Author: Verónica Savignano

Featured paper: Accurate engineering in spin valves manufacturing.

Posted on Thursday 28 de August de 2014

The scientific paper by members of the Brazilian community on Materials research featured this month is:

T. E. P. Bueno, D. E. Parreiras, G. F. M. Gomes, S. Michea, R. L. Rodríguez-Suárez, M. S. Araújo Filho, W. A. A. Macedo, K. Krambrock and R. Paniago.Noncollinear ferromagnetic easy axes in Py/Ru/FeCo/IrMn spin valves induced by oblique deposition. Appl. Phys. Lett. 104, 242404 (2014). DOI: 10.1063/1.4883886.

Accurate engineering in spin valves manufacturing

The production and characterization of spin valves is the theme of  a collaborative work between Brazil and Chile, whose results were published recently in the prestigious journal Applied Physics Letters (APL).

Spin valves are devices consisting of three or more layers of nanometric thickness composing a sandwich of magnetic and non-magnetic materials. Sensors consisting of such structures fulfill a fundamental role in reading the information written on the hard disc drives, among other applications.

The operation of spin valves is based on an effect called “giant magnetoresistance”, which was the reason behind the Nobel Prize in Physics in 2007. The giant magnetoresistance of spin valve consists of a large change in the electrical resistance in response to the action of a magnetic field. This resistance depends on the relative orientation among the magnetization of the magnetic material layers.

The magnetization of a magnetic material is determined by the orientation of the spins of its electrons. Electrons have two intrinsic features: electric charge and magnetic moment, the latter known as spin. Explore the degree of freedom of the electron spin in addition to its charge led to the emergence of a new field of research called spintronics.

Then, on giant magnetoresistance of spin valves, when the layers of magnetic material have the same direction of magnetization, the device reduces its electrical resistance and becomes a better conductor of electricity. When the magnetic layers acquire opposite directions of magnetization, a significant increase of electrical resistance occurs.

For better understand this effect and, later, the results presented in the article of APL, it is important to remember that the magnetization is a vector physical quantity and that, therefore, besides having an intensity, it has a direction (parallel, perpendicular) and an orientation (indicated by the arrowhead representing the vector). Usually, metallic multilayers composed of magnetic materials separated by a non-magnetic layer, as spin valves, have the magnetization of ferromagnetic layers coupled, says Thiago Bueno, first author of the APL article and PhD student in Physics at the Brazilian Federal University of Minas Gerais (UFMG), supervised by professor Roberto Magalhães Padilla. This coupling can result in parallel magnetization (called “collinear”) with same or opposite orientations, and also in non-collinear magnetization.

Ferromagnetic layers “making a sandwich” with a non-magnetic layer of ruthenium. The red and green arrows represent the direction and the way of magnetization of layers composed by Py and FeCo, respectively. (a) Parallel magnetizations with equal orientation; (b) Parallel magnetizations with opposite orientation; (c) Perpendicular magnetizations.

However, to magnetize the magnetic layers of the spin valve does not occur homogeneously in all directions; they feature the so-called magnetic anisotropy. “The magnetic anisotropy is an important magnetic property, because it establishes an easy direction of magnetization,” says Thiago Bueno. “This property is determined by a number of factors, including the types of materials, the thickness of layers, and the details of the method of sample manufacturing”.

On the work that originated the APL article, the team of scientists has made some adjustments to the method of spin valves manufacturing, obtaining interesting results on the properties of these devices.

Controlling the direction of magnetization

“This work was only possible due to the great collaboration between the parties along the preparation of samples of excellent quality, accurate experimental measures, interpretation of the data, until the publication of the results,” says Thiago Bueno.

Initially, at the Brazilian Center for Development of Nuclear Technology (CDTN in Portuguese) the team has made thin films composed of multi-layers with thickness of a few tens of nanometers. The films were obtained through the technique known as magnetron sputtering, in which argon ions are accelerated against the targets that contain the materials to be deposited, ripping off its atoms. With the aid of magnetrons, these atoms are deposited on a substrate, forming the layers of films. “Through this technique it is possible to obtain films with well-determined chemical composition, thickness and structural morphology,” says Thiago Bueno.

Oblique deposition scheme with 5 sputtering sources (magnetrons) producing an angle of 72 between them. The (β) angle between the direction of deposition and normal direction of the film is estimated at 38° for all sources.

