Argemiro Soares da Silva Sobrinho
@ita.br
Professor at Physics Department
Instituto Tecnológico de Aeronáutica - ITA
EDUCATION
Ph.D. on Physics Engineering
RESEARCH, TEACHING, or OTHER INTERESTS
Surfaces, Coatings and Films, Materials Science, Aerospace Engineering
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
André Luis de Jesus Pereira, Juan Angel Sans, Rosario Vilaplana, Sudeshna Ray, Prachi Tadge, Armstrong Godoy, Isabela M. Horta, Argemiro S. da Silva-Sobrinho, Plácida Rodríguez-Hernández, Alfonso Muñoz,et al.
MDPI AG
This study investigates the high-pressure structural and vibrational properties of nano-Sc2O3 using a combination of X-ray diffraction, Raman spectroscopy, and theoretical calculations. Nano-Sc2O3 maintains its cubic bixbyite structure up to 26.4 GPa, without evidence of phase transitions, contrasting with bulk Sc2O3, which transitions to a monoclinic phase around 25–28 GPa. Raman spectroscopy reveals a pressure-induced blue shift in the vibrational modes, indicating lattice compression, and the absence of new modes confirms the retention of the cubic symmetry. Theoretical predictions using density functional theory (DFT) closely match the experimental data, validating the computational approach we use to model the pressure-dependent vibrational behavior of nano-Sc2O3. Comparisons with previous studies seem to show that the nanoscale material exhibits enhanced structural stability compared to its bulk counterpart, likely due to size effects and surface energy contributions. These findings provide new insights into the behavior of nanomaterials under extreme conditions and highlight the potential applications of nano-Sc2O3 in high-pressure environments.
André Luis de Jesus Pereira, Juan Ángel Sans, Óscar Gomis, David Santamaría-Pérez, Sudeshna Ray, Armstrong Godoy, Argemiro Soares da Silva-Sobrinho, Plácida Rodríguez-Hernández, Alfonso Muñoz, Catalin Popescu,et al.
MDPI AG
We report a joint high-pressure experimental and theoretical study of the structural, vibrational, and photoluminescent properties of pure and Eu3+-doped cubic Y2O3 nanoparticles with two very different average particle sizes. We compare the results of synchrotron X-ray diffraction, Raman scattering, and photoluminescence measurements in nanoparticles with ab initio density-functional simulations in bulk material with the aim to understand the influence of the average particle size on the properties of pure and doped Y2O3 nanoparticles under compression. We observe that the high-pressure phase behavior of Y2O3 nanoparticles depends on the average particle size, but in a different way to that previously reported. Nanoparticles with an average particle size of ~37 nm show the same pressure-induced phase transition sequence on upstroke and downstroke as the bulk sample; however, nanoparticles with an average particle size of ~6 nm undergo an irreversible pressure-induced amorphization above 16 GPa that is completed above 24 GPa. On downstroke, 6 nm nanoparticles likely consist of an amorphous phase.
G. A. Filgueira, R. S. Pessoa, R. K. Yamamoto, C. Alves, and A. S. da Silva Sobrinho
Institute of Electrical and Electronics Engineers (IEEE)
Adriano de Oliveira, Argemiro S. da Silva Sobrinho, Douglas M. G. Leite, Jonas J. Neto, Rodolfo L. P. Gonçalves, and Marcos Massi
FapUNIFESP (SciELO)
João Chaves, William Chiappim, Júlia Karnopp, Benedito Neto, Douglas Leite, Argemiro da Silva Sobrinho, and Rodrigo Pessoa
MDPI AG
In the presented study, a novel approach for thermal atomic layer deposition (ALD) of Al2O3 thin films using plasma-activated water (PAW) as a co-reactant, replacing traditionally employed deionized (DI) water, is introduced. Utilizing ex situ PAW achieves up to a 16.4% increase in the growth per cycle (GPC) of Al2O3 films, consistent with results from plasma-enhanced atomic layer deposition (PEALD). Time-resolved mass spectrometry (TRMS) revealed disparities in CH4 partial pressures between TMA reactions with DI water and PAW, with PAW demonstrating enhanced reactivity. Reactive oxygen species (ROS), namely H2O2 and O3, are posited to activate Si(100) substrate sites, thereby improving GPC and film quality. Specifically, Al2O3 films grown with PAW pH = 3.1 displayed optimal stoichiometry, reduced carbon content, and an expanded bandgap. This study thus establishes “PAW-ALD” as a descriptor for this ALD variation and highlights the significance of comprehensive assessments of PAW in ALD processes.
Barbara S. Damasceno, Isabela M. Horta, Regiane S. de Oliveira, Raissa M. Pereira, Vanessa M. Schatkoski, Gerd Bacher, Marcos Massi, Gilmar P. Thim, André L. de J. Pereira, Argemiro S. da Silva Sobrinho,et al.
