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DAYS 1,2
Sunday, Monday, September 28, 29, 2008


Brazilian-MRS president Prof. Fernando Lázaro Freire Jr. with conference chairs Prof. Aldo Craievich, Prof. Reginaldo Muccillo and Prof. Osvaldo Novais de Oliveira Jr. at the opening of the conference.

The 7th Brazilian MRS Meeting (VII Encontro SBPMat) 2008 got off to an excellent start on Sunday, September 28, in Guarujá, São Paulo, Brazil. Guarujá is located on the Atlantic coast about 70 km from the City of São Paulo, and is a popular tourist attraction primarily for the beaches. The conference venue, the Casa Grande Hotel Resort, is located on a quiet part of Enseada Beach, one of the well known beaches there.


The conference started on Sunday with a special opening ceremony. The president of the Brazilian-MRS Prof. Fernando Lázaro Freire Jr. first welcomed everyone to the meeting. He mentioned that this is the seventh in the series of annual conferences and the conference has increased in size each year. The first conference had 300 participants while the present meeting had around 1500 abstracts submitted with an expected attendance of well over 1000. Next, meeting chairs Prof. Aldo Craievich and Prof. Osvaldo Novais de Oliveira Jr. in turn welcomed all participants to Guarujá and São Paulo. This was followed by a wonderful presentation by the University of São Paulo choral group led by Marcia Hentschel including seven different pieces. A reception was held after the opening ceremony.



Energetics of Nanomaterials

The first event of the conference was a plenary lecture on Monday morning by Prof. Alexandra Navrotsky (Univ. California, Davis, USA) on the energetics of nanomaterials. Nanotechnology is of course an important area of research in materials science today. Navrotsky described calorimetric studies of oxide nanoparticles which have established systematic trends in energetics at the nanoscale. Typically, idealized nanoparticles are considered for investigations. However, real nanoparticles do not have ideal characteristics, with a distribution of sizes, irregular varying shapes, defects, imperfectly controlled surfaces etc. With this in consideration, Navrotsky described the competition among polymorphism, surface energies and hydration. This has been shown to lead to a crossover in phase stability at the nanoscale. She described results for α-alumina and γ-alumina. She also discussed water adsorption results on iron oxides. Metastable polymorphs were found to have lower surface energy. Oxyhydroxides have a lower surface energy than oxides, and hydrated surfaces have lower surface energy than dry surfaces. Ultimately, surface energy depends on morphology. She also described the effects of morphology for ZnO. Nanoneedles were shown to have the highest surface energy, nanorods intermediate, and nanoparticles the smallest. Finally, she described thermodynamic effects in titania nanoparticles again by considering water adsorption on their surfaces.


Rational Design of LBL-Based Materials: Toward Soft Matter Devices

In the second plenary session, Gero Decher, from the Institute Charles Sadron and Université Louis Pasteur, Strasbourg, France, described layer-by-layer (LbL) farication processes for nanoassembley of soft matter devices. In his preliminary remarks, Decher said that the trend towards soft materials is a natural consequence of the ubiquitousness of carbon and the ease of synthesis, in contrast to inorganics. In addition, he compared the shortcomings of the “bottom up” and “top down” approaches in materials science, where there is currently a size gap for functional devices, to natural processes, which can seemingly make functional structures at any length scale. Furthermore, Decher maintained that, while one-step self-organization has been a dream of scientists for decades, this is not possible for lasagna, French pastry, or for functional nanostructures; step-by-step fabrication, such as LbL, is required. Citing several examples where surfaces are very important – hip-joint replacements, corneal implants, reflective coatings, and corrosion prevention, to name a few, Decher said that LbL is the ultimate nanofabrication tool developed so far.

His research group has recently added nanobags and micropouches to their nanostructural repertoire of layers, tubes and spheres. In a typical LbL process, a substrate is coated with a polyanion, washed, coated with a polycation, and washed again. This process can then be repeated innumerable times, making automation easily feasible. Reseachers in Decher’s group coated substrates by dipping them into solutions but more recently coating by spraying has proven to be quicker, with uniformly reproducible results. Citing published literature from other research groups, Decher said that other types of interactions between layers, such as covalent or van der Waals, have been exploited in LbL fabrications. Characterization of the layers was shown to be easily performed with UV-Vis spectroscopy, for example, the absorption increases linearly with the number of layers, which, combined with the number of x-ray reflections as a function of scattering angle, obtains the coating thickness as a function of the number of layers.

