Showing papers in "Critical Reviews in Solid State and Materials Sciences in 2007"
TL;DR: Ferroelectrics are dielectric materials that have spontaneous polarization in certain temperature range and show nonlinear polarization-electric field dependence called a hysteresis loop as discussed by the authors.
Abstract: There has been a resurgence of complex oxides of late owing to their ferroelectric and ferromagnetic properties. Although these properties had been recognized decades ago, the renewed interest stems from modern deposition techniques that can produce high quality materials and attractive proposed device concepts. In addition to their use on their own, the interest is building on the use of these materials in a stack also. Ferroelectrics are dielectric materials that have spontaneous polarization in certain temperature range and show nonlinear polarization–electric field dependence called a hysteresis loop. The outstanding properties of the ferroelectrics are due to non-centro-symmetric crystal structure resulting from slight distortion of the cubic perovskite structure. The ferroelectric materials are ferroelastic also in that a change in shape results in a change in the electric polarization (thus electric field) developed in the crystal and vice versa. Therefore they can be used to transform acoustic wav...
369 citations
TL;DR: This article attempts to review the current status of magnetite nanoparticles preparation and use, with a special emphasis on bio-medical applications, but also to outline the promises and challenges associated to this emerging technology.
Abstract: Nanotechnology has generated tremendous hopes in recent years toward the design of advanced functional materials, especially in the bio-medical field. Nano-sized-materials such as magnetite nanoparticles display indeed fascinating physico-chemical properties that, if tuned properly, can be exploited to design new bio-diagnostic and therapeutic strategies as well as innovative biotechnology methodologies. Owing to their biocompatibility and excellent magnetic properties, magnetite nanocrystals have been the object of a tremendous amount of research in the last decade and numerous (bio)applications have been reported. Importantly, advances in the synthesis of magnetite nanoparticles enable excellent control over their size, shape, and composition. Despite these remarkable progresses, many issues remain to be overcome for these nanotechnology products to revolution the medical practice. The fine control and application of colloidal nanostructures such as magnetite nanoparticles in complex biological systems ...
263 citations
TL;DR: In this paper, three classes of nanometer-thick, disordered, interfacial films in multicomponent inorganic materials are reviewed and critically assessed, and three types of films are evaluated.
Abstract: Recent observations of three classes of nanometer-thick, disordered, interfacial films in multicomponent inorganic materials are reviewed and critically assessed. The three classes of films are equ...
167 citations
TL;DR: In this paper, the role of the electron is discussed as a basic principle of its interaction with matter, which is same as for an ion, and the synthesis of nanostructures and their modification by ion beam technique is discussed.
Abstract: Ion beam irradiation is a potential tool for phase formation and material modification as a non-equilibrium technique. Localized rise in temperature and ultra fast (∼10−12 s) dissipations of impinging energy make it an attractive tool for metastable phase formation. As a matter of fact, a major component of materials science is dominated by ion beam methods, either for synthesis of materials or for its characterization. The synthesis of nanostructures, and their modification by ion beam technique will be discussed in this review article. Formation of nanostructures using ion beam technique will be discussed first. Depending on species (e.g., mass and charge state) and energy range, there are various modes for an energetic ion to dissipate its energy. The role of the electron will also be covered in this article as a basic principle of its interaction with matter, which is same as for an ion. By using a simple reactive ion beam or electron induced deposition, a secondary phase can be nucleated by ion beam ...
85 citations
TL;DR: In this paper, the electrical performance of the composites for the Nafion® and other perfluorinated membranes in DMFCs is evaluated and the effect of these modifications on various aspects, such as mobility of protons through the membrane, permeation of hydronium ions, and cross-over of methanol leading to the negative potential, have been discussed.
Abstract: Fuel cells are a replacement for the conventional energy resources. As early as 1839, William Grove discovered the basic operating principle of fuel cells by reversing water electrolysis to generate electricity from hydrogen and oxygen. A Direct Methanol Fuel Cell (DMFC) operates on liquid fuel, which is one of the exciting varieties of fuel cells. There are many problems with DMFCs such as the high cost of electrolyte membranes, high platinum loading, CO poisoning, fuel cross-over, and so on. In this review, research regarding the solution of these problems will be cited and discussed. The electrical performance (in respect to power density) of the composites for the Nafion® and other perfluorinated membranes in DMFC are evaluated. The effect of these modifications on various aspects, such as mobility of protons through the membrane, permeation of hydronium ions, and cross-over of methanol through the membrane leading to the negative potential, have previously been discussed. Therefore, the main focus of...
22 citations