Atomic Layer Deposition Applications 4

Atomic Layer Deposition Applications 4
Author: Ana Londergan
Publisher: The Electrochemical Society
Total Pages: 379
Release: 2008
Genre: Chemical vapor deposition
ISBN: 1566776503

The continuously expanding realm of Atomic Layer Deposition (ALD) Applications is the symposium focus. ALD can enable the precise deposition of ultra-thin, highly conformal coatings over complex 3D topography, with controlled composition and properties. This issue of the ECS Transactions contains peer reviewed papers presented at the symposium. Breadths of ALD Applications are featured: novel nano-composites and nanostructures, dielectrics for state-of-the-art transistors and capacitors, optoelectronics and a variety of other emerging applications.

Innovative Concepts Phase I

Innovative Concepts Phase I
Author: William Desisto
Publisher:
Total Pages:
Release: 2003
Genre:
ISBN:

Silica membranes were prepared using a novel technique of catalyzed-atomic layer deposition of silica within a mesoporous matrix. Pyridine was used to catalyze the silicon chloride attachment to the hydroxylated silica surface at room temperature. This half-reaction was followed by the hydration of the surface with water regenerating surface hydroxyls and completing one reaction cycle. The technique resulted in the self-limited pore size reduction of the mesoporous matrix to pore sizes near 1 nm. The self-limited reaction was presumed to be the exclusion of the large catalyst molecule from the pore entrance. In addition to pore size reduction, viscous flow defects were repaired without significantly reducing overall porosity of the membrane. In addition, we investigated the ability of amine-functionalization to enhance the CO{sub 2} transport in silica membranes. Specifically, we examined three synthesis techniques for functionalizing silica membranes with amino groups that resulted in different surface chemistries of the silica membranes. These differences were correlated with changes in the CO{sub 2} facilitation characteristics. It was found that high loadings of amino groups where interaction with the silica surface was minimized promoted the highest CO{sub 2} transport.

Synthesis of Ordered Mesoporous Silica and Alumina with Controlled Macroscopic Morphologies

Synthesis of Ordered Mesoporous Silica and Alumina with Controlled Macroscopic Morphologies
Author:
Publisher:
Total Pages:
Release: 2004
Genre:
ISBN:

This thesis investigates the synthesis of ordered mesoporous silica and alumina materials with unique microstructures and different morphologies using novel approaches based on template-assisted synthesis and chemical vapor deposition (CVD) techniques and their potential use in polymer reaction application. Template-assisted growth of mesoporous silica under acidic and quiescent conditions at an oil-water interface can generate mesostructured silica with fibrous and non-fibrous morphologies. Fibers are obtained due to slow and one-dimensional diffusion of precursors through the interface. Variation in conditions can alter the axial growth of silica and yield non-fibrous shapes. Fibers grow from their base attached to the interface and coalesce to form fibers with larger diameters. Gas transport in silica fibers is governed by Knudsen and surface diffusion mechanisms. Surface diffusion contributes to 40% of the flow reflecting highly smooth pores. Real Knudsen and surface diffusivities are in the order of 10E-3 and 10E-5 cm2̂/s respectively. The one-dimensional mesopores are 45 time longer than the fiber length and align helically around the fiber axis with a pitch of 1.05 micron. Mesoporous silica membranes were prepared by a novel counter diffusion self assembly (CDSA) approach. This approach introduces the precursors from the opposite sides of a hydrophobic supports and yields silica plugs grown within its pores. Silica plugs grow with thickness of 0.5 mm and have a mesoporous structure. Such mechanically strong membrane is potential in protein separation and polymer reaction applications. Mesoporous membranes with controlled pore microstructure can be also obtained using cyclic CVD modification of straight 20 nm pore alumina membranes. Leaving residual of precursors in the pore after introduction of each precursor causes deposition of alumina in a fractal structure suitable for gas separation. Purging the pore after each precursor causes deposition in atomic layer with cylindrical mesopores suitable for membrane reaction applications. Titanocene-supported MCM-41 was used as molecular extruder for preparation of 60 nm polyethylene nascent fibers with extended-chain crystalline structures. The nascent fibers aggregate into 1-30 ư m microfibers which further aggregate into fiber bundles. Mechanical properties, measured for the first time, demonstrated an improved tensile strength of the polyethylene product compared to commercial polyethylene fibers.

Powders and Fibers

Powders and Fibers
Author: Michel Nardin
Publisher: CRC Press
Total Pages: 685
Release: 2006-12-21
Genre: Science
ISBN: 1420016008

New analytical methods have provided further insight into the structure, surface characteristics, and chemistries of increasingly small particles. However, current literature offers information on only a limited number of powders being investigated. Written by renowned scientists in the field, Powders and Fibers: Interfacial Science and Application

Mesoporous Zeolites

Mesoporous Zeolites
Author: Javier García-Martínez
Publisher: John Wiley & Sons
Total Pages: 608
Release: 2015-05-26
Genre: Technology & Engineering
ISBN: 3527335749

Authored by a top-level team of both academic and industrial researchers in the field, this is an up-to-date review of mesoporous zeolites. The leading experts cover novel preparation methods that allow for a purpose-oriented fine-tuning of zeolite properties, as well as the related materials, discussing the specific characterization methods and the applications in close relation to each individual preparation approach. The result is a self-contained treatment of the different classes of mesoporous zeolites. With its academic insights and practical relevance this is a comprehensive handbook for researchers in the field and related areas, as well as for developers from the chemical industry.