In this study, the scientists set up an oblique deposition scheme by putting the magnetrons making an angle of 72o between them and inclined towards the sample. Using the oblique deposition scheme, scientists made spin valves with ferromagnetic layers up to 10nm-thickness, composed of metallic alloys (Py and FeCo), and separated by a non-magnetic layer of ruthenium (Ru) of thickness between 1nm and 3.5nm. The devices were characterized in the Physics Department at UFMG using ferromagnetic resonance (FMR), an extremely sensitive technique that provides relevant information on the magnetization of materials.

After the interpretation of experimental results, which involved researchers from the Pontifical Catholic University of Chile, the scientists concluded that the oblique deposition induced non-parallel magnetization directions (non-collinear) on ferromagnetic layers of manufactured spin valves.  “The angle between the easy axes, approximately equal to the angle between the magnetrons, was determined by the manufacturing geometry”, reinforces the author, Bueno. “One of the main contributions of our work is the demonstration that it is possible to manufacture spin valves where the axes of easy magnetization of ferromagnetic layers (Py and FeCo) are non-collinear,” he sums up.

According to the doctoral student, at the beginning of the work the authors already knew the oblique deposition effects in ferromagnetic/anti-ferromagnetic bilayers. With this study, the team took a step further and has investigated these effects in a more complex structure, the spin valve.

“We believe that our work will compel other researchers into manufacturing these devices, seeking new magnetic configurations between layers of the spin valve “, says Bueno.

Interviews with plenary lecturers of the XIII SBPMat Meeting: Luís Carlos (Universidade de Aveiro, Portugal).

Posted on Thursday 28 de August de 2014
Prof. Luís Carlos.

“Luminescence applied to nanomedicine” is the subject of one of the plenary lectures that the Materials research community is going to enjoy in our XIII SBPMat Meeting (João Pessoa, Brazil, September 28th to October the 2nd). The speaker will be the Portuguese physicist Luís António Ferreira Martins Dias Carlos, full professor at the University of Aveiro (Portugal), who got his Ph.D. in physics from the University of Évora (Portugal) in 1995 working on photoluminescence of polymer electrolytes incorporating lanthanide salts.

At the University of Aveiro, Luís Carlos created in 2000 a research group in functional organic-inorganic hybrids. The group has established an international network devoted to these luminescent hybrid materials with more than 30 research groups in Europe, China, Japan, Singapore, Brazil and Australia. Also at Aveiro, Luís Carlos has been, since 2009, the vice-director of the Centre for Research in Ceramics and Composite Materials (CICECO), one of the largest European institutes in the Materials and Nano fields.

He is member of the Lisbon Academy of Sciences (Physics section) since 2011. He was visiting professor of São Paulo State University (UNESP), Brazil, in 1999, 2012 and 2013, and of University of Montpellier 2, France, in 2008. He awarded a ‘Pesquisador Visitante Especial’ grant by the CNPq, Science Without Borders Program, Brazil in 2013.

He has co-authored more than 345 papers in international journals, 8 invited reviews, 5 book chapters, and 2 international patents. He has more than 8.050 citations, having h-index of 47. He has given 40 plenary and invited lectures at conferences. He is associate editor of the Journal of Luminescence.

Read our interview with the plenary speaker.

SBPMat newsletter: – Are there nanomedical applications to luminescent materials already on the market/spread in society? Please, give some high-impact examples. 

Luís Carlos: – Undoubtedly yes, there are luminescent materials with important applications in nanomedicine already on the market. I can highlight two examples:

1. Organic complexes based on lanthanide ions (as, for example, cryptates and β-diketonates) are sold as contrast agents for magnetic resonance imaging  (essentially using Gd³+) and luminescent markers (using Eu3+, Sm3+ and Tb3+) for fluoroimmunoassays. The fluoroimmunoassay is an immunological method for clinical diagnosis that is particularly relevant in prenatal and neonatal screening tests, as well as to detect proteins, viruses, antibodies, tumor biomarkers and medicine residues. In this respect, it is worth mentioning the work conducted by several researchers from the INCT INAMI (Brazilian National Institute of Science and Technology on Nanotechnology for Integrated Markers), implementing a prototype in the hospital environment in order to develop methods to diagnose the American cutaneous leishmaniasis, prostate cancer (PSA) and low density lipoprotein (LDL) by fluoroimmunoassay, using recombinant antigens marked with lanthanide ions complexes (for example, Eu3+, Tb3+ and Nd3+). The international market for contrast agents and luminescent markers based on lanthanide ions is valued in many hundreds of millions of US dollars.

