TATIANE DA SILVA NASCIMENTO
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Artigo IPEN-doc 28363 The effect of Er doping on local structure of magnetite nanoparticles2021 - RODRIGUES, PRISCILA S.; BURIMOVA, ANASTASIA; SALES, TATIANE S.N.; FILHO, ARNALDO A.M.; OTUBO, LARISSA; SAXENA, RAJENDRA N.; CARBONARI, ARTUR W.In this work Fe3O4:Er nanoparticles (NPs) with the characteristic size of ~ 11 nm were synthesized via classic co-precipitation method. Electron microscopy and X-ray diffraction were employed to probe the morphology and structure of the samples. Results revealed that samples synthesized in the Fd-3mZ structure with lattice constant close to that of pure magnetite. 111In probe generator was incorporated at synthesis in order to map the evolution of hyperfine magnetic field with temperature using time differential perturbed angular correlation (TDPAC) spectroscopy. The TDPAC results are discussed in terms of the effect of Er dopant on the magnetic properties and local structure of the NPs.Artigo IPEN-doc 27751 Synthesis and characterization of Fe3O4-HfO2 nanoparticles by hyperfine interactions measurements2021 - SALES, T.S.N.; BURIMOVA, A.; RODRIGUES, P.S.; MATOS, I.T.; CABRERA-PASCA, G.A.; SAXENA, R.N.; PEREIRA, L.F.D.; OTUBO, L.; CARBONARI, A.W.Nanoparticles (NPs) that combine biocompatibility and enhanced physical characteristics for biomedical applications are currently an area of intense scientific research. Hafnium oxide NPs are an innovative approach in the anticancer treatment by radiotherapy due to their low toxicity and enhancement of local dose in the tumor reducing the total radiation dose for the patient. The combination of this property with the excellent magnetic hyperthermia performance of Fe3O4 NPs can produce a promising nanomaterial for cancer therapy. In this work, we attempted to synthesize nanoscale samples of HfO2 doped with nominal 10 at.% Fe, and Fe3O4 doped with Hf at 10 at.% level using simple chemical routes. The crystal structure of the samples was characterized by X-ray diffraction. The material was irradiated with neutrons in a research reactor, the nuclear reaction 180Hf(n, γ)181Hf yielding the probe nucleus 181Hf(181Ta) used in the perturbed angular correlations experiments to measure hyperfine interactions. Despite their immediate response to the external magnetic field, at local level both samples showed only electric quadrupole interaction typical of the monoclinic hafnia indicating that Fe replaces Hf in HfO2 NPs, but, rather than substituting Fe, Hf enters magnetite in the form of HfO2 clusters. Transmission Electron Microscopy was exploited to study the morphology of these complex systems, as well as to localize hafnia clusters and understand the nature of their coupling to Fe3O4 specks.