Thin films research needs

Although considerable research has been conducted with Pd-alloy foils, tubes, and thinner composite membranes, long-term durability and stability need to be further demonstrated, especially in the fuel reforming or WGS operating conditions, for acceptance of this technology in a commercial sector. Furthermore, mass-scale and cost-effective production of industrial-scale Pd-alloy thin-film composite membranes need to be demonstrated to be competitive in the hydrogen production and purification market. 

It should be noted, however, that applicability of the thin-film optic-fiber sensor technology to pipelines for leak detection is still a challenge because pipelines are hundreds (even thousands) mile long. Additional research is needed to identify and develop sensors technologies for hydrogen leak detection along the pipeline. 

The origin of thin-film-composite reverse osmosis membranes began with a newly formed research institute and one of its first employees, Peter S. Francis. North Star Research and Development Institute was formed in Minneapolis during 1963 to fill a need for a nonprofit contract research institute in the Upper Midwest. Francis was given the mission of developing the chemistry division through support, in part, by federal research contracts. At this time the Initial discoveries by Reid and Breton ( ) on the desalination capability of dense cellulose acetate membranes and by Loeb and Sourlrajan (,2) on asymmetric cellulose acetate membranes had recently been published. Francis speculated that improved membrane performance could be achieved, if the ultrathin, dense barrier layer and the porous substructure of the asymmetric... 

Another area with a large research activity is also related to computer technology. It is electrodeposition of magnetic alloys for thin-film recording heads and magnetic storage media. Here new magnetic materials are needed that have properties superior to those of electrodeposited NiEe (Permalloy). These activities are reviewed by Andricacos and Romankiw (25) and Romankiw (32). 

A number of researchers have used surface energy libraries to examine the self-assembly of block copolymer species in thin films. It is well known that substrate-block interactions can govern the orientation, wetting symmetry and even the pattern motif of self-assembled domains in block copolymer films [29]. A simple illustration of these effects in diblock copolymer films is shown schematically in Fig. 6. However, for most block copolymer systems the exact surface energy conditions needed to control these effects are unknown, and for many applications of self-assembly (e.g., nanolithography) such control is essential. 

A list of previous books and reviews on block copolymers is given in the bibliography. There have been no authored books in the field since the volume by Noshay and McGrath in 1977, and this was primarily concerned with the chemistry and materials science. Most of the literature consists of outdated edited books, although a number of review articles have appeared recently. The field has advanced rapidly during the last two decades, with major new theoretical developments, discoveries of new morphologies and the initiation of research in new fields such as thin films, crystalline solids and gels in concentrated solutions. It is thus hoped that this book is timely and fulfils the need for an up-to-date summary of the fundamental physics of block copolymers. 

Table 1 of a paper by Murr (2) lists problems and/or concerns related to specific interface materials and specific components of SECS. In Table 2 of the same work, he related topical study areas and/or research problems to S/S, S/L, S/G, L/L, and L/G interfaces. It is also useful to divide interface science into specific topical areas of study and consider how these will apply to interfaces in solar materials. These study areas are thin films grain, phase, and interfacial boundaries oxidation and corrosion adhesion semiconductors surface processes, chemisorption, and catalysis abrasion and erosion photon-assisted surface reactions and photoelectrochemistry and interface characterization methods. The actual or potential solar applications, research issues and/or concerns, and needs and opportunities are presented in the proceedings of a recent Workshop (4) and summarized in a recent review (3). 

Silicon, diamond, and metal deposition are all examples of elemental deposition. Compounds, particularly oxides, are also deposited by chemical vapor deposition. Some of the important oxides deposited as thin films include SiC>2, BaTiC>3, LiNbC>3, YBa2Cu30,. indium-doped SnC>2, and LiCoC>2. These materials have properties such as superconductivity or lithium ionic conductivity that make their production as thin films a much-studied area of research. If the oxide is to be deposited on the bare metal (e.g., depositing SiC>2 onto Si), chemical vapor deposition is not really needed. Controlling the oxygen partial pressure and temperature of the substrate will produce the oxide film Whether the film sticks to the substrate is another question The production of SiC>2 films on Si is an advanced technology that the integrated-circuit industry has relied on for many years. Oxide films on metals have been used to produce beautiful colored coatings as a result of interference effects (Eerden et al., 2005). 

Because of the sequential nature of atomic layer deposition, it is a slow method for preparing thin films. The sequential nature, however, also produces a film of uniform thickness, referred to as a conformal film. This is important when the surface being coated is not atomically flat, but rather, has troughs and islands to be coated. Some of the most important technological materials, such as silicon and germanium, have not shown themselves to be amenable to the atomic layer deposition technique. This points to the need for continued research in the field of precursor synthesis. 

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