The manufacturing of LNLS accelerators and the national materials, by Prof. Cylon Gonçalves da Silva.

Picture of the storage ring of the synchrotron light source, in LNLS (Campinas, SP) in December, 1996, time of the start of its working, 7 months before the inauguration of the laboratory. (Credit M.B.JR)

When we started the construction of LNLS, in 1986, and much before that, in its “pre-history”, there already was the intention of involving the Brazilian national industry in the construction of the equipment. Looking back from 2015, it is difficult to imagine what the Brazilian industry was in 1985. It is even more difficult to conceive that, in some sectors, among them the metal-mechanical sector, it was more sophisticated than it is today. The opening of the Brazilian economy, required, but conducted in a confused and trapping manner by Collor Government, terminated with a good part of the most sophisticated industry that was in Brazil at that time. Out of all the materials required to construct the accelerators, two got highlight for their weight (literally): steel and copper. To the magnets and vacuum chambers, we needed steel, and to the coils of the electromagnets we needed OFHC copper with low content of oxygen.

I remember the visit made to our hangar, by an specialist in ultra-high vacuum of Balzers that states to us, in an arrogant manner, that “it is impossible to manufacture ultra-high vacuum chambers” with Brazilian steel. “You will have to import”. It is not required to say that it was a wonderful incentive so that we would look for a Brazilian supplier to our needs. Ricardo and I shared a healthy disregard to such type of specialist. I think we both thought, without speaking up, each time we´ve heard statements of such type, more or less the same thing: “Ah, yes! No way? You will see!” To the manufacturing of the magnets and vacuum chambers, there were two questions not answered. There would be in Brazil steel with the required characteristics? And the laser-cutting method that we intended to use would not affect in a negative manner the magnetic properties of the material on its edges? No one has used such technique to manufacture precision electromagnets until LNLS considered it as an option, given the very special conditions we were facing. When we started, no one had the answers to such questions. The experience showed that there was the required steel in Brazil, for the magnets (SAE1006, acquired in the national market and re-laminated by Mangels), as well as for the chambers (AISI 316L), and that the laser cutting was a feasible and very flexible technique to the production of batches relatively small of electromagnets*. This, naturally, did not occur from night to day. In another occasion, we could told the long history of the development of the processes for steel, for example, the vacuum chambers cleaning and welding, and, for the magnets, the improvement of the magnetic properties.

Another history, funnier, is the one of copper for the coils of the electromagnets. CERN has recommended the Finnish company Outokumpu to us, which was their supplier. It is clear that, with such recommendation, we were calm regarding the quality of the Finnish product. But, I was not satisfied with having to import copper. A research revealed the existence of Termomecânica in São Paulo, property of Salvador Arena. Referencing to my “specialists”, all of them were unanimous in two points: it was a best-quality company and a company owned by an exceptional businessman, one of the most dedicated to the technological development of his products, only a little moody. I thought he fitted in the profile of a potential supplier to LNLS, and there I went to explain the LNLS project and its needs to him. I was welcomed, I have heard for hours an explanation on the beautiful educational program that was the project of his heart, I could expose our project in a brief manner, but Arena was precise about it – “I do not enter in such business. I do not want anything with the government. I will not go right. Forget it, you will not reach it. Termomecânica will not supply to you.” (I put the text between quotes, safeguarding that they could not have been Arena’s exact words, but the sense is the same.)

I confess I got disappointed, but the talk was not in vain. It served to me to understand how he thought, and to outline a strategy to convince him. We imported, with the help of CERN, a ton of OFHC copper from Outokumpu (a fraction of what we needed) in the specifications required to the coils of the dipole of the ring. The copper supplied by Outokumpu was OFHC/OFE – 99.99% minimum Cu with up to 0.0010% max of oxygen.  As soon as the material arrived, I called to Salvador Arena to tell him: “You did not want to supply, I imported from Outokumpu, your competitor”. What was heard on the other side of the line cannot be reproduced in the profusion of the insulting words where Arena was prodigal. Underneath, I was referred to as frivolous and unreliable, and he assured me in the most emphatic terms that he has never said that Termodinâmica would not provide us with the copper of low content of oxygen we needed. And he virtually ordered me to go back there immediately with the specifications that they would develop the material to us. And it was what they did. Thanks to Outokumpu’s import strategy, the copper supplied by Termomecânica is until today complying with its role with distinction, not only in the dipoles, but in all electromagnets of LNLS (OHFC/OF certificate – 99.95% minimum Cu + Ag with up to 0.0010% max of oxygen, but with OFE quality). Also here, there is a long story of development made by the LNLS team, from the materials up to the finished product. But, let’s leave it to another opportunity.

