance to the film‐solution interface, while film deposits rapidly at ridges because of the low local resistance to the metal‐film interface. In agreement with the AFM results, enhanced oxide growth at ridges should start when the potential field in the film becomes two‐dimensional, as a result of the film growing to a thickness larger than the ridge height. © 2000 The Electrochemical Society. All rights reserved.

The galvanic current of stainless steel/silver atmospheric corrosion monitors exposed to the atmosphere for 4 months are analyzed to investigate the scaling behavior of corrosion. The time series of the galvanic current indicate that the galvanic current has a scaling property; a scaling relation predicted by the scaling theory is consistent with the experimental results of the stainless steel/silver atmospheric corrosion monitor and the Hurst coefficient representing the effect of long memory is related to the type of corrosion. © 2000 The Electrochemical Society. All rights reserved.

The electrochemical behavior of Al in phosphoric acid base slurry was investigated under chemical mechanical polishing (CMP) condition. The effect of applied potential on the CMP metal removal rate was also evaluated. The results from potentiodynamic polarization curve measurements indicated that a contact pressure in the range of 3 to 9 psi greatly modified the passivation behavior of Al in 5 vol % citric acid + 5 wt % slurry by a decrease in corrosion potential and an increase in passive current density. The experimental results also showed that CMP removal rate strongly depended on the contact pressure and potential applied. The potential dependence behavior of the removal rate could be divided into three regions depending on the direction of polarization and the magnitude of potential applied. The results of electrochemical impedance spectroscopy and Auger electron spectroscopy examinations showed that passive film formation on Al in the testing slurry was affected by the applied potential, which in term caused a change in the relative contribution of the corrosion and mechanical abrasion to the total removal rate of Al. © 2000 The Electrochemical Society. All rights reserved.

The galvanic interaction between electronically conductive polyaniline films doped with camphor sulfonic acid (PAni‐CSA), and aluminum alloy (AA) 2024‐T3 has been investigated for the purpose of assessing PAni‐CSA as a corrosion protection coating on AAs. Potentiodynamic polarization and zero resistance ammeter measurements of galvanic couples between PAni‐CSA and AA 2024‐T3 in 3.5% NaCl show that the AA dominates the mixed potential response and polarizes the PAni-CSA to approximately the potential of the freely corroding alloy (−0.54 V vs. Ag|AgCl). This observation indicates that conductive PAni coatings on Al are rapidly reduced to the nonconductive form on immersion in an aqueous electrolyte. The results also suggest that any corrosion protection of Al by PAni coatings is due to the barrier properties of the reduced polymer rather than anodic stabilization of passivity as observed with ferrous alloys. Mechanisms by which a PAni‐CSA coating might provide corrosion protection of exposed 20247‐T3 at defects in the coating are discussed. © 2000 The Electrochemical Society. All rights reserved.

We show in this communication that the polarization data of the hydrogen evolution reaction (HER) can be analyzed to calculate the hydrogen surface coverage and the rate constants of the hydrogen discharge and recombination reactions for metals which have very low permeabilities of hydrogen and on which the HER proceeds through a coupled Volmer discharge‐Tafel recombination mechanism. The analysis is applied to the results of the HER on copper and iron. For both metals, this polarization analysis yields exchange current densities that are comparable to the literature values and degrees of surface coverage which vary with potential in a manner that is well documented in the literature. The results on iron yield rate constants that are in a good agreement with those predicted in other studies using the Iyer, Pickering, and Zamanzadeh analysis. © 2000 The Electrochemical Society. All rights reserved.

Scaling of gold, bronze, and stainless steel was investigated in synthetic fresh and seawater. It is shown that the calcium carbonate precipitation rate increased from stainless steel, to bronze and then to gold whatever the composition of the scaling water. The morphology of the deposited scale depended on the substrate and on its surface state. For fast scaling, as with carbonically pure water, calcite was mainly deposited; for slower scaling vaterite was also observed. When foreign ions were added in the scaling water, aragonite appeared. In particular, for synthetic seawater, where magnesium ions are highly concentrated, aragonite is preferentially selected, so at the end of scaling aragonite covered the whole electrode surface. The kinetic parameters, which characterize a precipitation model, were extracted from impedance measurements through a fitting procedure. The morphology of the precipitated calcium carbonate was examined by means of a scanning electron microscope. © 2000 The Electrochemical Society. All rights reserved.

In situ surface X‐ray diffraction was used to identify the detailed structure of the passive film that forms on (000)− and (110)‐oriented iron single crystals in a borate buffer solution at +0.4 V vs. mercurous sulfate reference electrode, a high passive potential. The passive film is a new phase: a spinel with a fully occupied oxygen lattice, octahedral site occupancy of 80 ± 10%, tetrahedral site occupancy of 66 ± 10%, and an octahedral interstitial site occupancy of 12 ± 4%. The passive film forms with an epitaxial relationship to the substrate iron; for growth on Fe(001), film(001)||Fe(001) and , while for growth on Fe(110), film(111)||Fe(110) and . The in‐plane lattice parameter for the passive film (the LAMM phase) is 8.39 ± 0.01 Å for growth on both faces, and the out‐of‐plane lattice parameter is 8.25 ± 0.1 Å [Fe(001)] and 8.42 ± 0.1 Å [Fe(110)]. The passive film forms a nanocrystalline microstructure with numerous defects. Specifically, the grain size is 50–80 Å in‐plane and about 30 Å out‐of‐plane. There is a small mosaic spread of 2.5 to 4.1° and a high density of antiphase boundaries and stacking faults. The structure of the film determined in situ was found to be identical to that found for an emersed sample, indicating that the high potential film studied here is stable on removal from the electrolyte. Some of the implications of the film structure on passivity are discussed. © 2000 The Electrochemical Society. All rights reserved.

