DANILO LOPES COSTA E SILVA
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Artigo IPEN-doc 28822 Structural and thermal influence of niobia in aluminoborosilicate glasses2022 - COSTA-SILVA, D.L.; BARTOLOME, J.F.; SILVA, A.C.; MELLO-CASTANHO, S.The addition of small amounts of niobia (Nb2O5) in borosilicate glasses was explored. By analysis on thermal and structural changes, we found evidences that niobium integrates the glass structure in octahedral NbO6 coordination. Adding up to 8.0 mol% of Nb2O5, the oxide partially ruptured the glass structure, interfering in the BO3/ BO4 ratio, but the predominant network configuration was maintained. Thermally, there was an increase in the processing interval and the glasses became more resistant against crystallization, with the presence of niobia. Also, the oxide contributed to a notable decrease in the viscosity of the melts. The improvement of such properties were obtained by the controlled dispersion of the oxide in the glass network structure, avoiding large areas of phase-to-phase separation to preserve the desired ability of these glasses to incorporate a wide range of elements.Artigo IPEN-doc 28242 Mechanical and nuclear properties of soda-lime glasses containing boron and niobia2021 - SILVA, DANILO C.; CASTANHO, SONIA M.; VICENTE, ROBERTOArtigo IPEN-doc 26295 Niobium modified glass for nuclear waste immobilization2019 - SILVA, D.L.C. e; SILVA, A.C.; RAMBO, C.R.; CASTANHO, S.The impact of Nb2O5 addition to glasses belonging to the system SiO2-Na2O-CaO-B2O5-Al2O3 were investigated for nuclear waste immobilization applications. The glass samples, produced by the traditional melting method, were characterized by XRD, Differential Thermal Analysis (DTA) and Fourier-Transform Infrared Spectroscopy (FT-IR). The XRD results confirmed the amorphous state of the glasses and the thermal and FT-IR analyses revealed that Nb2O5 was dispersedly incorporated to the glass structure and that higher contents of the oxide result in a niobate network growth. The glasses showed good resistance to devitrification and are applicable for nuclear waste vitrification processes. These results show that the process is a promising alternative to produce a new family of glasses with optimized thermal resistance for the immobilization of nuclear wastes.