BRUNO SANTOS CORREA
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Resumo IPEN-doc 30169 Comparative local analysis of Ni/Ni3C nanoparticles synthed with oleylamine/oleic acid and oleylamine/palm kernel oil ligand pairs2023 - SILVA, CRYSTIAN W.C. da; OTUBO, LARISSA; SOUZA, KATIUSSE S. de; CARBONARI, ARTUR W.; CORREA, BRUNO S.; FREITAS, RAFAEL S. de; PASCA, GABRIEL A.; COSTA, CLEIDILANE S.In recent decades, Ni/Ni3C nanoparticles have been a topic of interest, especially for their catalytic and magnetic properties, promising as electrocatalysis, for example [1]. These systems are usually obtained by chemical methods, in the presence of ligands responsible for controlling their structure and morphology [2]. In this work, we carried out a comparative study of the hyperfine interactions occurring in Ni/Ni3C nanoparticles, synthed by thermal decomposition in the presence of oleylamine/oleic acid and oleylamine/palm kernel oil ligand pairs, at 513 K, for 3 hours. The local analysis was performed using perturbed correlation spectroscopy (PAC) in the temperature range from 30K to 300K, using the 111Cd probe, implanted in the samples by diffusion, during the synthesis. The parameters of the hyperfine interactions were compared to the results obtained by XRD, TEM and magnetization, indicating the obtainment of Ni/Ni3c nanoparticles of the core-shell type, showing a higher Ni3C content, greater distribution and lower saturation magnetization for nanoparticles synthed with palm kernel oil compared to those obtained with oleic acid. In addition, the hyperfine parameters showed the existence of regions with a quadrupole frequency of 24 MHz and a magnetic hyperfine field of 1T in both samples, which may be indicative of carbon-deficient Ni3C regions, predicted in the literature [3].Resumo IPEN-doc 29751 Magnetic properties of Er-doped Fe3O4 nanoparticles studied by perturbed angular spectroscopy2019 - CORREA, E.L.; BOSCH-SANTOS, B.; SALES, T.S.N.; CABRERA-PASCA, G.A.; CORREA, B.S.; CARBONARI, A.W.; OLESHKO, V.P.; DENNIS, C.L.Resumo IPEN-doc 27308 RE-doped Fe3O4 (RE = Eu, Gd, Er) nanoparticles for nanothermometry2019 - CORREA, E.; BOSCH-SANTOS, B.; SALES, T.; CABRERA-PASCA, G.; CORREA, B.S.; NETO, O.F.; CARBONARI, A.W.; OLESHKO, V.; DENNIS, C.Temperature affects every physical system, chemical reaction, and biological process. A new method, magnetic nanothermometry, is being explored to measure temperature throughout a volume. This method uses large changes in magnetization as function of temperature, which cannot be obtained with current magnetic nano-objects (MNO). To get a large magnetization change we have examined the magnetic properties of RE-doped Fe3O4 (RE = Eu, Gd, Er) MNO. Samples were synthesized by co-precipitation. For the doped material, RE+3 were chosen in order to replace the Fe+3 in the (Fe+2)(Fe+3)2O4 structure. Structural characterization was performed by X-ray diffraction and transmission electron microscopy. Hyperfine interaction parameters as a function of temperature (300 K to 873 K) were obtained by perturbed angular g-g correlation (PAC) spectroscopy using 111In(111Cd) as probe nuclei. To fit the PAC spectra, the 111Cd probes were considered to occupy three sites: tetrahedral, octahedral, and a third site where the probes are located at the nanoparticle surface [1]. The hyperfine magnetic field Bhf was calculated using the Larmor equation, and its behavior as a function of temperature follows a Brillouin-type transition. For example, the Curie temperature (TC) obtained for 5% Er-doped was approx. 846 K (FIG. 1), which is higher than the expected TC for pure Fe3O4 (approx. 