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Libro resumenes lacame 2014

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Libro de resúmenes LACAME 2014 México estudio de la Espectroscopia Mössbauer

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Libro resumenes lacame 2014

  1. 1. EDITADO POR: Agustin Cabral Prieto (ININ) Eduardo Carpiette (Dirección de Educación Continua ya Distancia – UAEM) Lorena Nara (IPN) Tobías Noel Nava (IMP) Oscar Olea (Facultad de Química-UAEM) IMPRESO Metepec, Estado de México. Octubre 2014 DISEÑO: Dirección de Educación Continua ya Distancia – UAEM
  2. 2. Índice de trabajos LACAME 2014 ..................................................................................................................................................... 1 Topics .................................................................................................................................................................. 2 Latin American Conference on the Application of Mössbauer Spectroscopy .................................................... 3 25 AÑOS DE CONGRESOS LATINOAMERICANOS DE ESPECTROSCOPÍA MÖSSBAUER................................. 5 Committees ........................................................................................................................................................ 7 Sponsors ............................................................................................................................................................. 8 Thanks ................................................................................................................................................................ 9 SCIENTIFIC PROGRAM ...................................................................................................................................... 10 Invited Speakers ............................................................................................................................................... 11 T02: CONTRIBUTIONS OF MÖSSBAUER SPECTROMETRY TO THE STUDY OF SOME OXIDE DILUTED MAGNETIC SEMICONDUCTORS: A CRITICAL REVIEW .......................................................................... 12 T05: CHEMISTRY AND ENVIRONMENTAL APPLICATIONS OF HIGH‐VALENT IRON‐OXO SPECIES ................ 13 T05: DESIGN OF SELF AND MATRIX‐SUPPORTED SYSTEMS OF IRON OXIDE NANOPARTICLES FOR CATALYTIC APPLICATIONS ................................................................................................................... 14 Participations .................................................................................................................................................... 15 T02: MÖSSBAUER SPECTROSCOPY AS SOURCE OF COMPLEMENTARY A PRIORI INFORMATION TO SOLVE CRYSTAL STRUCTURES FROM XRD POWDER DATA ............................................................................. 18 T02: NUMERICAL ANALYSIS OF BROAD MÖSSBAUER SPECTRA BY USING SIMPLE DISTRIBUTION FUNCTIONS .......................................................................................................................................... 19 T02: STRUCTURAL AND HYPERFINE PROPERTIES OF M‐DOPED SNO2 (M=TRANSITION METAL OR RARE EARTH ELEMENT) NANOPARTICLES ..................................................................................................... 20 T04: SYNTHESIS AND CHARACTERIZATION OF MAGNETITE NANOPARTICLES FUNCTIONALIZED WITH CARBOXYL AND AMINO ACIDS FOR BIOMEDICAL AND ENVIRONMENTAL APPLICATIONS ................. 23 T05: PHOTOCATALYTIC EFFECT AND MÖSSBAUER STUDY OF IRON TITANIUM SILICATE GLASS PREPARED BY SOL‐GEL METHOD ........................................................................................................................... 25 T06: 57Fe‐MÖSSBAUER STUDY OF ZIRCONIA CONTAINING IRON VANADATE CLYSTALLIZED GLASS WITH HIGH ELECTRICAL CONDUCTIVITY ....................................................................................................... 27 T08: CORRELATION BETWEEN MILLING TIME OF POWDER, AND THE TEMPERATURE OF SUBSTRATE ON THE PROPERTIES OF NdFe THIN FILMS ................................................................................................ 30 T08: IN γ‐Fe2MnGa COMPOUND DO Fe AND Mn ORDER MAGNETICALLY AT THE SAME TEMPERATURE? DO THEY COUPLE PARALLEL OR ANTIPARALLEL AT LOW TEMPERATURES? ....................................... 31
  3. 3. T08: MAGNETIC PROPERTIES OF TWO CORE/SHELL NANOPARTICLES COUPLED VIA DIPOLAR INTERACTION ............................................................................................................................................................. 32 T08: MÖSSBAUER AND STRUCTURAL STUDY OF ALLOYS Fe1‐XVX OBTAINED BY MECHANICAL ALLOYING .. 33 T08: MÖSSBAUER INVESTIGATIONS ON THE DESORBTION OF HYDROGEN AND HYDROXYL FROM THE IRON OXIDE NANOPARTICLES .............................................................................................................. 34 T08: MÖSSBAUER STUDY OF ALLOYS Fe67.5Ni32.5, PREPARED BY ALLOY MECHANICAL ................................ 35 T08: SPIN DYNAMICS IN COEXISTING ANTIFERROMAGNETIC AND SPINGLASS STATES OF MULTIFERROIC LEAD PEROVSKITES .............................................................................................................................. 36 T08: STUDY OF STRUCTURAL, OPTICAL AND MAGNETIC PROPERTIES OF Fe DOPED, Co DOPED, AND Fe‐Co CO‐DOPED ZnO .................................................................................................................................... 37 T08: SYNTHESIS AND CHARACTERIZATION OF NixCo1‐xFe2O4 Nanoparticles ................................................ 38 T08: SYNTHESIS OF SILVER ‐COATED MAGNETITE NANOCOMPOSITE FUNCTIONALIZED BY AZADIRACTHA INDICA .................................................................................................................................................. 39 T10: MÖSSBAUER AND XRD CHARACTERIZATION OF THE PHASE TRANSFORMATIONS IN A Fe‐Mn‐Al‐C AS. CAST ALLOY DURING TRIBOLOGY TEST ................................................................................................ 42 T10: STRUCTURAL STUDY ON Li2Fe1‐xNixSiO4 ............................................................................................... 43 Posters .............................................................................................................................................................. 44 Authors index ................................................................................................................................................. 133
  4. 4. 1 LACAME 2014 XIVth Latin American Conference on the Applications of the Mössbauer Effect ‐ LACAME 2014 LACAMEs are special scientific events. They are regional meetings that aim at stimulating the development of Mössbauer Spectroscopy (MS) in Latin American countries, all of them with unparallel common cultural roots, but most of them with limited resources. MS is a particular technique suitable for promoting the scientific development in these societies. The organization of a conference like LACAME gives the young scientists of the region who do not have many chances to visit other laboratories or attend the ICAME meetings the opportunity to improve their scientific progress, and brings to the scientific communities and young researchers the feeling of how experimental physics can be performed at a high level. As a consequence of these meetings, the Mössbauer community is growing in Latin America. New laboratories have been set up and the improvement of the existing ones has been observed. The collaboration, interchange and scientific agreements between laboratories, some of them isolated prior to the LACAME conferences, have been greatly enhanced. The XIVth Latin American Conference on the Applications of the Mössbauer Effect ‐ LACAME 2014 will be held from November 10th to 14th, 2014 in Mexico. LACAME started in 1988 in Rio de Janeiro and has grown steadily since then, changing the venue every two years from different nations where Mössbauer research laboratories exist. We do believe that the special ingredient added by LACAME will help flourish the development of science and MS in this part of the world; let us hope this trend continues growing. We welcome you all to LACAME‐2014. November 2014.
  5. 5. 2 Topics T01‐ Advances in experimentation and Data Processing T02‐ Amorphous, Nanocrystals and Nanoparticles T03‐ Applications in Soils, Mineralogy, Geology, Cements and Archaeology T04‐ Biological and Medical Applications T05‐ Catalysis, Corrosion and Environment T06‐ Chemical Applications, Structure and Bonding T07‐ Industrial Applications T08‐ Magnetism and Magnetic Materials T09‐ Multilayers, Thin Films and Artificially Structured Materials T10‐ Physical Metallurgy and Materials Science
  6. 6. Latin American Conference on the Application of Mössbauer Spectroscopy 3 Elisa Baggio Saitovitch We can not speak about Mössbauer spectroscopy in Latin America without speaking about Jacques Danon who passed away in 1989. He has initiate to work already in 1960 in this field at Brazilian Center for Research in Physics (CBPF), in Rio de Janeiro. He always insisted that we should not compete with the countries of north hemisphere but exercise our creativity in scientific research, looking for topics related with our region or having a new approach in frontier topics, addressing topics that can be studied in the frame of the scientific and technologic difficulties (not facilities). He always said: Lo que es importante, no son las técnicas y computadores, son las ideas. Solamente la creatividad puede generar un verdadero progreso tanto en la ciencia como en cualquier campo de la actividad humana. In the early days of Mössbauer spectroscopy in Latin America there was more interaction; this was not the case when I started to work in Mössbauer spectroscopy. Danon always mentioned collaboration with Augusto Moreno y Moreno, in Mexico, Carlos Abeledo and Albert Fech. He published the first lectures in Spanish on the Mössbauer effect given at the Escuela Latino Americana de Física that was held in Mexico, in 1968. In 1985, while participating in a commission to discuss the future of CLAF (Latin American Center for Physics) I realized how bad the scientific collaboration among Latin American groups doing research was; they tend to give priority to the interaction with groups in north hemisphere. The collaboration with our neighbors in Latin America would not occur spontaneously, it was necessary to be worked out because, more than the proximity, they have common problems. With these ideas in mind I went to a Brazilian meeting in Mössbauer spectroscopy, which was the last from a series going through all the groups (see H. Rechenberg report). Our idea was to change a bit the scope including all Brazilian groups working in Hyperfine Interaction. There I have made another proposition: open the meeting to all the Mössbauer groups in Latin America. This proposition was accepted and I suggested that the Chairperson should be Jacques Danon, knowing that I should do the heavy work. In November 1988 we organized in Rio, with the help of Rosa Scorzelli the first LACAME; the name of our meeting was inspired in the ICAME. At those days we were able to bring together more than 129 participants! I believe that most of the people working in this area came to Rio. It was difficult to contact all the people, in this case the contribution of Danon
  7. 7. was essential: he knew everybody. But there was no e‐mail, no telephone and the best communication was by telegram and fax. For the first time I learned about Raiza from Havana, Jaen in Panama or Aburto in Mexico. The situation in Brazil in 1989 was very favorable for our purpose; the inistry of Science and Technology had been just created. I was able to get support from several Brazilian institutions and foundations as CBPF, CNPq, CNEN, FINEP, CAPES and CLAF. The total budget was about US$ 50 000 and the invitation included air ticket, hotel and meals. Circa of 10 non Latin American scientist specialists in different fields were invited and contributed to the success of the conference. I still remember how the eyes of some students were shining when they could listen to these known specialists in Mössbauer spectroscopy. All the effort was worthwhile! After that we had the nice meeting in Cuba with the conversation with Fidel Castro and many non Latin American participants. Argentina, Chile, Peru, Colombia, Venezuela, Panama and Mexico (in 2004), it has been a long way, with a lot of efforts (the chair persons know it well), but the result is excellent. The number of participants has decreased along these 15 years. May be there is now less people in the field or less funds available, this we still need to find out. In Brazil the strong group of Porto Alegre, where I was introduced to Mössbauer spectroscopy, has only a minor activity and sometimes does not participate even in the Brazilian meetings. To compensate now we have the group of Vitoria and Ouro Preto, which are very active and have organized the last Brazilian meetings. New groups have been created in Peru (Victor Peña Rodrigues) and Colombia (Perez Alcazar) and they are very active as we could see in the last conferences. From the successive meetings we can follow the development of some students like Restrepo from Colombia. He gave a talk in Caracas as a senior scientist! Despite this conference became smaller they are very dynamic with a lot of discussion and interesting questions. I hope we can keep this atmosphere for Mexico. This meeting have been very important for the participants, researchers and students that do not have the opportunity to participate in the ICAMEs. Traditionally some few non Latin American specialists are invited speakers together with local researchers from areas where Mössbauer spectroscopy can be applied. For example, in Venezuela we had some talk about Petroleum industry. We try to avoid inviting the same non Latina American specialists in two successive meetings in order to cover different areas. The LACAME has contributed for the collaboration among LA groups and for spreading this spectroscopy in LA. All the applications are being studied, including minerals, meteorites, soils, superconducting and magnetic materials, milling, catalyses, corrosion, chemistry, thin films, heavy fermions, 4
