Alan J. Hurd

Eduardo Falabella Sousa-Aguiar

Alan J. Hurd

G.Solórzano

Alain Kiennemann

S. R. P. Silva

Carlos Alberto Soares

U. Reisgen

Sonja-Michaela Gross

Romero Gomes de Araújo

Martin Harmer

Interfaces and the movement of atoms within an interface play a crucial role in determining the processing and properties of virtually all materials. However, the nature of interfaces in solids is highly complex and it has been an ongoing challenge to link material performance with the internal interface structure and related atomic transport mechanisms. Interface complexions offer the missing link to help solve this universal problem. An interface complexion can be considered as a separate phase, which can be made to transform into different complexions (phases) with vastly different properties by heat treatment, thereby enabling the engineering control of material properties on a level not previously realizable. As such, complexions offer a solution to outstanding fundamental scientific mysteries such as the origin of abnormal (cancerous-like) grain growth in inorganic materials, a problem which leading researchers in the field have struggled to explain for the past 50 years. It will be shown that alumina has six complexions, and that we can control atom transport by many orders of magnitude by transitioning amongst the 6 complexions. It is then described how interface complexions will likely have widespread impact across all branches of material science and related disciplines.

Arben Merkoçi

Nanoscience and nanotechnology are offering novel opportunities for biosensing applications. The design of novel nanostructures with special optical and electrochemical properties and their integration into biosensing systems in general and particularly biosensors represent only one aspect of the research in this new field. The biosensor oriented nanotechnology will provide new tools for various applications in fields like medicine, environmental studies, and industry. Examples related to the integration of gold nanoparticles, quantum dots (QDs) and carbon nanotubes (CNT) in several detection systems will be presented. The use of nanoparticles for biosensing has generated great interest with the increasingly understanding of the structure and function of gene, especially for Human Genome Project. By the other side, sequence specific DNA detection has been a topic of significant interest, for its application in diagnosis of pathogenic and genetic diseases between other fields. DNA and protein detections methodologies based on several nanosctructures will be described. The use of QDs with special interest for the design of the so-called “DNA chips in solution” will be also emphasized. Beside nanoparticles, CNTs are offering a great promise in the design of novel biosensors. Distinctive properties of CNTs such as a high surface area, ability to accumulate analyte, minimization of surface fouling and electrocatalytic activity are very attractive for electrochemical (bio)sensing systems. The integration of CNTs in several matrix including cells forming novel bionanostructures with interesting applications in sensor technology will be other examples. The obtained results show remarkable electrochemical and mechanical advantages of CNT modified electrode compared to the unmodified ones.

Osvaldo Novais Oliveira Jr

The fabrication of heterostructures made of organic ultrathin films is discussed, with particular emphasis on the molecular control that allows one to optimize the performance of biosensors. The films are fabricated either with the Langmuir-Blodgett (LB) or the electrostatic layer-by-layer (LbL) methods, with which a variety of biomolecules may be immobilized together with other organic or inorganic components. High sensitivity in biosensors is achieved by exploiting the molecular recognition capability toward analytes, in cases where enzymes and antigens are immobilized. In addition to illustrating examples of biosensors, a discussion will be presented of physical methods to study molecular-level interactions, in an attempt to identify the mechanisms involved in biosensing.

Luiz Cláudio de Marco Meniconi

Several projects currently underway within Petrobras will be shown and discussed. The main objective of the research is to provide cold repair techniques – meaning no use of arc welding – to be applied to typical structures and equipment of the oil industry: offshore platforms, pipelines, pipework and tanks. The repair techniques make use of composites of glass and carbon fibers in thermosetting matrices. Some standards and recommended practices recently made available in the open literature served as reference documents for the repairs and will have their theoretical background discussed.

Kleber C. Mundim

Theoretical and computational molecular science will play a critical role in developing molecular-lever descriptions of chemical, physical and biological processes in natural and contaminated systems. To date, theoretical methods for studying fundamental nano-processes at the electronica level hold tremendous promise for enabling rational new materials. A primary difficulty in such king of research is that, as the size of the systems becomes larger and more comples, the empirical methods become less reliable.

Zachary - Fisk

We present the results of Cd-doping of the 115 heavy Fermion materials which acts in many ways like negative pressure. We speculate about the physics underlying this.

Marco Chaer Nascimento

In several fields of science there has been an increasing demand for new materials with specific properties, for a diversity of applications. Also important, is the possibility of modifying the properties of some materials in order to make them appropriate for use under extreme conditions. In this talk we will show how a combination of different methodologies (ab-inito, DFT and classical) can be used for those purposes. In particular, we will look at the design of materials with non-linear optical properties, flame retardant materials, catalysts and lubricants. (CNPq, FAPERJ, PRONEX, Instituto do Milênio de Materiais Complexos).

