Thesis (MEng) - School of Engineering and Science, Swinburne University of Technology, 2008. / Thesis submitted for the degree of Master of Engineering, School of Engineering and Science, Swinburne University of Technology, 2008. Typescript. Includes bibliographical references (p. 98-101).

Thesis (M. Phil.)--University of Hong Kong, 2005. / Title proper from title frame. Also available in printed format.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2005. / Includes bibliographical references (leaves 118-133). Also available in electronic version.

Thesis (M.S.) -- Worcester Polytechnic Institute. / Keywords: palladium composite membrane; leak formation. Includes bibliographical references (leaves 107-112).

Thesis (Ph. D.)--Lehigh University, 2000. / Includes vita. Includes bibliographical references (leaves 139-148).

Magister Philosophiae - MPhil / Pd based membranes are known for their incredible selectivity towards H2. In order for Pd membranes to display high H2 selectivity, a defect free layer of Pd needs to be deposited onto a support. Although various fabrication techniques do exist, many researchers have attempted to produce defect free Pd-based films, using electroless plating. The first step in the preparation technique involves “seeding” of the support structure. Even though these seeds, if well distributed and anchored to the support, are crucial in order to obtain the defect free Pd layer, they hardly ever received attention from the science community. This thesis reports findings on various seeding methods as well as the resulting microstructures of the Pd films formed as a result of the type of seeding method employed. Finally the quality of the membranes using the most promising seeding technique was determined by subjecting the membranes to permeance tests with N2 at both high and low temperatures as well as with H2 at high temperatures.

This thesis reports the first detailed study of the stoichiometry control mechanisms and physical properties of ZnO films deposited by dc planar magnetron sputtering of a Zn target in a reactive Ar/0₂ atmosphere. Control of film stoichiometry was achieved using a subsidiary rf discharge at the substrate and a reactive gas baffle surrounding the target. The reactive gas baffle was shown to enhance film oxidation by decreasing the metal flux to the substrate and increasing the oxygen partial pressure near the substrate. Rutherford backscattering analysis of film stoichiometry demonstrated that the effect of the rf discharge was to increase the O/Zn composition ratio. This oxidation was shown to occur through preferential resputtering and preferential evaporation of excess Zn and by activation and ion plating of oxygen species. Resputtering and evaporation rates were found to be enhanced above that expected for bulk Zn, due to the weak bonding of surface adatoms during film growth. Conducting ZnO films produced at various values of the rf-induced substrate bias voltage were characterized for electrical, optical and structural properties using Hall probe,. X-ray diffraction, electron microscope, and visible and infrared spectroscopy techniques. Films deposited at low substrate bias (0 to -50V) were found to have a large Zn excess (15%) resulting in low electron mobilities (1 cm²/Vs), high resistivities (10⁻² Ωcm) and were strongly absorbing in the visible. Films deposited at high substrate bias were nearly stoichiometric, optically transparent and had high electron mobilities (15 cm²/Vs) resulting in low resistivity (10⁻³ Ωcm). The optical properties of transparent conducting films for wavelengths 0.4 to 20 /im were modelled by the Drude theory of free electrons using measured electrical transport properties. The original goal of this work, to develop a heat mirror coating suitable for manufacture, was achieved by bias sputter deposition of ZnO onto uncooled polyester sheet at deposition rates approaching 75 nm/min. The best heat mirror films had a transmission to solar energy of 75% and an 85% reflection of 300 K blackbody radiation. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

<p>The widespread commercialization of electric vehicles is currently hindered by their inability to compete with conventional gasoline-powered vehicles in terms of refueling time. The main barrier to achieving fast charge of lithium-ion batteries is the plating of metallic lithium on the surface of the graphite negative electrode, which is known to occur most prevalently at high C-rates, low temperatures, and high states of charge (SOC). While it is accepted that the lithium plating process is largely reversible, the factors affecting the reversibility of lithium plating have not been thoroughly investigated. This work seeks to determine the most influential factors affecting the reversibility of lithium plating in order to devise strategies to mitigate long-term damage to the cell if lithium plating has been detected. It was determined that the temperature during the rest phase following plating has the most significant influence on plating reversibility, with cells undergoing rest at 30 ℃ exhibiting nearly twice the Coulombic inefficiency of cells undergoing rest at 0 ℃. Additionally, a novel technique was developed to observe the relaxation processes directly in a graphite electrode just after lithium plating has occurred. The occurrence of electrochemical stripping and the dissolution of overshooting phases in graphite were verified through direct <i>in-situ</i> observation. A two-part model is presented to describe the progression of the relaxation processes in graphite after lithium plating occurs under high rate operation.</p>

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements of the degree of Master of Science. November 1995. / The preparation of supported cobalt and gold catalysts by the technique of electroless plating, and the establishment of the influence of synthesis variables on the physical properties of the supported catalyst, forms the basis of this dissertation. In both the cases of cobalt and gold supported on extruded cylindrical alumina pellets, the penetration profile of the metal into the support showed dependence on the pH of the activation solution, while the metal loading onto the same support showed no dependence on pH of the activation solution at all. The variables involved in the plating process of the activated pellets, namely: i) the concentration of the activation solution, ii) pH and temperature of the plating bath, iii) plating time, and Iv) variation of the concentrations of components of the plating bath all influenced the mass of metal loaded onto the support, but not the penetration characteristics. It is therefore possible to prepare a supported catalyst with very specific , properties using the above information. Under similar conditions, with extruded alumina pellets as support and with the specific plating formulations used, gold showed higher metal loadings at lower gold concentrations than cobalt.

This study focused on improvement of electroless plating methods by use of particular bath additives. The techniques developed here can enable us to plate very thin layers selectively on a nonconductive substrate and thus create metallized features on a nanoscale. Through the development of such bottom-up techniques this work contributes a key technology to achieving self-assembled nanocircuits. The use of additives in an electroless plating environment can modify the barriers to nucleation (or seeding) and growth. Two additives, namely 3-mercapto-1-propanesulfonic Acid (MPS) and 1,3-propanedisulfonic acid (PDS), notably increased the selectivity of electroless metallization on chemically modified surfaces, which can be used to create patterned structures. More specifically, the additives increased the growth rate of metal on an aminosilane-coated surface relative to an uncoated surface. This work includes an examination of metal layer thickness and conductivity in addition to selectivity. The layer thickness was determined through the use of atomic force microscopy on surfaces that exhibited conductivity. The conductivity of the surface metal was determined through a measurement on a four-point probe measurement. In this series of experiments, the disulfonate-containing additive PDS provided the highest nucleation density, highest conductivity and the best selectivity ratio. The palladium metal deposit on the PDS-treated surface was nearly uniform in height and its conductivity approached the bulk conductivity of palladium with a metal height of less than 30 nm. MPS-treated surfaces also provided increased nucleation density when used during the seeding step, but the resulting conductivity was less than that of the PDS treated samples. We recommend the use of PDS as an effective electroless plating additive for use in palladium electroless plating processes.