  8. 8. etc. However we still hope to be able to improve the shearing of the facilities among the groups and establish bilateral official exchange programs. On a regular basis the LACAME conferences are organized in Latin America, each two years and we succeeded in organizing and reinforcing the collaboration among the Mössbauer community in Latin America. Except for the conference in Chile the Proceedings have been published by Hyperfine Interaction. 25 AÑOS DE CONGRESOS LATINOAMERICANOS DE ESPECTROSCOPÍA MÖSSBAUER Por estos días se están cumpliendo los 25 años de nuestra existencia como comunidad latinoamericana de espectroscopía Mössbauer. Es con enorme alegría que queremos celebrar este aniversario. En 1988, con la excepción de Brasil, que realizaba desde1982 encuentros locales de jóvenes investigadores, en nuestro continente había algunos laboratorios dispersos con investigadores que pretendíamos hacer buena ciencia sin muchos medios a pesar las grandes dificultades que se presentaban en nuestros países. Esto cambiaría para siempre cuando, entre el 31 de octubre y el 4 de noviembre de 1988 se organizó el primer Congreso Latinoamericano de Espectroscopía Mössbauer. Allí nos conocimos y rápidamente nos identificamos como formando parte de una comunidad científica. En estos veinticinco años, hemos crecido individual y colectivamente y nos sentimos miembros de una realidad que trasciende las fronteras de nuestros países para constituirse en una unidad latinoamericana que encuentra gran placer y ventaja en colaborar con colegas de otros países de la región y reencontrarse con viejos (y no tan viejos) amigos cada dos años en los LACAME y en numerosas colaboraciones entre distintos miembros de la comunidad. En este tiempo hemos visto aparecer laboratorios de luz sincrotrón, centros de microscopía electrónica, la Internet. En nuestras propias instituciones se han agregado nuevas técnicas que como la calorimetría o la magnetometría nos han permitido profundizar enormemente nuestras investigaciones. Sin embargo, todo esto no ha desviado nuestra convicción de que lo que nos une es la espectroscopía Mössbauer. En otros continentes esta realidad es de mucha menor intensidad o simplemente no existe ya. Pero ciertamente en América latina nuestros congresos gozan de prestigio y de entusiasmo, con nuevos jóvenes que se sienten parte de esta comunidad convocante que tiene un gran reconocimiento internacional. 5
  9. 9. Por eso, el Comité Latinoamericano de Espectroscopía Mössbauer saluda jubilosamente a los colegas latinoamericanos y hace votos para que las nuevas generaciones tengan éxito en sus esfuerzos de continuar y mejorar lo que ya ha sido hecho hasta aquí. 6
  10. 10. 7 Committees Intenational Committee E.M. Baggio Saitovitch CBPF Brazil N.R. Furet Bridón CNIC Cuba F. González Jiménez UCV Venezuela J.A. Jaén UP Panamá R.C. Mercader UNLP Argentina N. Nava IMP México V.A. Peña Rodríguez UNMSM Perú G.A. Pérez Alcázar UV Colombia Carmen Pizarro USACH Chile Local organizing committee Humberto Arriola S. Facultad de Química, Universidad Nacional Autónoma de México Agustín Cabral Prieto Instituto Nacional de Investigaciones Nucleares Naria Adriana Flores Fuentes Escuela Superior Físico‐Matemáticas, Instituto Politécnico Nacional Arturo García Borquez Escuela Superior Físico‐Matemáticas, Instituto Politécnico Nacional Eduardo Gómez Garduño DECyD, Universidad Autónoma Estado México Ezequiel Jaimes Figueroa DECyD, Universidad Autónoma Estado México Rafael López Castañares Facultad de Química, Universidad Autónoma Estado México Fabiola Monroy Guzmán Instituto Nacional de Investigaciones Nucleares Noel Nava E. Instituto Mexicano del Petróleo Oscar Olea Cardoso Facultad de Química, Universidad Autónoma Estado México Oscar F. Olea Mejia Facultad de Química, Universidad Autónoma Estado México Jesús Soberón M. Investigador
  11. 11. 8 Sponsors Abdus Salam International Centre for Theoretical Physics Sociedad Química de México Universidad Autónoma del Estado de México Consejo Mexiquense de Ciencia y Tecnología Instituto Nacional de Investigaciones Nucleares Instituto Mexicano del Petróleo
  12. 12. 9 Thanks Los Comités Internacional y Local de la XIV Latin American Conference on the Applications of the Mössbauer Effect aprecian y agradecen profundamente al Rector de la Universidad Autónoma del Estado de México, Dr. en D. Jorge Olvera García, por habernos permitido realizar esta conferencia en las instalaciones de la Dirección de Educación Continua y a Distancia (DECyD‐UAEM). Así mismo, agradecemos al Maestro Ezequiel Jaimes Figueroa, Director de la DECyD‐UAEM, por todo el apoyo y facilidades que nos brindó durante la organización de dicha conferencia, así como a su equipo de trabajo por su invaluable aportación para preparar el compendio de los resúmenes que se presentan en este libro.
  13. 13. 10 SCIENTIFIC PROGRAM SUNDAY NOV. 9 MONDAY NOV. 10 TUESDAY NOV. 11 WEDNESDAY NOV. 12 THURSDAY NOV. 13 FRIDAY NOV. 14 9:00 Opening Ceremony 9:00 J A Jaen 9:00 Mira Ristic VideoC 9:00 Elisa Baggio‐ Saitovitch 9:00 Roberto C. Mercader 9:30 Cesar A Barrero M 9:45 Coffee 9:45 Coffee 9:45 Coffee 10:15 Coffee 10:05 V Sharma 10:00 Coffee 10:05 F.J. Litterst 10:05 Edilso Reguera 10:35 Edson P 10:50 W. T. Herrera City tour 10:50 P.M.A. Caetano 11:10 Dagoberto Oyola Lozano 11:30 Herojit Singh 11:50 J.J. Beltrán 12:10 J. L. López 10:50 Concluding Remarks 11:20 G.A. Pérez Alcázar 11:30 S. Kubuki 11:40 José Domingos Fabris 11:50 Aguirre‐Contreras Next LACAME 12:00 Y. Takahashi, 12:10 Benítez Rodríguez 12:20 Lunch 12:30 Lunch 12:30 Lunch 14:00 Rojas Martínez 14:00 POSTER SESSION1 14:00 POSTER SESSION2 14:20 J. A. H. Coaquira 18:00 Registration Latin American Round Table 19:00 – 21:00 Welcome
  14. 14. Invited Speakers 11
  15. 15. T02: CONTRIBUTIONS OF MÖSSBAUER SPECTROMETRY TO THE STUDY OF SOME OXIDE DILUTED MAGNETIC SEMICONDUCTORS: A CRITICAL REVIEW J.J. Beltrán1, A. Punnoose2, K. Nomura3, E.M. Baggio-Saitovitch4, and C.A. Barrero1 1Grupo de Estado Sólido, Facultad de Ciencias, Universidad de Antioquia, Medellín, Colombia. 2Department of Physics, Boise State University, Boise, USA 3Department of Applied Chemistry, School of Engineering, The Tokyo University, Tokyo, Japan 4Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro, Brazil. 12 *Corresponding author: e-mail: cesar.barrero@udea.edu.co Keywords: Fe doped ZnO, Fe doped SnO2, nanoparticles. Topic: T02- Amorphous, Nanocrystals and Nanoparticles In 2005, the prestigious journal Science [1] posed a list of 125 unsolved scientific questions, one of them being: “is it possible to create magnetic semiconductors that work at room temperature?”. In 2008, Coey et al. [2] mentioned that the origin of the magnetism in Diluted Magnetic Semiconductors (DMS) is one of the most puzzling investigations. And to date we can say that the understanding of such phenomena is still a great challenge in materials science. In fact, there is no agreement between the various theoretical and experimental studies performed on the origin of the ferromagnetic signal in DMS, particularly in Oxide-DMS (ODMS). From the experimental side, the use of different characterization techniques, including Mössbauer spectrometry (MS), is an important requirement to achieve a better understanding of the phenomena. In this presentation we will show some examples of the contributions that 119Sn and 57Fe MS have done to the characterization of Fe-doped ZnO [3], Fe-Co codoped ZnO [4], Fe-doped SnO2 [5-7] and Fe-Sb codoped SnO2 [8,9] nanoparticles. We will show how this technique has contributed to the: (i) demonstration of the absence of both spurious phases and clustering of dopants, (ii) determination of the preferable sites, high or low spin character, and oxidation states of the transition metal (TM) ions, (iii) identification of the preferable location of the TM ions, either at the surface, at the interior or in the whole nanoparticles, (iv) identification and characterization of defects, (v) proper characterization of the electronic, crystallographic, and magnetic properties, and their possible relations, (vi) and determination of the TM ions that are involved in the magnetic ordering. References [1] Kennedy and Norman, Science 309 (2005) 82. [2] J.M.D. Coey, K. Wongsaprom, J. Alaria, and M. Venkatesan, J. Phys. D.: Appl. Phys. 41 (2008) 134012. [3] J.J. Beltrán, J.A. Osorio, C.A. Barrero, C.B. Hanna and A. Punnoose, J. Appl. Phys. 113 (2013) 17C308. [4] J.J. Beltrán, C.A. Barrero, A. Punnoose, J. Phys. Chem. C, V. 19 (3) (2014) [5] A. Punnoose, K. Dodge, J.J. Beltrán, K.M. Reddy, N. Franco, J. Chess, J. Eixenberger, and C.A. Barrero, J. Appl. Phys. 115 (2014) 17B534 [6] J.J. Beltrán, L.C. Sánchez, J. Osorio, L. Tirado, E.M. Baggio-Saitovitch, and C.A. Barrero, J. Mater. Sci. 45 (2010) 5002 [7] K. Nomura, C.A. Barrero, J. Sakuma, and M. Takeda, Phys. Rev. B 75 (2007) 184411 [8] K. Nomura, C.A. Barrero, K. Kuwano, Y. Yamada, T. Saito, E. Kuzmann, Hyperfine Interact. 191 (2009) 25. [9] K. Nomura, E. Kuzmann, C.A. Barrero, S. Stichleutner, and Z. Homonnay, Hyperfine Interact. 184 (2008) 57.
  16. 16. T05: CHEMISTRY AND ENVIRONMENTAL APPLICATIONS OF HIGH-VALENT IRON-OXO SPECIES Virender K. Sharma1*, Radek Zboril2, Libor Machala2, and Karolina Siskova2 1Departent of Environmental and Occupational Health, School of Public Helath, Texas A&M University 1266 TAMU, SPH 101, College Station, Texas. 2 Regional Centre of Advanced Technologies and Materials, Departments of Experimental Physics and Physical Chemistry, Faculty of Science, Palacky University, 78371 Olomouc, Czech Republic 13 *Corresponding author: e-mail: vsharma@sph.tamhsc.edu Keywords: Ferrate, oxidation, decontamination Topic: T05- Catalysis, Corrosion and Environment The chemistry of iron has been developed early in the history of mankind as it is the basic metal of the industrial society and its ore is profoundly present globally. Iron as the most abundant transition element, present in alloy with nickel, and constitutes about a third of entire mass of the Earth’ crust. Iron is important for most of the living organisms. Iron has a unique range of valence states from zero to +6 oxidation states, which have numerous applications in medicine, energy, nanotechnology, biocatalysis, energy, and environmental remediation. Examples of biocatalysis include involvement of high-valent oxoiron(IV) (FeIV = O) and oxoiron(V) (FeV = O) species in a number of enzymatic systems (1). These high-valent iron species participate in halogenation, epoxidation, and hydroxylation reactions. In the last decade, our research group is researching the simple oxo-compounds of higher-valent iron species, commonly called ferrates (FeVIO42-, Fe(VI), FeVO43-, Fe(V), and FeIVO44-, Fe(IV)) in aqueous solution, which have shown their applications in energy materials, green organic synthesis, and waste remediation (2). Examples of remediation are oxidative transformations of toxic inorganic and organic contamination to non-toxic by products, inactivation of virus and bacteria, and removal of toxic metals (e.g. arsenic) (3, 4). The focus of the presentation will be on demonstrating the chemistry and applications of these high-valent iron species in water treatment technology. Mössbauer spectra of Fe(VI), Fe(V), Fe(IV) and Fe(III) species can be used to distinguish these iron species in the solid phase and in the solution mixture. The isomer shift values of ferrates decreased almost linearly and can be expressed as Δ (mm s-1) = 1.084 – 0.326 × OS (1) Mechanisms of the reactions of ferrates with different contaminants were studied using Mössbauer spectroscopy in conjunction with other spectroscopic and surface techniques. Figure 1 shows the example of studying the removal of arsenic by Fe(VI) in which ex-situ and in-situ removal by Fe(III), generated from Fe(VI), differ. Figure 1. Different mechanisms of arsenic removal by Fe(III), ex-situ sorption (left) and Fe(VI) induced in-situ structural incorporation (right) (5). References [1] J. Hohenberger, K. Ray, and K. Meyer, Nature Commun. 3720 (2012). [2] V. K. Sharma, Coord. Chem. Rev. 257 (2013) 494-510. [3] E. Casbeer, V.K. Sharma, Z. Zajickova, and D.D. Dionysiou, Environ. Sci. Technol., 47 (2013), 4572-4580. [4] V.K. Sharma, J. Environ. Manage. 92 (2011), 1051-1073. [5] R. Prucek, J. Tucek, J. Kolařík, J. Filip, Z. Marušák, V.K. Sharma, and R. Zboril, Environ. Sci. Technol. 47 (2013) 3283-3292.