Decher showed many applications for devices fabricated using the LbL method; one, close to the Frenchman’s heart, was wine classification by taste sensors. Other examples included light-emitting diodes, compartmentalized films, functionalization of nanoparticles, giant nanomembranes, and films with inorganic barrier layers. Citing work previously published by another research group, Decher showed how a texture sensor with fidelity comparable to the human finger was fabricated with a modified LbL process. Descher said that the next generation of LbL materials will include drug-delivery devices, implantable materials, and living multilayers – artificial tissues that can be embedded with human cells.


The Consequence of Air Pollution and Possible Materials Science Solutions

Particulate matter pollution is already a serious issue around the globe. In his plenary talk in the evening, Agusti Sin (Pirelli Eco Technology, an off-shoot of Pirelli and Co., Italy) described various materials science solutions to this problems being pursued in his company. A lot of the work he presented was done at Pirelli labs. Specifically, he described the use of ceramics in various applications including environmental sensors, oxygen sensors, fuel cells, oxygen generation, and diesel particle filter. He devoted a significant part of his talk discussing diesel particle filters that will be produced by Pirelli Eco Technology, with plants in Italy and Romania. The total particulate matter, TPM, in diesel exhaust includes a solid fraction, a soluble organic fraction and sulfates. Particulate matter is a serious health hazard, particularly for the lungs, and there are strict European limits coming into effect by 2014 as to the extent of such particulate matter that can be released into the atmosphere. The Pirelli filter uses silicon carbide, because of its resistance to heat and temperature variations. It also uses a Pt catalyst on a supporting alumina layer which is present on a honeycomb structure. The system uses particulate ignition and catalytic regeneration. It can be retrofitted into existing diesel buses and trucks. It can be separately installed in passenger cars. Real life tests on buses showed reduction in particulate matter emission of upto 97% fulfilling the requirements for European emission standards. In fact, the exhaust downstream from the filter was found to be cleaner than ambient air.


Symposium L: High Resolution Electron Microscopy
The new paradigm in TEM - On the way to the ultimate limits of optics

Knut Urban (Research Center Julich, Germany) gave the first talk in symposium L on aberration-corrected transmission electron microscopy, which is leading to remarkable resolutions enabling materials researchers to peer deeply into materials right up to the atomic scale. He started by describing the basics of electron optics and the problems with aberration encountered in conventional systems. The original Scherzer's theory for phase contrast yields a large point spread function. A new theory for phase contrast was proposed a few years back that reduces the point spread allowing for very fine contrast. He showed the example of SrTiO3 wherein Sr, Ti and O atoms can be separated in the image. He then described the negative spherical aberration imaging (NCSI) technique and showed the example of the Σ3 {111} twin boundary in BaTiO3 wherein the atomic separation distances at the twin boundary can be determined, which different from those in the untwinned crystal. The vertical atomic separations at the twin boundary were determined to be 0.267 nm for Ti-Ti and 0.214 for Ba-Ba, which were confirmed to be very close to other experimental data. Finally, Urban described the current push towards picometer microscopy, edging towards the limits of electron optics. He described the data for the 90° tilt boundary in YBa2Cu3O7 and ferroelectric domain walls in PZT. He used the latter example to suggest that atomic scale structure can now be used to drive physical properties of the material by allowing for the understanding of even minute changes at the atomic scale.

(HR)TEM as a tool to characterize nanomaterials

High resolution TEM, along with various associated techniques, is ideal for nanotechnology, said Marcelo Orlandi (Universidade Estadual Paulista, Brazil). The main focus of this presentation was the characterization of tin oxide and tin-doped indium oxide (ITO) nanobelts grown from the vapor phase.The nanobelts with a rectangular cross-section were obtained by a reduction carbothermal method. The belts are single-crystalline and can grow in SnO or SnO2 phase depending on the synthesis conditions. The SnO2 belts were found to grow by an indirect vapor-solid process. The SnO nanobelts formed dendritic structures on the sides likely caused by a self-catalytic VLS process. The SnO nanobelts, being thermodynamically unstable, change to the SnO2 phase after a thermal treatment, resulting in a volume reduction and formation of cracks and cavities. Orlandi's ultimate motivation in presenting this work was to demonstrate the versatility of HRTEM in studying nanomaterials.