 Prof. Cylon Gonçalves da Silva

* I thank Guilherme Franco, Osmar Bagnato, and Ricardo Rodrigues, of LNLS team, for having refreshed my memory on the types of steel deployed, as well as the technical details of OFHC copper.

CAPES’s Materials Area Anniversary. Part 1.

At the end of January, 2014, the Brazilian community of Materials research celebrates an anniversary: the Materials Area of CAPES reaches its sixth year of existence. CAPES is the government agency linked to the Brazilian Ministry of Education in charge of promoting high standards for post-graduate courses in Brazil.

In fact, it was on January 30th, 2008, that CAPES’s published a press release announcing the introduction of changes to its table of areas. Such table lists the areas of knowledge and it is used in the evaluations of the post-graduation programs in Brazil. The changes disclosed in such note included the insertion of the Materials Area, which up until then did not exist, and which from then on would be a part of the Multi-disciplinary greater area, which had been recently created.

One day prior to such disclosure, an official letter from CAPES’s Evaluation Office had been sent to all coordinators of post-graduation programs previously identified as possibly being grouped into the new area. The official letter informed that a recent meeting of CAPES’s Superior Board had approved the creation of the new Materials area of evaluation, and also that physicist Lívio Amaral, a professor from the UFRGS (Federal University of the State of Rio Grande do Sul) had been appointed as the pro-tempore coordinator. In addition, the official letter asked the coordinators who deemed it to be in the interest of their programs to become connected to the new area of evaluation, to inform CAPES of their decision.


In September, 2012, professor Amaral had taken part in a meeting at the headquarters of CNPq (Brazilian Council for the Scientific and Technological Development) called by Professor Celso de Melo, who was a director in the council. The theme of the meeting was the Materials Science and Engineering area, and the Advisory Boards of such body. The other participants of the meeting were the professors Glória de Almeida Soares (from COPPE-UFRJ), Elson Longo (from UFSCar) and João Marcos Alcoforado Rebello (from COPPE-UFRJ).

A document signed by the participants of the meeting pointed some problems with the evaluation of research projects in the Materials Area. To sum it up, due to the fact that there was no Advisory Board for the Materials Area at that time, the projects and other requests pertaining to Materials Science or Engineering were often appraised with debatable parameters or sent from area to area until someone was found who could evaluate them, a situation which significantly increased the number of appeals received by the CNPq and the time to reply to the requesting researcher. To solve such issue, the document proposed initially the creation of a committee with representatives from the several areas of knowledge involving Materials and also that the scientific societies with any relation to Materials were to be called to the debate, to find a solution fully backed by the technical and scientific community.

“This matter of the inclusion of a Materials area in the government fostering agencies had been considered since the mid-90s”, Lívio Amaral states. “That occurred within the context of creation of a Brazilian Materials society, having the MRS as a reference, which ended up occurring in the early 00s. At the time, there was a lot of debate in several situations, such as in the Brazilian Meetings on Condensed Matter Physics of the Brazilian Physics Society”, he adds.

In parallel, professor Amaral had been following-up on that matter within CAPES, where he was the coordinator of the Physics and Astronomy Area. According to Amaral, by means of evaluations conducted every three years, it was possible to verify that several post-graduation programs, regardless of the names they had and by which of CAPES’s areas they were encompassed, were awarding master and doctorate degrees with intellectual production in Materials. “Since, in addition to being department coordinator, I also took part in CAPES’s Technical and Scientific Council, I had the opportunity to take that entire matter to debate in such Council”, the professor  comments.

At that time, Jorge Almeida Guimarães, who would become CAPES’s president in 2004, was the coordinator of the Biological Sciences II Area and, like professor Amaral, took part in the Technical and Scientific Council and was a professor in the UFRGS. “We discussed at length the need to create two new areas, the Materials and Biotechnology areas”, Lívio Amaral tells us.