2. Luminescent nanoparticles (“quantum dots”, QDs, and nanocrystals incorporating lanthanide ions) have played a major role in the last years thanks to very important applications for diagnosis by optical imaging and therapy techniques. Recent estimates value the international market for luminescent nanoparticles in the medical field in over 20 million US dollars. A notable example in the treatment of tumors is the local hyperthermia. Local hyperthermia, also referred as local thermotherapy, is a type of treatment in which biological tissues (typically cancer cells)  are exposed to temperatures above 45° C, irreversibly damaging them and causing their death (the collateral damage to the healthy tissues surrounding the tumor is usually minimal). Numerous clinical trials with hyperthermia are being currently performed around the world so we can better comprehend and improve the technique. For example, the use of luminescent or magneto-luminescent particles (with magnetic ions such as Iron or Cobalt), vectored to bind to specific points in the cancer cells, enabling the local heating by the absorption of electromagnetic radiation and magnetic induction, respectively, is a new type of local hyperthermia. Precise temperature control in the irradiated area, limiting the effects of high temperature on the rest of the body, still is one of the key challenges for the popularization of the technique.

SBPMat newsletter: –  Could you briefly describe the main challenges in the field of luminescence applied to nanomedicine?

Luís Carlos: – I can point out two examples: improving the imaging techniques for diagnosis and developing luminescent micro/nanothermometers which allow mapping the intracellular temperatures with a resolution of the order of tenths of a degree.

In regard to imaging applications in nanomedicine, emitting centers in the near-infrared region (for example, lanthanide ions such as Nd3+ and Yb3+, QDs and organic dyes) have great advantages over those in the visible region.  For instance, biological tissues present less autofluorescence in the near-infrared window, which enables a better signal-to-noise discrimination and improves the sensibility to detection. Also, in comparison to the ones in the visible region, near-infrared photons interact less with biological tissues, which reduces the risk of disturbance or damage in the observed biological system. Thus, there is no doubt that the synthesis of new luminescent nanoparticles, emitting efficiently in near-infrared (in some cases producing persistent luminescence, i.e., light emissions that last for minutes, hours or even days, after the excitation is over), will lead us to a revolution in fluorescence microscopy, with the development of in vitro and in vivo imaging techniques in near-infrared (whose radiation penetrates deeper into the biological tissue, when compared to visible light).

The development of luminescent micro/nanothermometers to map the intracellular temperature, particularly in cancer cells, will surely improve our current perception on their pathology and physiology, optimizing early diagnosis and therapeutic processes (as seen above in the case of local hyperthermia).  These non-invasive thermometers are a critical tool for better understanding a set of cellular processes followed by alterations in temperature, such as cell division, gene expression, or changes in the metabolic activity. Finally, the development of luminescent nanothermometers in the near-infrared region,  which are capable of sensing heat and penetrate deeper into the biological tissue, will pave the way for in vivo thermal sensing and imaging (in small animals, in a first stage).

SBPMat newsletter: – Under your viewpoint, which are the main contributions you made to the field of Materials Science and Engineering during your scientific career? Could you please include a selection of 3 or 4 of the most important publications among your work in your answer?

Luís Carlos: – Normally, our latest works tend to seem to be the most important… Regardless, I understand that my main contributions to Materials Science and Engineering are related to the development of i) luminescent organic-inorganic hybrid materials, ii) ratiometric nanothermometers based on the characteristic emission of lanthanide ion pairs (Eu3+/Tb3+ and Er3+/Yb3+) and iii) nanoplatforms combining nanoheaters (metal particles of Gold or Silver) and nanothermometers which allow to increase the local temperature by laser irradiation while simultaneously mapping such temperature increase with precision. The following four papers illustrate these contributions:

Full Colour Phosphors From Eu(III)-Based Organosilicates. L. D. Carlos, Y. Messaddeq, H. F. Brito, R. A. Sá Ferreira, V. de Zea Bermudez, S. J. L. Ribeiro, Adv. Mater. 12, 594–598 (2000)