Elsevier BV
Isabela Machado Horta, Barbara Souza Damasceno, Regiane Santana de Oliveira, André Luis de Jesus Pereira, Marcos Massi, Argemiro Soares da Silva Sobrinho, and Douglas Marcel Gonçalves Leite
Elsevier BV
Armstrong Godoy-Junior, André Pereira, Barbara Damasceno, Isabela Horta, Marcilene Gomes, Douglas Leite, Walter Miyakawa, Maurício Baldan, Marcos Massi, Rodrigo Pessoa,et al.
MDPI AG
In this study, we report the use of a radiofrequency plasma-assisted chemical vapor deposition (RF-CVD) system with a hollow cathode geometry to hydrogenate anatase TiO2 thin films. The goal was to create black TiO2 films with improved light absorption capabilities. The initial TiO2 was developed through magnetron sputtering, and this study specifically investigated the impact of hollow cathode hydrogen plasma (HCHP) treatment duration on the crucial characteristics of the resulting black TiO2 films. The HCHP treatment effectively created in-bandgap states in the TiO2 structure, leading to enhanced light absorption and improved conductivity. Morphological analysis showed a 24% surface area increase after 15 min of treatment. Wettability and surface energy results displayed nonlinear behavior, highlighting the influence of morphology on hydrophilicity improvement. The anatase TiO2 phase remained consistent, as confirmed by diffractograms. Raman analysis revealed structural alterations and induced lattice defects. Treated samples exhibited outstanding photodegradation performance, removing over 45% of methylene blue dye compared to ~25% by the pristine TiO2 film. The study emphasized the significant impact of 15-min hydrogenation on the HCHP treatment. The research provided valuable insights into the role of hydrogenation time using the HCHP treatment route on anatase TiO2 thin films and demonstrated the potential of the produced black TiO2 thin films for photocatalytic applications.
A.L.J. Pereira, J.A. Sans, O. Gomis, D. Santamaría-Pérez, S. Ray, A. Godoy-Jr, A.S. da Silva-Sobrinho, P. Rodríguez-Hernández, A. Muñoz, C. Popescu,et al.
Elsevier BV
André Petraconi, Felipe Miranda, Eduardo Prado, Bruno Braite, Fernando Gasi, Edison Bittencourt, Georgio Valadares, Marcos Massi, Gilberto Petraconi, and Argemiro da Silva Sobrinho
Springer Science and Business Media LLC
R. S. de Oliveira, H. A. Folli, I. M. Horta, B. S. Damasceno, J. H. C. Augstrose, W. Miyakawa, A. L. J. Pereira, M. Massi, A. S. da Silva Sobrinho, and D. M. G. Leite
FapUNIFESP (SciELO)
This work reports on the properties of GaN films grown by reactive magnetron sputtering onto glass substrate kept at relatively low temperature (400°C), using different RF power applied to the Ga target. Their structural, morphological, vibrational and optical properties were characterized by X-ray diffraction, atomic force and scanning electron microscopies, Raman spectroscopy and UV-vis spectrophotometry. The films have wurtzite phase with strong preferential orientation in the c -axis direction. Moreover, two clear contributions to the (0002) diffraction peak could be found, indicating the presence of two different morphologies, which were discussed in terms of the formation of an intermediate layer between the substrate and a dominating columnar-like microstructured film.