Hans Nowak

In the last 30 years new experimental techniques and new theoretical approaches in solid state physics have led to the discovery of new phenomena like high Tc superconductivity and quantum Hall effect and the discovery of new materials like high Tc superconductors, fullerenes and quasicrystals. Within the Density Functional Theory physicist have developed in these years a better description of the many-body electron-electron interaction which provides today a more realistic description of the electron structure of matter. The spin of the electron is now treated on the same level as the electronic charge distribution and has it made possible to construct new magnetic properties of matter. Together with the new experimental techniques it is now possible to design agglomerations of atoms with dimensions of nanometers and different forms, the nanostructures which show new and varied electronic and magnetic properties. The latest generation of electronic structure calculations in bulk material with or without impurities or stress, surfaces and nanostructures can be divided in two groups: (i) methods which use ab initio norm conserving pseudo potentials, a large basis set which give rise to sparse matrices which can be fastly diagonalized by new computer methods. The WIEN package is one of the most used. Quantum Monte Carlos methods like Car-Parinello which move nuclei and electrons on the same level use these pseudo potentials too. (ii) methods which use a minimal basis set by resolving the Schroedinger equation inside non overlapping spheres around the nuclei with spherical symmetry and plane waves in the intermediate relatively flat region between the spheres. The basis which is energy dependent can be linearized with respect to the energy. The basis set can be reduced more if one makes the spheres so large that they fill the total space of the system. In this approximation, the Atomic Sphere Approximation (ASA), the minimal basis set reduces to few states coming from the spherical potential inside the atomic spheres.

Armando Beltrán Flors

Tellurium oxide (TeO2) and TeO2-based glasses are promising active materials for optical switching devices due to their large nonlinear polarizability and for optical amplifiers due to their large cross section for stimulated Raman scattering Three crystalline phases of TeO2 are well documented. The paratellurite alpha-TeO2 and the tellurite beta -TeO2 phases have been known for a long time. Recently, a third crystalline polymorph metastable at normal conditions, gamma -TeO2, has been identified by x-ray powder diffraction of recrystallized tellurite glasses doped with metal oxides. In this work, we investigate further the three crystalline phases of TeO2 alpha , beta and gamma by computing their structural and vibrational properties from first principles. We aim at providing a compelling assignment of the experimental Raman and IR peaks to specific phonons which would allow one to identify the vibrational signature of the different structural units in the crystals and in the glass. We have performed calculations of the electronic structure of crystalline TeO2 alpha , beta and gamma, in the framework of the Density Functional Theory (DFT) with the hybrid B3LYP functional, using the ab-initio total-energy program CRYSTAL 2006. Equilibrium geometries have been obtained by optimizing the internal and lattice structural parameters at several volumes and fitting the energy versus volume data with a Birch Murnaghan EOS. The band structure and the partial DOS of alpha , beta and gamma -TeO2 have been also calculated. By applying an electric field, our calculations allow to estimate the linear and non linear refractive index and some components of the non linear susceptibility tensor of these structures. The calculated vibrational frequencies, heat capacities, energy band gaps, lattice constants and ionic displacements are in reasonable agreement with experiment when available. In addition, we find that the bonding is almost entirely ionic with a small covalent component.

William A. Lester

The quantum Monte Carlo method has become recognized for its capability of describing the electronic structure of atomic, molecular and condensed matter systems to high accuracy.* This talk will briefly outline the method with emphasis on new developments connected with trial function construction, linear scaling, and applications to large systems. Findings for a representative collection of recently investigated systems will be discussed including atomization energies and bond dissociation energies. This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, Chemical Sciences Division of the U.S. Department of Energy under Contract No. DE-AC03-76SF00098, and by the CREST Program of the U. S. National Science Foundation. The calculations were carried out both at the U. S. National Energy Research Supercomputer Center (NERSC) and the Graphics Laboratory, Department of Chemistry, University of California, Berkeley.

Geraldo José da Silva

In this work we present studies of intercalation and diffusion of water in the synthetic clay Ni-Flurohectorite by utilizing the X-Ray techniques of Absorption (XAFS) and of Scattering (XRD) of the LNLS and we show the importance of the connection between experiment and optimization numerical methods contributing to the reliability of the experimental results in a way that experiments suggest simulations and simulations can suggest further experiments.

Flamínio Levy Neto

Structural composites are special material systems, which incorporate two or more phases, normally on a macroscopic scale, as well as present low weight combined with high mechanical strength and stiffness. One of the phases is usually discontinuous (e.g. fibers, whiskers or particles), stiffer and stronger and is called the reinforcement, whereas the less stiff and weaker phase is continuous and is denominated the matrix (e.g. polymeric, ceramic or metallic). The behavior of a composite depends on the volume fractions of the reinforcement and the matrix, as well as on their geometry and individual properties, among other factors (e.g. the orientation of the fibers). The main purpose of this presentation is to show the audience: (i) the basic mechanical behavior of polymeric structural composites reinforced with fibers (e.g. carbon, kevlar and E-glass), which are subjected to typical service loads in engineering applications; and (ii) the most important parameters involving the manufacture of such composites. The fabrication process adopted also defines the properties of composites. So, this presentation, in addition, is concerned with the influence of the manufacturing process on the mechanical behavior of structural composites.