Symposium F: Electrochemistry of Nanostructured and Biological Macromolecules

On the interactions between metallic nanoparticles and biomolecules: Fundamental studies and applications in sensing
In a contributed talk, Valtencir Zucolotto presented results of fundamental studies on the interactions between nanoparticles and biomolecules but with the ultimate goal of curing or preventing diseases that are problems to his native Brazil, e.g., Leishmanuasis detection, which relies on microscopic examination of samples and is problematic due to frequent false positives with Chagas disease. Zucolotto showed that antigenic membrane proteins from protozoa could be identified and isolated, and then incorporated into nanostructured films fabricated using a layer-by-layer technique. The capacitance of these films shows a signature distinct from films lacking the membrane proteins. Zucolotto developed similar sensor systems for Pasteurelosis and hemophilia. In other work, Zucolotto complexed gold nanoparticles with dendrimers for dopamine and methionine sensing; complexed gold nanoparticles with enzymes for urea detection; showed that Ag and Au nanoparticles sometimes allow stem cells to grow faster than the control; and showed evidence that nanotubes are incorporated into cell membranes during formation.

MnO2 nanostructured electrode prepared by electrodeposition over a colloidal crystal template as cathode for lithium battery

In a contributed talk in Symposium F (Electrochemistry of nanostructured and biological materials), Tania M. Benedetti, from the University of Sao Paulo, Brazil, presented her research on MnO2 nanostructured electrodes. Working towards the goal of supercapacitors, which fill the void between regular capacitors and batteries, Benedetti noted that magnesium oxides offer high specific energy at low cost, and are environmentally advantageous but they display low stability after successive charge-discharge cycles. Decreasing the solid-state diffusion path would reduce mechanical stress during charging/discharging, and, in addition, improve capacitance because additional intercalation sites would be available for lithium intercalation. Benedetti and co-researchers fabricated a nanostructured electrode prepared by depositing polystyrene (PS) spheres from a colloidal suspension over gold previously deposited on quartz. MnO2 was then electrodeposited with the PS nanospheres, acting as a template, subsequently removed with THF. The electrode structure was characterized with SEM and showed significantly more surface area than a control, fabricated without the PS template. Electrochemical measurements were performed with a typical electrolyte and with an ionic liquid. The results are encouraging but Benedetti expects improved performance, especially after following suggestions made by attendee, and Plenary Lecturer, Gero Decher.

Systematic study of cathodic pre-treatment influence on surface properties and electrochemical behavior of boron doped diamond produced at different doping levels
In a contributed talk Matsushima et al. presented work on boron-doped diamond (BDD) films, which have been shown to be conductive and have application in energy-storage devices. In order to develop a method to rigorously control diamond growth patterns, required to produce electrodes with surface properties suitable to the application, the researchers performed a systematic study of deposition, characterization, and electrochemical sensitivity of BDD using four different doping levels. BDD samples were prepared with the hot filament chemical vapor deposition (CVD) technique, using the standard mixture of H2 and CH4. Diamond quality and morphology were characterized by Raman spectroscopy and x-ray diffraction, while the film surfaces were analyzed by contact angle measurements, cyclic voltammetry, and synchrotron X-ray photoelectron spectroscopy. The researchers found that the doping level influences the level of sp2 C-C bonding at the film’s grain boundary as well as the defect level in the diamond lattice.

Symposium G: Theoretical and Experimental Advanced in the Development of New Materials
A survey on the joint use of experimental and theoretical methods and techniques in materials science

Addressing a mostly Brazilian audience in Spanish, Professor Juan Andres, from Jaume I University, Spain, used slides in English to survey the computational methods currently used in materials science. Stating that an atomistic level of understanding is mandatory to discover new synthetic routes and to better comprehend solid state properties, Andres said that electronic structure theory has progressed from a descriptive tool to an analytic tool and is now routinely used in the interpretation of experimental results. Furthermore, in addition to the two established components of science – experiment and theory – computational simulation has emerged as a third component. With the observation of phenomena at an atomic scale just beginning to be realized, Andres envisages the role for computational simulation to include predictions of chemical stability, free energy, and chemical reactions, while structure property relationships will continue the traditional link between theory and experiment. Rather than be competitive disciplines, experiment, theory, and computation are complementary tools. Andres demonstrated his viewpoint with several case studies, including growth mechanisms of pure and mixed metal oxide nanostructures; structural and electronic properties of metal oxides; high-symmetry and low-symmetry forms of perovskite-based materials; transverse inversion polarization in ferroelectrics; defects in crystal structures; photoluminescence; the formation of microscopic facets; and the formation of Au zig-zag nanotubes.








  • The 7th Brazilian MRS meeting is being covered for the Meeting Scene by Dr. Gopal Rao (Materials Research Society, Warrendale, Pennsylvania, USA), and Dr. Steve Trohalaki (Air Force Research Lab, Wright Patterson AFB, Ohio, USA).
     Gopal Rao                    Steve Trohalaki
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