F. S. Miranda, E. S. P. Prado, R. J. Silva, A. M. Ribeiro, F. R. Caliari, F. L. Calciolari, A. S. Silva Sobrinho, and G. Petraconi
FapUNIFESP (SciELO)
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E. S. P. Prado, A. Essiptchouk, G. Amaral-Labat, A. S. da Silva Sobrinho, G. Petraconi, M. R. Baldan, and F. S. Miranda
Springer Science and Business Media LLC
E. S. P. Prado, F. S. Miranda, L. G. de Araujo, G. L. Fernandes, A. L. J Pereira, M. C. Gomes, A. S. da Silva Sobrinho, M. R. Baldan, and G. Petraconi
Informa UK Limited
ABSTRACT This is an experimental study on the decolorization efficiency and the degradation of organic compounds from textile wastewater by the ozonation process in a batch system. The effects of different sample volumes of textile wastewater over time were investigated. The experiments were performed in a 1 L glass reactor with a magnetic stirrer and a bubble diffuser at the bottom to feed the ozone. The applied cumulative ozone dosage varied at 120 gO3 L−1, 60 gO3 L−1, and 30 gO3 L−1, and the total interaction time for each test was 1 h. To investigate the physicochemical properties of the textile wastewater (solid and liquid phases) before and after the treatment, multiple analytical characterization methods were used: Thermal Gravimetric Analysis, Scanning Electron Microscopy coupled with Energy-Dispersive X-ray Spectroscopy, X-ray diffraction, Fourier Transform Infrared spectroscopy, and Spectrophotometer. The most perceptive change was observed in the color of the liquid medium, which turned from black to transparent, and a visual color number indicator known as DurchsichtFarbZahl (DFZ) was used for the evaluation of this process. Absorbance values decreased about 3.5 times after 5 min of treatment with a 0.15 L sample volume, and these values differed for tests with larger sample volumes. FTIR spectroscopy demonstrated that the bands’ intensities associated with the C − H, C − N, and C − O decrease during treatment. On the other hand, it was possible to conclude that combining treatment methods to improve the degradation of persistent compounds after the ozonation process is necessary. Finally, the ozonation of the textile wastewater proved to be effective at removing color due to its high reaction capacity. Graphical Abstract
E. S. P. Prado, F. S. Miranda, A. R. Marquesi, A. Essiptchouk, G. A. Labat Amaral, A. S. da Silva Sobrinho, G. Petraconi, and M. R. Baldan
Informa UK Limited
ABSTRACT The processing of coal tar pitch (CTP) to produce clean fuel gas and carbon black (CB) is studied in a plasma reactor equipped with a direct-current plasma torch. The composition of the gas produced and energy costs were estimated theoretically for the CTP pyrolysis and gasification processes by two oxidants, namely oxygen and water vapor. We have found that the main gaseous compounds obtained in the pyrolysis and gasification processes are hydrogen (H2), carbon monoxide (CO), and very often carbon dioxide (CO2). For the pyrolysis case, the mean value of the synthesis gas concentration reaches a major value of 98 vol.% (H2 – 81 vol.%, CO – 17. vol.%). However, only 23% of the initial CTP is transformed into gas phase at 1100 K and its content increases up to 37.4% at a temperature of 3000 K. For oxygen gasification, the syngas quantity is little less compared to the pyrolysis case and attains 96.6 vol.% (H2 – 26.5 vol.%, CO – 70.1 vol.%) for T > 1100 K. An intermediate syngas content for the water steam gasification is 97.8 vol.% (with H2 – 55.8 vol.% and CO – 42.0 vol.%). The CB produced was composed of well-defined spherical particles of 30-nm size. Furthermore, it is composed of carbon (98.2%), and followed by oxygen (1.8%) with a surface area of 97 m2 g−1. The thermal plasma system shows high efficiency in conversion of CTP into high-value-added products. GRAPHICAL ABSTRACT
Isabela Machado Horta, Barbara Souza Damasceno, Douglas Marcel Gonçalves Leite, Argemiro Soares da Silva Sobrinho, André Luis de Jesus Pereira, and Armstrong Godoy-Jr
CRC Press
Dilermando Nagle Travessa, Geovana Vilas Bôas Guedes, Aline Capella de Oliveira, Argemiro Soares da Silva Sobrinho, Virginie Roche, and Alberto Moreira Jorge
Elsevier BV
Daniela T.R. Uebele, Claudio A. Téllez Soto, Nierlly K.A.M. Galvão, Carla R. Tim, Argemiro S. da Silva Sobrinho, Rodrigo S. Pessoa, and Laurita dos Santos
Elsevier BV
William Chiappim, Benedito Botan Neto, Michaela Shiotani, Júlia Karnopp, Luan Gonçalves, João Pedro Chaves, Argemiro da Silva Sobrinho, Joaquim Pratas Leitão, Mariana Fraga, and Rodrigo Pessoa
MDPI AG
The growing need for increasingly miniaturized devices has placed high importance and demands on nanofabrication technologies with high-quality, low temperatures, and low-cost techniques. In the past few years, the development and recent advances in atomic layer deposition (ALD) processes boosted interest in their use in advanced electronic and nano/microelectromechanical systems (NEMS/MEMS) device manufacturing. In this context, non-thermal plasma (NTP) technology has been highlighted because it allowed the ALD technique to expand its process window and the fabrication of several nanomaterials at reduced temperatures, allowing thermosensitive substrates to be covered with good formability and uniformity. In this review article, we comprehensively describe how the NTP changed the ALD universe and expanded it in device fabrication for different applications. We also present an overview of the efforts and developed strategies to gather the NTP and ALD technologies with the consecutive formation of plasma-assisted ALD (PA-ALD) technique, which has been successfully applied in nanofabrication and surface modification. The advantages and limitations currently faced by this technique are presented and discussed. We conclude this review by showing the atomic layer etching (ALE) technique, another development of NTP and ALD junction that has gained more and more attention by allowing significant advancements in plasma-assisted nanofabrication.