  17. 17. T05: DESIGN OF SELF AND MATRIX-SUPPORTED SYSTEMS OF IRON OXIDE NANOPARTICLES FOR CATALYTIC APPLICATIONS I.O. Pérez de Berti1, J.F. Bengoa1, S.G. Marchetti1, R.C. Mercader2* 1CINDECA, CONICET, CICPBA, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 47 Nº 257, 1900 La Plata, Argentina 2 Instituto de Física La Plata, CCT-CONICET, Departamento de Física, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 115 y 49, 1900 La Plata, Argentina *Corresponding author: e-mail: mercader@fisica.unlp.edu.ar Keywords: Fischer-Tropsch reaction, semi-model catalysts, Mössbauer characterization, pre-synthesized nanoparticles Topic: T05- Catalysis, Corrosion and Environment 14 Metallic nanoparticles are widely used as supported catalysts in many industrial chemical reactions. A detailed understanding of the enhancement that the nanoparticles bring about in the stability, activity, and selectivity of the solids requires quasi-model catalysts with well-defined surfaces and supported nanoparticles of homogeneous size. The usual way of synthesizing catalysts of supported nanoparticles is to impregnate the solid with a solution that contains the metal salts that will give rise to the catalyst. However, this route doesn't necessarily lead to a catalyst close to the ideal conditions. The Fischer-Tropsch synthesis is a reaction in which a mixture of hydrogen and carbon monoxide converts into liquid hydrocarbons mediated by the presence of a catalyst. The reaction process can be written as: nCO + (2n+1) H2  CnH2n+2 + nH2O In spite that it was developed in the 1920s and that it has been intensively used over many decades, the intrinsic mechanism of how it proceeds is not fully known. In particular, the activity and selectivity depend on factors that are not easy to isolate. One of them is the so-called structure sensitivity. To be able to study the diverse influence of the different parameters in the activity and selectivity of the catalysts, we set about to prepare quasi-model catalysts by a route different from the usual one; we pre-synthesized systems of narrowly size-distributed nanoparticles and introduced them afterwards into the already synthesized matrix. In this talk we will describe the results obtained after the preparation of Fischer-Tropsch catalysts made up 3 nm maghemite nanoparticles supported on SBA-15 matrices. The catalysts were prepared by pre-synthesizing γ-Fe2O3 particles and further embedding them into a modified SBA-15 matrix. The results showed that the solid kept its structural properties over impregnation, activation and catalytic reaction performed in realistic conditions. Out of the many techniques by which we characterized the solids, Mössbauer spectroscopy was the one that yielded the more helpful results allowing the identification of all the relevant intervening iron species. Figure 1. Mössbauer spectra of γ-Fe2O3/SBA-15 catalysts measured at the temperatures indicated after a catalyst reaction conducted at 20 atm. As an example of the results that will be considered in the talk, Fig. 1 displays the Mössbauer spectra of two catalysts that produced a high activity and a good olefin/paraffin ratio over the Fischer-Tropsch reaction at 20 atm after being activated in a CO-H2: CO atmosphere (left) and H2 atmosphere (right). Both solids underwent catalysis tests and were measured in a specially designed cell that enabled keeping the same reactor atmosphere when taken over to the Mössbauer spectrometer.
  18. 18. Participations 15
  19. 19. T01‐ Advances in experimentation and Data Processing 16
  20. 20. T02‐ Amorphous, Nanocrystals and Nanoparticles 17
  21. 21. T02: MÖSSBAUER SPECTROSCOPY AS SOURCE OF COMPLEMENTARY A PRIORI INFORMATION TO SOLVE CRYSTAL STRUCTURES FROM XRD POWDER DATA Edilso Reguera Center for Applied Science and Advanced Technology, Legaria Unit, National Polytechnic Institute, Mexico, D. F., Mexico; Corresponding author: e-mail: edilso.reguera@gmail.com Topic: T02- Amorphous, Nanocrystals and Nanoparticles Mössbauer spectra provide information on the coordination geometry for the atom involved in the - resonant nuclear absorption, on the nature of first and second neighbors, and on its electronic structure and relative occupation of structural sites in the solid. All this information is relevant to solve the crystal structure of new materials from XRD powder data. To solve the crystal structure of a new material the best option is to have diffraction data from a single crystal. Such possibility is available only for a small fraction, usually < 10 %, of practical situations. In a single crystal experiment, the diffraction pattern is the Fourier Transform for the sample in the inverse space and the crystal model to be refined (in the direct space) is obtained from the Inverse Fourier Transform of the recorded diffraction pattern. In XRD powder experiment, the 3D structural information is projected in 1D space. From this fact, the crystal structure for this kind of data must be solved through an ill-posed problem. This supposes the availability of a priori structural information or boundary conditions for the mathematical problem to be solved. Such a priori information is usually obtained from spectroscopic techniques. Nuclear, electronic and vibrational spectra contain information on the local symmetry (coordination geometry) and nature of the first neighbors for the atom(s) involved resonant absorption and re-emission. In this contribution, the scope of Mössbauer spectroscopy in that sense is discussed, from several illustrative examples, where the crystal structure was solved and then refined, using the corresponding Mössbauer spectra as source of the required a priori structural information. 18
  22. 22. T02: NUMERICAL ANALYSIS OF BROAD MÖSSBAUER SPECTRA BY USING SIMPLE DISTRIBUTION FUNCTIONS B. Aguilar-García1, A. Sandoval-Nandho1, I. García-Sosa2 O. R. López-Castañares3, O. Olea-Cardoso3 and A. Cabral-Prieto2(*) 1Universidad Autónoma Metropolitana-Cuajimalpa, Avenida Vasco de Quiroga 4871, Cuajimalpa, Santa Fe Cuajimalpa, 05300 Ciudad De México, D.F. 2 Instituto Nacional de Investigaciones Nucleares, Departamento de Química, Apdo. Postal 18-1027, Col. Escandón, Deleg. M. Hidalgo, C. P. 11801, México. D. F., México. 3Universidad Autónoma del Estado de México, Paseo Universidad #100, Universitaria, 50130 Toluca de Lerdo, Estado de México *Corresponding author: e-mail: agustin.cabral@inin.gob.mx Keywords: Broad Mössbauer spectra, hyperfine distributions, goettite Topic: T02- Amorphous, nanocrystal and nanoparticles 19 The analysis of broad Mössbauer spectra is usually handled by using the convolution between the Gaussian and Lorentzian lines. There are, however, many cases were this convolution does not give meaningful results because the Mössbauer spectra are the result of a complex superposition of several patterns and the discrete hyperfine parameters are difficult to calculate from them. In such cases the use of hyperfine distribution functions are preferred [1]. In this paper simple distribution functions are used to analyze the Mössbauer spectrum of Goethite nanoparticles. The asymmetrical triangle is shown in Fig. 1. Figure 1 (a) Mössbauer spectrum of goethite nanoparticles recorded at 77K. (b) Asymmetrical triangular distribution function may be used to properly fit this spectrum. Typical representations of the hyperfine field distributions (HFD) for this nano material are as shown in Fig. 2 (a) and (b), obtained with known methods [1, 2]. Figure 2. (a) Step distribution function [1], (b) Fourier series expansion [2]. Figure 3. (a) Gaussian, (b, c) Rational, (d) binomial distribution functions. Figure 3 shows, on the other hand, three atypical representations of the HFD. The decaying curve, after the maxima, does not appear which seems to be unnecessary for cases like this. If it does such a decay is abrupt as indicated in figs. 1 (a). Fig. 2 (a) and (b) or Fig. 3 (b). In all these cases there is always a question left: what of the seven HFDs, here presented, represents best the experimental data. Morup et al. [3] reproduces the asymmetry of a Mössbauer spectrum by using an asymmetrical distribution function for the crystal size of nanomaterials. Thus, Fig. 3 (d) may be the best searched solution instead of Fig. 2 (b). In all presented cases the same order of magnitude for squared Ji is, however, acceptable. References [1] J. Hesse, A. Rübartsch, Journal of Physics E 7 (1974) 526. [2] Window, B.: J. Phys. E: Sci. Intrum. 4, 401 (1971) [3] S. MØrup , H. TopsØe and J. Lipka, Journal de Physique Colloque C6, sup.12, Tome 37, (1976) C6- 287.
  23. 23. T02: STRUCTURAL AND HYPERFINE PROPERTIES OF M-DOPED SNO2 (M=TRANSITION METAL OR RARE EARTH ELEMENT) NANOPARTICLES J. A. H. Coaquira1, F. H. Aragón1, J. C. R. Aquino1, R.Cohen2, L.C.C.M. Nagamine2, P. Hidalgo3, D. Gouvêa4 1Instituto de Física, Universidade de Brasília, Núcleo de Física Aplicada, Brasília DF 70910-900, Brazil. 2 Instituto de Física, Universidade de São Paulo, SP 05508-090,Brazil 3Faculdade Gama-FGA, Sector Central Gama, Universidade de Brasília, Brasília, DF 72405-610, Brazil. 4Departamento de Metalurgia e Engenharia de Materiais, Escola Politécnica, Universidade de São Paulo, São Paulo SP 05508-900, Brazil. *Corresponding author: e-mail: coaquira.ja@gmail.com Keywords: M-doped SnO2 nanoparticles, Mössbauer spectroscopy, structural properties Topic: T02- Amorphous, Nanocrystals and Nanoparticles The possibility of using the magnetic properties of magnetic gas sensing materials instead of their conventional electrical properties is moving forward the interest for dilute magnetic semiconductor oxides. The SnO2 compound is a wide band-gap (~3.5 eV) semiconductor and widely used as a conventional gas sensor due to its high reactivity with environmental gases. The doping of this semiconductor using transition metals changes its sensitivity, selectivity and time response with respect to a number of pollutant gases. However, the use of magnetic gas sensors requires that the sensing material shows magnetic order above room temperature. Although reports indicate room temperature ferromagnetic properties of transition-metal- doped SnO2 thin films and powders, the origin of that order is not clear yet [1]. 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 10.0 mol% 5% 2.5 mol% Transmission (a. u.) 7.5 mol% P (QS) P (QS) QS (mm/s) P (QS) QS (mm/s) P (QS) QS (mm/s) 0.0 mol% -8 -6 -4 -2 0 2 4 6 8 Velocity (mm/s) 0 1 2 3 4 5 6 7 QS (mm/s) 12 Experimental data 8 4 0 -4 Figure 1. Room-temperature Mossbauer spectra of Gd-doped SnO2 nanoparticles. Isomer shift (IS) as a function of the Gd content. In this work, we report the study of the structural and magnetic properties of M-doped SnO2 (M=transition metal or rare earth element) nanoparticles synthesized by a polymer precursor method [2]. X-ray diffraction patterns indicate the formation of only the rutile phase for the whole set of samples. Undoped SnO2 nanoparticles show an average particles size of ~11 nm and this size shows a decreasing tendency as the M content is increased, regardless the M dopant. This crystalline size is further corroborated by TEM images. Magnetic measurements, carried out in a wide range of temperature and applied magnetic field, suggest the coexistence of ferromagnetic and paramagnetic phases. Depending on the dopant content, a ferromagnetic behavior which survives until high temperatures is determined. Mössbauer spectra, carried out using a Ca119mSnO3 radiation source, show no evidences of magnetic splitting and, depending on the doping element (M), room temperature Mössbauer spectra are well resolved by considering doublets. The origin of these doublets and the effects on the quadrupole splitting and isomer shift due to the doping are discussed in this work. References [1] W. Wang, Z. Wang, Y. Hong, J. Tang, and M. Yu, J. Appl. Phys. 99 (2006) 0M115. [2] D. Gouvêa, A. Smith, J. P. Bonnet, Eur. J. Solid State Inorg. Chem. 33 (1996) 1015. 0 2 4 6 8 10 -8 IS (x10-3mm/s) Gd content (%)
  24. 24. T03‐ Applications in Soils, Mineralogy, Geology, Cements and Archaeology 21
  25. 25. T04‐ Biological and Medical Applications 22
  26. 26. T04: SYNTHESIS AND CHARACTERIZATION OF MAGNETITE NANOPARTICLES FUNCTIONALIZED WITH CARBOXYL AND AMINO ACIDS FOR BIOMEDICAL AND ENVIRONMENTAL APPLICATIONS W. T. Herrera1, A.G. Bustamante Domínguez1, M. Giffoni2, E. Baggio-Saitovitch2 and J. Litterst3 1 Ceramics and Nanomaterials Laboratory, Department of Physics, National University of San Marcos (UNMSM), A.P. 14-0149, Lima 14, Perú. 2 Brazilian Center for Physics Research (CBPF), 22290-180, Rio de Janeiro, Brazil. 3 Institute for Physics of Condensed Matter, Technische Universität Braunschweig (TU Braunschweig), Mendelssohnstrasse 3, D-38106 Braunschweig, Germany. *Corresponding author: e-mail: wiliam@agdes.pe Keywords: magnetite nanoparticles functionalized, magnetic nanoparticles Topic: T04 - Biological and Medical Applications 23 This work involves the synthesis of magnetite nanoparticles (NPs) functionalized with lauric acid (LA), oleic acid (OA) and lysine (Lys). The synthesis was carried out using a chemical route of co-precipitation. This route allows the production of NPs functionalized using a basic infrastructure, low cost of production, the latter very important, especially if we consider the potential applications in the field of environmental remediation. In the case of biomedical applications also chemical route is the best alternative in this case however requires a more extensive characterization and clinical trials. After synthesis of functionalized NPs these were characterized with the techniques: X-ray diffraction (XRD), transmission electron microscopy (TEM), Mössbauer spectroscopy (MS), vibrating sample magnetometry (VSM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and thermogravimetry analysis (TGA). Of the analysis made by the different techniques we concluded that functionalized NPs are of very good quality. All were magnetic with magnetic saturation of 60 emu/g, for the case of NPs coated with AL. The XRD and TEM measurements show that the NPs have an average size between 9 and 11 nm with spinel crystal structure with lattice parameter of 8.37 Å. XPS measures determined that iron atoms has a valence of +3 and +2, with a total ratio of iron atoms Fe3+:Fe2+ of 2:1. Of the FTIR measurements we show that AL and AO molecules are chemically bound to the surface of the NPs. By TGA measures we calculate the number of functionalized molecules. In the case of NPs coated with AL and AO were 1974 and 1486, respectively. References [1] Gupta, A.K., Gupta, M., Biomat. (2005) 26, 3995. [2] Kas, R., Sevinc, E., Topal, U., Acar, H.Y., J. Phys. Chem. (2010) 114, 7758. [3] Tsedev Ninjbadgar, et al, Solid State Sciences 6, (2004) 879–885. [4] Katerina Kluchova et al. Biomaterials 30 (2009) 2855–2863.
