Interview with a winner of the CNPq award for undergraduate research.

Posted on Wednesday 21 de December de 2016

We interviewed Gleison Adriano da Silva, one of the winners of the 13th edition of the Special Award in Scientific and Technological Initiation (undergraduate research) of the Brazilian National Council for Scientific and Technological Development (CNPq). The young man, who in November graduated in Physics from the Federal University of Amazonas (UFAM), won the scientific initiation research award in the area of Exact Sciences, Earth and Engineering for his work on structural, thermal and optical characterization of semiconductor systems. The CNPq award highlighted six papers (the best in scientific initiation research and the best in technological initiation research in each area of knowledge) out of 467 works submitted, sent by 167 education and research institutions in Brazil.

The work that earned Gleison the award was developed over three scientific initiation projects that he developed within the Materials Group of the Physics Department of UFAM, under the guidance of Professor Sérgio Michielon de Souza, with funding from the Amazonas Research Foundation (FAPEAM) and CNPq. In these projects, nanostructured semiconductor materials were synthesized by a simple and low cost process. The materials were analyzed using X-ray diffraction, differential scanning calorimetry, micro-Raman spectroscopy, and photoacoustic absorption techniques, and showed good potential to be used as thermoelectric materials in the direct conversion of heat into electricity.

Gleison received a scientific initiation grant (first from FAPEAM and later from CNPq) shortly after beginning the Physics course at UFAM in 2011. His advisor, Sérgio Michielon de Souza, was a new professor at this institution that year and was putting together the Materials Laboratory at the Physics Department, a process in which Gleison actively participated. The first work phase was dedicated to the manufacture and study of Cd-Se system, and its results were published [http://dx.doi.org/10.1016/j.molstruc.2014.06.023] in September 2014 in the Journal of Molecular Structure (Elsevier), while he worked on the second work phase, focused on the Ni-Sb system. Also in September 2014, Gleison presented the partial results of the second phase of this work at the XIII SBPMat Meeting held in João Pessoa (PB). His poster received the Bernhard Gross award for the best presentation of the symposium S, dedicated to posters on advanced materials. In May 2015, the final results of the research on the Ni-Sb system were published [http://dx.doi.org/10.3139/146.111211] in the International Journal of Materials Research (publisher Carl Hanser Verlag GmbH & Co.). In September 2015, Gleison presented the third work phase, dedicated to the Sn-Se system, at the XIV SBPMat Meeting in Rio de Janeiro (RJ).

Finally, in July 2016, Gleison had the honor to receive the Scientific and Technological Initiation Outstanding Award, in Porto Seguro (BA), during the 68th Annual Meeting of the Society for the Advancement of Science (SBPC). It was the third time he was indicated by the Dean of Research and Post Graduation program of UFAM to compete for the CNPq award, and this time he won the award, with the final research results on the Ni-Sb system and the partial research results on the Sn-Se system. Three months later, Gleison defended his completion course work (TCC), from the studies of Ni-Sb and Sn-Se systems, and obtained a bachelor’s degree in Physics from UFAM.

See our interview with Gleison.

SBPMat newsletter: – Where were you born? Where did you live until starting university at UFAM?

Gleison Adriano da Silva: – I am originally from Central Brazil, Brasilia (DF), and it all started in 2008 when I applied to be a missionary/community worker of the Roraima Diocese in the North of Brazil, under the command of former titular bishop Dom Roque Paloscci, to work in communities in the lower Rio Branco up to its mouth in Rio Negro.

In 2009, I successfully passed the ENEM exam in Forest Engineering at UFAM, campus Manaus (AM). Without financial assistance, I lived in a hostel in Manaus (AM), however, after the selection process in the Secretary of Community Affairs, moved to the University’s Student Housing, UFAM. In 2011, due to the lack of affinity with the Forest Engineering course, I changed to the Physics course at the Institute of Exact Sciences of UFAM.

SBPMat newsletter: – Could you tell us briefly how your interest in science and research began? Was it at the university, during your childhood, in school?

Gleison Adriano da Silva: – It all happened very fast. Soon after I began the physics course in UFAM, I was invited to do scientific research by Professor Sérgio Michielon de Souza and upon joining the Materials Research Group in the Physics Department of UFAM, I had the opportunity to conduct scientific research focused on the determination of crystal structures, micro/nano-structural evolution and phase transformation in intermetallic materials using computer software and analytical techniques in the Materials Laboratory.