Nanoscopic Photoluminescence Memory as a Fingerprint of Complexity in Self-Assembled Alkylene/Siloxane Hybrids. L. D. Carlos, V. de Zea Bermudez, V. S. Amaral, S. C. Nunes, N. J. O. Silva, R. A. Sá Ferreira, J. Rocha, C. V. Santilli, D. Ostrovskii, Adv. Mater. 19 341–348 (2007)

A Luminescent Molecular Thermometer for Long-Term Absolute Temperature Measurements at the Nanoscale. C. D. S. Brites, P. P. Lima, N. J. O. Silva, A. Millán, V. S. Amaral, F. Palacio, L. D. Carlos, Adv. Mater. 22, 4499–4504 (2010)

All-In-One Optical Heater-Thermometer Nanoplatform Operative From 300 to 2000 K Based on Er3+ Emission and Blackbody Radiation. M. L. Debasu, D. Ananias, I. Pastoriza-Santos, L. M. Liz-Marzan, J. Rocha, L. D. Carlos, Adv. Mater. 25, 4868–4874 (2013)

Interviews with plenary lecturers of the XIII SBPMat Meeting: Karl Leo (TU Dresden, Germany).

Posted on Thursday 28 de August de 2014

The German physicst Karl Leo studied physics at the Albert Ludwigs University of Freiburg (Gemany) and obtained the “Diplomphysiker” degree with a thesis on solar cells at the Fraunhofer Institute for Solar Energy Systems (Germany).  In 1988, he obtained the PhD degree from the University of Stuttgart for a doctoral thesis performed at the Max Planck Institute for Solid State Research in Stuttgart. From 1989 to 1991, he was a postdoc at AT&T Bell Laboratories (United States). In 1991 he joined the RWTH Aachen University (Germany) as an assistant professor and obtained the Habilitation degree. In 1993 he joined the Dresden University of Technology (Germany) as a professor of optoelectronics. Since 2001 until 2013, he has been also with the Fraunhofer Institute for Photonic Microsystems, being head of department and then director.

He won some of the most prestigious German awards in science, technology and innovation, such as the Leibniz award (2002) and the German Future Prize (2011).

He is the author of more than 550 refereed publications, with more than 23.000 citations, having an H index = 73 (Google Scholar).  He is (co-)inventor of approximately 50 patent families.

Since 1999 he has co-founded 8 spin-off companies, such as Heliatek and Novaled, which have employed more than 250 people and raised more than 60M€.

Prof. Karl Leo with an organic solar cell module on test on the roof of Kaust university, in Saudi Arabia.

Read our interview with the lecturer.

SBPMat newsletter: – Under your viewpoint, which are your main contributions in the field of Materials Science and Engineering? Please think about papers, patents, spin-off companies, products etc.

Karl Leo: – I spent most of the last decades improving organic semiconductors and developing new device concepts for organic semiconductor devices. One example is the development of controlled electrical doping, which allowed much higher electrical conductivities. As a result, we could e.g. realize white organic light emitting diodes which are more efficient than fluorescent tubes. As device principle, we e.g. developed novel vertical transistors which can drive very high currents so that they can be used to drive OLED displays.

SBPMat newsletter: – Please give us a short teaser about your plenary talk at the XIII SBPMat meeting. What do you intend to broach?

Karl Leo: – I will talk about highly efficient organic devices, touching both organic LED and organic solar cells. I will describe the challenges in materials research and the importance of new device concepts.

SBPMat newsletter: – Could you choose some of your main publications (about 3 or 4) on the topics of your plenary lecture to share them with our public?

Karl Leo: –

1. Doped Organic Transistors: Inversion and Depletion Regime. Lüssem, B., Tietze, M.L., Kleemann, H., Hoßbach, C., Bartha, J.W., Zakhidov, A. and Leo, K. , Nature Comm. 4, 2775 (2013).

2. Phase-locked coherent modes in a patterned metal-organic microcavity. Brückner, R. Zakhidov, A., Scholz, R., Sudzius, S., Hintschich, S.I., Fröb, H., Lyssenko, V.G. and Leo, K., Nature Photonics 6, 322–326 (2012).

3. White organic light-emitting diodes with fluorescent tube efficiency. Reineke, S.; Lindner, F.; Schwartz, G. et al., Nature 459, 234 (2009).

SBPMat newsletter: –  Feel free to leave other comments to our readers from the Materials research community.