  27. 27. T05‐ Catalysis, Corrosion and Environment 24
  28. 28. T05: PHOTOCATALYTIC EFFECT AND MÖSSBAUER STUDY OF IRON TITANIUM SILICATE GLASS PREPARED BY SOL-GEL METHOD Y. Takahashi1*, S. Kubuki1, K. Akiyama1, K. Sinkó 2 and T. Nishida3 1Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, Minami-Osawa 1-1, Hachi-Oji, Tokyo 192-0397, JAPAN 2Institute of Chemistry, Faculty of Science, Eötvös Loránd University, Pázmány P.s. 1/A, Budapest 1117, 25 Figure 1. XRD patterns of FSxTi with 'x' of (A) 10 and (B) 40 annealed at (a) 400 oC and (b) 1000 oC for 3h. 102 100 98 96 94 92 90 100 95 90 85 (A-a) (A-b) (B-a) (B-b) Figure 2. FeMS of FSxTi with 'x' of (A) 10 and (B) 40 annealed at (a) 400 oC and (b) 1000 oC for 3h. HUNGARY 3Department of Biological and Environmental Chemistry, Faculty of Humanity-Oriented Science and Engineering, Kinki University, Kayanomori 11-6, Iizuka, Fukuoka 820-8555, JAPAN *Corresponding author, e-mail: takahashi-yusuke3@ed.tmu.ac.jp Keywords: photocatalyst, silicate glass Topic: T05- Catalysis, Corrosion and Environment 1. Introduction Anatase type TiO2 is well known as a photocatalyst activated by the UV light [1]. It will be more effective to develop photocatalysts which show their activity under visible light irradiation. Recently, Takahashi et al. reported that 50Fe2O3·50SiO2 (in mass %) glass had photocatalytic activity under the visible light [2]. This result implies that iron silicate glass might be a practical photocatalyst with high efficiency. In this study, we report a relationship between local structure and visible light activated photocatalytic effect of iron titanium silicate glass prepared by sol-gel method. 2. Experimental Iron titanium silicate glasses with a composition of 50Fe2O3•(50-x)SiO2·xTiO2 (in mass %, x = 10-40, abbreviated as FSxTi) were prepared by sol-gel method. Reagent chemicals of Si(OC2H5)4, Fe(NO3)3•9H2O, Ti(OCH(CH3)2)4, HNO3, and C2H5OH were poured into a beaker and well mixed for 2 h at RT. After having been agitated by reflux-heat method at 80 oC for 2 h, the solution was poured into a glass vial and dried at 60 oC for 3 days to obtain dark brown gel samples. The samples were annealed between 400 and 1000 oC for 3 h in air. For the structural characterization, 57Fe-Mössbauer spectra (FeMS) were measured by a constant acceleration mode with a source of 57Co(Rh) with -Fe as a reference and X-ray diffractmetry (XRD) was carried out at 2θ between 10° and 80° with an interval and scanning rate of 0.02° and 5° min-1, respectively. X-ray with the wavelength of 1.54 Å generated by Cu filament was targeted by electron accelerated by 300 mA and 50 kV. 3. Results and Discussion As shown in Figs. 1 (A-a) and (B-a), XRD patterns of FSxTi with x of 10 and 40 annealed at 400 oC showed halo patterns due to amorphous structure, while intensive diffraction peaks attributed to crystalline phases of Fe2TiO5, -Fe2O3 and TiO2 were observed when annealed at 1000 oC (Figs. 1 (A-b) and (B-b)). FeMS of FS10Ti annealed at 1000 oC for 3 h showed a sextet with  of 0.38 mm s-1,  of - 0.22 mm s-1and int of 50.6 T due to α-Fe2O3 and a doublet with  of 0.38 mm s-1 and  of -10 -5 0 5 10 Velocity / mms-1 -10 -5 0 5 10 Velocity / mms-1 105 100 95 90 85 80 100 98 96 94 92 90 0.76 mm s-1 due to Fe2TiO5 (Fig. 2 (A-b)). - Fe2O3 could not be detected from the XRD pattern and the FeMS of FS40Ti annealed at 1000 oC. These results indicate that the kinds and fraction of crystalline phases precipitated in FSxTi can be controlled by the annealing conditions and the chemical composition. The photocatalytic effect of FSxTi is presented on the day of the conference. References [1] A. Fujishima, K. Honda, Nature 238 (1972) 37-38. [2] Y. Takahashi, S. Kubuki, K. Akiyama, K. Sinkó, E. Kuzmann, Z. Homonnay, M. Ristić, T. Nishida, Hyperfine. Interact. 226 (2014) 747-753
  29. 29. T06‐ Chemical Applications, Structure and Bonding 26
  30. 30. T06: 57Fe-MÖSSBAUER STUDY OF ZIRCONIA CONTAINING IRON VANADATE CLYSTALLIZED GLASS WITH HIGH ELECTRICAL CONDUCTIVITY K. Matsuda1, S. Kubuki1*, K. Akiyama1 and T. Nishida2 1 Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, Minami-Osawa 1-1, Hachi-Oji, Tokyo 192-0397, JAPAN. 2 Department of Biological and Environmental Chemistry, Faculty of Humanity-Oriented Science and Engineering, Kinki University, Kayanomori 11-6, Iizuka, Fukuoka 820-8555, JAPAN. *Corresponding author: e-mail: kubuki@tmu.ac.jp Keywords: vanadate glass, electron hopping, heat-treatment, monoclinic vanadium-zirconia, beta-vanadium bronzes Topic: T06- Chemical Applications, Structure and Bonding 100 98 96 100 98 96 27 Introduction Vanadate glass is known as a semiconductor with the electrical conductivity () of 10-7-10-5 S cm-1 due to 3d electron (polaron) hopping from VVI (or VIII) to VV [1]. A drastic increase in  of up to 100 Scm-1 was observed for barium iron vanadate glass, BaO-Fe2O3- V2O5 caused by heat treatment (HT), which has a registered trademark of ‘NTAglassTM’ [2]. This unique electrical property shows that vanadate glass will be a good candidate for electrode of secondary batteries. In order to find a vanadate glass with higher , we have investigated several vanadate glasses. In the present study, we report a new conductive vanadate glass containing ZrO2 with high  value without HT. Experimental A new vanadate glass with the composition of xZrO2・ 10Fe2O3・(90−x)V2O5 (x=0-30), abbreviated as xZFV, was prepared by a conventional melt-quenching method under the melting temperature and time of 1200-1400 oC for 1h. For comparison, another vanadate glass with the composition of xZrO2・(20- x)CaO・10Fe2O3・70V2O5 (x=0-20), abbreviated as xZCFV, was prepared under the same condition. Isothermal heat treatment was performed at 500 oC for 100 min in air. 57Fe-Mössbauer spectra were measured by constant acceleration method. 57Co(Rh) and -Fe were used as a source and a reference, respectively. Measurements of  were carried out by DC four-probe method. Results and Discussion Two doublets with isomer shift () and quadrupole splitting () of 0.42±0.01 and 0.29±0.01 mm s-1, 0.34±0.03 and 1.48±0.06 mm s-1 were observed from the 57Fe- Mössbaeur spectrum of heat-treated 20ZFV glass, respectively of which is ascribed to FeIII2VV4O13 and an amorphous FeIII-VIV-O phases [3] (Fig. 1(a)). On the other hand, three paramagnetic doublets with and  of 0.39±0.01 and 0.33±0.04, 0.40±0.01 and 0.65±0.04, and 0.32±0.01 and 1.12±0.03 mm s-1 were observed from 0ZCFV glass (Fig. 1(b)), which is ascribed to FeIIIVVO4 [4]. These results may suggest that when a glass contained few network-modifiers (NWM), iron ion partially reduces vanadium from VV to VIV. (a) (b -4 -3 -2 -1 0 1 2 3 4 Velocity / mm-1s Figure 1. 57Fe-Mössbauer spectra of (a) 20ZFV and (b) 0ZCFV heated at 500 oC for 100min. A gradual increase in was observed from 6.3×10-5 to 2.9×10-3 S cm-1 with increasing ZrO2 content from 0 to 30 mol%. However, the drastic increase in due to HT, which could be observed in 0ZCFV, did not occur for xZFV glass. It is concluded that introduction of zirconia into vanadate glass results in higher conductivity without HT. In addition, we found that it is favorable for vanadate glass to contain less than 20 mol% of Ca2+ for the drastic increase in caused by HT. References [1] N.F. Mott, Adv. Phys. V. 16 No.61 (1967) 49 [2] T. Nishida, Jpn. Patent (2006) No. 3854985. [3] A. Brückner, G.-U. Wolf, M. Meisel, R. Stösser, H. Mehner, F. Majunke and M. Baerns, J. Catal. V. 154 (1995) 11 [4] S. Kubuki, K. Matsuda, K. Akiyama and T. Nishida, J. Radioanal. Nucl. Chem. V. 299 (2014) 453
  31. 31. T07‐ Industrial Applications 28
  32. 32. T08‐ Magnetism and Magnetic Materials 29
  33. 33. T08: CORRELATION BETWEEN MILLING TIME OF POWDER, AND THE TEMPERATURE OF SUBSTRATE ON THE PROPERTIES OF NdFe THIN FILMS Y.A. Rojas Martínez, D. Oyola Lozano, H. Bustos Rodríguez Department of Physics, University of Tolima, A.A. 546, Ibagué, Colombia *Corresponding author: e-mail: yarojas@ut.edu.co Keywords: Mössbauer spectrometry, Thin films, Mechanical alloy Topic: T08- Magnetism and Magnetic Materials In this study we report the structural and magnetic properties, obtained by 57Fe Mössbauer spectrometry (MS) and X-ray diffraction (XRD), and Physical Properties Measurement System (PPMS), of amorphous rare-earth transition metal alloys of compositions Nd0.257Fe0.743 prepared by mechanical alloying during 12, 24, and 48 hours to study the influence of the milling time of powders. The films were prepared by DC sputtering technique deposited on Kapton substrate, at substrate temperature varying at 77°K,300°K, 450°K, To study the influence of the temperature substrate in their magnetic and structural properties. The X-rays results show that the α-Fe and amorphous phase in all the samples are present. The first decreases while the second one increase, with increase of the milling time and the substrate temperature, respectively. Mossbauer spectrometry results show that the amorphous phase in samples are ferromagnetic and appears as a hyperfine field distribution and a broad doublet. When the milling time and the substrate temperature increases, the paramagnetic contribution increase too. 30