SBPMat newsletter: – In your opinion, what is the main contribution of the winning work? Or, what are the main contributions of the winning works?

Gleison Adriano da Silva: – An interesting observation is that the awarded investigations were coincidentally related to the 2014 and 2015 UNESCO celebratory themes – International Year of Crystallography and International Year of Light. From this perspective, the main contributions in the award-winning works were related to X-ray diffraction techniques, that is, changes and stability of crystallographic phases of samples of the Ni-Sb and Sn-Se semiconductor system during the solid state synthesis, where strong structural stability of nickel antimonide crystals (NiSb) and remarkable metastability of tin selenide crystals (SnSe) were observed.

A simple work that presents microstructural and thermodynamic characteristics of two new nanostructured materials of scientific and technological interest subjected to non-complex synthesis route and of low cost.

SBPMat newsletter: – What were the guiding criteria to conduct outstanding quality research at the national level? To what factors do you attribute this achievement?

Gleison Adriano da Silva: –There is no Columbus’ egg or success recipe, only hard work. Nothing happens without effort. As an undergraduate with a scientific initiation grant, I was always the first to arrive and the last to leave the lab. The achievement is the recognition of work, however, nothing can be done alone.

SBPMat newsletter: – Please leave a message for our readers who are conducting scientific initiation research work in the Materials area.

Gleison Adriano da Silva: – Believe in your potential and in the potential of your investigations. It is the dream that moves us, but it is not enough to dream, you must chase the dream. I also urge you to consider this as encouragement to disseminate your research results in scientific events in Brazil, especially in the SBPMat Annual Meetings.

SBPMat newsletter: – What are your plans now that you have graduated?

Gleison Adriano da Silva: – After this long process, I will probably look for a Graduate Program at the University of Brasilia (UNB) or at some renowned SP institution.

SBPMat newsletter: – Feel free to make another brief comment.

Gleison Adriano da Silva: – I would like to thank the congratulations letters and praise I received from the Head of the Physics Department of UFAM, Professor Marcílio de Freitas; from the Director-President of FAPEAM, Professor Maria Olívia de Albuquerque Ribeiro Simão; and from Senator Vanessa Grazziotin, Brazil’s National Congress (http://www.senado.leg.br/atividade/rotinas/materia/getPDF.asp?t=195150&tp=1).

I would also like to thank the city of Manaus (AM), the UFAM and all who directly or indirectly contributed to my personal and academic background.

Interviews with plenary lecturers of the XII SBPMat Meeting: Mercouri G. Kanatzidis (Northwestern University – USA).

Posted on Friday 26 de July de 2013

About two-thirds of all used energy is lost as waste heat. Bulk thermoelectrics (materials that can directly convert temperature differences to electric voltage and vice-versa) can improve this current situation by transforming some of the waste heat into useful electricity, but, in most cases their conversion efficiency is not sufficient to allow for commercial use. This efficiency is related to the ability of electrons to traverse the materials as they are excited by heat and to phonon scattering, and it is measured by the so-called ZT values (the higher a material’s ZT, the higher its conversion efficiency).

Efforts have been made to enhance the efficiency of thermoelectric materials, mainly by nanostructuring them. In his plenary talk at the XII SBPMat Meeting, professor Mercouri Kanatzidis (Northwestern University, USA) will present his panoscopic approach to highly efficient thermoelectrics. This approach considers not only the nanostructure of the material but also its mesoscale architecture. Using this strategy, professor Kanatzidis and his collaborators developed the top-performing thermoelectric system at any temperature, a lead telluride (PbTe) – based material. The achievement was published in the journal Nature in September 2012 (doi:10.1038/nature11439). The speaker will also address in his talk the substitution of tellurium by sulfur or selenium in thermoelectric materials for cost reduction.

Professor Kanatzidis obtained his BSc from Aristotle University (Greece) and his PhD in chemistry from the University of Iowa. He was a University Distinguished Professor of Chemistry at the Michigan State University before moving to the Northwestern University, where he heads a research group focused in solid-state inorganic chemistry. Mercouri is also the editor-in-chief of the Journal of Solid State Chemistry and Senior Scientist at the Materials Science Division of the Argonne National Laboratory.

See below our interview with the lecturer.

SBPMat: – Could you exemplify some possible concrete applications of high-performance thermoelectric materials in daily life? In your opinion, how far is the real use of thermoelectric materials from the state-of-the-art?

