Iumrs Icem 2002

Even before it was identified as a science and given a name, nanotechnology was the province of the most innovative inventors. In medieval times, craftsmen, ingeniously employing nanometer-sized gold particles, created the enchanting red hues found in the gold ruby glass of cathedral windows. Today, nanomaterials are being just as creatively used to improve old products, as well as usher in new ones. From tires to CRTs to sunscreens, nanomaterials are becoming a part of every industry. The Nanomaterials Handbook provides a comprehensive overview of the current state of nanomaterials. Employing terminology familiar to materials scientists and engineers, it provides an introduction that delves into the unique nature of nanomaterials. Looking at the quantum effects that come into play and other characteristics realized at the nano level, it explains how the properties displayed by nanomaterials can differ from those displayed by single crystals and conventional microstructured, monolithic, or composite materials. The introduction is followed by an in-depth investigation of carbon-based nanomaterials, which are as important to nanotechnology as silicon is to electronics. However, it goes beyond the usual discussion of nanotubes and nanofibers to consider graphite whiskers, cones and polyhedral crystals, and nanocrystalline diamonds. It also provides significant new information with regard to nanostructured semiconductors, ceramics, metals, biomaterials, and polymers, as well as nanotechnology’s application in drug delivery systems, bioimplants, and field-emission displays. The Nanomaterials Handbook is edited by world-renowned nanomaterials scientist Yury Gogotsi, who has recruited his fellow-pioneers from academia, national laboratories, and industry, to provide coverage of the latest material developments in America, Asia, Europe, and Australia.

First Self-Contained Source Entirely Dedicated to Nanocarbons Carbon nanotubes (CNTs) attract a good deal of attention for their electronic, mechanical, optical, and chemical characteristics. But nanostructured carbons are not limited to nanotubes and fullerenes-they also exist as nano-diamonds, fibers, cones, scrolls, whiskers, and grap

Size, Shape, and Synthesis Key to “Tuning” Properties The discovery and rapid evolution of carbon nanotubes have led to a vastly improved understanding of nanotechnology, as well as dozens of possible applications for nanomaterials of different shapes and sizes ranging from composites to biology, medicine, energy, transportation, and electronic devices. Nanotubes and Nanofibers offers an overview of structure–property relationships, synthesis and purification, and potential applications of carbon nanotubes and fibers, including whiskers, cones, nanobelts, and nanowires. Using research on carbon nanotubes as a foundation to further developments, this book discusses methods for growing and synthesizing amorphous and nanocrystalline graphitic carbon structures and inorganic nanomaterials, including wet chemical synthesis, chemical vapor deposition (CVD), arc discharge, and others. It also describes boron nitride and metal chalcogenide nanotubes in detail and reviews the unique properties and methods for characterizing and producing single-crystalline semiconducting and functional-oxide nanowires. The chapters also identify challenges involving the controlled growth, processing, and assembly of organic and inorganic nanostructures that must be addressed before large-scale applications can be implemented. Edited by award-winning professor and researcher Dr. Yury Gogotsi, Nanotubes and Nanofibers offers a well-rounded perspective on the advances leading to improved nanomaterial properties for a range of new devices and applications including electronic devices, structural composites, hydrogen and gas storage, electrodes in electrochemical energy-storage systems, sorbents, and filters.

This book describes available tribology technologies and introdces a comprehensive overview of tribology. General, up-to-date knowledge on how tribology is approached in various related areas of research, both experimental and computational is provided.

This dissertation employs doping to investigate basic gallium nitride (GaN) crystal properties and to solve challenges of the hydride vapour phase epitaxy (HVPE) growth process. Whereas the first chapter is a short introduction to the history of the GaN single crystal growth, the 2nd chapter introduces to current crystal growth techniques, discusses properties of the GaN material system and the resulting influence on the applicable crystal growth techniques. HVPE, as a vapour phase epitaxy crystal growth method will be explained in greater detail, with focus on the used vertical reactor and its capabilities for doping. The 3rd chapter then focusses on point defects in GaN, specifically on intentionally introduced extrinsic point defects used for doping purposes, i.e. to achieve p-type, n-type or semi-insulating behaviour. Different dopants will be reviewed before the diffusion of point defects in a solid will be discussed. The in-situ introduction of iron, manganese, and carbon during crystal growth is employed in chapter 4 to compensate the unintentional doping (UID) of the GaN crystals, and therefore to achieve truly semi-insulating behaviour of the HVPE GaN. However the focus of this chapter lies on the characterisation of the pyroelectric coefficient (p), as semi-insulating properties are a necessary requirement for the applied Sharp-Garn measurement method. The creation of tensile stress due to in-situ silicon doping during GaN crystal growth is the topic of the 5th chapter. The tensile stress generation effect will be reproduced and the strain inside the crystal will be monitored ex-situ employing Raman spectroscopy. The n-type doping is achieved by using a vapour phase doping line and a process is developed to hinder the tensile strain generation effect. The 6th chapter concentrates on the delivery of the doping precursor via a solid state doping line, a newly developed doping method. Similar to chapter 5, the doping line is characterised carefully before the germanium doping is employed to the GaN growth. The focus lies on the homogeneity of the germanium doping and it is compared compared to the silicon doping and the vapour phase doping line. Benefits and drawbacks are discussed in conjunction with the obtained results. The germanium doping via solid state doping line is applied to the HVPE GaN growth process to measure accurately growth process related properties unique to the applied set of GaN growth parameters.