Analía Vázquez

Extensive application of synthetic and traditional polymer materials results in increasing volume of polymeric waste and methods are needed for safe and relatively quick elimination of these materials from the environment. The development of biodegradable polymers has been accepted as one of the way to reduce environmental problems by waste plastics. Starch based polymer, polycaprolactone and polyhydroxalcanoates polymer were studied. In order to modify the mechanical and physical properties of the biodegradable polymer, a new kind of biocomposites was investigated: the nanocomposites made from natural filler. Nanoclay and cellulose fibers were used as reinforcement of biodegradable polymers. Modified clay was utilized and it was correlated to the hydrophilic character of the polymers. The feasibility of extracting cellulose from sisal fiber, by means of two different procedures was also carried out. The extraction procedures that were used led to purified cellulose. Finally, nano-cellulose was produced by the acid hydrolysis of obtained cellulose and characterized by Atomic Force Microscopy (AFM). Results of mechanical properties and their modelization; and barrier to vapor properties will be included.

Lavinia Alves Borges

The most conventional techniques do not seem to be adequate for identifying and characterizing the mechanical behavior of non-conventional materials or structures as, for instance, any general sort of composites. For these materials, more reliable and robust identification approaches are required. Therefore, the aim of this work is to present techniques to identify constitutive parameters suitable to describe non-conventional materials' mechanical behavior. The present identification approaches fit in the so called model updating that seeks matching experimental results to analytical modeling. Two classes of methodologies are discussed. The first one combines experimental stress or modal analysis with optimization formulations in order to determine the elastic and/or viscoelastic constants of composite materials. Finally, the strength properties of heterogeneous materials are assessed by mixing nanoindentation's experiments results, micromechanics , homogenization and limit analysis theories. Based on this framework a general procedure is developed in order to define the strength properties of porous materials, composed of a solid phase and pore space. The extension of this methodology to study the strength properties of composites is discussed.

Juan Andrés

The presentation will summarize our recent results obtained by means of the joint use of experimental and theoretical methods and techniques on some relevant studies in material science. Extensive benchmarks and applications will be presented, covering different fields: i) Phase transitions driven by pressure. ii) Metal intercalation and diffusion processes in solid materials. iii) Growth mechanism of pure and mixed metal oxide nanostructures. iv) Formation of conducting zig-zag nanotube like structures from polymers composed of Au32 (Ih) units. v) Development of multifunctional compounds combining conductivity and ferromagnetism behavior.

José Arana Varela

Recent findings on photoluminescence (PL) at room temperature of some disordered perovskite type materials prepared by the polymeric precursor method and annealed at different temperatures are presented. Intense and broad visible photoluminescence (PL) band was observed at room temperature in structurally disordered powders and thin films. These materials were characterized by means of x-ray diffraction, Raman spectroscopy, band structure, density of states, Mulliken charge and atomic force microscopy analysis. Quantum mechanical calculations showed that the local disorder of the network modifier atom has a very important role in the charge transfer involved in the green PL emission. Based on these findings it was proposed that the pseudocubic structure of these perovskites presents a long-range tendency for cubic symmetry, while the short-range displacements bring the solid solution to a tetragonal symmetry. The theoretical and experimental results are in good agreement, both indicating that the generation of the intense visible PL band is related to simultaneous structural order and disorder in the perovskite lattice. Some examples of structure are analyzed.

Francesc Illas

Material science handles complex systems having the common feature of a rather rigid atomic structure but nevertheless with a virtually infinite number of atoms. Computational simulations may complement experiments by bringing important complementary information regarding physical mechanisms relevant to several technologies or unravel the molecular mechanism of complex reactions taking place at the surface of catalysts. However, the very large number of variables involved makes it necessary to assume certain simplifications. Depending on the problem one may rely on classical methods or require a more accurate quantum mechanical treatment. In the latter case, the exceedingly large number of atoms in the system does not allow for a full ab initio calculation of the whole system and the use of models is unavoidable. Two families of broadly used models are often used which are generally known as the cluster and periodic approaches. In first one the material is roughly represented but electronic correlation can be accurately described. In the second approach the material may be more properly represented but electronic correlation described roughly, mainly through density functional theory with concomitant problems in the description of excited states. The present contribution will describe in some detail how these models can be used to obtain a deeper insight in the electronic structure and corresponding properties of various relevant materials. Several examples will be presented covering spectroscopy of point defects in solids, magnetic interaction in superconducting cuprates or chemical reactions taking place at the surface of a model catalyst.

João Batista Lopes Martins

We have studied single wall nanotubes and the effects of growing nanotube diameter and size along its axis. The armchair and zigzag structures of ZnO, SnO2 and TiO2 were calculated using the semiemprirical AM1 method and ab-initio Hartree-Fock and B3LYP methods. The interatomic distance was optimized in order to search for the stable structure minimum energy. The structure of minimum energy is used for the analysis of energy variation, gap (HOMO-LUMO) and charge values.