722 K) [2]. Magnetization as a function of temperature shows a 70 % change in magnetization around 100 K for Er-doped Fe3O4 (FIG.2), which is an improvement in temperature on pure Fe3O4 (below 50 K) [3]. Current work is focused on correlating the temperature range in which the magnetization change occurs and determining if it depends on the dopant element.Resumo IPEN-doc 27090 Hyperfine interaction study of iron oxide nanoparticles coated with Amazon ucuúba, bacaba and açaí, oils by PAC spectroscopy using 111In-111Cd nuclear probe nuclei2019 - CORREA, B.S.; COSTA, M.S.; SENA, C.; CABRERA-PASCA, G.A.; CARVALHO JUNIOR, R.N.; SAXENA, R.N.; CARBONARI, A.W.The use of nanoparticles coated with different materials have been the subject of study by many researchers to improve the quality of nanomaterials for biomedical applications such as controlled drug delivery, image contrast and treatment of cancer by magnetic hyperthermia [1]. In this work we used ucuúba (virola surinamensis), bacaba (Oenocarpus bacaba Mart.) and açaí (Euterpe oleracea Mart.) oils to coat Fe3O4 nanoparticles. The ucuúba, bacaba and açaí are native tree of the Amazon forest, whose oils are rich in fatty acids present in different proportions, such as, lauric, myristic, steatic, oleic, palmitic, and linoleic acid. These pure oils, free of solvents, were obtained by the extraction method with carbon dioxide in the supercritical state [2], and added during the synthesis process of iron oxide nanoparticles by thermal decomposition method [3]. The samples were characterized by X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Perturbed Angular Correlation (PAC) spectroscopy. The XRD results confirmed the formation of Fe3O4 phase. The TEM results determined the average size to be (> 5 nm) and possible spherical morphology of the magnetite nanoparticles. In order to perform the PAC measurements, 111In-111Cd probe nuclei were diffused in the powder samples at 973 K for 2.5 h. PAC measurements permitted the determination of electric quadrupole and magnetic dipole -hyperfine parameters as a function of temperature. The Curie temperature in each case was determined to be ~ 855 K.Resumo IPEN-doc 27089 Effects of surfactant on the morphology of α-Bi2O3 synthesized by the Sol-gel method2019 - PAES, S.C.; CORREA, B.S.; COSTA, M.S.; SENA, C.; CABRERA-PASCA, G.A.; SAXENA, R.N.; CARBONARI, A.W.Nano and micromaterial research, with a well-defined size and shape, has attracted attention from researchers in the areas of chemistry, physics, engineering and biomedicine, due to the wide range of possible applications such as: health, environment, catalysis and miniaturization of electronic devices. In this sense, the chemical routes of synthesis, such as Sol-Gel, are more prominent because it allows the production of particulate materials and thin films, with controllable size and morphology. In this work, bismuth oxide microparticles were synthesized by the Sol-Gel method using metallic bismuth (99.999% purity) in acid solution. Initially, bismuth was diluted with nitric acid solution and distilled water. After dilution, citric acid (600 mg) and ethylene glycol were added. The volume of ethylene glycol was varied from 1 to 3.75 mL, in order to study the morphological effects of its concentration. The samples were then subjected to the calcination process at 673 K for 12 hours. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS) and Raman spectroscopy. The XRD diffractograms and the Raman spectrum vibration bands showed that the synthesized samples correspond to the bismuth oxide in the alpha phase (α-Bi2O3) [1-3]. The EDS results show typical elements of bismuth oxide, without contaminants. The SEM images revealed different morphologies, ranging from the formation of flakes to microspherical particles with good size distribution (diameter 0.7 and 2.0 μm). All samples have a crystalline structure and vibration modes corresponding to the α-Bi2O3 phase, but these have totally different morphologies, which proves the dependence of the morphology with the concentration of ethylene glycol. In order to perform the PAC measurements, 111In-111Cd probe nuclei were diffused in the samples during synthesis. PAC measurements permitted the determination of electric quadrupole - hyperfine parameters as a function of temperature, from 50 to 673 K.Resumo IPEN-doc 27088 Study by perturbed angular correlation spectroscopy with 111In-111Cd of iron oxide