In addition, Amaral recalls that another favorable coincidence then occurred. CAPES’s president at the time was Professor Abílio Afonso Baeta Neves, who had previously been the dean of post-graduation in UFRGS when the program of post-graduation in Materials Science had been submitted to the university, by initiative from professors of the Physics department, Amaral included, and of the Engineering and the Chemistry departments. “In summary, in that scenario, the discussion regarding new areas, inside and outside the Technical and Scientific Council, was very frequent due to such circumstances”, professor Amaral sums it up.

Meeting of CAPES’s Technical and Scientific Council, at the time of professor Abílio Baeta Neves’s presidency. At the table, the third one from the right is the president; the sixth, the one speaking, is professor Jorge Guimarães; the seventh is profesor Lívio Amaral. (Picture provided by Lívio Amaral)

The decision for the creation

According to Amaral, in July, 2007, CAPES held a meeting in Brasília, to consider the possible creation of a new area of knowledge, to be called “Materials”. Representatives from several post-graduation programs were invited, including professor Lívio, who was at the time the coordinator of UFRGS’s program.

The official letter-invitation sent by CAPES’s Evaluation Office contained: “The agency has been granted to such area the importance it deserves, considering the relevance of the creation of new materials for the current science and technology. CAPES’s Superior Council, in addition, has already authorized this Office to create the area at hand. For such decision, the meeting to be held in July 31st shall be decisive, for it will allow us to conclude if such innovative measure is in the interests of the programs – and of the Brazilian science and technologies. The new area would encompass all programs that – currently divided into different areas of knowledge – highlight this theme, which is a priority for the Country and for applied sciences”.

“The meeting was, therefore, conclusive for the creation of the new area and designed the initial milestones for the same”, Amaral states. Thus, on January 25th, 2008, CAPES’s Ordinance No. 09 was published, which ordinance, in its article 3, created two new areas of knowledge, “Materials” and “Biotechnology”, and designated their pro tempore coordinators.


List of post-graduation programs that adhered to the Materials area (as of March, 2008).

1. Program of Post-Graduation in Materials – UNIVERSIDADE DE CAXIAS DO SUL

2. Program of Post-Graduation in Materials Science – UNIVERSIDADE FEDERAL  DO RIO GRANDE DO SUL

3. Program of Post-Graduation in Materials Engineering and Science – UNIVERSIDADE FEDERAL DO CEARÁ

4. Program of Post-Graduation in Materials Science – UNIVERSIDADE FEDERAL DE PERNANBUCO

5. Program of Post-Graduation in Materials Science and Technology – UNIVERSIDADE ESTADUAL PAULISTA “JÚLIO DE MESQUITA FILHO” – UNESP-BAURÚ

6. Program of Post-Graduation in Materials Engineering – UNIVERSIDADE DE SÃO PAULO – ESCOLA DE ENGENHARIA DE LORENA

7. Program of Post-Graduation in Materials Engineering and Science – UNIVERSIDADE FEDERAL DO RIO GRANDE DO NORTE

8. Program of Post-Graduation in Materials Engineering and Science – UNIVERSIDADE DE SÃO PAULO – SÃO CARLOS


10. Program of Post-Graduation in Materials Engineering and Science – UNIVERSIDADE FEDERAL DE SANTA CATARINA.



Some information about the scientific work of Professor Gross.

Great part of the scientific activity of Prof. Bernhard Gross which came before his studies on electrets receive very little attention but are priceless. The papers on electrets started to have international prominence and repercussion after the 70’s and continued until early 80’s. I will comment a little about what he produced since the beginning of his career until the 60’s.

While still in Stuttgart, Germany, he published some papers about latitude corrections in detectors used to study cosmic rays in the atmosphere [references 1 and 2]. These articles were published in German. His work was soon generalized by E. J. Williams and published by Nature magazine [3]. Later on, this correction became known as “Gross’s transformation”. In the celebrated book about cosmic rays, published in 1950 [4], chapter 3 is dedicated to “Gross’s transformation”.