Karl Leo: – The field of materials research is as exciting as ever, and in the field of organic semiconductors, we are still in the beginning, maybe where silicon was in 1970…

Postdoctoral positions available at the Center for Research, Technology and Education in Vitreous Materials in São Carlos, Brazil.

Posted on Monday 18 de August de 2014

Applications for postdoctoral fellowships are invited for conducting fundamental or applied research at the Center for Research, Technology and Education in Vitreous Materials (CeRTEV) in São Carlos, Brazil.

The period of the fellowships is two years, starting in January 2015, renewable for two additional years upon mutual consent.

CeRTEV is an 11-year, approximately USD$22 million joint effort of the Federal University at São Carlos (UFSCar), the University of São Paulo
(USP) and the State University of São Paulo (UNESP), to conduct fundamental and applied research in the area of Functional Glasses and Glass-Ceramics. The center comprises 14 faculty members, including some of the world experts in vitreous materials and structural characterization techniques. Research will focus on new glasses and glass-ceramics and the development of structure/crystallization/properties correlations (mechanical, optical, electrical, catalytic, biological) for technological applications.

Applicants should have a PhD degree in Physics, Chemistry, Materials Science or Engineering, and have a genuine interest in conducting interdisciplinary research in an international environment. Previous experience in glass science, solid state physics or chemistry is advantageous. The monthly fellowships (non-taxable) include ca. R$ 6.000,-
plus 15% professional expenses. Travel expenses from and to their home countries will also be covered. The three sister universities are equal opportunity employers and are committed to increasing the proportion of women and ethnic minorities in academia.

Please send your application including CV, list of publications, a 2-3 page research proposal, and the names and email addresses of two references by October 15, 2014 to Prof. Edgar D. Zanotto (dedz@ufscar.br).

SBPMat newsletter. English edition. Year 1, issue 7.

Posted on Monday 4 de August de 2014

Brazilian Materials Research Society (SBPMat) newsletter

News update from Brazil for the Materials community

 

English edition. Year 1, issue 7. 

Greetings, .

XIII SBPMat meeting (João Pessoa, September 28th to October 2nd)
– Have you made your registration yet? Take advantage of our discounts up to Aug/15.  Here.

– If you are a student and submitted an abstract that has been approved, you may send your extended abstract up to Aug/08 and apply to compete for the Bernhard Gross Award. Here.

– Accommodation options? There are some here.
– 24 companies and institutions already chose to attend our meeting as exhibitors. If your organization also wishes to be a part of the event, contact us at rose@metallum.com.br.

 


We interviewed the French scientist Jean-Marie Dubois, specialist in quasicrystals (ordered, but aperiodic structures on solid materials) and pioneer in patenting applications for them. He told us a little about his main contributions to the field of Materials and gave a teaser on the theme of his plenary lecture in the XIII SBPMat Meeting: he will talk about quasicrystal structures, found in metallic alloys, polymers, oxides and artificial nanostructures, and their unprecedented properties. In the picture, Jean-Marie Dubois (on the left) and Dan Shechtman, who received a Nobel Prize in 2011 for the quasicrystals, using equal ties, both decorated with the Penrose tiling, an example of aperiodicity.  Read our interview with Jean-Marie Dubois here.








We also interviewed the Italian chemist Roberto Dovesi, one of the creators of CRYSTAL, a computational tool for ab initio quantum calculations used in the study of several solid materials properties. The CRYSTAL code is currently used in over 350 laboratories around the world.  In his plenary lecture in the XIII SBPMat Meeting, Dovesi will attempt to demonstrate that today quantum simulations may be very useful tools to complement experiments.  Read our interview with Roberto Dovesi here.












Featured paper with Brazilian participation






A group of scientists, coordinated by Brazilian researchers, used a Helium Ion Microscope (HIM) located in Silicon Valley, in the United States,  to engrave nanometric periodic patterns in graphene sheets, giving an innovative use to the instrument. The fast, simple and precise technique could be used by the electronics industry to produce graphene semiconductive devices, which could replace the silicon ones. The lead author of the paper published in Applied Physics Letters told us the story behind the study and announced that, soon, Brazil is going to have its first HIM.  Read the story.







Reading recommendations






Science stories based on papers published in journals with high impact factor.


– Ultralight material formed from polymeric, metallic and ceramic microstructures, produced by 3D printers (Science). Read it here.


– Friction at the nanoscale: while carbon nanotubes are superlubricants, boron nitride nanotubes display a high level of friction (Nature Materials). Read it here.


