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Artigo IPEN-doc 27153 High-saturation magnetization in small nanoparticles of Fe3O4 coated with natural oils2020 - CORRÊA, BRUNO S.; COSTA, MESSIAS S.; CABRERA-PASCA, GABRIEL A.; SENA, CLEIDILANE; PINTO, RAFAEL H.H.; SILVA, ANA P.S.; CARVALHO JUNIOR, RAUL N.; ISHIDA, LINA; RAMON, JONATHAN G.A.; FREITAS, RAFAEL S.; SAIKI, MITIKO; MATOS, IZABELA T.; CORRÊA, EDUARDO L.; CARBONARI, ARTUR W.The enhancement of nanoparticle’s magnetic properties with a suitable coating is the main tool to increase their potential as an effective candidate for applications in different areas, especially in biomedicine. In the work here reported, Fe3O4 nanoparticles coated with natural oils were synthesized by iron (III) acetylacetonate thermal decomposition and the effects of the coating on the magnetic properties of these particles have been investigated. The oils were extracted from three Amazon fruits seeds: açaí, ucuúba, and bacaba by CO2 supercritical extraction process, and the relative percentage composition of fatty acids were determined by gas chromatography. A systematic study of crystalline, morphological, and magnetic properties revealed a saturation magnetization (Ms) enhancement and high values of the anisotropy constant for Fe3O4 samples when coated with açaí and ucuúba oils, which present a large percentage of saturated total fatty acid. Our results indicate that nanoparticles with sizes smaller than around 5 nm present Ms values as high as that found for bulk Fe3O4 and, consequently, much higher than Ms values for nanoparticles usually coated with oleic acid. The nuclear techniques neutron activation analysis and perturbed angular correlations were used to better characterize the nanoparticles.Resumo IPEN-doc 24605 Production and study of nanoparticles magnetic properties by hyperfine interactions2017 - NASCIMENTO, N.M.; CORREA, E.L.; BOSCH-SANTOS, B.; MATOS, I.T.; CABRERA-PASCA, G.A.; CARBONARI, A.W.In the past years nanotechnology was highlighted as a quick growing field, with many applications in science and technology including information storage, drug delivery and medical images, in which gadolinium-based nanoparticles (NPs) have been studied as contrast agent for magnetic resonance image. On the other hand erbium oxide NPs present potential for many applications due to their optical, electrical and photoluminescence properties, and can be used in display monitors, carbon nanotubes for "green" chemistry and in bioimaging, and iron-based NPs have been studied for application in hyperthermia due to its superparamagnetic properties. At the Hyperfine Interactions Laboratory (LIH) NPs are synthesized by thermal decomposition and co-precipitation. Structural characterization is made using X-ray diffraction (XRD) and transmission electron microscopy (TEM) and magnetic properties are studied by magnetization, both at partner laboratories, and perturbed angular correlation (PAC) spectroscopy using 111In(111Cd) as probe nuclei at LIH. PAC spectroscopy is based on the angular correlation between nuclear radiations emitted by radioactive probe nuclei, which is a well-established method in nuclear spectroscopy. Perturbation occurs in this correlation by electromagnetic interactions external to the nucleus when it is inserted in a material, which can provide information on the electronic distribution of the neighborhood. In this work, an important material was investigated by PAC spectroscopy using 111In, which decays to 111Cd by electron capture, as probe nuclei. Results have shown that NPs produced by thermal decomposition present narrow size distribution, with average size of 5 nm. On the other hand, results related to NPs produced by co-precipitation have shown that NPs don’t have a homogeneity in size and shape distribution.Artigo IPEN-doc 21145 Síntese de nanopartículas de óxido de ferro utilizando óleo de ucuúba2015 - CORREA, BRUNO S.; SILVA, ANA P.S.; CORDEIRO, RENATO M.; MATOS, IZABELA T.; CORREA, EDUARDO L.; EFFENBERGER, FERNANDO B.; SENA, CLEIDILANE; CARVALHO JUNIOR, RAUL N.; SAIKI, MITIKO; CARBONARI, ARTUR W.