Mercouri Kanatzidis (M.K.): – Thermoelectric materials can be applied to internal combustion engines to help harvest exhaust heat and generate electricity that can be applied to the vehicle’s electrically driven devices. This will raise the overall efficiency of the vehicle. There is a staggering amount of energy in exhaust heat of a fossil fuel powered engine. Major auto companies in the US, Germany and Japan are actively developing this technology. Depending on the price of oil, government regulations and cost of the technology the implementation of thermoelectric materials in autos, trucks, etc may take anywhere from a couple of years to decades.

SBPMat: – Which are the thermoelectrics´ next challenges for materials science and engineering?

M.K.: – The current state of performance of thermoelectric materials is adequate for commercial applications. The next challenges lie in the fabrication of actually thermoelectric modules and devices that will pass the necessary testing before final application. Challenges such as long term stability, low cost assembly and fatigue testing need to be addressed.

SBPMat: – Can you share with us, very briefly, the story of the genesis of your panoscopic approach to highly efficient thermoelectric materials?

M.K.: – About ten years ago we had a novel material composition which had two unlikely characteristics. It had a very high electrical conductivity and thermoelectric power combined with surprisingly low thermal conductivity. The thermal conductivity was lower than theory could explain. This material was first of its kind (referred to as LAST for lead, antimony, silver, tellurium) at that time to display a breakthrough ZT of 1.6, nearly double of the then state of the art. Because of this we delved deeply onto its “guts” using transmission electron microscopy in collaboration with Professors Polychroniadis and Frangis of the University of Thessaloniki in Greece. A few months after they received the samples they reported to us on their findings with a somewhat disappointing note saying that the materials were very complex and inhomogeneous on the nanoscale, therefore impure. In discussions I detected reluctance to deal with the material again. They did. In my lab however we immediately recognized that this very inhomogeneity and the nanoscale precipitates it contained was the root cause of the surprisingly very low thermal conductivity and the very high ZT. This was consistent with theoretical predictions emerging at the time that nanoscale precipitation in a matrix can result in great reduction in thermal conductivity. So we got very excited. We had discovered nanostructuring in thermoelectrics. After our paper appeared in Science in 2004, the thinking of the thermoelectrics community quickly shifted from pursuing single phase materials to focusing on more complex two-phase nanostructured materials. Now the great majority of activity in the community is in nanostructured materials.

The new paradigm led to additional breakthroughs such as how to design and synthesize nanostructured materials, and to higher ZT as well. The panoscopic approach was realized when we were challenged to create two-phase materials that did not degrade electronic transport through them. While matrix of a thermoelectric material with a small amount of a second phase in it can achieve unprecedented levels of low thermal conductivity, it nevertheless is an “impure system” and electrons transported through such a medium know this. Thus, in most cases the second phase degrades the electrical properties and higher ZTs are not realized.

imagem mercouri — State of the art thermoelectric: (a) A mesoscaled granular composite of broad range of grain sizes to scatter long mean free path phonons. (b) Wwithin a single grain a ubiquitous nanostructuring is in place of a second phase that scatters short and intermediate mean free path phonons. The (a)/(b) combination results in a very low levels of thermal conductivity.

My group members Kanishka Biswas and Lidong Zhao and our collaborators Ctirad Uher and Vinayak Dravid noticed that when SrTe was added to p-type PbTe in as much as 2-4% concentration the hole carriers were behaving as if no SrTe was there. The explanation to this puzzle came from the recognition which was backed by theoretical calculations that the conduction bands in PbTe and SrTe were similar in energy and the holes as a result could traverse the SrTe nanoparticles with no scattering. This led to the concept to band alignment between matrix and second phase. The PbTe-SrTe material with its nanostructuring and band alignment was another material with ZT~1.7. As we realized that different ZT improving mechanisms could be integrated in a single system without the effect of one interfering with those of the other, we extended our approach to trying to integrate all possible mechanisms. We managed to properly introduce electronic band engineering for thermoelectric power enhancement and mesoscale engineering for further reduction on the thermal conductivity to reach the point we now are a record breaking ZT of 2.2. This is very exciting and bodes well for further breakthroughs in the near future.

SBPMat: – Feel free to leave any other comments about your plenary lecture for our readers.

M.K.: – My lecture will be aimed at reaching the broad but scientifically informed audience at the meeting to outline the current state and thinking in the field of thermoelectrics.

See the abstract of Mercouri Kanatzidis plenary lecture “Electrical power from heat: All-scale hierarchical thermoelectrics with and without earth-abundant materials”.

See Professor Kanatzidis biographical sketch.