Navegação Ciências Exatas e da Terra por Autor "Teixeira, Sergio Ribeiro"

Resultados 1-20 de 32

    • Atomic level mixing induced by Kr irradiation of FeCo/Cu multilayers 

      Graff, Ismael Leandro; Geshev, Julian Penkov; Teixeira, Sergio Ribeiro; Amaral, Livio; Traverse, Agnes (2008) [Artigo de periódico]
      The effects of Kr ion irradiation of FexCo1−x /Cu multilayers are investigated by means of magnetic and x-ray measurements. The irradiation was performed at room temperature with 600 keV of Kr, and the fluences were ranged ...

    • Bias dependence of magnetoresistance in Fe-Al/sub 2/O/sub 3/ granular thin films 

      Boff, Marco Aurelio Silveira; Geshev, Julian Penkov; Schmidt, Joao Edgar; Flores, Wladimir Hernandez; Antunes, Arlei Borba; Gusmao, Miguel Angelo Cavalheiro; Teixeira, Sergio Ribeiro (2002) [Artigo de periódico]
      This paper reports on the magnetotransport behavior of Fe–Al2O3 granular thin films when the injected dc current is varied. The electric resistance as a function of temperature, magnetoresistance, and the current vs applied ...

    • Change of the electrical properties in Fe-Al/sub 2/O/sub 3/ granular films 

      Boff, Marco Aurelio Silveira; Teixeira, Sergio Ribeiro; Schmidt, Joao Edgar; Antunes, Arlei Borba (2004) [Artigo de periódico]
      A systematic study of the electrical resistance as a function of the temperature was performed in Fe-Al2O3 granular thin films. Our findings revealed a nonlinear dependence of the current versus voltage in the low field ...

    • Effect of thermal calcinations on the charge transfer resistance of tantalum nitride nanotubes 

      Khan, Sherdil; Severo, Tiago Cassol; Santos, Marcos José Leite; Teixeira, Sergio Ribeiro (2016) [Artigo de periódico]
      Nanotubes of Ta3N5 were synthesized by thermal Nitridation of Ta2O5 nanotubes under ammonia gas environment. The effect of Nitridation temperature and time was evaluated. Electrochemical impedance spectroscopy was applied ...

    • Environment of hafnium and silicon in Hf-based dielectric films : an atomistic study by x-ray absorption spectroscopy and x-ray diffraction 

      Morais, Jonder; Miotti, Leonardo; Bastos, Karen Paz; Teixeira, Sergio Ribeiro; Baumvol, Israel Jacob Rabin; Rotondaro, Antonio L.P.; Chambers, James Joseph; Visokay, Mark R.; Colombo, Luigi; Alves, Maria do Carmo Martins (2005) [Artigo de periódico]
      The atomic structure of HfSiO and HfSiON was investigated before and after thermal annealing using x-ray diffraction and x-ray absorption spectroscopy. In HfSiO, the Hf atoms are arranged in a monoclinic HfO2 structure ...

    • Epitaxial fe/cu superlattices on Si(111) 

      Schreiner, Wido Herwig; Mosca Junior, Dante Homero; Teixeira, Sergio Ribeiro; Mattoso Filho, Ney Pereira (1992) [Artigo de periódico]
      We report on the successful epitaxial growth of Fe/Cu superlattices on Si( 111) wafers at room temperature. The superlattices were characterized with x-ray diffraction, conversion electron Mossbauer spectrometry, and ...

    • Ferromagnetic resonance in ag coupled ni films 

      Rezende, Sergio Machado; Moura, J.A.S.; Aguiar, F.M. de; Santos, Carlos Alberto dos; Schreiner, Wido Herwig; Teixeira, Sergio Ribeiro (1993) [Artigo de periódico]
      We present an X-band ferromagnetic resonance (FMR) study of polycrystalline single Ni films and of two Ni layers separated by an Ag layer at room temperature. Films were deposited by sputtering on glass using Ag over- and ...

    • Gel-combustion-synthesized ZnO nanoparticles for visible light-assisted photocatalytic hydrogen generation 

      Ramasami, Alamelu Kannan; Ravishankar, Thammadihalli Nanjundaiah; Nagaraju, Ganganagappa; Ramakrishnappa, Thippeswamy; Teixeira, Sergio Ribeiro; Balakrishna, R. Geetha (2017) [Artigo de periódico]
      Zinc oxide nanoparticles (ZnO NPs) synthesized by the gel combustion technique using a bio-fuel, cassava starch (root tubers of Manihot esculenta), have been characterized by various techniques. The X-ray diffraction pattern ...

    • Growth kinetics of solid-state-reacted fe-zr multilayer films 

      Paesano Junior, Andrea; Teixeira, Sergio Ribeiro; Amaral, Livio (1991) [Artigo de periódico]
      Multilayers of Fee0.33Zr0.67, prepared by electron beam evaporation, have been characterized by conversion electron Mijssbauer spectroscopy, Rutherford backscattering spectroscopy, and x-ray diffraction. Two phases, one ...

    • Growth of TiO2 nanotube arrays with simultaneous Au nanoparticles impregnation: photocatalysts for hydrogen production 

      Feil, Adriano Friedrich; Migowski, Pedro; Scheffer, Francine Ramos; Pierozan, Matheus Daniel; Corsetti, Rodrigo Ruzicki; Rodrigues, Melissa Machado; Pezzi, Rafael Peretti; Machado, Giovanna; Amaral, Livio; Teixeira, Sergio Ribeiro; Weibel, Daniel Eduardo; Dupont, Jairton (2010) [Artigo de periódico]
      Um novo método para a fabricação de nanotubos (NTs) de TiO2 organizados e impregnados com nanopartículas (NPs) de ouro foi desenvolvido, e as propriedades estruturais, morfológicas e ópticas dos NTs obtidos foram investigadas. ...