Norton M. Grant

Nanomaterials show properties that are often very different from those of the same material in bulk form. Gold has been prized for hundreds of years because of its inertness. In the form of nanoparticles gold has been shown to be a very potent catalyst. As a thin film gold is highly reflective, but gold nanoparticles show interesting and potentially very useful optical absorption. At the nanoscale, glass has properties that are different from those of plate glass. In this presentation I will describe our work in exploring how the novel properties of nanomaterials can be exploited for alternative energy applications. For example, silica glass nanosprings with high surface areas and unique surface structures have been developed for nondissociative storage of hydrogen. Molecular adsorption has been demonstrated at liquid nitrogen temperatures, and more importantly, at room temperature. Desorption occurs at the moderate temperature of 100°C. X-ray photoelectron spectroscopy analysis of electron core level shifts indicates that the adsorption sites for H2 are Si atoms on the nanospring surface and that a monolayer of molecular H2 is adsorbed after eight Langmuirs of exposure. XPS also indicates that a second monolayer of H2 is adsorbed upon completion of the first monolayer. The significance of this observation is that multilayer adsorption is essential if nanostructured materials are to meet hydrogen storage targets necessary for enabling the “hydrogen economy”. Because the silica nanosprings can be synthesized at temperatures as low as ~300°C, they can be grown on polymer substrates, making them amenable for formation into complex large-surface-area structures that are essential for practical hydrogen storage applications. I will also discuss our work in building hierarchical nanostructures for solar energy capture. In this application we are using plasmon resonance absorption in precious metal nanoparticles to create devices that show broad solar spectrum absorption.

A. R. Yavari

Copper was the first metals used by mankind and bronze (copper and tin-based) and brass (copper and zinc-based) have been in use since thousands of years ago. Like in the distant past, copper is widespread in modern civilization with applications as varied as in wires and cables, jewelry, radiators and pipings, roofing, tooth filling, screws and nails and computer boards. Modern science and engineering can fashion various materials in desired nanostructures with new properties and it is timely to design and explore nanostructured copper. We have developed a method for creating scratch-resistant nanocrystalline layers on near eutectic alloys containing 90% copper by copper-mould casting. Some of our alloys have yield strengths in excess of 1.8 GPa making them mechanically more resistant than many stainless steels but with a range of colors. Depending on elemental additions, the colors can vary from copper-like to gold-like.

Clécio C. de Souza Silva

The unique properties of perfect conductivity and diamagnetism of superconducting materials are used in innumerous applications, ranging from very sensitive magnetic flux detectors and ultrafast AD converters to low loss transmission lines and fast flying trains. All these applications require control or manipulation of nanoscale structures called vortices. Vortices are linear whirlpools of superconducting current encircling quantized magnetic flux that thread all important superconducting materials exposed to a magnetic field. For some applications, e.g., quantum electronic devices like SQUID sensors, vortex motion induces parasitic noise, reducing the device sensibility. While for other applications, like superconducting rectifiers, vortices play the main role in the working principle of the device. Superconducting films nanoengineered with mesoscopic vortex traps have recently achieved an unprecedented level of manipulation of vortex motion and enhancement of superconducting properties [1-4]. These structures are able to pin and manipulate vortices individually, giving rise to enormous critical currents and noise reduction. In this talk, we will discuss the material processing and physical properties of nanostructured superconducting films and their potential for application. Recent experiments on vortex manipulation using such devices will be presented [2-4]. We will give particular focus on hybrid superconductor-ferromagnetic structures, namely superconducting films with on-top arrays of ferromagnetic nano- or microdots, and show how magnetism, a well-known antagonistic to superconductivity, can enhance the superconducting properties of these devices with a suitable engineering.

Pedro D. Portella

Due to their relatively simple microstructure, single crystal superalloys allow a useful insight into deformation mechanisms. On the other hand their intrinsic anisotropy poses difficult questions to the measurement and interpretation of strain. In this paper we describe the mechanical response of uncoated specimens of different superalloys to fatigue loading including thermo-mechanical and biaxial fatigue. The concomitant changes in the gamma / gamma prime microstructure as well as the damage evolution are presented and set into relation to the observed mechanical behavior. On the basis of this extensive experimental basis, a viscoelastic anisotropic model was developed and calibrated for different alloys. Finally, some practical applications are considered.

Carlos A. Paz de Araújo

Memory devices are used in almost every electronic device in the world. The quest for a true nonvolatile memory device intrinsically combines standard microelectronics/semiconductor devices with ceramic materials which have properties beyond those provided by semiconductors. In the past 25 years, a range of devices using a variety of phenomena found in complex oxides have been studied and some brought to full production. Currently, the commercially dominant nonvolatile memory is without a doubt, the FLASH devices which use quantum tunneling and charge trapping as the storage mechanism in modified field effect transistors. However, as the semiconductor industry continues to move towards higher levels of integration, it has become clear that FLASH devices and field effect transistors in general have found their practical and quantum scaling limits. Synthesis and deposition of ultra thin-films of complex oxides led to the successful commercialization of ferroelectric materials of the perovskite and Aurivilius series of bismuth based layered perovskites in the last few years. Currently over 10 million devices are made per year using this low power, high speed and seemingly indestructible ferroelectric memories. Other ferroelectric memories using PZT are also at about the same level of production. Applications such as smart cards with mixed signal advanced circuitry and stand-alone devices are now entering 130 nanometers design rules. When combined with high k integrated ferroelectrics (eg. BST) for non-memory applications, ferroelectric thin-film devices have surpassed in the last 10 years the production level of over 1 billion devices. Other competitive devices such as Magnetic Tunneling Junction (MRAMs) and Phase change memory (PCMs), have also achieved some successes but not nearly as much as the FeRAM by the number of applications and devices sold in "real world" products. Now, the challenge is to move FeRAM to take a bigger piece of the over 230 Billion dollars per year semiconductor market. Although these successes for the FeRAM are certainly welcome, the industry needs to move towards System-on-Chip (SOS) requiring memory arrays to be integrated in 65 and 45 nanometers photolithography. This automatically creates opportunities to innovative materials with low annealing temperatures (around 450 C) and low thermal budget, in order to match the complex device processes of the advanced silicon manufacturing of these technology nodes. Work in atomic layer Deposition and MOCVD for Aurivilius materials is still in progress to move FeRAMs into these design rules.