  34. 34. T08: IN γ-Fe2MnGa COMPOUND DO Fe AND Mn ORDER MAGNETICALLY AT THE SAME TEMPERATURE? DO THEY COUPLE PARALLEL OR ANTIPARALLEL AT LOW TEMPERATURES? Edson Caetano Passamani Depto de Física, Universidade Federal do Espírito Santo, 29075-910, Vitória, ES, Brazil Heusler alloys (HAs) are generically represented by the stoichiometric X2YZ formula, where X and Y atoms are, in principle, d-elements with more than half-filled and less than half-filled shells, respectively and Z are atoms with sp-shell electrons. This series of compounds has potential for technological application including spintronics devices. They usually stabilize at room temperature, either with L21-type (Fm3m – number 225) full Heusler alloy (HA) or with C1b-type (F-43m) half-HA structure. Specifically, for the Fe2MnGa HA there are several controversies reported in literature; either related with its crystal structure or with its magnetic state at high and low temperatures (above 300 K and below 200 K). According to first principles calculations, Fe2MnGa HA should have the stable L21-type structure, as typically found in most of full HAs. However, it was recently reported the L12-type as its stable configuration, determined by electronic calculation. Experimental results seem also to be contradictory from the structural viewpoint because the samples are no single crystalline phase. From magnetic viewpoint, a ferromagnetic (FM) state is expected to be the ground state for the L21-type as well for the L12-type structure; a ferrimagnetic (FI) configuration is 0.02 eV high in energy. An additional controversy is related to the existence of exchange bias (EB) effect, which is attributed to an antiferromagnetic (AF) state that appears at low temperatures. However, there is no direct proof for a coexistence of FM and AF states in this material, except for the presence of the loop shifting effect at low temperatures. Then, as the γ-Fe2MnGa HA has iron as a natural constituent, 57Fe Mossbauer spectroscopy could be a suitable method to investigate Fe environment and its magnetic state, considering that Mn atoms govern the alloy magnetism. Thus, in this work, bulk and local magnetic properties of the single phase polycrystalline γ-Fe2MnGa Heusler alloy have been studied in a broad temperature range and under high applied magnetic fields using X-ray diffraction, magnetization measurements and Mössbauer spectroscopy. X-ray diffraction data of the γ-Fe2MnGa alloy indicate stabilization of a L12-type structure and no structural phase transformation induced by thermal effect. While magnetization experiments have shown that the Mn sublattice is ferromagnetic well above 300 K, 57Fe Mössbauer spectroscopy indicates that Fe-sublattice orders magnetically at 200 K and couple antiparallel with Mn sublattice. This ferrimagnetic state is responsible for the magnetization reduction in low temperatures observed at low temperature. Due to high magnetic anisotropy of this material, a large vertical (magnetization-axis) and horizontal (field-axis) magnetization loop shift effects are observed in field-cool process for fields up to 5T, consequently they cannot be purely attributed to the exchange bias effect, as reported in literature for this Heusler compound. 31
  35. 35. T08: MAGNETIC PROPERTIES OF TWO CORE/SHELL NANOPARTICLES COUPLED VIA DIPOLAR INTERACTION W. R.Aguirre-Contreras1,*, and A.M. Schönhöbel1 1Grupo de Metalurgia y Transiciones de Fase, Facultad de Ciencias Naturales y Exactas, Universidad del Valle. Cali, Colombia *Corresponding author: e-mail: william.aguirre@correounivalle.edu.co Keywords: Magnetic core/shell nanoparticles, Monte Carlo simulation, Metropolis algorithm, dipolar interaction, Ising Model Topic: T08- Magnetism and Magnetic Materials We have used Monte Carlo simulations by Metropolis algorithm to study the magnetic properties of two identical core/shell nanoparticles with spherical shapes. A three-dimensional Ising Model with ferromagnetic (antiferromagnetic) nearest-neighbor couplings for core (shell) has been used on a body-centered cubic lattice and we have considered that nanoparticles are coupled by dipolar interactions. Zero-field cooling simulations were performed to obtain magnetization, susceptibility and Edward-Anderson factor as a function of dimensionless temperature. We also present the phase diagram as a function of the distance between nanoparticles and radii. References [1] A. Weizenmann and W. Figueiredo. Int. Journ. of Mod. Phys. C, V. 23(08) (2012) 1240006–1 [2] A. Weizenmann and W. Figueiredo. Phys. A, (2010) 389 [3] Liu W, Zhong W, Du YW., J. Nanosc. Nanotechnol. 8(6) (2008) 278 [4] D. Kechrakos and K. N. Trohidou. Appl. Phys. Lett. 81 (2002) 4574 32
  36. 36. T08: MÖSSBAUER AND STRUCTURAL STUDY OF ALLOYS Fe1-XVX OBTAINED BY MECHANICAL ALLOYING Dagoberto Oyola Lozano, Yebrayl Antonio Rojas Martínez, Humberto Bustos Rodríguez 1Department of Physics, University of Tolima, A.A. 546, Ibagué, Colombia *Corresponding author: e-mail: doyola@ut.edu.co Keywords: Mechanical Alloying, Mössbauer Spectroscopy, Laves phase Topic: T08- Magnetism and Magnetic Materials In the present work we studied the structural and magnetic properties of milled powders to 12, 48 and 72 hours of the Fe1-xVx with x= 0.1, 0.3, 0.5 and 0.7 obtained by mechanical alloying. The samples were characterized by Mössbauer spectroscopy and, X-ray diffraction. For times all of milling results Mössbauer spectra reveal that the samples show a behavior paramagnetic for x>0.5, and its pattern of X-ray diffraction indicates the presence of the Fe, V and FeV phases. For times greater than 48 hours of milling Fe1-xVx system with x>0.7 tends to an amorphous structure. 33
  37. 37. T08: MÖSSBAUER INVESTIGATIONS ON THE DESORBTION OF HYDROGEN AND HYDROXYL FROM THE IRON OXIDE NANOPARTICLES L. Herojit Singh, S. S. Pati, A. C. de Oliveira and V. K. Garg Institute of Physics, University of Brasília, 70910-970 Brasília, DF, Brazil *Corresponding author: e-mail: loushambam@gmail.com Keywords: Mössbauer spectrum, reduction, topotactical transformation Topic: T08- Magnetism and Magnetic materials 34 Magnetite (Fe3O4) due to its unique magnetic properties, it plays an important role in biological applications such as hyperthermia, gene targeting etc. Stoichiometry of magnetite dictates the magnetism of magnetite. Iron oxide nanoparticles were synthesized through precipitation of FeSO4.7H2O in the presence of NaOH maintaining the pH value of 11. XRD of the as prepared nanoparticles confirmed the single phase formation of Fe3O4 having crystallite size of 60 nm as derived using Debye Scherer formula. Mössbauer spectra of the as prepared nanoparticles and after subsequent thermally treated at various temperatures at 10-6 mbar are depicted in Fig 1. These spectra could be resolved into four subspectra. (a) IS = 0.68 mm/s ,QS = 0.03 mm/s, absorption 47%, Hint = 453 kG corresponds to Octahedral site of Fe3O4 (b) IS = 0.29 mm/s ,QS = 0.03 mm/s, absorption 26 %, Hint = 488 kG corresponds to tetrahedral site of Fe3O4 (c) The third subspectra with an area of 4 % corresponds to goethite (α-FeOOH) and (d) the fourth component with 23 % area, Hint of 464 kG, QS = 0.14 mm/s and IS = 0.33 mm/s. corresponds to hematite (α-Fe2O3) The presence of hematite could not be observed by XRD, because thermal treatment altered the stoichiometry of Fe3O4 with fine nanoparticles. The heat treatment at 423K reduced the octahedral component to 37 % and the tetrahedral part increased to 38%. Surfaces with defects such as oxygen vacancies dissociates from H2O that came into contact into H+ and OH-that got adsorbed resulting to hydrogenated surface. The dissociated H+ and OH- could not recombine due to the Jahn-Teller distorted surface that could kinetically hinder recombinative desorption. Mild heat treatment desorbs the H+ and OH– driving away oxygen from the particles. Therefore the reduction of α-FeOOH to off-stoichiometric magnetite take place at 423 K and in the process some fraction of magnetite got oxidized leading to decrease of octahedral fraction by 10 %. However thermal treatment at 423 K is not sufficient to drive away oxygen from the non-cubic fraction and thus remains unchanged. Increase in thermal treatment temperature to 523 K reduces the non-cubic to off-stoichiometric magnetite. Fig1. Mössbauer spectra of the nanoparticles and the subsequent treated at various temperatures. Further increase in the temperature i.e. at 523 K reduces α-Fe2O3 and α-FeOOH to off-stoichiometric magnetite. The Mössbauer spectra of the nanoparticles after subjecting to 773 K are resolved into Fe3O4 and 13 % γ-Fe2O3. As the temperature increases from a 773 K temperature the H and OH are desorbed from the surface of the nanoparticles causing recombination resulting in diminution of the rate of reduction of the particles. Further increase in the temperature (above 873 K) the adsorbed H and OH no more acts as the reducing agent therefore topotactical transformation of α-FeOOH to α-Fe2O3 takes place and the α-Fe2O3 nucleates to larger particles experiencing the hyperfine field of a bulk α-Fe2O3. Acknowledgements: This work was supported by CAPES project A 127-2013; LHJ and SSP thankfully acknowledge post doctoral fellowships.
  38. 38. T08: MÖSSBAUER STUDY OF ALLOYS Fe67.5Ni32.5, PREPARED BY ALLOY 35 Fe67.5Ni32.5 Fe67.5Ni32.5 without sieve -8 -6 -4 -2 0 2 4 6 8 1.00 0.98 0.96 0.94 1.01 1.00 0.99 0.98 0.97 0.96 1.00 0.98 0.96  m RT Mφssbauer spectra of the MA Fe67.5Ni32.5 samples milled for 10 h. relative transmission [%] relative transmission [%] m m Relative transmition [%] -8 -6 -4 -2 0 2 4 6 8 0.94 V[mm/s] MECHANICAL E.D. Benítez Rodríguez1, H. Bustos Rodriguez1, D. Oyola Lozano1, Y. A. Rojas Martínez1 y G.A. Pérez Alcázar2 1Department of Physics, University of Tolima, A.A. 546, Ibagué, Colombia 2) Instituto Nacional de Investigaciones Nucleares, Departamento de Química, Apdo. Postal 18-1027, Col. Escandón, Deleg. M. Hidalgo, C. P. 11801, México. D. F., México. *Corresponding author: e-mail: edbenitezr@ut.edu.co, hbustos@ut.edu.co Keywords: Mechanical alloying, X-Ray Diffraction, FeNi alloys, Mössbauer Spectrometry Topic: T08- Magnetism and Magnetic Materials We present the study Mössbauer of the system Fe67.5Ni32.5, prepared by mechanical alloying (MA). The structural, electronic and magnetic properties of alloys were analyzed using the techniques of x-ray diffraction (XRD), spectroscopy Mössbauer (MS) and PPMS (Physical Properties Measurement System), respectively. Samples are prepared with powders of iron and nickel in high purity (99.99%), is the respective stoichiometry of powders and powders in a planetary mill of high energy, alloy during a period of 10 hours with a 20: 1 ratio, from mass to mass of dust balls. Alloys are then sieved in different mesh: 18, 35, 60, 120, 230, 400 y 500 which are respectively equivalent a: 1mm, 500 μm, 250 μm, 125 μm, 63 μm, 38 μm y 25 μm. Mössbauer spectra in all alloys present a ferromagnetic behavior (see figure 1). In the graphs ZFC and FC, apparently exists in unscreened spin glass transition below 50K, which is reached to notice a bit in sample sizes between 63 and 125 micron and disappears for smaller sizes than 25 microns. This means that this phase is related to the larger particles. Besides the curve FC as low temperature is nearly constant for the first two and it may be due to magnetic dipole interaction is less intense for small particle as in this FC curve increases at low temperatures.