Results are presented from a systematic study to develop and optimize a metallorganic chemical vapor deposition process for the growth of high brightness cerium‐doped strontium sulfide (SrS:Ce) thin films for electroluminescent (EL) display applications. Growth of SrS:Ce was investigated in the temperature range from 400 to 530°C using strontium(2,2,6,6‐tetramethyl‐3,5‐heptadionato)trimer , tetrakis(2,2,6,6‐tetramethyl‐3,5‐heptadionato)cerium , and hydrogen sulfide as reactants. Various Sr and reactant flows and associated partial pressures were examined to explore corresponding effects on the film's physical, chemical, and optical properties. Film structural and compositional properties were analyzed by Rutherford backscattering spectrometry, nuclear reaction analysis for hydrogen profiling, X‐ray diffraction, X‐ray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy. EL measurements were carried out on SrS:Ce‐based dielectric‐sulfur‐dielectric stacks. The results of these studies yielded key correlations between process parameters and film texture, grain size, and EL performance. In particular, the highest EL performance was obtained for films with a predominantly (200) orientation, grain size larger than 1.0 μm, and Ce dopant level ∼0.14 atom %. A brightness of and efficiency of 0.22 lm/W were observed, as measured at 40 V above threshold voltage and 60 Hz frequency. © 2000 The Electrochemical Society. All rights reserved.

Local deposition of Ni‐P alloys on highly pure aluminum, commercially pure aluminum, Al‐Cu‐Mn, Al‐Mg, and Al‐Si‐Mg alloys was attempted by anodizing, laser irradiation, and electroless plating. Specimens were first anodized at 15 V in 16% , and then irradiated with a pulsed Nd‐yttrium‐aluminum‐garnet laser in a solution. Nickel‐phosphorous electroless plating was finally carried out in a solution with 0.6 ppm of ions. The effect of alloying elements on the Ni‐P deposition during electroless plating was investigated. Anodic oxide films on all the specimens were sufficiently stable in Ni‐P electroless plating solution and able to ensure local deposition of Ni‐P only at the laser‐irradiated areas. The deposition rate of Ni‐P on all the aluminum alloy specimens was higher than that on highly pure aluminum. The effect of the alloying elements on the Ni‐P deposition in electroless plating is discussed in terms of the catalytic function in Ni‐P electroless deposition and the inhibition of the oxide film formation during laser irradiation. © 2000 The Electrochemical Society. All rights reserved.

Amorphous Co‐Mo‐Ni alloy films are prepared by electroplating. The phase transformations and microstructure evolutions during thermal annealing under hydrogen atmosphere are clarified. The structure is amorphous if annealing temperature is lower than 200°C. Nanocrystallites precipitate out of the amorphous matrix if the temperature is within the range of 300 to 600°C. At 600°C, amorphous matrix transforms into the supersaturated ε‐Co plus some . Annealing at temperature higher than 800°C, ε‐Co is converted into α‐Co, with becoming the major phase. © 2000 The Electrochemical Society. All rights reserved.

We present results of magnetic resonance experiments on a large number of KOH solutions in which silicon has been dissolved. The goal of the experiments is to clarify the chemical composition of concentrated alkaline solutions after etching of silicon. It is confirmed that the initial etching product of wet‐chemical etching of silicon in KOH is a silicate monomer. Increasing the silicon content of the solution gives rise to silicate polymerization products. The often reported aging of etching solutions is due to silica in the etchant. © 2000 The Electrochemical Society. All rights reserved.

The electrochemical deposition of gold on n‐type silicon from solutions was investigated by performing a detailed study of the nucleation and growth kinetics. Deposition occurs by progressive nucleation and diffusion‐limited growth of three‐dimensional hemispherical islands over a wide range of potentials and concentrations. It is shown that for a silicon/gold electrode, the applied potential is dropped over the silicon/gold interface at potentials more positive than 0 V, while at potentials more negative than 0 V, the applied potential is dropped over the Helmholtz layer at the gold/solution interface. The influence of these observations on the applicability of nucleation models derived for metal‐on‐metal deposition to metal deposition onto semiconductors is discussed. © 2000 The Electrochemical Society. All rights reserved.