    • In situ electrical resistivity of thin-film beta-nial under ar irradiation at 77 k 

      Costa, Jose Antonio Trindade Borges da; Vasconcellos, Marcos Antonio Zen; Teixeira, Sergio Ribeiro; Scherer, Claudio; Baibich, Mario Norberto (1992) [Artigo de periódico]
      We report on the dose dependence of the in sítu electrical resistivity of a thin-film NiAl alloy under 120-keV-Ar-ion irradiation at 77 K. The results show two different behaviors. First, the values of resistivity increase, ...

    • Integrity of hafnium silicate/silicon dioxide ultrathin films on Si 

      Morais, Jonder; Miotti, Leonardo; Soares, Gabriel Vieira; Teixeira, Sergio Ribeiro; Pezzi, Rafael Peretti; Bastos, Karen Paz; Baumvol, Israel Jacob Rabin; Rotondaro, Antonio L.P.; Chambers, Jim J.; Visokay, Mark R.; Colombo, Luigi (2002) [Artigo de periódico]
      Rapid thermal annealing at 1000 °C of (HfO2)12x(SiO2)x pseudobinary alloy films deposited on Si were performed in N2 or O2 atmospheres. The effects on the atomic transport, structure, and composition were investigated using ...

    • Ionic liquid assisted hydrothermal syntheses of Au doped TiO2 NPs for efficient visible-light photocatalytic hydrogen production from water, electrochemical detection and photochemical detoxification of hexavalent chromium (Cr6+) 

      Ravishankar, Thammadihalli Nanjundaiah; Vaz, Maurício de Oliveira; Ramakrishnappa, Thippeswamy; Teixeira, Sergio Ribeiro; Dupont, Jairton (2017) [Artigo de periódico]
      Au/TiO2 NPs have been successfully prepared at 130 C in one day using an ionic liquid assisted hydrothermal method using methoxyethyl methyl imidazolium methanesulfonate as the ionic liquid, titanium(IV) isopropoxide and ...

    • Low potential barrier height effects in magnetic tunneling junctions 

      Cruz de Gracia, Evgeni Svenk; Dorneles, Lucio Strazzabosco; Schelp, Luiz Fernando; Teixeira, Sergio Ribeiro; Baibich, Mario Norberto (2007) [Artigo de periódico]
      This paper reports on the study of deposited (Ni81Fe19/AlOx /Co) magnetic tunnel junctions by magnetron sputtering, with the insulating layer obtained by plasma oxidation of Al. Concentration of the tunnel current in small ...

    • Magnetic properties of Nd/Fe double layers grown on Si(111) by electron beam evaporation 

      Fermin, Jose R.; Azevedo, Antonio; Rezende, Sergio Machado; Pereira, Luis Gustavo; Teixeira, Sergio Ribeiro (1998) [Artigo de periódico]
      In-plane ferromagnetic resonance (FMR) has been used to study the room-temperature magnetic and crystalline properties of Nd/Fe bilayers. Several samples were grown by electron beam evaporation onto Si(111) substrates, for ...

    • Magnetic susceptibility of fe/cu multilayers : ferromagnetic, antiferromagnetic, and spin-glass phases 

      Oliveira, A.J.A. de; Ortiz, Wilson Aires; Mosca Junior, Dante Homero; Mattoso Filho, Ney Pereira; Schreiner, Wido Herwig; Teixeira, Sergio Ribeiro (1998) [Artigo de periódico]
      In this work we present low-field magnetic measurements on multilayers of Fe 1.5 nm and Cu 1.5 nm layers, repeated 10 times, grown on Si~111! and Fe 5 nm/CaF2 40 nm/Si(111), substrates. Magnetic characteristics of a ...

    • Negative differential magnetization for Ni nanoparticles in Al 

      Fonda, Emiliano; Teixeira, Sergio Ribeiro; Geshev, Julian Penkov; Babonneau, David; Pailloux, Frederic; Traverse, Agnes (2005) [Artigo de periódico]
      Using a layer-by-layer deposition technique, Ni thin films were sandwiched between AlOx layers in an Al matrix. By using x-ray-absorption spectroscopy, grazing incidence small-angle x-ray scattering, and highresolution ...

    • Novel 3D‑fower shaped KTaO3 perovskite for highly efcient photocatalytic and ­H2 generation ability 

      Sumedha, H. N.; Shashank, Manjunatha; Teixeira, Sergio Ribeiro; Praveen, Beekanahalli Mokshanatha; Nagaraju, Ganganagappa (2022) [Artigo de periódico]
      Treatment of industrial wastewater is one of the biggest challenges that mankind is facing today to prevent environmental pollution and its associated adverse efects on human health. Environmentalists across the world have ...

    • Origin of the magnetization reversal of an Fe thin film on Si(111) 

      Santos, Mauricio Cougo dos; Geshev, Julian Penkov; Schmidt, Joao Edgar; Teixeira, Sergio Ribeiro; Pereira, Luis Gustavo (2000) [Artigo de periódico]
      The magnetic behavior of a 60-Å Fe film grown on Si (111) is reported and discussed. Scanning tunneling microcopy images showed Fe stripes along one of the (110) directions in the (111) plane, which favors easy magnetization ...

    • Phase formation in Zr-Fe multilayers : effect of irradiation 

      Motta, Arthur T.; Paesano Junior, Andrea; Birtcher, R.C.; Brückmann, Magale Elisa; Teixeira, Sergio Ribeiro; Amaral, Livio (1999) [Artigo de periódico]
      We have conducted a detailed in situ study of phase formation in Zr–Fe metallic multilayers using irradiation and thermal annealing. Metallic multilayers with near equiatomic and Fe-rich overall compositions and with ...