  39. 39. T08: SPIN DYNAMICS IN COEXISTING ANTIFERROMAGNETIC AND SPINGLASS STATES OF MULTIFERROIC LEAD PEROVSKITES S. Chillal1, F.J. Litterst2,4 *, S.N. Gvasaliya1, T. Shaplygina3, S.G. Lushnikov3, J.A. Munevar4, E. Baggio Saitovitch4 and A. Zheludev1 1 ETH Zürich, Laboratory for Neutron Scattering and Magnetism, 8093 Zürich, Switzerland, 2 Technische Universität Braunschweig, 38106 Braunschweig, Germany.3 Ioffe Physical-Technical Institute RAS, 194021St.Petersburg, Russia. 4Centro Brasileiro de Pesquisas Físicas, 22290-180 Rio de Janeiro, Brazil. *Corresponding author: e-mail: j.litterst@tu-bs.de Keywords: multiferroics, spin dynamics, perovskites, Mössbauer spectroscopy Topic:T08- Magnetism and Magnetic Materials 0.2 0.1 0.08 0.04 0.00 36 PbFe1/2Nb1/2O3 (PFN) and PbFe1/2Ta1/2O3 (PFT) belong to the family of PbB’xB’’1-xO3 perovskites which have inherent chemical disorder at the B-site. Due to this disorder, complex magnetic phase diagrams are expected in these materials that undergo ferroelectric transitions already above room temperature. Magnetic ground states ranging from simple antiferromagnetic to incommensurate structures have been reported [1]. As recently shown for PFN and PFT via macroscopic characterization, neutron scattering and 57Fe Mössbauer spectro-scopy, both compounds reveal antiferromagnetic transitions at 145 K and 153 K, respectively, followed by a spinglass transition around 10 K, below which antiferromagnetism coexists with a spinglass [2,3]. We suggest that the mechanism which is responsible for such a non-trivial ground state can be explained by a speromagnet-like spin arrangement (Fig. (1)). Figure 1. Schematic of the coexisting antiferromagnetic spinglass phase in the ground state of PFN and PFT. Mössbauer spectroscopy reveals strongly temperature dependent broadenings (Fig. (2a,b)) of magnetic hyperfine patterns. This may originate from dynamic mechanisms and some inhomogeneous broadening. Notably, there is found an unusual increase of the mean magnetic hyperfine field below 50 K (Fig. (2c)) that is accompanied by a decrease in the antiferromagnetic magnetic Bragg peak intensity as measured by neutron scattering (Fig. (2d)). This is indicative for the onset of magnetic freezing on the time scale of Mössbauer spectroscopy resembling earlier findings in re-entrant spinglass systems [4]. We shall present a coherent analysis of the spin dynamics and its temperature dependent development along the different magnetic regimes, as probed by 57Fe. 50 40 30 20 10 0 7500 5000 2500 Figure 2. a), b) The distribution of hyperfine fields in PbFe1/2Nb1/2O3 at 4K and 30K, c) temperature dependent mean magnetic hyperfine field at the Fe3+ ion as observed by Mössbauer spectro-scopy, d) AF Bragg peak intensity measured by neutron scattering at wave vector (½, ½, ½) References [1] G.A. Smolenskii and I.E. Chupis, Sov. Phys. Usp. 25 (1982) 475. [2] S. Chillal, et al., Phys. Rev. B 86 (2013) 220403R. [3] S. Chillal, et al., Phys. Rev. B 87 (2014) 174418. [4] R.A. Brand, et al., J. Phys. F 15 (1985) 1987, and references given there Fe3+ Nb5+ Φ 0 50 100 150 200 250 300 0 Temper ature (K) Intensity (a.u.) QAF=(1/2, 1/2, 1/2) <Bhf> (T) b d 0.0 -20 0 20 40 60 80 Probability 4 K Bhf (T) 30 K a) b) c) d)
  40. 40. T08: STUDY OF STRUCTURAL, OPTICAL AND MAGNETIC PROPERTIES OF Fe DOPED, Co DOPED, AND Fe-Co CO-DOPED ZnO J.J. Beltrán1*, J.A. Osorio1, C.A. Barrero1 and A. Punnoose2 1Grupo de Estado Sólido, Sede de Investigación Universitaria, Universidad de Antioquia, Medellín, Colombia 2 Department of Physics, Boise State University, Boise, Idaho 83725-1570, United States *Corresponding author: E-mail address: jjbj08@gmail.com Keywords: Diluted magnetic semiconductors, ZnO, Mössbauer spectra. Topic: T08-Magnetism and Materials Magnetic. Several works have reported ferromagnetic (FM) behavior in Fe doped, Co doped and Fe- Co co-doped ZnO systems, but there are a lot of controversies about the observed ferromagnetism. Then, careful structural and magnetic investigations with high quality single-phase 37 samples are desired to investigate in detail this controversy. In this work, we explore the effect of Fe doping, Zn1-xFexO, Co doping, Zn1-xCoxO and Fe-Co co-doping Zn1-xFexCoxO with x =0.0, 0.01, 0.03 and 0.05 on the crystallographic, structural, optical and magnetic properties of zinc oxide nanoparticles, prepared by Sol-Gel method. These fine powders of the as-obtained product, after being annealed at 550 oC for 1h, were characterized by X ray diffraction (XRD), optical absorption, X-ray photoelectronic spectroscopy (XPS), electron paramagnetic resonance (EPR) at RT and as a function of temperature, RT 57Fe Mössbauer spectroscopy and magnetic measurements as a function of applied magnetic field and as a function of temperature [1, 2]. The XRD patterns showed that the formation of hexagonal wurtzite ZnO crystal structure in all samples was discerned as the only single phase. Optical absorption results displayed that Co doped ZnO samples exhibited smaller band gaps (Eg) than Fe doped ZnO samples and that Fe-Co co-doped ZnO nanopowders showed intermediate values. In RT 57Fe Mössbauer spectra for all Zn1-xFexO samples only paramagnetic signals were detectable, ascribed to Fe3+. For x=0.05 the introduction of a third doublet was clearly necessary, which was attributed to spinel phase ZnFe2O4. In contrast, the spectra of Zn1-xFexCoxO sample did not show this third doublet, suggesting that Co ions might be preventing the formation of ZnFe2O4. XPS and EPR results showed only Co2+ ions for Zn1-xCoxO samples with x =0.01 and 0.03, and with further doping, mixed valence of Co2+ and Co3+ were evidenced, while in Fe-Co co-doped ZnO samples this mixed valence was observed for all doping concentration. Additionally, variable temperature EPR studies in Zn1- xFexCoxO suggested that some Co2+ ions are weakly FM coupled. Interestingly, pure ZnO sample exhibited very weak ferromagnetism, which might arise from the presence intrinsic defects that can become magnetic. The RT M vs H data of all doped and co-doped samples exhibited a linear component superimposed on a saturating FM-like magnetization. The FM character of Zn1-xFexO and Zn1-xCoxO were similar to each other, but increased compared with that of undoped ZnO. Now, Zn1-xFexCoxO samples showed higher FM behavior in comparison to the presence of only one of these cations. We deem that more probably the main role of Fe3+ ions in ZnO structure may be related to the formation of defects on the surface region, while Co ions have higher effect in its electronic properties. In Zn1-xFexCoxO the magnetic signal has been interpreted in terms of the charge transfer ferromagnetism involving mixed valence ions, most likely Co3+−Co2+ in addition to changes in the electronic structure associated with the presence of defects in the nanoparticles. The study suggested that the simultaneous introduction of Fe and Co ions in ZnO lattice has a strong synergistic effect because they eliminated the formation of the ZnFe2O4 and gave the strongest ferromagnetic signal in comparison to the presence of only one of these cations. References [1] J.J. Beltrán et.al J. Phys. Chem. C 118 (2014) 13203−13217. [2] J.J. Beltrán et.al J. Appl. Phys. 113 (2013) 17C308.
  41. 41. T08: SYNTHESIS AND CHARACTERIZATION OF NixCo1-xFe2O4 Nanoparticles P.M.A. Caetano1, P. R. Matos1, A. S. Albuquerque1, L.E. Fernadez-Outon2, J.D. Ardisson1 and W.A.A. Macedo1 1Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Serviço de Nanotecnologia, Belo Horizonte, Minas Gerais, Brasil. 2 Universidade Federal de Mina Gerais (UFMG), Departamento de Física, Belo Horizonte, Minas Gerais, Brasil. *Corresponding author: e-mail: patriciamacaetano@gmail.com Keywords: Ferrite, magnetism, nanostructure Topic: T08 - Magnetism and Magnetic Materials Nanostructured magnetic systems have been intensively investigated due to the different behavior of the materials at least one of their dimensions is in the nanometer range1. Among the nanostructured materials, ferrites, iron oxides of the type MFe2O4 (M = divalent metal ion) have been widely studied due to their magnetic properties, some of which are of great potential for application in the manufacturing of sensors with high sensitivity, e.g. for biomedical applications, such as hyperthermia, among others2,3. The present work consists in the synthesis and the investigation of structural and magnetic properties of nanostructured NixCo(1- x)Fe2O4 (with x = 0, 0.25, 0.5, 0.75 and 1.0) for hyperthermia applications. Ferrite nanoparticles were synthesized by coprecipitation and calcined at 700 °C, for 2 h. The nanoparticles were characterized by X-ray diffraction (XRD), Mössbauer spectroscopy and vibrating sample magnetometry (VSM). The capacity of heat generation of the ferrites, dispersed in deionized water when submitted to an AC field (198 kHz and 220 Oe), was investigated. The XRD patterns, Fig.1 (a), showed well defined peaks, indicating the formation of the desired spinel phase. The average particle size was about 30 nm as calculated from Scherrer's formula. The magnetization curves showed that the coercivity and saturation magnetization increase due to the increase of cobalt content, as can be seen in Table 1. Table 1 – Saturation magnetization and coercivity of the ferrite samples Saturation magnetization (MSat) and Coercivity (Hc) NixCo1-xFe2O4 X=1 X=0.75 X=0.5 X=0.25 X=0 MSat (emu/g) 20 42 49 63 66 Hc (Oe) 150 490 920 1000 1413 38 (b) Figure 1 (a) XRD patterns and (b) Mössbauer spectra of ferrite samples studied. Mössbauer spectra of the ferrite samples, measured at 80 K, are shown in Fig.1 (b). The spectra were fitted with two sextets referring to the Fe3+ ions present in tetrahedral and octahedral sites. Samples with higher content of Ni showed significant heating, reaching temperatures higher than 50 oC after 30 min under an alternating magnetic field due to both Brownian motion and magnetisation reversal. Our results indicated that, the control of Ni and Co content, and the nanoparticle concentration, would allow for the tailoring of the heating capabilities of these ferrites being a promising material for several applications, such as hyperthermia. This work is supported by CAPES (PNPD), CNPq and FAPEMIG. References [1] Q.A. Pankhurst, J.Connolly, S.K. Jones, J. Dobson, J. Phys. D: Appl. Phys., 36, R167 (2003). [2] C.A. Sawyer, H. Habib, K. Miller, K.N. Collier, C.L. Ondeck, M.E. McHenry, J. Appl. Phys. 105, 07B320 (2009). [3] B. D. Cullity, Introduction to Magnetic Materials (Addison-Wesley, London, 1972).