The deposition rate of TiN was measured in a hot‐wall chemical vapor deposition reactor using gas mixtures at 1 bar total pressure and 950–1470 K. With respect to HCl, the reaction order was found to be −3. From the experimental results, a reaction model was derived that assumes (Reaction I) to be the rate‐determining reaction in the homogeneous gas phase, and (Reaction III) to be the slow heterogeneous step. The heterogeneous reaction preceding Reaction III, which may be described as (Reaction II) , was assumed to be sufficiently fast to attain equilibrium. Reaction II accounts for the strongly retarding effect of HCl on the rate of TiN deposition. By proper adaptation of the rate constants and the activation energies of Reactions I and III, the numerical simulation led to deposition rates in good agreement with the measured values. © 2000 The Electrochemical Society. All rights reserved.

The equilibrium constants of the formation of isopolymolybdates heteropolymolybdate and Mo(VI)‐citrate complexes and were determined from factor analysis of Raman spectra and visible absorption spectra to calculate the chemical species present in acidic Ni‐Mo alloy plating baths. On the addition of citrate to a Ni(II)‐Mo(VI) bath, (i) the polymolybdates were decomposed by the formation of complex, and then (ii) and complexes formed. This complex formation was necessary for the alloy deposition, but an excess addition of citrate, which results in the formation of complex, lowered the current efficiency. The deposition behavior of Ni‐Mo alloy from Ni(II)‐Mo(VI)‐citrate baths was compared with that of pure Ni from Ni(II)‐citrate baths, in which concentrations of Ni(II)‐species are identical to those in the corresponding Ni(II)‐Mo(VI)‐citrate baths. The alloy deposition behavior is strongly governed by the ease of Ni deposition, indicating that the electrodeposited nickel induces the deposition of molybdenum. © 2000 The Electrochemical Society. All rights reserved.

The goal of this study was to improve our understanding of diamond growth reactors. Direct relationships were set up between key parameters at a microscale level and diamond film characteristics. The coupled action of plasma variables, such as microwave power density, substrate temperature, and percentage of methane, on the density of the key species that control diamond growth was studied by spectroscopic diagnostics and modeling. The influence of local conditions on the domain of validity of the Van der Drift model, which describes texture development from a random distribution of diamond nuclei, is discussed. The results suggested that different chemical kinetic models, which depend on plasma conditions, must be used to describe "diamond" growth by chemical vapor deposition. © 2000 The Electrochemical Society. All rights reserved.

The etching process of thin films of in HF‐free solutions containing and was investigated by kinetic and electrochemical experiments. Etching involved the simultaneous oxidation of the alloy and reduction of . During etching, a Nb oxide is formed on the surface, which is dissolved by and . A rate equation is derived that describes the influence of both and on the etch rate. © 2000 The Electrochemical Society. All rights reserved.

The anomalous electrodeposition of NiCoFe ternary alloys was examined. Ni deposition in the ternary system appeared inhibited compared with its single‐metal deposition, which characterizes typical anomalous behavior. Fe deposition was enhanced, similar to recent findings in codeposited binary alloys. Both catalytic and inhibiting effects were observed for Co deposition. The inverse Tafel slopes for both the metal reduction reactions and the side reactions were determined and compared with the values obtained during the single‐metal reductions. A common change in the inverse Tafel slopes suggested a dependent kinetic relationship between the metal and side reaction rate during NiCoFe alloy deposition. © 2000 The Electrochemical Society. All rights reserved.

We report on the fabrication and characterization of silicon oxynitride (SiON) layers for applications as planar optical waveguides in the 1550 nm wavelength region. The optically guiding SiON waveguide core layer has a relatively high refractive index of 1500 and is sandwiched between two silicon oxide cladding layers with a lower refractive index of 1450. The SiON layer is deposited by plasma‐enhanced chemical vapor deposition using silane, nitrous oxide, and ammonia as gaseous precursors. Waveguide bends with a radius of curvature as small as 1.5 mm can be realized because of the high refractive index difference achievable between core and cladding layers. This allows the fabrication of compact, relatively complex integrated optical waveguide devices. The deposition process and the characterization of the SiON films are discussed. The strengths of this high refractive index contrast planar waveguide technology are illustrated using the example of an optical add/drop filter for wavelength division multiplexing applications in the field of optical communication systems. © 2000 The Electrochemical Society. All rights reserved.

Raney‐Ni cathodes were prepared by leaching aluminum from Ni‐Al precursor alloys . The catalytic activity for the hydrogen evolution reaction was investigated in 1 M NaOH at 303 K. The hydrogen overpotentials of Raney‐Ni electrodes obtained from and were lower than those from nickel rich alloys (NiAl and ). Especially, yielded the most active Raney‐Ni cathode. This is because the fast aluminum leaching from phase gives large surface area of the electrode, the formation of small micropores, and the appearance of the Ni phase. © 2000 The Electrochemical Society. All rights reserved.