– New method for producing perovskite solar cells with good costs and efficiency (Nature Materials). Read it here.


– Scientists propose a model for fullerenols structure and are one step closer to biomedical applications (Chemical Science). Read it here.

Materials news from the Brazilian National Institutes of Science and Technology (INCTs).


– 3D chips may be quick and cheap. Read it here.

On the market, or almost there.


– Oral hygiene products incorporated with silver nanostructures: technology developed in Brazil prevents 99% of bacteria and fungi. More.


– For licensing: bionanocomposite for bone grafting tested in vitro and in vivo, developed in Brazil. More.


– For licensing: Cesium phosphate filter with functionalized nanotubes, very efficient for heavy metals. More.

Book review


– New book on eco-friendly polymer nanocomposites (types, processes and properties). Read it here. 


 







Upcoming events in the area






– 2º Workshop Adesão Microbiana e Superfícies. Here.


– 13th European Vacuum Conference + 7th European Topical Conference on Hard Coatings + 9th Iberian Vacuum Meeting. Here.


– 19th International Conference on Ion Beam Modification of Materials. Here.


– XIII SBPMat Meeting. Here.


– International Symposium on Crystallography – 100 years of History. Here.


– Congresso Brasileiro de Engenharia Biomédica (CBEB). Here.


– MM&FGM 2014 – 13th International Symposium on Multiscale, Multifunctional and Functionally Graded Materials. Here.


– X Brazilian Symposium on Glass and Related Materials (X-BraSGlass). Here.











To suggest news, opportunities, events or reading recommendations items for inclusion in our newsletter, write to comunicacao@sbpmat.org.br.





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Interviews with plenary lecturers of the XIII SBPMat Meeting: Roberto Dovesi (Universita’ degli Studi di Torino, Italy).

				

			Posted on Thursday 31 de July de 2014		

			


	

		
The Italian chemist Roberto Dovesi, full professor at Universita´degli Studi di Torino, where he heads the Theorical Chemistry Group, will be one of the plenary speakers in our XIII SBPMat Meeting. Dovesi will talk about theoretical calculations applied to materials.


His scientific activity focuses on the use of a quantum-mechanical approach to solid state chemistry, physics, materials science and surface science. In particular, his primary activityis the implementation of ab initio computer programs for the study of the electronic structure of periodic compounds.


Dovesi is one of the creators of CRYSTAL, a computational tool for the characterization of crystalline solids.The CRYSTAL project started in 1976, and involved (and still involves) a large number of collaborators from many countries. The first version of the software was released in 1988, and then new versions have followed. CRYSTAL is today a licenced program used in more than 350 laboratories in the world. In the last five years, more than 30 PhD students and post-docs from European countries visited the Torino Theoretical Chemistry Group in order to be introduced to the formal aspects and use of the CRYSTAL code.


Every year Dovesi’s group organizes international schools on the quantum-mechanical simulation of solids. One of them was held in 2012 in Brasil. This year four such schools are organized in Perth (Australia), Jahnsi (India), Regensburg (Germany), London (UK) (see at the EVENTS entry in the CRYSTAL web site) .


Roberto Dovesi is the author of more than 250 papers published in international journals and of one book (with Cesare Pisani and Carla Roetti) published by Springer in 1989. Since 1985, he received more than 7.000 citations with h-index=51.


Read our interview with the lecturer.


SBPMat newsletter: – Share with us, very briefly, the story of the developement of CRYSTAL since the first idea up to commercialization.


Roberto Dovesi: – In 1970 Cesare Pisani, Carla Roetti and myself decided to explore the possibilities of simulation as a complement to experiment in the study of crystalline solids.


We started to develop small codes on the basis of the analogy with the codes that were appearing in the litterature as produced mainly by USA universities. In 1976 we started to implement an ab initio quantum mechanical code for solids, using tools and methodologies that were common to the Theoretical Chemistry community (as opposed to the Solid State community). It took 4 years of very hard study and coding to have a first, preliminary result, the band structure of graphite, and its total energy. Eight years later, in 1988, CRYSTAL was ripe enough to be publicly distributed by QCPE (Quantum Chemistry Program Exchange). CRYSTAL has been the first periodic code distributed publicly to the scientific community.