  42. 42. T08: SYNTHESIS OF SILVER -COATED MAGNETITE NANOCOMPOSITE FUNCTIONALIZED BY AZADIRACTHA INDICA J. L. López1, C. Carioca Fernandes1, D. M. Sá Oliveira1, M. Amorim Lima1, J. H. Dias Filho2, R. Paniago3 and K. Balzuweit3 1Centro de Ciências Biológicas e da Natureza, Núcleo de Física, Universidade Federal do Acre, Rio Branco, AC 69915-900, Brazil. 2) Departamento de Ciências Exatas, Universidade Estadual de Montes Claros, 39.401-089, Minas Gerais, Brazil. 3) Departamento de Física, Universidade Federal de Minas Gerais, 31270-901, Belo Horizonte, Brazil. *Corresponding author: e-mail: jorge0503@gmail.com Keywords: Nanoparticles,functionalization, Topic: T08- Magnetism and Magnetic Materials 39 Magnetic nanoparticles of iron oxides such as magnetite (Fe3O4) were coated with silver and then functionalized with extract of Azadirachta indica (Neem) forming a composite for use as non-toxic for the control of insect pests magnetic boots. The development of these composites requires a detailed study of the synthesis and magnetic properties of the functionalized nanoparticles to be used as an insecticide. In agriculture Azadirachta indica is used as a natural pesticide [1] and it was our interest to develop functionalized composite magnetic nanoparticles to combat Spodoptera frugiperda which is a pest of major importance in maize by reducing up to 34% crop productivity. This nanobiotechnological insecticide could also be applied to other type of pest. Magnetic fluids based on Fe3O4 has been synthesized using the condensation method by coprecipitating aqueous solutions of FeSO4, HCl and FeCl3, oleic acid mixtures in NaOH at room temperature [2-3]. Coating of Fe3O4 magnetic nanoparticles was achieved by dispersing this magnetite in AgNO3 solution containing specific amount of urea in vigorous stirring and mixture of sodium hydroxide solution and polyvinyl pyrrolidone (PVP), as stabilizer polymer, was added and finally a solution glucose was mixture. In the next step magnetite-silver core-shell nanoparticles were functionalized by Azadirachta indica. Samples with an average particle diameter ~7 nm and different concentrations of extract were studied by Mössbauer spectroscopy and dc magnetization measurements in the range of 4.2–250 K. The saturation magnetization (Ms) at 4.2 K were determined from M vs 1/H plots by extrapolating the value of magnetizations to infinite fields, to 3 - 5 emu/g and coercivity to 20- 50 Oe. The low saturation magnetization value was attributed to spin noncollinearity predominantly at the surface. From the magnetization measurements a magnetic anisotropy energy constant (K) between 1.3 - 3 ×104 J/m3 were calculated. Fe3O4 functionalized spectra at room temperature showed a singlet due to superparamagnetic relaxation and two sextets at low temperature. The line form in spectra Mössbauer vary with the temperatures it were simulated using a model of superparamagnetic relaxation of two levels (spin ½) and theory stochastic. It was taken into account that a distribution of the size of the particles that obeys a log-normal. References [1] A. H. Varella Bevilacqua H., B. Suffredini, M.M. Bernardi, Rev. Inst. Ciências da Saúde; 26(2) (2008)157. [2] J. L. López, J.H. Dias Filho, R. Paniago, H. – D. Pfannes, K. Balzuweit, Revista ECIPerú, 10(2) (2014) 5. [3] Y.M. Wang, X. Cao, G.H. Liu, R.Y. Hong, Y.M. Chen, X.F. Chen, H.Z. Li, B.Xu, D.G. Wei, J. Magn. Magn, Mater. 323 (2011) 2953.
  43. 43. T09‐ Multilayers, Thin Films and Artificially Structured Materials 40
  44. 44. T10‐ Physical Metallurgy and Materials Science 41
  45. 45. T10: MÖSSBAUER AND XRD CHARACTERIZATION OF THE PHASE TRANSFORMATIONS IN A Fe-Mn-Al-C AS. CAST ALLOY DURING TRIBOLOGY TEST J. Ramos1, J. F. Piamba2, H. Sánchez3, and G.A. Pérez Alcázar2* 1Universidad Autónoma de Occidente, Km. 2 vía Jamundí, Cali, Colombia 2Universidad del Valle, Departamento Física, A.A. 25360, Cali, Colombia 3Universidad del Valle, Escuela de Materiales, A.A. 25360, Cali, Colombia *Corresponding author: e-mail: gpgeperez@gmail.com Keywords: Fermanal steels, DRX, Mossbauer spectrometry, tribology Topic: T10- Physical Metallurgy and Materials Science 42 In this study Fe-29Mn-6Al–0,9C-1,8Mo-1,6Si- 0,4Cu (%w) alloy was prepared in an induction furnace. Chemical analysis of the as-cast sample was performed by optical emission spectrometry; Pin on Disk Tribometer (ASTM G99) at room temperature was used to evaluate the mass loss. Microstructure was characterized by Optical Microscopy, Ray X Diffraction and Transmission Mossbauer Spectroscopy. The obtained microstructure of the as-cast sample is of dendritic type and its XRD pattern (not shown here) was refined with the lines of the austenite with a volumetric fraction of 99.39% and lattice parameter of 3.67 Å, and the lines of the martensite with a volumetric fraction of 0.61% and lattice parameters of 2.91 and 3.09 Å. 1,00 0,95 0,90 0,85 exp total fit1 -9 -6 -3 0 3 6 9 relative transmission V [mm/s] Figure 1. Mossbauer spectrum of the as-cast sample. Fig. 1 shows the Mossbauer spectrum of the as-cast sample and it was fitted with a singlet which corresponds to the austenite. After the tribology test, using a charge of 3N, the surface of the sample was examined and in Fig. 2 its XRD pattern is shown. The refinement of this pattern was performed with the lines of the austenite phase with a volumetric fraction of 97.89% and lattice parameter of 3.67 Å, and also the lines of the martensite with a volumetric fraction of 2.21% and lattices parameters of 2.90 and 3.09 Å. Figure 2. XRD pattern of the surface of the as-cast sample after the wear test. Finally Fig. 3 shows the Mossbauer spectrum of the surface of the as-cast sample after the wear test. 1,00 0,95 0,90 0,85 exp total fit1 fit2 fit3 fit4 fit5 -12 -9 -6 -3 0 3 6 9 12 relative transmission V [mm/s] Figure 3. Mossbauer spectra of the surface of the as-cast sample after the wear test This spectrum was fitted with a big paramagnetic site with similar parameters of that shown in Fig. 1, which corresponds to the austenite phase of Fe and a hyperfine magnetic field distribution which is associated to the disordered martensite which appear in the surface as a consequence of the wear process. The martensite is the responsible of the hardening of the material.
  46. 46. T10: STRUCTURAL STUDY ON Li2Fe1-xNixSiO4 J.A. Jaén1, M. Jiménez2, E. Flores3, A. Muñoz2, J.A. Tabares4, and G.A. Pérez Alcázar4 1Depto. de Química Física, CITEN, Edificio de Laboratorios Científicos-VIP, Universidad de Panamá, Panamá 2Depto. de Física, Universidad de Panamá, Panamá 3Escuela de Física, Universidad de Panamá, Panamá 4Departamento de Física, Universidad del Valle, AA 25360, Cali, Colombia *Corresponding author: e-mail: juan.jaen@up.ac.pa Keywords: Orthosilicates, Li2FeSiO4. Topic: T10- Physical Metallurgy and Materials Science Li2FeSiO4 is a promising cathode material for Li-ion 43 battery applications [1]. This material has good electrochemical activity and high cycling stability, but poor electronic conductivity and lithium ion mobility. One manner to improve the electrochemical performance is to dope with an isovalent cation [2-4]. Li2Fe1-xNixSiO4 (x=0, 0.10, 0.15, 0.20 and 0.30) samples were prepared via solid state reaction to study the effects of doping Ni on the crystal structure of the orthosilicate. The phase structure, morphology and composition of Li2Fe1-xNixSiO4 nanocrystals were investigated by X-ray diffraction (XRD), Mössbauer spectroscopy (MS), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS), respectively. Mössbauer spectra are shown en Figure 1. X-ray diffraction data accompanied by Rietveld refinement and Mössbauer measurements showed that both, the pristine and doped Li2Fe1- xNixSiO4, basically crystallize in a monoclinic structure with (P21/n) symmetry. The doped materials up to 5% mol of Ni2+ retain the monoclinic structure and lattice parameter, which indicates that doping agent introduces into the structure of Li2FeSiO4 without destroying the lattice structure. There is a small increase of volume of the unit cell and slight changes in local environments around the FeO4 and SiO4 tetrahedra with increasing Ni doping. The crystallite size calculated from the Scherrer equation is about 60 nm. Some small amounts of electrochemical deleterious impurities, Fe2+ and Fe3+ phases, and unreacted Li2SiO3 are detected. Samples doped with more than 10 mol% contain some magnetic impurity of Fe-Ni alloy as a result of the reduction of the Fe2+ provided in the raw materials by residual carbon. The in situ formed carbon may enhance the electronic conductivity of the electrode, and effectively suppresses the grain growth of Li2FeSiO4 [5-7]. Magnetic measurements indicated that the lithium iron orthosilicate is a paramagnetic ceramic which becomes antiferromagnetic below 23 K. Nickel dopant does not modify the paramagnetic nature of this cathode material. Figure 1. Room temperature Mössbauer spectra of Li2Fe1-xNixSiO4 samples. References [1] A. Nytén, A. Abonimrane, M. Armand, T. Gustafsson and J.O. Thomas, Electrochem. Commun. 7 (2005), 156-160. [2] Y.H. Chen, Y.M. Zhao, X.N. An, J.M. Liu, Y.Z. Dong, Electrochim. Acta 54 (2009), 5844- 5850. [3] C. Deng, S. Zhang, S.Y. Yang, B.L. Fu and J. Ma, J. Power Sources 196 (2011), 386–392. [4] B. Shao and I. Taniguchi, J. Power Sources, 199 (2012) 278-286. [5] L.M. Li, H.J. Guo, X.H. Li, Z.X. Wang, W.J. Peng, K.X. Xiang and X. Cao, J. Power Sources 189 (2009), 45-50. [6] Z. Yan, S. Cai, L. Miao, X. Zhou and Y. Zhao, J. Alloys Compd. 511(1) (2012), 101-106. [7] Z. Yan, S. Cai, L. Miao, X. Zhou and Y. Zhao, J. Alloys Compd. 511(1) (2012), 101-106.
  47. 47. Posters 44
  48. 48. T02 CHARACTERIZATION OF NATURAL ZEOLITE CLINOPTILOLITE FOR SORPTION OF 45 CONTAMINATNS E. Xingu-Contreras1, G. García-R1, I. García-Sosa2 and A. Cabral-Prieto2(*) 1Instituto Tecnológico de Toluca, Avenida Tecnológico S/N, Fraccionamiento. La Virgen, c. p. 52149, Metepec, Estado de México, México. 2) Instituto Nacional de Investigaciones Nucleares, Departamento de Química, Apdo. Postal 18-1027, Col. Escandón, Deleg. M. Hidalgo, C. P. 11801, México. D. F., México. *Corresponding author: e-mail: agustin.cabral@inin.gob.mx Keywords: zeolites, nanomaterials, Móssbauer. Sorption. Topic: T02- Amorphous, nanocrystal ans nanoparticles Cd contaminated rivers is one of the ambient problems that society is facing since long time ago. The traditional chemical routines produce secondary to use procedures of green chemistry [1]. In this sense present study a Mexican pretreated natural zeolite, products that the environment is further contaminates. So, new methodologies are necessary to remediate these ambient problems by trying the Clinoptilolite, with adsorbed nano crystals of Fe0 is used to remove Cr(II) in aqueous phase. The characterization of this pretreated zeolitic material, before and after the sorption process was made using X-ray diffraction (XRD), Scanned electron microscopy (SEM/EDS) and Mössbauer spectroscopy. The XRD patterns of this zeolitic material are characteristic the Clinoptilolite zeolite only. Figure 1 XRD patterns of the treated Clinoptilolite. (a) Tarjeta JCPDS, (b) natural zeolite, (c) natural zeolite with Fe0 nanoparticles. From SEM, nano particles of different size were observed ranging from 8 to 120 nm. The Mössbauer spectra of these zeolite materials may consist of a well defined quadrupole double superimposed to broad magnetic pattern. From the isothermal curves of adsorption 35 mg of Cd(II) /g of natural zeolite can be removed from aqueous media. Figure 2. SEM image of the natural zeolite with nano particles of Fe0, prepared with 0.54 g of FeCl3 6 H2O per g of natural zeolite [2]. Figure 3. Typical Mössbauer spectrum of natural zeolite with Fe0 core-shell nano particles.