His first paper in Brazil was regarding electrical properties of zeolites [5] which, together with the work on delayed effects on dielectric solids [6] and, later on, on static charges on dielectrics [7], marked the beginning of his research in the field of Materials, which would culminate with famed studies about electrets after the 60’s. However, some seminal works on mathematical models applied to visco-elastic systems were very significant. These works were published in the last years of the 40’s [8-11]. As a result of this works, Gross published a book on the subject, which is still used as essential reference for the field of rheology of solids [12].

Circa 1950, Gross performed a series of studies on the effects of radiation on vitreous and polymeric systems [13.14]. With these studies, he discovered an electrical current in dielectric solids, which was related to the Compton Effect, originating celebrated and seminal work [15]. This effect explained the phenomenon occurring in nuclear plants, which had remained unexplained until then. The glass windows used as protection to radiation spontaneously cracked after being used for some time. Gross was invited by the Radiation Research Center in New York and, together with local researchers, he proved that Compton currents were responsible for the degradation of glass [16]. Right after that, Gross invented the Compton dosimeter [17], which he patented in the Unites States, but lost it for the American army after a legal battle.

Still in Brazil, Gross started his first studies about electrets [18, 19]; being the first to manufacture what he called radioelectrets. After retiring from the National Institute of Technology, he was invited to be in charge of the Department of Scientific and Technical Information of the International Agency of Atomic Energy, in Vienna, where he stayed until the end of the 60’s. He published some relevant papers about scientific information [20] and returns as a researcher in the field of electrets in the 70’s.

Professor Roberto Mendonça Faria
Researcher on Group of Polymers “Prof. Bernhard Gross” (USP São Carlos)
Prof. Bernhard Gross’s PhD student, between 1980 and 1984.


[1] For the Pressure Dependence of the Ionization by Cosmic Ray (Zur Druckabhängigkeit der Ionisation durch. Ultrastrahlung), B. Gross, ZEITSCHRIFT FUR PHYSIK Volume: 78 Issue: 3-4 Pages: 271-278 DOI: 10.1007/BF01337596 Published: MAR 1932.
[2] For the absorption of the ultra radiation (Zur Absorption der Ultrastrahlung), ZEITSCHRIFT FUR PHYSIK, B. Gross,  Volume: 83 Issue: 3-4 Pages: 214-221 DOI: 10.1007/BF01331141 Published: MAR 1933.
[3] Spectrum and latitude variation of penetrating radiation, E. J. Williams, Nature, 512 (1933).
[4] Cosmic rays, L. Janossy (1950), Oxford at Clarendon Press.
[5] On the electric conductivity of Zeolite, B. Gross, ZEITSCHRIFT FUR KRISTALLOGRAPHIE Volume: 92 Issue: 3/4 Pages: 284-292 Published: DEC 19.
[6] On after-effects in solid dielectrics, B. Gross, PHYSICAL REVIEW Volume: 57 Issue: 1 Pages: 57-59 DOI: 10.1103/PhysRev.57.57 Published: JAN 1940.
[7] STATIC CHARGES ON DIELECTRICS, B. Gross, BRITISH JOURNAL OF APPLIED PHYSICS Volume: 1 Issue: OCT Pages: 259-267 DOI: 10.1088/0508-3443/1/10/304 Published: 1950.
[8] ON CREEP AND RELAXATION, B. Gross, PHYSICAL REVIEW Volume: 71 Issue: 2 Pages: 144-144 Published: 1947.
[9] ON CREEP AND RELAXATION, B. Gross, JOURNAL OF APPLIED PHYSICS Volume: 18 Issue: 2 Pages: 212-221 DOI: 10.1063/1.1697606 Published: 1947.
[10] ON CREEP AND RELAXATION .2, B. Gross, JOURNAL OF APPLIED PHYSICS Volume: 19 Issue: 3 Pages: 257-264 DOI: 10.1063/1.1715055 Published: 1948.
[11] FRICTIONAL LOSS IN VISCO-ELASTIC SUBSTANCES, B. Gross, JOURNAL OF APPLIED PHYSICS Volume: 21 Issue: 2 Pages: 185-185 DOI: 10.1063/1.1699622 Published: 1950.
[12] Mathematical structure of the theories of Viscoelasticity, B. Gross, Paris, Hermann Press (1953).
[13] IRRADIATION EFFECTS IN BOROSILICATE GLASS, B. Gross, PHYSICAL REVIEW Volume: 107 Issue: 2 Pages: 368-373 DOI: 10.1103/PhysRev.107.368 Published: 1957.
[14] IRRADIATION EFFECTS IN PLEXIGLAS, B. Gross, JOURNAL OF POLYMER SCIENCE Volume: 27 Issue: 115 Pages: 135-143 DOI: 10.1002/pol.1958.1202711511 Published: 1958.
[15] THE COMPTON CURRENT, B. Gross, ZEITSCHRIFT FUR PHYSIK Volume: 155 Issue: 4 Pages: 479-487 DOI: 10.1007/BF01333129 Published: 1959.
[16] BETA-PARTICLE TRANSMISSION CURRENTS IN SOLID DIELECTRICS, B. Gross, A. Bradley & A. P. Pinkerton, JOURNAL OF APPLIED PHYSICS Volume: 31 Issue: 6 Pages: 1035-1037 DOI: 10.1063/1.1735740 Published: 1960.
[17] Compton Dosimeter for measurements of penetrating x-rays and gamma rays, B. Gross, RADIATION RESEARCH Volume: 14 Issue: 2 Pages: 117-& DOI: 10.2307/3570883 Published: 1961.
[18] GAMMA IRRADIATION EFFECTS ON ELECTRETS, B. Gross & R. J. D. Moraes, PHYSICAL REVIEW Volume: 126 Issue: 3 Pages: 930-& DOI: 10.1103/PhysRev.126.930 Published: 1962.
[19] POLARIZATION OF ELECTRET, B. Gross & R. J. D. Moraes, JOURNAL OF CHEMICAL PHYSICS Volume: 37 Issue: 4 Pages: 710-& DOI: 10.1063/1.1733151 Published: 1962.