Manganese oxide thin films were deposited on transparent conducting tin oxide glass substrates by potentiostatic anodic electrolysis of alkaline solution of a manganese ammine complex at 298 K. The effects of varying deposition potentials on the microstructure and the electrochromic (EC) properties of the films were investigated. Characterization of films by X‐ray diffraction revealed that two distinct potential regions (lower and higher than 0.3 V vs. Ag/AgCl) were available for the film deposition; the crystal structure of the film deposited at lower and higher regions were and/or and , respectively. X‐ray photoelectron spectroscopy (XPS) analyses of the films featuring exchange splitting effect on Mn 3s spectra indicated that the valence of manganese in the films prepared at lower and higher potential regions are mixtures of divalence‐trivalence and of trivalence‐tetravalence, respectively. The XPS analysis also revealed that terminal chemical bonding species of the films are a mixture of hydroxide (Mn‐O‐H) and oxide (Mn‐O‐Mn). The mechanism of the EC process, by which the color change between brown and light yellow occurs, could be explained in terms of the transformation between these two oxygen groups in Mn‐O‐H and Mn‐O‐Mn, accompanied by the change in valence of Mn. The EC durability of the films in switching performance was also assessed. © 2000 The Electrochemical Society. All rights reserved.

Nucleation and growth mechanism of polypyrrole films was investigated on vapor deposited gold/highly oriented pyrolytic graphite by current‐time transient (i‐t) measurements and atomic force microscopy. It was found that the nucleation and growth was an instantaneous two‐dimensional process before nuclei overlapping and progressive three‐dimensional after nuclei overlapping. The polypyrrole structure was observed to be zigzag or screw‐type and particle‐like for thin and thick films, respectively. © 2000 The Electrochemical Society. All rights reserved.

The effect of iodide ions on the kinetics of both the hydrogen evolution reaction. HER, and the hydrogen absorption reaction, HAR, on iron (steel) membranes was investigated using an electrochemical hydrogen permeation cell. Iodide ions inhibit the HER by decreasing the rate constant of proton discharge. Iodide enhances the HAR, and in turn increases the concentration of hydrogen inside the metal, although it decreases the hydrogen surface coverage. The increased HAR rate is due to an increase in the composite rate constant of the hydrogen absorption step at the metal surface. © 2000 The Electrochemical Society. All rights reserved.

Nanocomposite films consisting of particles and Zn (thickness, 10 to 15 μm) were formed on steel plates by using an occlusion electrodeposition method. Scanning electron micrographs demonstrated that particles were incorporated throughout the film. The uptake increased significantly with addition of ions to the electrodeposition bath. A positive correlation was observed between the uptake and the photocatalytic activity for gas‐phase oxidation of . Postannealing of the sample in air at 673 K produced ZnO whiskers with a preferred orientation of plane, while the same treatment of the Zn/steel sample yielded granular ZnO polycrystals. The particles‐ZnO whiskers composite film exhibited a very high photocatalytic activity, which was greater than of the sample by a factor of 1.5. © 2000 The Electrochemical Society. All rights reserved.

The electro‐oxidation of methanol at a platinum microelectrode in poly(N‐isopropylacrylamide‐co‐acrylic acid) (NIPA‐AA) gels was studied as a function of temperature. Diffusion coefficients of methanol in NIPA‐AA gels of various copolymer concentrations were determined from the steady‐state voltammetric currents over the temperature range 5–55°C. Transport parameters (diffusion coefficients and activation energies of diffusion) were compared to those for undiluted methanol, and related to the transport properties of uncharged probe molecules of 1, 1'‐ferrocenedimethanol in both liquid and gel media. Diffusion of uncharged species, methanol and 1, 1'‐ferrocenedimethanol, in the gels was as fast as in liquid media, with diffusion coefficients close to for both species at 25°C. Activation energies of diffusion for methanol and 1, 1'‐ferrocenedimethanol in the gels were smaller than those observed in liquid media, they did not depend on the copolymer concentration in the range 1.3–2.5%; and their average values were 9.3 ± 0.4 and 11.8 ± 0.7 kJ/mol for methanol and 1, 1'‐ferrocenedimethanol, respectively. © 2000 The Electrochemical Society. All rights reserved.

An effective and computationally economical scheme, which unifies density functional description of a metal electronic structure and the classical molecular dynamics description of an electrolyte in contact with the metal, is described. The density functional part of the scheme comprises Car‐Parinello and related formalisms. This scheme allows the extension to longer time scale of the simulation of metal‐electrolyte interface while keeping fairly good accuracy in the prediction of the metal electronic structure. The numerical scheme is implemented in the relatively simple model of a metal cluster surrounded by an electrolyte. The elementary event of an atom leaving a metal surface as an ion stabilized by solvent molecules has been studied. In particular the potential of mean force of the ion as it dissolves was evaluated. The evolution of the solvation shell of the ion as it leaves the surface is calculated as a further example. © 2000 The Electrochemical Society. All rights reserved.

An anatase film (75 ± 5 nm thick) was formed on film (580 ± 80 nm thick) coated soda‐lime glass by a sol‐gel method . Depth profiles of the compositions determined by X‐ray photoelectron spectroscopy confirmed that the amounts of and ions are negligibly small throughout the film. The activities for four kinds of photocatalytic reactions (v) were examined under no external applied potential in comparison with those of a standard sample . The bilayer‐type photocatalyst showed remarkably higher activities for oxidations , whereas the activities for reductions are lower . These results could be explained by efficient charge separation via the interfacial electron transfer from to . © 2000 The Electrochemical Society. All rights reserved.