Roger C. Reed

The aeroengine business has been facing tremendous pressures to bring its products to market more quickly and at lower cost. Around the world, numerical modelling is seen as a beneficial activity, which can help in this regard. But what are its advantages and limitations? Where does the usefulness end and the hype begin? In this seminar, the presenter will discuss his experiences with the use of numerical modeling for the design of superalloys and components fabricated from them. Modeling is possible at different lengthscales: (i) at the component lengthscale, e.g. for the simulation of the casting of single crystal components or for the welding of compressor and combustor sections (ii) at the microstructural scale, to elucidate the damage mechanisms occurring on the scale of the gamma prime precipitates and the dislocations and (iii) at the electronic scale, where the bonding controls factors such as rates of diffusion and the cohesive energy. Some case studies will be presented and then some overall conclusions will be drawn.

Mark Aindow

Ni-based superalloys exhibit an attractive combination of mechanical properties and corrosion/oxidation resistance at high temperature, leading to their use in a variety of gas turbine engine components including blades and discs. Grain size plays an important role in controlling the mechanical properties, including; tensile strength, low cycle fatigue life and creep resistance. In many cases, a fine uniform grain size can only be achieved in turbine components by using powder metallurgy (P-M) processing. Grain growth during consolidation and subsequent thermo-mechanical processing is inhibited by dispersions of second-phase particles, such γ’ phase and inert carbides and borides, but the details of these effects are not well understood. In our work we have performed experimental studies of grain growth in P-M superalloys and correlated these with electron microscopy observations of grain-boundary/particle interactions. It has been found that samples processed above and below the γ’ solvus exhibit normal grain growth up to a limiting grain size dictated by the distributions of the γ’ phase and the inert precipitates, respectively. For samples processed close to the γ’ solvus, however, abnormal grain growth occurs leading to a markedly higher and rather inhomogeneous grain size. The origins and significance of these phenomena will be discussed.

Olivier Chauvet

In this paper, we present and we discuss the electrical and thermal transport properties of SWNT based nanocomposites with a polymethylmetacrylate (PMMA) matrix. The composites films have been prepared by solution mixing with a SWNT content f between 0 and 8% in volume. The analysis of the electrical transport at low temperature and under strong magnetic field allows to be more precise about the transport mechanism. Electrical transport is due to hopping of localized carriers with a contribution of the mesoscopic Coulomb charging energy. The localization of the carriers is related to the presence of bundles in the nanocomposite.

Ricardo Lobo

Mutiferroic materials are compounds that show at least two coexisting ferroic orders (ferroelectric, ferromagnetic, ferroelastic). A particular interest is present in those materials showing concomitant ferromagnetism and ferroelectricity, which are unfortunately present in only a very small number of compounds. In practice, a large interest is given to systems showing ferroelectricity coexisting with any type of magnetic order. Renormalization of the phonon structure is a well established consequence of ferroelectric transitions and probes looking at the phonon spectra are invaluable tools to understand these transitions. In this talk, we will discuss the zero field infrared spectra of multiferroic materials TbMnO3 and BiFeO3 as well as classical ferroelectrics. The behavior of soft modes in these materials will be discussed. Correlations between the magnetic transition and the phonon spectra can help to better understand the coupling between the magnetic and electrical order parameters.

Gustavo A Rivas

Electrochemical (bio)sensors have received considerable attention in the last years because they represent an interesting alternative for the fast, sensitive and selective quantification of different analytes. In this presentation new strategies for the design and characterization of electrochemical (bio)sensors will be discussed. Electrochemical glucose biosensors based on: a)The entrapment of glucose oxidase within metallic nets or within composites containing metallic micro/nanoparticles; b)The use of electrogenerated permselective polymeric membranes; and c) The construction of supramolecular architectures by self-assembling of polyelectrolytes, will be presented. The advantages of using (bio)sensors based on carbon nanotubes (CNT), either dispersed in mineral oil (carbon nanotubes paste electrode) or in polymeric matrices (CNT-modified glassy carbon electrodes), for the highly sensitive and selective quantification of glucose, aminoacids, albumin, uric acid, neurotransmitters, DNA, herbicides, phenols and catechols, will be also discussed. The new alternatives demonstrated to be highly useful for the rational design of (bio)sensors for the quantification of several compounds of clinical, pharmacological and environment interest and open the doors to new developments based on the use of different biorecognition layers and transduction schemes.

Ernesto Chaves Pereira de Souza

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Wayne Z.Y. Wang

This presentation reports the recent progress on the development of zwitterionic NLO chromophores for applications in electro-optic devices. A new series of NLO chromophores are derived from TCNQ and its analogs with picolinium salts and show the unprecedented values of the figure of merit. We have also demonstrated a new practical approach toward processable NLO materials with large e-o coefficients (e.g., r33 = 65-110 pm/V at 1550 nm) and excellent temporal stability (85 °C in air over 1200 hours) by using a crosslinkable, hyperbranched PQDM-based oligomer as a macromolecular guest and a commercially available polymer as a host.