Bernhard Gross: father of research on electrets in Brazil.

In June 1933, the physicist and engineer from Sttutgart, Germany, Bernhard Gross disembarked in the city of Rio de Janeiro.  After developing some research on cosmic rays as a collaborator and coming to the conclusion that it was hard to find a job as a physicist in his country, the 28 year-old man decided to try a life in Brazil. At this point, Gross had already published a few scientific articles.

Why did Gross come to Brazil, a country that had very few institutions, infrastructure and human resources for research at the time? At an interview conducted in 1976, Gross said that his interest in Brazil started in his childhood, during a trip with the family to the cities of Rio de Janeiro, São Paulo, Porto Alegre and Pelotas, in which he had a taste of adventure and romance.

Right after his arrival in Rio, Gross spoke at a few lectures about cosmic rays at Escola Politécnica do Largo de São Francisco and, thus, he started to meet people connected to science in the city.  In January 1934, he got his first job at the Institute of Meteorology. That same year, he published the first of many scientific articles written in Brazil. In 1999, at the age of 94, he would publish the last of around 200 articles.

Gross made internationally relevant and impressive contributions in various topics, such as Gama rays, electrical circuits and dielectric materials, with research developed in Brazil. Gross addressed scientific challenges with a lot of competence, from both the theoretical and the experimental point of view, and he gave specific attention to the application of Maths in Physics.

Besides doing science according to international standards, since the 30’s and 40’s, Gross published the results of his work in scientific journals in Brazil and abroad, such as the Annals of the Brazilian Academy of Science, the Journal of Applied PhysicsPhysical Review, Journal of Chemical Physics and the German magazine Zeitschrift für Angewandte Physik, among others.  In addition, Gross traveled a lot around the world, spending some time working in the United States (at Bell labs and the Massachusetts Institute of Technology), in England (at Electrical Research Association), in Austria (as a member of the scientific committee for the International Agency of Atomic Energy, international organization dedicated to the pacific use of atomic energy), among other destinations. Finally, Gross managed to bring to Brazil researchers from abroad in many occasions.

By continuously working in various themes, Gross started in Brazil the research on Physics of Condensed Matter, the pillar of Materials Science and Engineering, in a pioneering way.

The electrets

One of the fields that received more scientific contributions from Bernhard Gross is the study of electrets, dielectric materials (insulators), which possess permanent electrical charge for being permanently polarized.