  49. 49. The sorption of Cd(II) using natural zeolite alone removes 30 mg of Cd(II)/g, suggesting that iron nano particles may favor the removal of heavy metals more efficiently. References [1] Lázar, K., Beyer, H., Onyestyák, G., Jönsson, B., Varga, L., & Pronier, S. NanoStructured Materials, 12, (1999). 155- 158. [2] Yuvakkumar, R., Elango, V., Rajendran, V., & Kannan, N. Digest Journal of Nanomaterials and Biostructures", (2011). 1771-1776. 46
  50. 50. T02 NOVEL PROTOCOL FOR THE SOLID‐STATE SYNTHESIS OF MAGNETITE FOR 1.000 0.995 0.990 0.985 0.980 -12 -9 -6 -3 0 3 6 9 12 Velocity (mm/s) -10 -5 0 5 10 Velocity (mm/s) 47 MEDICAL PRACTICES D.L. Paiva, A.L. Andrade, J.D. Fabris, J.D. Ardisson, and R.Z. Domingues 1Department of Chemistry CCEB, Federal University of Ouro Preto, 35400-000 Ouro Preto, Minas Gerais, Brazil. 2Federal University of the Jequitinhonha and Mucuri Valleys (UFVJM), 39100-000 Diamantina, Minas Gerais, Brazil. 3Laboratory of Applied Physics, Center for the Development of the Nuclear Technology, 31270-901 Belo Horizonte, Minas Gerais, Brazil. 4Department of Chemistry ICEx, Federal University of Minas Gerais (UFMG), 31270-901 Belo Horizonte, Minas Gerais, Brazil. *Corresponding author: e-mail: jdfabris@ufmg.br Keywords: Biomedicine, Nanotechnology, Sucrose Topic: T02- Amorphous, Nanocrystals and Nanoparticles Real benefits of nanotechnology both in industrial processes and in medicine are being inimitable. Reducing sizes may significantly change some physical and chemical properties, including electrical conductivity, magnetic response, active surface area, chemical reactivity, and biological activity, relatively to the corresponding characteristics of the bulk counterpart material. The way nanoparticles are synthesized may determine their morphological uniformity, their particle sizes distribution and, as a critical feature for clinical purposes, their purity. These conditions become one of the key-issues for researchers in nanoscience and developers in nanotechnology, particularly to plan the synthesis of maghemite (-Fe2O3) or magnetite (Fe3O4) with controlled form, size in the nanoscale and magnetically induced hyperthermic behavior, if the material is to be destined to medical clinical practices. This work was devoted to the synthesis of magnetite nanoparticles by reducing the chemical oxidation state of iron (III) in a commercial synthetic maghemite. The direct solid-state chemical conversion procedure that was first used by Pereira [1] to obtain magnetite by mixing and burning a natural hematite (Fe2O3) with glucose was found unsuccessful, in the present case. Instead, the magnetite could only be effectively produced by putting the reacting mixture of the starting synthetic commercial maghemite mixed with sucrose in a furnace at 400 oC for 20 min. The after-reaction residual carbon was removed with an oxidant chemical agent to render the suitably pure magnetic oxide. The samples were characterized by Mössbauer spectroscopy; powder X-ray diffraction and Fourier transform infrared (FTIR). The 298 K-Mössbauer spectrum collected for the starting maghemite and the corresponding parameters are given in Figure 1 and Table 1. Figure 2 shows the spectrum and the corresponding parameters (Table 2) for the obtained magnetite by using a mass ratio maghemite:sucrose of 1:5. Relative transmission Figure 1. 298 K-Mössbauer spectrum for the starting commercial synthetic maghemite. Table 1: Hyperfine parameters of the fitted Mössbauer spectra recorded at 298 K. */mms-1 2/mms-1 Bhf/T RA/% 0.33 0.01 50.3 77 0.30 -0.06 48.8 13 1.0043 0.9960 0.9877 Relative transmission Figure 2. 298 K-Mössbauer spectra for the obtained magnetite after the calcinations of maghemite with sucrose.
  51. 51. Table 2: Hyperfine parameters of the fitted Mössbauer spectra recorded at 298 K. */mms-1 2/mms-1 Bhf/T RA/% 0.65 0.04 45.9 64 0.27 -0.02 48.9 34 *Relative to Fe. Acknowledgements: Work supported by FAPEMIG and CNPq (Brazil). JDF is indebted to CAPES (Brazil) for granting his Visiting Professorship at UFVJM under the PVNS program and to CNPq for the grant # 305755-2013-7. Reference [1] Pereira, MC (2009) Preparação de novos catalisadores tipo Fenton heterogeneous à base de óxidos de ferro formados em litologia de itabirito. DSc thesis. UFMG, Brazil. In Portuguese. 48
  52. 52. T02 MÖSSBAUER STUDIES OF POLYANILINE COATED MAGNETIC NANOPARTICLES J.C. Maciel1,2, A.A.D. 49 Merces2, M. Cabrera2, W.T. Shigeyosi3, S. D. de Souza4, M. Olzon-Dionysio4, C.A. Cardoso3 and L.B. Carvalho Jr.2 1Universidade Federal de Roraima, Boa Vista, RR, Brazil. 2Laboratório de Imunopatologia Keizo Asami, Universidade Federal de Pernambuco, Recife,PE, Brazil. 3Departamento de Física, Universidade Federal de São Carlos, São Carlos, SP, Brazil. 4 Universidade Federal dos Vales de Jequitinhonha e Mucuri, Diamantina, MG, Brazil *Corresponding author: e-mail: jackeline_maciel@hotmail.com Keywords: PANI, magnetic nanoparticles, magnetite Topic:T02- Amorphous, Nanocrystals and Nanoparticles Polyaniline (PANI) draws special attention among other conducting polymers due to the simple synthetic methodology, good environmental stability, optical activity, controllable doping [1], easy tunability of its electronic properties and high levels of electromagnetic shielding performances at microwave frequencies with a low mass by unit of surface [2]. The aim of this work is to study the structural and magnetic characteristics of polyaniline coated magnetic nanoparticles for their application as an insoluble support for enzyme immobilization. The differences in the crystalline behavior of magnetic nanoparticles and polyaniline coated magnetic nanoparticles (mPANI) are analyzed using XRD measurements. Fig. 1 shows XRD patterns for magnetic nanoparticles and mPANI. Figure 1. XRD patterns. The 2θ peaks at 18.44°, 30.30°, 35.67°, 43.37°, 53.80°, 57.35°, 62.97°, 71.43° and 74.48° are attributed to the crystal planes of magnetite. According to Yu et al. [3], the absence of the (221) reflections, corresponding to maghemite, suggests magnetite as a predominant phase. In this work, the absence of this peak was also observed. However, we cannot rule out the presence of maghemite in the samples produced, as the FTIR results, for example, suggest otherwise (Fig. 1). Fig. 2 shows the adjusted Mössbauer spectra at 298 K for magnetic nanoparticles and mPANI, where the contribution of two magnetic subspectra corresponds to Fe3+ in the tetrahedral position and [Fe3+/Fe2+] in the octahedral coordination in the spinel structure. Figure 2. Mössbauer spectra at room temperature. In Fig. 2, the presence of a doublet at the center of the spectrum can be observed. This doublet emanates from ferric iron in a non-spherical place, which perhaps comes from the rim of the iron oxide core. The Mössbauer spectrum could not be fitted with two discrete tetrahedral and octahedral sites along with a doublet because of the superposition of relaxing sextet and doublet patterns. To block the superparamagnetic relaxation effect, the Mössbauer spectrum should be recorded at a low temperature. According to Mössbauer spectra and the hyperfine parameters, it is clear that the process to obtain the mPANI does not interfere significantly with the nature of the oxide. However, a small percentage of maghemite must be present in the samples due to the oxidation process. References [1] K.R., Reddy et al., React. Funct. Polym., V (67) (2007) 943. [2] B., Belaabe et al., J. Alloy Compd., V(527) (2012) 137. [3] R.E., Vandenberghe et al., Hyperfine Interact., V(126) (2000) 247.
  53. 53. T02 STRUCTURAL AND MICROSTRUCTURAL CHARACTERIZATION OF THE AlFe NANOSTRUCTURED INTERMETALLIC OBTAINED BY MECHANICAL MILLING 50 R.Rocha Cabrera, M. Pillaca, C.V. Landauro, J. Quispe- Marcatoma Facultad de Ciencias Físicas, Universidad Nacional Mayor de San Marcos, Ap. Postal 14-0149, Lima 14, Perú *Corresponding author: e-mail: jquispem@unmsm.edu.pe Keywords: Al-Fe system, nanostructuration. Topic: T2- Amorphous, Nanocrystals and Nanoparticles Nowadays, intermetallic AlFe alloys have taken attention of many researchers for their application in different branches of industry. This is due to the high corrosion resistance and low density of these systems [1]. In particular, AlFe alloys have interesting mechanical and magnetic properties, where the order or disorder in the sample is of crucial importance to define its physical behavior [2]. In this sense, the nanostructuration process gives us the possibility to change its structure and, consequently, manipulate the physical properties as function of the average grain size [3]. In the context described above, in the present work we investigate the structure and micro-structure of the nanostructured intermetallic AlFe (50 at.% Al). Solid samples were produced using the arc furnace technique under Ar-atmosphere. Subsequently, the alloys were thermally annealed at 600°C during 48 hours. The nanostructured samples were obtained by means of mechanical milling employing a high energy ball milling equipment (SPEX 8000). The obtained products were characterized by powder X-ray diffraction (XRD) and transmission Mössbauer spectroscopy (TMS). The XRD results indicate that the annealed solid samples can be indexed as a single AlFe phase. The sample milled up to 20 hours presents AlFe nano-grains with a solid solution of Al in Fe, i.e. Fe(Al). The results of TMS show that the local order around Fe sites is of the B2-type. References [1] V.N. Antonov, O.V. Krasovska, E.E. Krasovskii, Y.V. Kudryavtsev, V.V. Nemoshkalenko, B.Y. Yavorsy, Y.P. Lee and K.W. Kim, Phys. Condens. Matter 9,11227, (1997). [2] H. Wu, I. Baaker, Y. Liu, X. Wu and J. Cheng, Intermetallics 19, 1517, (2011). [1] C. Suryanayana., Prog. Matter. Sci., 46, 1 (2001).
  54. 54. T03 CHARACTERIZATION OF PIGMENT FROM THE TAMBO COLORADO ARCHAEOLOGICAL SITE BY MÖSSBAUER SPECTROSCOPY -10 -5 0 5 10 Velocity ( mm s-1 ) 51 A. Trujillo, E. Zeballos- Velásquez, V. Wright, M. Mejía 1Laboratorio de Arqueometría, 2Laboratorio de Cristalografía Facultad de Ciencias Físicas, Universidad Nacional Mayor de San Marcos. Ap. Postal 14-0149. Lima, Perú. 3 Instituto Francés de Estudios Andinos, Avenida Arequipa 4500, Casilla 18-1217, Lima, Perú. *Corresponding author: aletruj70@gmail.com Keywords: Pigments, Mössbauer spectroscopy, X-Ray Diffractometry Topic: T03- Applicationsin Soils, Mineralogy, Geology, Cements and Archaeology. The Tambo Colorado archaeological site, located on the right bank of the Pisco Valley (290 Km South of Lima), is of importance because of its monumentality, colorful and the apparent good condition, features that make it attractive to different visitors and researchers. Most of the studies about this site have been directed to make architectural records, interpretations of the function and use of areas of the site, as well as its strategic importance during the Inca conquest; interpretations of the symbolic importance of the mural paintings of the site have also been made. However, these studies do not have been articulated integrally with descriptions and records of the site, so it is considered useful to carry out an investigation involving the analysis of the nature of the materials, as well as an adequate understanding of the state of conservation of its architecture [1]. In the present work are analyzed samples of pigments from the Tambo Colorado site, using Mössbauer Spectroscopy by transmission and x-ray diffractometry, in order to study the structure of these materials. In Figure 1 are shown the Mössbauer spectrum of the sample Tambo RN. In the study of pigments containing iron, Mössbauer Spectroscopy has proven to be a useful and sensitive tool to identify the presence of iron sites that differ from one another not only in its octahedral or tetrahedral coordination but also in small deviations from the ideal geometry, in addition to the differences in their chemical environments [2]. In this sense, this research will contribute to achieve these goals, because the conservation requires a critical approach based on the definition of the main characteristics of the object to be treated, which can be achieved with a qualitative and quantitative understanding of the physico-chemical properties of the object in study [3]. 1.005 1.000 0.995 0.990 0.985 0.980 0.975 0.970 0.965 Figure 1. Mossbauer spectrum of sample Tambo RN. Relative transmission (%) References [1] Wright V. Proyecto de Investigación Tambo Colorado. Instituto Francés de Estudios Andinos. Lima (2012). [2] U, Casellato; P, Vigato; U, Russo, M, Matteini, Journal of Cultural Heritage 1 (2000) 217-232. [3] D, Hradila; T, Grygara; J, Hradilova; P, Bezdicka.. Applied Clay Science 22 (2003) 223– 236.