A low‐temperature process with good step coverage of silicon nitride (SiN) formed by low‐pressure chemical vapor deposition (LPCVD) has been successfully developed by using hexachlorodisilane (HCD). HCD‐SiN showed a higher deposition rate than the conventional LPCVD technique performed at temperatures above 700°C. SiN films can be deposited down to 250°C using HCD. Deposition characteristics, film composition, and film properties under integrated circuit fabrication processes are measured mainly in terms of deposition temperature dependence. A low‐k HCD‐SiN film, formed at 450°C with a permittivity of 5.4, was applied on Cu films as an oxidation and diffusion barrier layer. The film shows excellent barrier properties and is advantageous for realizing high‐performance very large scale integrated devices with Cu interconnects. © 2000 The Electrochemical Society. All rights reserved.

The volume removal rate properties for a floating polishing process under different lubricating conditions are investigated. The lubricating conditions are those that make the pad in noncontact with the work surface. Under this noncontact condition, the abrasive particles will play two roles in work material removal. One role is to accumulate the energy or power from shear stress field of slurry flow. The other role is to transmit the accumulated energy or power to work surface atoms in a certain efficiency. Accordingly, it is proposed that the machining capability of an abrasive particle is mainly a function of its sustained shear stress, from an energy point of view. It is shown that the removal rate has distinct properties under different lubricating conditions. If the slurry between pad and work surface is in the isoviscous‐elastic lubricating regime, the removal rate will be related positively to pad speed and slurry viscosity. On the other hand, the removal rate is related negatively to speed and slurry viscosity when the lubrication is in the isoviscous‐rigid regime. © 2000 The Electrochemical Society. All rights reserved.

The surface of p‐type GaN was treated with HCl, , KOH, and aqua regia solutions before the deposition of Pd metal, and the ohmic contact formation mechanism was studied by observing the change of ohmic characteristics with the pretreatment of the surface. Contact resistivity decreased in sequence with treatment using HCl, , KOH, and aqua regia solutions. The contact resistivity on p‐type GaN treated with boiling aqua regia was decreased by two orders of magnitude in comparison with the HCl treated one. The amounts of oxygen and carbon atoms on p‐type GaN were reduced with the same sequence of surface treatment and the aqua regia solution is most effective in selectively removing surface removing surface oxides without etching the p‐type GaN. This provides evidence that the reduction of contact resistivity originates from the selective removal of surface oxides, acting as an impeding barrier for hole injection from metal to p‐type GaN. Contact resistivities did not change when the hole concentration was varied from to in both the HCl treated and aqua regia treated samples. This suggests that the formation of ohmic contact on p‐type GaN can be explained by the thermionic emission of holes at the interface of Pd with p‐type GaN. The Schottky barrier height deduced from both electron affinity of GaN and work function of Pd is much differ from the value of about 0.35 to 0.45 eV experimentally determined using contact resistivities. This process that the Fermi level pinning at acceptor‐type point defects on the surface of p‐type GaN to the ohmic contact on p‐type GaN. © 2000 The Electrochemical Society. All rights reserved.

A numerical model was developed to predict gas‐phase nucleation of particles during silane pyrolysis. The model includes a detailed clustering mechanism for the formation of hydrogenated silicon clusters containing up to ten silicon atoms. This mechanism was coupled to an aerosol dynamics moment model to predict particle growth, coagulation, and transport. Both zero‐dimensional transient simulations, at 1–2 atm pressure, and one‐dimensional steady‐state stagnation‐point flow simulations, at 1–2 Torr pressure, were conducted. The effects of carrier gas, temperature, pressure, silane concentration, and flow rate were examined. The results predict that hydrogen as carrier gas, compared to helium, suppresses nucleation, and that particle formation for the case of hydrogen carrier gas increases strongly with increasing initial silane‐to‐hydrogen ratio. For the conditions examined, predicted particle nucleation rates increase dramatically with increasing temperature. The effect of total pressure depends on the pressure regime: at 1–2 atm pressure particle formation is predicted to be insensitive to pressure, whereas at 1–2 Torr particle formation is predicted to increasing strongly with increasing pressure.The predicted effects on particle formation of temperature, pressure, carrier gas, and silane concentration are all qualitatively consistent with published experimental results. In the stagnation‐point flow simulations the flow rate is found to affect particle dynamics because of the opposed effects of convective transport toward the heated water and thermophoretic transport away from the wafer. © 2000 The Electrochemical Society. All rights reserved.

The integrity of the metallization under different annealing ambients has been investigated by Rutherford backscattering spectrometry (RBS), transmission electron microscopy (TEM), X‐ray diffractometry (XRD), Auger electron spectroscopy, scanning electron microscopy, and atomic force microscopy techniques. Results from XRD and TEM show that the as‐deposited amorphous barrier crystallizes upon annealing at 500°C, forming a crystalline phase. The sheet resistance of metallization remains unchanged upon annealing in Ar or up to 750°C. No observable interdiffusion was detected by RBS upon annealing at temperatures below 500°C, in Ar or . However, above 500°C, the integrity of metallization begins to degrade due to out‐diffusion of a small amount of Ta into Cu. On the other hand, in an ambient, the sheet resistance of the metallization is found to increase drastically upon annealing at a temperature above 200°C, an observation that has been attributed to the formation of porous Cu oxide layer. Delamination of Cu oxide from oxide/barrier interface occurs at 400°C. The result highlights the importance of isolating metallization from oxygen exposure during back end processing. © 2000 The Electrochemical Society. All rights reserved.