The genesis of Gross’s research about electrets refers to work produced by him in Brazil in 1934: a request from Light, the electricity and telephone company, who wanted to know which was the resistance of the isolation on their telephone cables. By making measures, Gross realized that the cables presented a phenomenon which had fascinated him for some time, called “dielectric absorption”.

In the interview of 1976, Gross reports: “What Light wished to know I could resolve within a reasonable amount of time. Now, I took the opportunity to study the behavior of insulators, in a more basic way.” Gross saw the technological interest in research activities as very important, without this limiting the scientific curiosity to a mere resolution of technological issue.

In the early 40’s, Gross and his team still researched on dielectric materials at the National Institute of Technology (INT) in Rio de Janeiro. Bernhard Gross had read about electrets and, due to sheer curiosity, he started to make a series of measures together with French researcher Line Ferreira-Denard, who worked at INT. The experimental work originated two initial publications in 1945 and in 1948, and it allowed them to explain for the first time the behavior of electrets. In 1957, Gross conducted a systematic study about the behavior of fields that were generated when, while injecting electrons in charged solids, electrons were stuck in “traps”.

It was also within the context of dielectrics and electrets that Joaquim da Costa Ribeiro developed the comprehension of the thermodynamic effect or “Costa Ribeiro effect”, in which a dielectric acquired permanent polarization and charge by means of the application of an external electical field.

The electret microphone

The knowledge developed by Gross about electrets enabled the advancement on industrial applications of this material, from which the most commonly known is the electret microphone, created inside Bell labs by  Gerhard Sessler and James West, who applied for  patent of the invention in 1962. Millions or billions of units of this kind of microphone have been produced per year.

In order to get to the electret microphone, Sessler and West used the theory developed by Gross and a method described by him to charge materials through electron beams. But researchers at Bell lab used as raw material Teflon leaves, whose mechanical properties, low conductivity and opportunity to be manufactured as thin plates allowed the application on microphones. A charged thin leaf of Teflon is moved by the action of sound vibrations and it induces electical charges, transforming sound vibrations into electrical vibrations.

“I admit that at the time I did not think of practical applications”, said Gross during the 1976 interview about the research on electrets. The scientist explained the reasons: he did not have adequate material for industrial application (he used carnauba wax and plexiglass); the difficulty in applying for patent at the time was too great and he needed to gather various skills in order to reach a device as a microphone.

The Sessler microphone was not the only one based on the knowledge developed by Gross. In the history of the Sttutgart physicist and his electrets, there was a case of direct technological exchange, related to Preston Murphy, his American assistant specialized in electrostatic. Gross met him in one of his travels and managed to get him a contract to work in Rio de Janeiro for the National Committee of Nuclear Energy. Murphy went to Brazil around 1957 and stayed for about six years, in which he gained knowledge and expertise.  According to Gross, “when coming back to the US, I joined a company where he developed a kind of electrect microphone, based on the knowledge he acquired here, taking advantage of the American extraordinary capability to make gadgets, a virtue I do not possess. He arranged a few contracts there and assembled a big production line of electret microphones”.

Acknowledging the contribution of Gross in electrets

The advancement promoted by Gross in research on electrets was recognized worldwide. Gerhard Sessler dedicated the book “Electrets”, initially edited by him in 1980, to Bernhard Gross. In an article published in the Brazilian Journal of Physics in 1999, Sessler states that Gross laid the cornerstones of modern research on electrets, guided its evolution for over a century and helped establish the field as a respected subject of modern science.

In addition, international events of the field also honored the German physicist, like the 3rd and 5th International Symposium on Electrets, occurring respectively in São Carlos (Brazil) and Heidelberg (Germany) for Gross’s 70th and 80th birthday.

In Brazil, many scientists graduated under his influence. Among others, we can name Armando Dias Tavares, Francisco Oliveira Castro, Guilherme Leal Ferreira, Joaquim Costa Ribeiro, Plínio Sussekind Rocha, Roberto Faria, Sérgio Mascarenhas and Yvonne Mascarenhas. Research groups were inspired by Gross, especially in Rio de Janeiro and São Carlos, such as Grupo de Polímeros “Bernhard Gross“, created in the middle of the 70’s at USP São Carlos, from visits of Gross to the university.

In 2002, Bernhard Gross passed away in São Carlos, at the age of 97.