nanoparticles synthesized using Amazon ucuúba, bacaba and açaí, oils2019 - CORREA, B.S.; COSTA, M.S.; SENA, C.; CABRERA-PASCA, G.A.; CARVALHO JUNIOR, R.N.; SAXENA, R.N.; CARBONARI, A.W.The use of nanoparticles coated with different materials are also a subject of study by many scientists to improve the quality of nanomaterials for biomedical applications such as controlled drug delivery, image contrast and treatment of cancer by magnetic hyperthermia [1]. In this work was used ucuúba (virola surinamensis), bacaba (Oenocarpus bacaba Mart.) and açaí (Euterpe oleracea Mart.) oils to coat Fe3O4 nanoparticles. The ucuúba, bacaba and açaí are native tree of the Amazon forest, whose oils is rich in fatty acids present in different proportions, such as, lauric, myristic, steatic, oleic, palmitic, and linoleic acid. These pure oils, free of solvents, was obtained by the extraction method with carbon dioxide in the supercritical state [2], and added to the synthesis process of iron oxide nanoparticles by thermal decomposition method [3]. The samples were characterized by X-ray diffraction (XRD), it was possible to verify the formation of Fe3O4 nanoparticles by the position and width of the intensity peaks. Transmission electron microscopy (TEM) were used to observe the average size (> 5 nm) and possible spherical morphology of the magnetite nanoparticles. In order to perform perturbed angular correlation spectroscopy (PAC) the powder samples were heated at 973 K for 2,5 h to diffuse the 111In-111Cd probe nuclei. Using this technique, it is possible determine the electric quadrupole and magnetic dipole hyperfine parameters of the samples as a function of temperature, and it was determined the Curie temperature of ~ 855 K for both samples. The results showed that it is possible synthesized Fe3O4 nanoparticles using ucuúba, bacaba and açaí oils.Resumo IPEN-doc 26822 Can natural oils improve the properties of magnetic nanoparticles?2019 - CORREA, B.S.; COSTA, M.S.; CABRERA-PASCA, G.; SENA, C.; PINTO, R.H.; CARVALHO JUNIOR, R.N.; FREITAS, R.S.; SAIKI, M.; CORREA, E.; CARBONARI, A.W.The use of nanoparticles coated with different materials have been studied by many researchers to improve the quality of nanomaterials for biomedical applications such as controlled drug delivery, image contrast and treatment of cancer by magnetic hyperthermia [1]. In this work, we used oils extracted from ucuúba (Virola surinamensis), bacaba (Oenocarpus bacaba Mart.) and açaí (Euterpe oleracea Mart.) to coat Fe3O4 nanoparticles. The ucuúba, bacaba and açaí are native trees of the Amazon forest, whose oils are rich in fatty acids, such as lauric, myristic, steatic, oleic, palmitic, and linoleic acid, with different proportions. These pure oils, free of solvents, were obtained by the extraction method with carbon dioxide in the supercritical state [2], and then added during the synthesis process of iron oxide nanoparticles by thermal decomposition method [3]. The results of X-ray diffraction confirmed the formation of Fe3O4 single phase. The average size around 3 nm and spherical morphology of the magnetite nanoparticles was determined by transmission electron microscopy. The study of magnetic properties revealed a saturation magnetization (Ms) enhancement and high values of the anisotropy constant for Fe3O4 samples when coated with açaí (91.4 emu.g-1; 4.6 105 J.m-3) and ucuúba (80.6 emu.g-1; 9.3 105 J.m-3) oils, which present a large percentage of saturated total fatty acid. The results indicate that nanoparticles with sizes smaller than around 5 nm present Ms values as high as those found in bulk Fe3O4 and higher than those usually obtained for nanoparticles coated with oleic acid [4]. The neutron activation analysis (NAA) nuclear technique was used to determine with high accuracy the mass of Fe in the Fe3O4 core of nanoparticles in order to normalize the magnetization values [5]. These results show that natural oils have a great potential to produce stable and quality nanoparticles as compared with conventional coated.