Kurt Strecker

Silicon nitride (Si3N4) and Silicon carbide (SiC) ceramics are both covalently bonded materials and therefore do not readily sinter. Highly dense materials can only be obtained by the use of additives which promote sintering. Furthermore, relatively high temperatures in excess of 1800oC and protecting atmospheres have to be employed in the sintering process. Properties, processing methods and applications of these ceramic materials will be discussed. Silicon nitride ceramics were developed in the 1970s and '80s in a search for fully dense, high strength and high toughness materials with the objective to replace metals with ceramics in advanced turbine and reciprocating engines to give higher operating temperatures and efficiencies. Although the ultimate goal of a ceramic engine has never been achieved, silicon nitride has been used in a number of industrial applications, such as engine components, bearings and cutting tools. Silicon carbide, first sinthetisized by Acheson in 1884, is widely used as abrasive material due to its elevated hardness and as refractory in high temperature applications. It is also used in the fabrication of parts where high corrosion resistance and/or thermal conductivity is required, such as mechanical seal, heat exchanger and thermocouple protection tube.

Mark Thompson

There has been a great deal of interest in developing new materials for the fabrication of light emitting diodes (OLEDs). We have prepared a range of intensely luminescent Ir(III) and Pt(III) complexes, which have found application in both monochromatic and white OLEDs. The role of the Ir and Pt in these complexes is to achieve efficient emission from the triplet excitons formed in the electroluminescence process. In my talk I will briefly discuss device architectural and materials choices that are made to improve efficiencies to their limits. Using this approach we have achieved internal efficiencies of nearly 100%. The key issue here is the interplay between the ligand based and MLCT excited states. The former is largely involved in tuning the emission colour, while the later is critical for achieving efficient phosphorescent emission at room temperature. Through careful design of ligands and metal complexes, we have achieved efficient electroluminescence, ranging form the near-UV into the near-IR. We have also investigated the use of heavy metal complexes in organic solar cells. These complexes can have high molar absorptivities, carrier conductivities and exciton diffusion lengths, all important parameters in designing high efficiency solar cells. These solar cells have structures reminiscent of those used in organic LEDs, however, the materials choices are markedly different. I will discuss the differences in device structure and briefly review the state of the art in efficiency. I will give the most recent results we have obtained with heavy metal complexes as donor materials in organic solar cells.

Alexandre G Brolo

The surface plasmons (SP) from gold nanoparticles and from nanostructured Au surfaces can be directly excited using visible radiation [1]. The surface plasmon resonance (SPR) depends on the dielectric properties at the metallic surface. This property is readily explored for the determination of surface binding events in biomedical research [2]. We have developed a biosensor based on SPR technology using arrays of sub-wavelength holes (nanoholes) in a gold film [3,4]. This integrated device was used for an affinity test involving the biotin – streptavidin system. Among the main advantages of arrays of nanoholes in microfluidic applications is the collinear optical geometry, which greatly simplifies the alignment and allows easier miniaturization compared to the traditional reflection arrangement used in SPR sensing. The surface plasmon excitation also leads to the localization of electromagnetic field at specific sub-wavelength regions within the nanostructures [1]. When compared to the “free molecule”, the spectroscopic response from species adsorbed on these “hot spots” shows an extraordinary enhancement. This phenomenon is the main mechanism behind surface-enhanced Raman scattering (SERS). Our group and collaborators have been working on a variety of novel nanostructures that support SERS and other surface-enhanced processes. These include immobilized nanoparticles in glass and metallic surfaces [5], arrays of nanoholes of various shapes [6,7] and scratched gold surfaces [8]. We will particularly discuss our recent investigations on parallel slits fabricated on a gold film. In this case, the spectroscopic response was found to depend on the orientation of the electric field polarization relative to the slit direction. The slits were milled on 100 nm gold films deposited on glass using focussed ion beam (FIB). Nanostructures with different slit width were fabricated and characterized by white light transmission. The transmission spectra at two different linear polarizations (electric field parallel and perpendicular to the major axis of the slits) presented distinct surface plasmon resonance. The nanostructures were coated with monolayers and films of oxazine 720 for SERS and surface-enhanced fluorescence (SEFS) measurements, respectively. In all experiments, a 633 nm laser excitation was used. SERS and SEFS experiments were realized using both polarization arrangements and the ratio between the surface-enhanced responses were analyzed. A preferential enhancement was observed for excitation polarized perpendicular to the slits. These results indicate that polarized surface-enhanced spectroscopy can potentially be used in applications in analytical chemistry.

Rodrigo B. Capaz

We study the mechanical and electromechanical properties of carbon nanotubes and graphene using first-principles and empirical methods. An analysis of the bonding and antibonding characters of electronic states in these materials provides a unified view on a variety of phenomena such as the band gap dependence with hydrostatic pressure and temperature and the mechanical response upon charge injection. We also use classical molecular dynamics simulations to investigate the mechanical behavior of such systems under external perturbations.