See also

Article by Professor Roberto Mendonça Faria about other research lines of Professor Bernhard Gross, written for SBPMat newsletter.

More information:

Interviews, photos etc. about Bernhard Gross:
Gerhard. M. Sessler. Bernhard Gross and the evolution of  modern electret research. Braz. J. Phys., vol. 29 n.2, São Paulo, June 1999.
Sergio Mascarenhas. Bernhard Gross and his contribution to physics in Brazil. Braz. J. Phys., vol.29, n.2, São Paulo, June 1999.
Gerhard M. Sessler. Bernhard Gross and Electret Research: His Contributions, our Collaboration, and what Followed. IEEE Transactions on Dielectrics and Electrical Insulation    Vol. 13, No. 5, October 2006.

History of materials research: Joaquim da Costa Ribeiro and the thermo-dielectric effect.

Graduation of Costa Ribeiro, 1928. Source: Acervo Costa Ribeiro/ Arquivos Históricos em História da Ciência/CLE-Unicamp.

Graduated as a civil engineer and mechanical electrician engineer in 1928 by the Brazilian National School of Engineering, Costa Ribeiro became a lecturer at the newly founded University of Brazil (today UFRJ) and became part of the National Institute of Technology, which had a better laboratory infrastructure than the university. Thus, Costa Ribeiro participated in two of the very few institutions devoted to teaching and research in science existing in Brazil at the time.

Since 1943, Costa Ribeiro worked with German physicist Bernard Gross, who arrived in Brazil in 1933 and organized the first physics course in Rio de Janeiro two years later. Costa Ribeiro and Gross, giants of Brazilian science, can be considered the national pioneers of condensed matter physics, discipline that is among the pillars of the materials field. By the time they developed their studies, research in Physics in Brazil focused on the Nuclear and Particle fields, developed by scientists such as Cesar Lattes, Mário Schenberg and Jayme Tiomno.

Initially, Costa Ribeiro studied new methods for measuring radioactivity and applying them to Brazilian minerals, achieving notable contributions. Then, he began studying dielectric materials (solid electrical insulators), such as naphthalene and carnauba wax (typical palm tree from Northeastern Brazil), and electrets (solids with quasi-permanent electric charge).

It was then that Costa Ribeiro first observed an interesting effect while working with some dielectric materials. Fusion by heating without the application of external electric fields, caused an electric current to appear in the insulating material. Once solidified, the samples remained charged, constituting electrets. In conclusion, all it took for forming the electret, was the natural solidification of dielectric material after being melted by heating. According to Bernard Gross´s memory, recovered in an article by Professor Guilherme Leal Ferreira , this first experiment was performed with carnauba wax.

The elucidation of the phenomenon

In an interview of the Historical Archives of CLE/Unicamp, held in 1988, scientists Jayme Tiomno and Elisa Frota Pessoa, who were Costa Ribeiro´s students and his aides in the thermal-dielectric effect, shared their memories about the process that led to the elucidation of the phenomenon. According to them, in 1943, Costa Ribeiro decided to take the examination for the position of Professor in the University of Brazil, for which he had to prepare a thesis with original research. The professor then took the suggestion of Bernard Gross and studied pure organic electrets.

“He started by repeating the preparation of the electret using naphthalene and observing its properties. (…) He worked intensely, usually in the afternoons and evenings. One night, after putting the molten naphthalene in a cell to solidify and apply the electric field, he had to stop and leave. On the next day, he removed the naphthalene solid disc to melt and restart, but he decided to examine it using the electrometer. It was an electret!”

Yet, this was not the thermo-dielectric effect, but a static effect, according to Tiomno, who described: “After preparing several electrets without the application of an external electric field, he realized that the effect was stronger when cooling was faster – it was an effect of solidification rate. He, then, built an ingenious and very-well finished apparatus with which he could observe the movement of the liquid naphthalene interface with that solidified by cooling, simultaneously measuring the solidification rate (or melting) and the intensity of the electric current detected in a Wulf electrometer. Upon the verification of the correlation of these quantities, the thermo-dielectric phenomenon or Costa Ribeiro effect was discovered.

Costa Ribeiro in his lab, 1952. Source: Acervo Costa Ribeiro/ Arquivos Históricos em História da Ciência/CLE-Unicamp.