For the first time, the time‐dependent change in the concentrations of organic species adsorbed on a silicon wafer surface is modeled using numerical calculations based on rate theory. An equation composed of the adsorption rate from the gas phase to the silicon wafer surface and the desorption rate from the silicon wafer surface is developed accounting for competitive processes in a multicomponent system. This equation can describe and predict the actual increase and decrease in the surface concentrations of propionic acid ester, siloxane (D9), and di(2‐ethylhexyl)phthalate. It is also indicated that the organic species having a large adsorption rate with a small desorption rate remains in significant abundance on the silicon wafer surface for a very long period after cleaning. © 2000 The Electrochemical Society. All rights reserved.

In situ of 3C‐SiC films during growth by chemical vapor deposition on Si(111) substrates using single organosilane precursors [trimethylsilane and silacyclobutane ] was investigated by Hall effect measurements, secondary‐ion mass spectrometry (SIMS), and reflection Fourier transform infrared spectroscopy (FTIRS). The electron concentration in SiC films grown from trimethylsilane can be readily controlled by the flow rate. Reflection FTIRS study of the efficiency yielded results consistent with those from Hall effect and SIMS measurements. The doping efficiency in SiC films grown with silacyclobutane is much lower than that for films grown from trimethylsilane. The electrical properties of the n‐type 3C‐SiC films were investigated by Hall effect measurements from 80 to ∼400 K. The highest electron mobilities at 83 and 300 K are 2115 and , respectively. The corresponding carrier concentrations are and . © 2000 The Electrochemical Society. All rights reserved.

Wear behavior between a Si tip and a film in KOH solution at various pH values has been examined by using an atomic force microscope. We found that the Si tip removal amount strongly depended on the solution pH value and was at a maximum at pH 10.2–12.5. This result indicates that wear behavior of the Si tip is similar to that of actual chemical mechanical polishing of a Si wafer. It was also found that the Si removal volume in moles was approximately equal to that of irrespective of the solution pH value. This equality implies that a Si‐O‐Si bridge is formed between one Si atom and one molecule at the wear interface, followed by the oxidation of the Si tip, and finally the bond rupture by the tip movement and the silica species including the Si‐O‐Si bridge is dissolved in the KOH solution. © 2000 The Electrochemical Society. All rights reserved.

A new novel pretreatment technology for integration of organic low‐dielectric material in copper interconnects for ultralarge scale integration applications is developed. Using plasma treatment, two extremely important advantages were achieved in spin‐on organic polymer (SOP), including the reduction of copper diffusion and the improvement of ashing resistance. A copper/SOP/Si capacitor structure is used to study the electrical characteristics of SOP film after ashing treatment or postanneal. Higher barrier capability and better ashing resistance can be achieved by the SOP layer after plasma treatment. After annealing at 500°C for 60 min, secondary ion mass spectroscopy depths profile shows that the Cu atoms do not penetrate into the SOP when they are pretreated by plasma. Furthermore after the ashing step, the carbon atoms in the SOP film almost remain the same when they are pretreated by plasma. On the other hand, the concentration of carbon in as‐cured SOP is no longer seen. The reason of improving ashing resistance and better barrier capability was due to the organic polymer film rearranging to form a carbon‐containing silicon nitride film. © 2000 The Electrochemical Society. All rights reserved.

An in situ monitor for metallic contamination in dilute hydrofluoric acid (HF) was developed and demonstrated detection of 20 parts per trillion Cu in a 500:1 HF bath. The monitor is based on the contactless measurement of minority‐carrier lifetime and is designed as part of a point‐of‐use dilute HF recycling system. Reducible ions in solution were detected as they deposit on the surface of a silicon monitor wafer. The sensitivity of the monitor is determined by (i) the signal‐to‐noise ratio of the surface coverage measurement, (ii) rate of metal deposition from the solution of interest, and (iii) the maximum time allowed for detecting contamination. Such an in situ monitoring system could simultaneously reduce cost of ownership, through limiting yield excursions, and reduce environmental impact by reducing chemical consumption. © 2000 The Electrochemical Society. All rights reserved.

The buffer layers of in (polycrystalline silicon) structure were prepared by metallorganic chemical vapor deposition (MOCVD) and dc magnetron sputtering. The barrier layers of deposited by MOCVD showed a stable interface, and did not affect the surface morphology of the platinum bottom electrode even at a high annealing temperature of 800°C. The barrier layers effectively prevented the interdiffusion of Pt, O, and Si at annealing temperatures above 700°C in ambient. On the other hand, the barrier layers of formed by dc sputtering showed severe intermixing and strongly influenced the platinum morphology at high temperature annealing. Contacts in and Pt/dc sputtered structures showed the specific contact resistance of and , respectively. The barrier layers of formed by MOCVD in structure were attractive for integration of high dielectric constant . © 2000 The Electrochemical Society. All rights reserved.