Antônio José Roque da Silva

Due to environmental and safety issues, the research in the area of sensors has attracted a great deal of attention. Carbon based materials, such as nanotubes or graphene ribbons may be useful materials to be employed as nanosensors. In many situations these structures are functionalized with dopants in order to increase their interaction with the molecules to be detected. Real sensors are complicated devices, and if we focus on either on a single tube or a single graphene ribbon functionalized with defects, these defects are usually randomly displaced along the one dimensional structure. We will discuss a methodology to investigate the transport properties of such a device, with lengths of the order of 0.1 micron. As an example, we will focus on nitrogen doped nanotubes, and their behavior as ammonia sensors. CNx nanotubes can display a measurable variation in resistance upon exposure to ammonia. We present a microscopic model for the origin of these variations. We studied, using Total Energy DFT calculations, a (5,5) CNT containing pyridine-like N atoms replacing C atoms, and how the NH3 molecule binds to these sites. We also investigate how these defects affect the charge transport properties using a Non-Equilibrium Greens Function formalism. We initially studied a defect composed by a vacancy surrounded by 3 pyridine-like rings. The most stable adsorption configuration for the ammonia molecule adsorbed close to this defect is dissociative, with an amino group (NH2) fragment bound to one of the nitrogens and a H atom bound to another. This configuration leads to an increase in the conductance and cannot, therefore, explain the increase of resistance that has been experimentally observed. We then investigate a variety of other configurations in order to propose possible causes for the resistance increase. We find that a divacancy surrounded by 4 pyridine-like defects is the most stable N-defect, instead of the previously proposed one. The ammonia also dissociates into NH2 and H. Moreover, the calculated change in conductance after the NH3 dissociation has the correct trend when compared to the experimental results. Finally, we will present results for tubes with many defects randomly displaced and we will investigate how the conductance changes with the ammonia coverage.

Pablo Ordejón

I will describe the TranSIESTA method[1], developed five years ago to describe the electronic transport properties of nanoscale devices out of equilibrium. The method is based on a Non-Equilibrium Green’s Function formulation of the transport problem, together with a Density Functional Theory description of the electronic potential. I will briefly discuss the basic features of the method, and also its limitations and shortcomings, and then I will mainly present examples of different applications in the context of metallic nanowires, molecular bridges, and solid state ferroelectric tunneling junctions.

F. Ruette

Parametric quantum methods (PQMs, semiempirical) applied to materials and surfaces have shown a great potentiality for specific fields of chemistry and physics of materials. Several areas of nano particle research have been undertaken with those methods, emphasizing in: mechanisms of surface reactions, stability of intermediates, vacancy diffusion, fuel cells, location of defects, formation of monolayers, coverage effects, elastic constants, density of states, electronic transfer, relative adsorption energies, particle migration, magnetic properties, band gap, nanoparticle interaction with support surfaces, location of dopants, cohesive energy, energy-level spectrum, and interaction between adsorbates. Theoretical foundations are given in a general way with the intention to show that elementary parametric functional (EPF) spaces are fundamental to represent basic interactions between the atomic components in a molecule. The importance of parameterization techniques to optimize parameters is also emphasized. The employment of PQMs in modeling nanoparticles is pertinent because can provide, in a rapid way (103-104 faster than DFT and HF), qualitative worthy results that may be very useful in the resolution and understanding of technological problems.

S. Sanvito

Electronic transport is rapidly becoming the key physical phenomenon for a multitude of applications. It is the at the foundation of the microelectronics and data-storage industries and it now occupies a common place in sensors and nano-detectors technology. Importantly, the continuous miniaturization of transport devices (transistors, interconnects etc.), is now reaching the limit where classical Ohm's laws do not apply and a fully quantum mechanical picture needs to be used. Theory can play an important role in this arena, since first principles methods allow us to make quantitative predictions without using any adjustable parameter. In this talk I will present recent results obtained with our code transport Smeagol, which combines state-of-the-art non-equilibrium transport methods with accurate density functional theory [1,2] (www.smeagol.tcd.ie). In particular I will present examples involving systems with a large number of degrees of freedom, a challenge that can be tackled only by a highly sophisticated code. First I will address the long-standing question around the conductive state of DNA. This is a rather elusive question and metallic, semiconducting and even superconductive properties have been measured. Here we investigate the transport through a polymeric poly-G/poly-C DNA strands sandwiched between gold electrodes and attached via thiol end groups. Our results demonstrate, in contrast to what commonly believed, that the Guanine-derived HOMO state is not responsible for the transport, which instead is dominated by molecular orbital with considerable amplitude over the sugar backbone. Then, I will turn my attention to magnetic molecules. Here the question is whether or not an electrical measurement alone can allow one to read the magnetic state of the molecule itself. I will show results for Mn12 sandwiched between magnetic and non-magnetic electrodes and demonstrate the influence of the magnetic spin-state on the transport properties of the device.