Dissemination of the research

Ribeiro´s first publication describing the effect is dated 1943. Entitled “Sobre a eletrização da cera de carnaúba na ausência de campo elétrico exterior“, the communication was made in the form of a presentation to the Brazilian Academy of Science and then, in an article published in the records of the institution.  In 1945, the thermo-dielectric effect was subject of a thesis presented by Costa Ribeiro to the National Faculty of Philosophy of the University of Brazil in the examination for a position of Professor of General and Experimental Physics. In 1953, the Brazilian Academy of Science awarded him the Einstein Award for the thermo-dielectric effect.

In the interview to CLE/Unicamp, Jayme Tiomno and Elisa Pessoa also talked about the dissemination of the effect abroad. According to them, it began by Costa Ribeiro in Argentina, in meetings of the Argentinian Physics Association in 1945 and 1948. Also in 1948, invited by the University of Paris, Costa Ribeiro conducted three lectures at Sorbonne. In 1951, a summary of his work, which had been published in English in the Records of the Brazilian Academy of  Science, was indexed in the “Physics Abstracts”. In 1954, the scientist held four lectures on his research, in the United States, at the Massachusetts Institute of Technology, in the Bureau of Standards (current National Institute of Standards and Technology), at Yale University and at General Electric.

In May 1950, US scientists Everly J. Workman and Steve E. Reynolds published a paper in Physical Review describing the same phenomenon, observed by them in the phase transition between water and ice. Consequently, the phenomenon of electrification of insulating materials in such change phase is reported in literature under various names, sometimes “Costa Ribeiro effect”, sometimes “Workman-Reynolds effect” or, simply “thermo-dielectric effect.”

The article by Professor Leal Ferreira on the Costa Ribeiro effect states that it is known today that the phenomenon of electrification of dielectrics generated by their solidification had been mentioned in the eighteenth century by Stephen Gray, one of the pioneers of experimental studies on electrical conduction. Ferreira highlights in his article that much beyond the merit of priority of discovery, there is Joaquim Costa Ribeiro´s merit of persistence in experimentally studying the effect found – merit increased by the precarious conditions of work at the time in Brazil.

Despite having a tendency of “getting by” alone, from the construction of his laboratory tools to the interpretation of results, Costa Ribeiro had collaborators in his studies on thermo-dielectric effect. Tiomno, for instance, contributed greatly to the theoretical part, up to a point where he was given a special thanks from the Professor in the thesis presented to the University of Brazil. Armando Dias Tavares and Sergio Mascarenhas were also collaborators and followers of research on the topic.

Regarding the effect applications, Mascarenhas says that the phenomenon has more fundamental than applied science value, although there are some applications, as described in a 1968 article about its use in aeronautical sector radiometers (L.D. Russel and B.H. Beam, Journal of Spacecraft and Rockets, vol. 5, pg. 1501, 1968). “Unfortunately, the effect is little taught in traditional courses,” laments Mascarenhas.

Costa Ribeiro and his wife. Fonte: Acervo Costa Ribeiro/ Arquivos Históricos em História da Ciência/CLE-Unicamp.

More about Joaquim Costa Ribeiro

Married to a French woman, to whom he dedicated many of his poems, Costa Ribeiro was the father of eight children. In order to support his family, at a time when university professors earned a few minimum wages, the scientist had multiple concurrent jobs. He taught at several institutions and schools.

Co-workers and relatives describe him with adjectives like: humanistic, serene, humble, resourceful, self-educated, handy, intuitive, intelligent and thorough.

Very catholic, questioned by his students on how to reconcile religion and science, he said: “It’s simple, I completely separate them. When I am in religion, I am in religion; when I am in science, I am in science”.

In addition to his scientific contributions, Costa Ribeiro played important roles in creating the Brazilian Center for Physical Research, CBPF, (1949) and the Brazilian Federal Council for Scientific and Technological Developmente, CNPq, (1951). He also participated in several national and international initiatives on the use of nuclear energy.

He died in 1960 in Rio de Janeiro.

II ONU consulting meeting on pacific applications of of atomic energy, May 1955. Source: Acervo Costa Ribeiro/ Arquivos Históricos em História da Ciência/CLE-Unicamp.