In this paper, a way of measuring the surface energy of room‐temperature wafer bonding is presented. The method consists of introducing well‐defined defects, or "spacers," at the bond interface. Here mesas were used as spacers. From the resulting nonbonded area, around the spacers, the value of the surface energy is obtained. Results from surface energy measurements show that there is good agreement between the "razor‐blade" method and our "mesa‐spacer" method. By using the mesa‐spacer method, several of the problems associated with the razor‐blade method are avoided. The method also allows the nondestructive measurement of the surface energy, which is interesting for applications in manufacturing of microsystems. © 2000 The Electrochemical Society. All rights reserved.

The persistent photoconductivity (PPC) of undoped low temperature grown n‐AlGaAs has been investigated by temperature‐dependent resistance measurements. Five distinct peaks were observed in the resistance measurement results during recovery of the PPC, and the PPC remained up to 260 K. In a sample with a low donor concentration of , a new current‐dependent PPC also was observed at around 25 K. © 2000 The Electrochemical Society. All rights reserved.

Cobalt(III) tetra(3‐methoxy‐4‐hydroxylphenyl) porphyrin can be irreversibly bound to a platinum electrode through a sol‐gel network. Based on our finding that cobalt metalloporphyrin catalyzes dioxygen reduction near 0 mV (vs. Ag/AgCl), the electrocatalytic kinetics of oxygen reduction has been studied by cyclic voltammetry and rotating disk voltammetric methods. A possible reaction mechanism is suggested for the observed catalysis. In the presence of cyanide, the electrocatalytic reductive current for dioxygen is decreased due to the strong binding of cyanide ions to the cobalt metal center. A simplified model is proposed to describe this poisoning effect based on the Koutecký‐Levich theory and coordination equilibrium between cyanide and the electrocatalyst. The model is well supported by the experimental results. The poisoning effect can be used for highly sensitive cyanide detection. © 2000 The Electrochemical Society. All rights reserved.

The photoluminescent intensities of nanocrystal ZnS:Tb and ZnS:Eu synthesized using a new technique were 2.5 and 2.8 times higher than those of bulk phosphors. Taking charge compensation into account, the luminescent efficiency of the nanocrystals can be improved. The cathodoluminescence of the nanocrystals was observed for the first time. These nanocrystal phosphors are promising for field emission display, electroluminescence, plasma‐display panels, and cathode ray tubes. © 2000 The Electrochemical Society. All rights reserved.

The sol‐gel route was used for the preparation of Fe/V oxide films with a molar ratio Fe:V = 1:2. Transmission electron microscopy (TEM) measurements of films prepared at 300°C showed that the films consist of a phase with the grains (1 nm) embedded in an amorphous phase. TEM measurements of films heated at 400°C agreed with the X‐ray diffraction results, confirming grains with dimensions up to 50 nm. Charge capacities per unit thickness were determined in a 1 M carbonate (PC) electrolyte using cyclic voltammetry (1.5 to −1.5 V vs. Ag/AgCl, 4.8 to 1.8 V vs. Li). The IR spectroscopic result is the assignment of the bands between 1000 and to V‐O (terminal) and V‐O‐V/V‐O‐Fe (bridging) stretching modes of tetrahedra. Ex situ IR spectra of films (400°C) charged/discharged to various extents showed that at low charging terminal and bridging modes are affected by lithium insertion. Higher chargings result in the amorphization of the films and in the appearance of a broad absorption below 600 nm ascribed to the modes. The optical response of films is evaluated in terms of photopic transmittance and chromaticity coordinates. Results confirmed that films are suitable for use in electrochromic transmissive (smart) windows. © 2000 The Electrochemical Society. All rights reserved.

Composite films have been deposited on indium tin oxide coated glass by pulsed laser reactive ablation in the ambient gases, and different molar ratio Ta/Ti of composite films were prepared using the superposed tantalum and titanium sheets with a suitable selection of the area ratio as a target. Electrochemical and electrochromic behaviors of composite electrodes are investigated by cyclic voltammetry and in situ visible transmittance measurements. Results show that the composite film with the presence of small amounts of within can significantly improve electrochemical and electrochromic properties. The composite film with Ta/Ti ratio of 4.3 exhibits excellent electrochromic efficiency of at 500 nm, and shows superior insertion capability of Li ions to pure and . © 2000 The Electrochemical Society. All rights reserved.

The photoluminescence behavior of phosphor was investigated by measuring emission and excitation spectra, and decay curves. The relative emission intensity and the decay time have been monitored as a function of concentration for both and transitions. The decay behavior of transition, for which well known cross‐relaxation has been accepted as a main factor, was analyzed by direct quenching mechanism on the basis of dipole‐dipole interaction. It is, however, impossible to characterize the transition using the direct quenching scheme. In fact, the decay curves of transition could be analyzed by intercenter energy migration. Another type of cross‐relaxation was suggested to explain the quenching of transition. © 2000 The Electrochemical Society. All rights reserved.