Pascoal José Giglio Pagliuso

Recent studies in the family of heavy fermions superconductors CeMIn5 (M=Rh, Ir and Co) have revealed very rich phases as a function of doping and hydrostatic pressure. For instance, alloying studies in Ce(Rh,Ir,Co)In5 reveal superconductivity(SC) (Tc  2.3 K) over a wide range of compositions, which coexists with a magnetically ordered state with TN  4 K for CeRh1-x(Co, Ir)xIn5 (0.30  x  0.6). Furthermore, various experiments suggest that the unconventional superconductivity in these compounds develops out of a non-Fermi-Liquid normal state in the vicinity of a T = 0 antiferromagnetic transition where quantum critical fluctuations control the physical properties, and there are many similarities to the phase diagram of the cuprates. To what extent the properties of these materials may represent a new route for searching for new intermetallic superconductors with higher-c will be discuss.

Auro Atsushi Tanaka

Transition metal macrocycles as metallophthalocyanines and metalloporpyrins have been widely exploited in industry and academia for a variety of applications, ranging from conventional dye stuffs to coatings for read/write CD-ROM's and as an anti-cancer agent. In addition, based on their redox tuning by the choice of metal ion in the macrocycle cavity and peripheral substituents on the ring, such compounds have been also extensively used for modification of electrode surfaces and subsequent applications in the fields of sensors and catalysis. In this section, the investigations involving carbon and graphite electrodes modified with metallophthalocyanines and/or metalloporphyrins either adsorbed on, simply dispersed as small microcrystals or anchored to polymer matrices, will be highlighted as electrochemical sensors for biological, clinical and environmental compounds.

Victor Teixeira

Dry reforming of methane with CO2 to produce synthesis gas (CO + H2) has received considerable attention in recent years as it constitutes a very attractive route for the conversion of two low-cost products which can be used for the production of liquid hydrocarbons in the Fischer–Tropsch reaction or in the production of methanol. One advantage of CO2/CH4 reforming is the low H2:CO ratio in syngas formation; the process opens the possibility of combining steam reforming, partial oxidation, and dry reforming for the generation of a syngas with a desired H2:CO ratio. The initial composition of the solution containing lanthanum nitrate and nickel nitrate and glycine was based on the total oxidizing and reducing valences of the oxidizer and fuel using concepts in propellant chemistry and the proportion of each reagent was defined according to its respective molar amounts. La-Ni oxides supported on alpha alumina were successfully prepared by microwave assisted combustion reaction method, using urea and glycine as fuel and tested as catalysts precursors in the dry reforming of methane with CO2 to syngas between 500 and 800oC. The samples were characterized by X-ray diffraction (XRD), BET specific surface area, temperature programmed reduction and oxidation (TPR-TPO), and scanning electron microscopy (SEM). The results obtained by XRD, confirmed the crystallization of the Ni2La3O6,92, La2NiO4 and LaNiO3 oxide structures. The catalysts were tested in reduced form. High CH4 and CO2 conversion were obtained. Dry reforming of methane with CO2 to produce synthesis gas (CO + H2) has received considerable

Fabio Bellot Noronha

Não Informado

Heinz von Seggern

For an overall success of Organic Electronics the simple technological realization of organic devices is important. For the realization of an organic CMOS inverter as one of the basic elements for low-energy-consuming devices the availability of p- and n-type field-effect transistors is essential. In this presentation a novel technique will be presented that allows for the realization of such transistors by interface modification of the gate insulator dielectric by means of chemical or UV treatment. It will be shown that in case of a SiO2 dielectric electron traps can be eliminated at the gate insulator surface by means of deposition of traces of calcium. A normally p-type pentacene transistor, built on top of is dielectric, is converted to an n-type transistor. The opposite is possible for a PMMA dielectric, which normally supports n-type conduction in a pentacene OFET. In this case an UV irradiation in humid air generates electron traps at the gate insulator surface, which completely suppress any n-conduction and promote only p-conduction. In the talk the underlying physics will be highlighted and possible implications for device fabrication will be discussed.

Roberto Luiz Moreira

Multiferroics are material that posses two independent ferroic order parameters that can interact. These systems are attracting the attention of the scientific community, owing to technological potentialities of using mixed effects such as magnetoelectricity, magnetoelasticity, flexoelectricity and other higher order effects.[1,2] This recent interest and the efforts of theoreticians and experimentalists have increased the understanding of the underlying physical phenomena, leading to the development of new materials, where multiferroic effects can be predicted or enhanced. Deep investigations about the physical properties of multiferroic materials require knowledge and facilities from different areas, like phase transitions, magnetism, elasticity and ferroelectricity, and, therefore, a strong cooperation between scientists from different backgrounds. A particular interest is being paid to magnetoelectric (ME) materials, because of the potential of applications in low-consumption devices for data storage and in a new four-bit architecture for spintronics (four states logics replacing the binary one).[3] However, ME multiferroics are quite rare, because of the antagonism concerning their symmetries and electronic structure (ferromagnetic oxides require partially filled 3d shells, being usually electronic conductors – ferroelectrics need empty 3d shells, being isolants or highgap semiconductors). Moreover, these materials are hardly obtained.[4] For instance, the ferroelectric/antiferromagnet BiFeO3, one of the most promising and investigated ME multiferroic nowadays, is available only in the form of thin films, ceramics or small crystals with dimensions smaller than 1 mm. In this talk we will focus on the physics of ME multiferroic systems. A particular attention will be paid on the spiral cicloidal materials and to the role of magnetic incommensurabity in the appearing of a new ferroelectric order.[5,6] In particular, our recent results on BiFeO3 and MnWO4 will be presented.