In the meantime many new collaborators where joining the group from many countries (I want to mention at least one of them, Vic Saunders, fron the Daresbury Laboratory, U.K). In the following years many new public releases have been distributed (1992, 95, 98, 2003, 2006, 2009, 2014), each one corresponding to generalizations and extensions of the code in many directions. The last release (CRY14) has been distributed in more than 200 laboratories in less than one year.


The Raman spectrum of Pyrope.


SBPMat newsletter: – Please explain to our broad audience what can be done with CRYSTAL in the field of Materials Science and Engineering.


Roberto Dovesi:- CRYSTAL can be used for studying many ground state properties of systems periodic in 1 (nanotubes, polymers), 2 (monolayers, slabs) and 3 (crystals) dimensions; solid solutions, molecules and clusters can be investigated too. Hartree-Fock and DFT of various flavours are the available hamiltonians. A very large set of properties can be studied, the list can be found at www.crystal.unito.it. A short list includes the elastic, piezo-electric, photo-elastic, dielectric, polarizability and hyperpolarizability tensors, the IR and RAMAN spectra, the electron and phonon band structure.


SBPMat newsletter: – Please choose some of your main publications (about 3 or 4) to share them with our public.


Roberto Dovesi: –


1. Raman Spectrum of Pyrope Garnet. A Quantum Mechanical Simulation of Frequencies, Intensities, and Isotope Shifts. Lorenzo Maschio, Bernard Kirtman, Simone Salustro, Claudio M. Zicovich-Wilson, Roberto Orlando and Roberto Dovesi. J. Phys. Chem. A, 2013, 117 (45), pp 11464–11471.


2. Structural, electronic and energetic properties of giant icosahedral fullerenes up to C6000: insights from an ab initiohybrid DFT study. Yves Noel, Marco De La Pierre, Claudio Marcelo Zicovich Wilson, Roberto Orlando, Roberto Dovesi. Phys Chem Chem Phys. 2014, Jun 11; 16(26):13390-401.


3. Symmetry and random sampling of symmetry independent configurations for the simulation of disordered solids. Philippe D’Arco, Sami Mustapha, Matteo Ferrabone, Yves Noël, Marco De La Pierre, Roberto Dovesi. J Phys Condens Matter. 2013 Sep 4; 25(35): 355401.


SBPMat newsletter: – Tell us what do you intend to broach in your plenary talk at SBPMat meeting.


Roberto Dovesi: – I will try to show that nowadays quantum mechanical simulation can be an useful complementary tool to experiment. The decreasing cost of the harware, and the availability of powerful, accurate and general computer codes permits to perform simulations also to non experts. I will show that the number of available properties makes simulation very interesting.


			


	


			
				


	

		
Featured paper: Graphene sheets engraved with helium ions.

				

			Posted on Tuesday 29 de July de 2014		

			


	

		
 The scientific paper by members of the Brazilian community on Materials research featured this month is:


Archanjo, B.S.; Fragneaud, B.; Cancado, L.G.; Winston, D.; Miao, F.; Achete, C.A.; Medeiros-Ribeiro, G. Graphene nanoribbon superlattices fabricated via He ion lithography. Appl. Phys. Lett. 104, 193114 (2014); http://dx.doi.org/10.1063/1.4878407.


Graphene sheets engraved with helium ions


In a study led by researchers from Brazil and recently published in Applied Physics Letters (APL), scientists have engraved, on graphene sheets, nanosized periodic patterns, using a new method for that application, the helium hion beam lithography.


The team of scientists used a helium ion microscope (HIM) in order to bombard graphene with these ions and, thus, engrave parallel lines of length 1mm and width of only 5 nm, defining, among them, 20 nm-width ribbons (nanoribbons).


In addition to being quick and simple, the method has proven to be very accurate: it generated point defects smaller than other similar techniques and significantly preserved the atomic structure of the nanoribbons.


The new method extends the application possibilities of graphene, which, it is worth highlighting, is a flat material (it is only one atom tall) composed of densely packed carbon atoms, and which stands out because it can be used in nanoscale and for its high mechanical resistance, great electricity and heat conduction, transparency, and flexibility, among other properties.


“Direct writing in graphene using the focused beams of helium ions allows the fast manufacturing of different devices”, says Braulio Archanjo, researcher at the Brazilian National Institute of Metrology, Quality, and Technology (Inmetro) and lead author of the APL’s article. As an example, Archanjo mentions the possibility of manufacturing, in a near future, in pure graphene, the so-called “PN junctions”, essencial structures in semiconductor devices such as diodes and transistors, widely used in the production of electronics. Today, these structures are basically made in silicon.