Bernardo Magaldi, Júlia Karnopp, Argemiro da Silva Sobrinho, and Rodrigo Pessoa
MDPI AG
This work reports on the (zero-dimensional) global model study of argon plasma chemistry for a cylindrical thruster based on inductively coupled plasma (ICP) whose output has a system of two grids polarized with each other with direct current potential. The global model developed is based on particle and energy balance equations, where the latter considers both charged and neutral species. Thus, the model allows the determination of the neutral gas temperature. Finally, this study also investigated the role of excited species in plasma chemistry especially in the ions production and its implications for propulsion parameters, such as thrust. For this, the study was carried out in two different scenarios: (1) one taking into account the metastable species Arr and Arp (multi-step ionization), and (2) the other without these species (single-step ionization). Results indicates a distinct behavior of electron temperature with radiofrequency (RF) power for the investigated cases. On the other hand, the gas temperature is almost the same for investigated power range of up to 900 W. Concern propulsion analysis, a thrust of 40 mN at 450 W was verified for case (1), which represents a remarkable thrust value for electric thrusters.
M.F.S. Gonçalves, G. Petraconi Filho, A.A. Couto, A.S. da Silva Sobrinho, F.S. Miranda, and M. Massi
Elsevier BV
Isabela Machado Horta, Armstrong Godoy, Barbara Souza Damasceno, André Luis de Jesus Pereira, Douglas Marcel Gonçalves Leite, and Argemiro Soares da Silva Sobrinho
Elsevier
Viviane Maria Gonçalves de Figueiredo, Alecsandro de Moura Silva, Marcos Massi, Argemiro Soares da Silva Sobrinho, José Renato Cavalcanti de Queiroz, João Paulo Barros Machado, Renata Falchete do Prado, and Lafayette Nogueira Junior
Maad Rayan Publishing Company
Background. New surface treatments have been proposed to expand the clinical indications of zirconia prostheses. This study aimed to evaluate the effect of silica and fluorine nanofilms on zirconia ceramic on the resin cement bond strength. Methods. Zirconia blocks and discs underwent different surface treatments: untreated zirconia (CON), sandblasted, silica-coated alumina particles (30 µm) (SC), silica nanofilm (SN), and fluorine nanofilm (FN). Nanofilm deposition was performed through plasma enhanced chemical vapor deposition (PECVD). Zirconia surfaces were characterized on disks by morphology (atomic force microscopy, AFM), chemical analysis (x-ray photoelectron spectroscopy, XPS), and contact angle analysis. A silane coupling agent was applied on each treated surface, and a cylinder of resin cement was built up. Half of the specimens in each group were submitted to 6000 thermal cycles (TC). Bond strength was analyzed using the shear test, and the fractographic analysis was performed with stereomicroscopy and SEM/EDS. Statistical analysis was performed through one-way ANOVA and Tukey test in the non-aged and aged specimens. Results. Nanofilms modified the zirconia surface, which became more hydrophilic and chemically reactive. Chemical bonding between Si-O was found in SN, and FN promoted a fluorination process on the ceramic surface, converting zirconia into zirconium oxyfluoride. Specimens of the SN (TC) group failed on pre-testing. FN (TC) bond strength (3.8 MPa) was lower than SC (TC) and CON (TC) after shearing. Adhesive failure predominated in the experimental groups. Silica nanofilm failure occurred after aging. Conclusion. Silica and fluorine nanofilms deposited by PECVD did not promote effective bonding between zirconia and resin cement.
R. S. de Oliveira, H. A. Folli, C. Stegemann, I. M. Horta, B. S. Damasceno, W. Miyakawa, A. L. J. Pereira, M. Massi, A. S. da Silva Sobrinho, and D. M. G. Leite
FapUNIFESP (SciELO)
December 8, 2021 This work reports the properties of GaN films grown onto c-Si (100) at relatively low substrate temperature (400°C) by reactive magnetron sputtering. The study depicts the effect of working pressure and RF power on the GaN film structural, vibrational and optical properties characterized by X-ray diffraction, atomic force and scanning electron microscopies, Raman spectroscopy and spectroscopic ellipsometry. Unusual low pressure deposition condition (0.40 Pa) was achieved by using a separated argon inlet directed to the Ga target surface, resulting in improved crystalline quality of the films. In this condition, the preferential crystalline orientation, the surface morphology and the optical gap of the GaN films show a strong dependence on the RF power applied to the Ga target, where low RF power (30-60 W) was responsible for increasing the c -axis orientation and the optical gap, while higher RF power (75-90 W) decreased the overall crystal quality and increased
William Chiappim, Aline Sampaio, Felipe Miranda, Gilberto Petraconi, Argemiro Silva Sobrinho, Paulo Cardoso, Konstantin Kostov, Cristiane Koga‐Ito, and Rodrigo Pessoa
Plasma Processes and Polymers Wiley