8 mol %‐yttria‐stabilized zirconia (YSZ) thin films as an oxygen ion conductor were deposited by radio frequency magnetron sputtering, and the oxygen gas sensing properties of YSZ were investigated using the structure of substrate/Ni‐NiO/Pt/YSZ/Pt. X‐ray diffractometry was employed to study the structure of YSZ and Ni‐NiO films, and energy dispersion X‐ray was used to investigate the composition of Ni‐NiO thin films. The gas‐sensing test was carried out for a film structure exposed to oxygen‐controlled environments. The steady‐state electromotive force (EMF) values were measured as a function of oxygen partial pressure and operating temperature (573 to 973 K). The fabricated gas sensor cells showed good oxygen sensing properties at the temperature range from 673 to 773 K. However, the sensors were unstable at the operational temperatures above 873 K possibly due to the enhanced interdiffusion of the materials in the multilayer. Also the operation of the sensor at temperatures below 573 K was not good because the temperature was not sufficient to cause ionic conduction in the cell. At the optimum temperature range, the experimental EMF values measured as a function of oxygen partial pressure were close to the theoretically calculated EMF values. © 2000 The Electrochemical Society. All rights reserved.

A tubeless packaging technology for field emission display (FED) devices is developed using indirect glass‐to‐glass electrostatic bonding with an intermediate amorphous silicon layer at a low temperature of 230°C. The glass‐to‐glass bonding mechanism is investigated by secondary‐ion mass spectroscopy. To evaluate the vacuum sealing capability of a FED panel packaged by this method, the leak characteristics of the vacuum were examined by spinning rotor gauge for 6 months and the electron emission properties of the panel was measured continuously for different amounts of time over a 26 day period. In order to examine the effect of the removal of the exhausting tube on the enhancement of vacuum efficiency, we have calculated a theoretical vacuum level in the panel based on conductance and throughput and compared with experimental values. © 2000 The Electrochemical Society. All rights reserved.

Enhancement of emission intensity of rare‐earth ion‐doped by Al addition has been investigated. In and , addition of 23 mol % Al intensifies emission by more than 200 times. On the other hand, in other rare‐earth ions, the addition of 20 mol % Al intensifies emission at most by three times. This observation implies that 4f–5d transition plays an important role in the emission enhancement. In doped with a rare‐earth ion other than or , a photoluminescence (PL) spectrum is changed, probably due to a decrease in the effective concentration of the ion in . The temperature dependence of PL spectra shows that the energy transfer from carriers to or ions is much more efficient than that to other rare‐earth ions in . It can be speculated that the energy transfer in or occurs from carriers to or ion via 4f–5d transitions, which are much higher in oscillator strength than 4f–4f transitions. © 2000 The Electrochemical Society. All rights reserved.

Primary emphasis was placed on electrophoretic deposition of the low‐voltage phosphor to the indium‐tin oxide coated glass for the application of field emission display. The suspension was prepared with ZnS:Cu, Al green phosphor, isopropyl alcohol, nitride, and glycerin. The phosphor deposited by various parameters, such as deposition time and applied voltage, was examined in detail. In addition, a comparison was made by analyzing luminance properties of the phosphor mixed with and without the conducting powder of less than 1 μm size. The measurement was performed as a function of concentration from 3 to 15 wt %. The enhanced impact of the indium powder mixing on the phosphor was clearly demonstrated by the aging performance curve at 1000 V excitation voltages with a current density of . The optimum mixing concentration of the powder was 10% in this investigation. © 2000 The Electrochemical Society. All rights reserved.

We propose an oxygen surface exchange model in which the effect of vacancies at the gas‐mixed ionic electronic conductor interface are included and apply the model to isotope exchange, oxygen permeability, and electrical conductivity relaxation. We deduce relationships between the surface‐exchange coefficients associated with these phenomena and extend the treatment of the conductivity relaxation to large changes in oxygen partial pressure, where the commonly used assumption of first order reaction rate breaks down. We apply the model to interpret the permeation and electrical conductivity relaxation measurements in . Transport in the material is almost completely surface limited, and data were interpreted in terms of a single surface‐exchange coefficient. © 2000 The Electrochemical Society. All rights reserved.

The extreme conductivity enhancement (by a factor of up to ) in composites as well as the anomalous phase transition to the α‐phase with a large hysteresis of 50°C was confirmed by conductivity, differential scanning calorimetry, and in situ X‐ray diffractometry (XRD). All the composites exhibited an activation energy of 0.29 ± 0.02 eV in conductivity which was identified with the migration enthalpy for transport in the disordered close‐packed layers in AgI system. A close examination of the XRD patterns shows the existence of a seven‐layer polytype (7H) for AgI with the stacking sequence ABCBCAC. This may account for anomalies in the composites in contrast to the ideal space charge effect in and composites. Since the stacking arrangement can be regarded as a heterostructure of β‐AgI (ABABAB...) and γ‐AgI (ABCABC...) with a sub‐Debye length spacing, the conductivity enhancement may be attributed to the mesoscopic multiphase effect predicted earlier. The hysteresis can be attributed to the elastic effects in the martensitic transformation between α‐AgI and 7H‐AgI. © 2000 The Electrochemical Society. All rights reserved.

Abstract not Available.