AFM topographic image (3D) of graphene surface on SiO2.


The story of the work


In the context of studies on graphene metrology performed in the recent years at Inmetro, reports Archanjo, emerged the idea of manufacturing, in a controlled manner, periodic “defect” patterns, such as the parallel lines of the APL work. In 2012, an Inmetro team, in collaboration with researchers of the Federal University of Minas Gerais (UFMG), published a paper on periodic patterns engraved on graphene using a beam of gallium ions through FIB (focused ion beam) equipment.


Later, in a meeting of Archanjo with professors Carlos Achete, from the Federal University of Rio de Janeiro (UFRJ) and from Inmetro, and Gilberto Medeiros, from UFMG and from the research and development laboratory of Hewlett-Packard (HP Labs), a second work was planned, which would use, instead of FIB equipment, a HIM equipment, which resolution is up to ten times higher, but which is still not available in Brazilian territory.


So Archanjo spent three weeks in Silicon Valley, in the United States, using the HIM of HP Labs to make lithography in graphene samples manufactured at Inmetro. “We brought together the expertise we have here regarding graphene defects with the expertise of the HP Labs researchers regarding using a microscope of focused beams of helium ions”, summarizes the Inmetro researcher.


When he went back to Brazil with several graphene samples with engraved periodic patterns, the team began, at Inmetro, the study of such samples through atomic force microscopy and Raman spectroscopy. “This stage of the work was performed together with professors Benjamin Fragneaud, from the Federal University of Juiz de Fora (UFJF) and Luiz Gustavo Cançado, from UFMG”, tells Archanjo.


HIM: soon in Brazil


In the first semester of 2015, announces Archanjo, Brazil should have its first helium ion microscope. “The experience we gained performing the study at HP Labs will allow us to install it and use it”, says the researcher. The equipment will be available at Inmetro.


			


	


			
				


	

		
Made in Brazil: incorporating silver nanostructures into oral hygiene products eliminates 99% of bacteria and fungi.

				

			Posted on Monday 28 de July de 2014		

			


	

		
A research on the incorporation of silver with antibacterial properties on surfaces, conducted by the  Center for the Development of Functional Materials (CDMF in Portuguese), one of the Research, Innovation and Dissemination Centers of the São Paulo Research Foundation (FAPESP) is being applied to toothbrushes.


OralGift, a company with 12 years of experience in the oral hygiene business, in association with CDMF and NANOX Tecnologia, released a new line of products coated with the NanoxClean technology. Produced with silver nanostructures incorporated into the raw materials, the surface of the product is protected against microorganisms and bacteria.


The researchers responsible for this work explain that damp environments, mainly bathrooms, display a large amount of bacteria and fungi. When toothbrushes are left exposed, there is a high possibility of contamination.


The technology incorporating silver nanostructures eliminates 99% of the bacteria and fungi accumulated on  toothbrush and the cases used to keep them, as well as tongue cleaners.


The CDMF Director, Professor Eldon Longo, clarifies the importance of the association between the research developed at the university and the industrial-scale innovation made in companies:  “Nanox is a first world company in innovation, with high technology. It develops products based on nanotechnology, mainly to healthcare. This innovation, released on the market, is another example of creativity in transforming knowledge into wealth for the country”.


 About CDMF


The Center for the Development of Functional Materials (CDMF) is one of the Research, Innovation and Dissemination Centers (CEPID in Portuguese) supported by FAPESP (São Paulo Research Foundation), and the National Institute of Science and Technology of Materials in Nanotechnology,  and counts with the collaboration of São Paulo State University (Unesp), Federal University of São Carlos (UFSCar), University of São Paulo, (USP) and the Nuclear and Energy Research Institute (Ipen).


Facebook profile: https://www.facebook.com/INCTMNCMDMC


NANOX


NANOX Tecnologia is located in São Carlos city (Brazil), and was created from a project developed by three young UFSCar students, which they improved during their graduate studies in the Chemistry Institute of Unesp at the Araraquara campus.


The company was among the first ones engaged in the field of nanotechnology in Brazil, and is currently considered the largest in its business in the country, being the first national company to export nanotechnology.


(From Fernanda Vilela – CDMF)