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- Valorização de recursos minerais : contribuição do projecto MinReMol para uma recuperação sustentável do rénio a partir de resíduos mineirosPublication . Silva, Teresa; Figueiredo, M. Ondina; Santos, Renata; de Oliveira, Daniel Pipa Soares; Veiga, JP; Batista, Maria Joao
- Contribution to the Understanding of the Colour Change in Bluish-Grey LimestonesPublication . Silva, Teresa; De Oliveira, Daniel Pipa Soares; Veiga, JP; Lisboa, Jose; Carvalho, Jorge; Barreiros, M. Alexandra; Coutinho, ML; Salas-Colera, Eduardo; Vigário, RogérioABSTRACT: Bluish-grey limestones have been extensively used as ornamental stones for decoration purposes in buildings, as well as in works of art, and accordingly, have been the target of intense exploration. In Portugal, the Jurassic limestone massif known as the Macico Calcario Estremenho (MCE), has been the source of grey-coloured ornamental stones, namely the Azul Valverde (one of the most well-known bluish-grey limestones) and Atlantic Blue varieties, both of which may undergo colour changes in outdoor environments. In this sense, it is important to understand the sudden colour change from bluish-grey to yellow/beige in the same limestone block in a quarry, or even, what happens to the colour when polished limestone is placed outdoors. This study was undertaken using various techniques, namely XRF (X-ray fluorescence spectrometry), XRD (X-ray diffraction), SEM (scanning electron microscopy), DTA-TG (differential thermal analysis/thermogravimetry) and colourimetry. Synchrotron radiation was also used at the European Synchrotron Radiation Facility (ESRF, Grenoble, France) where XANES (X-ray Absorption Near Edge Structure) spectra at Fe K-edge were collected to ascertain the speciation state of Fe in different coloured zones of the limestone, previously checked by EDXRF (energy dispersive X-ray fluorescence). The presence of Fe2+ and Fe3+ are responsible for the greyish and yellow/brown colour, respectively. On the other hand, the UV radiation from the sun causes a quickened and severe bleaching/fading on the dark blue/grey polished limestone.
- Towards the recovery of by-product metals from mine wastes : an X-Ray absorption spectroscopy study on the binding state of rhenium in debris from a centennial Iberian Pyrite Belt minePublication . Figueiredo, M. Ondina; Silva, Teresa; Veiga, JP; de Oliveira, Daniel Pipa Soares; Batista, Maria JoaoRhenium is a very scarce element, occurring in the Earth's crust mainly carried by molybdenite (MoS2). Due to a very low availability comparative to actual industrial demand, rhenium is nowadays one of the most expensive mineral commodities and an increased interest is focused on exploring residues resulting from a long-term mining, particularly of sulphide ore deposits. It is therefore noteworthy to assign the presence of rhenium (in a concentration up to 3 ppm) in the waste materials from the old sulphur factory at the abandoned mine of São Domingos (Iberian Pyrite Belt, Southeast Portugal), exploited since the Roman occupation of Iberia. Aiming at a potential sustainable recovery of rhenium as a by-product, X-ray near-edge absorption spectroscopy (XANES) was applied to clarify the Re-binding and mode of occurrence by comparing Re L3-edge XANES spectra obtained from mine waste samples (previously fully characterized by X-ray laboratory techniques) with similar spectra collected from Re-rich molybdenites (Mo1-xRexS2) and from Re-O model compounds configuring various valences and coordination environments of rhenium ions. Obtained results are commented, ruling out a possible Re-S binding and rather conforming with the binding of rhenium to oxygen in the analysed mine waste materials.
- Variações da produtividade oceânica ao largo da Península Ibérica durante o MIS 5 e a sua relação com a Circulação Thermohalina = Open ocean productivity changes off Iberia during MIS 5 and its relation to the Atlantic Meridional Overturning CirculationPublication . Nave, Silvia; Lebreiro, Susana; Kissel, Catherine; Guihou, Abel; Figueiredo, M. Ondina; Silva, Teresa; Michel, Elizabeth; Cortijo, Elisa; Labeyrie, Laurent; Voelker, Antje H. L.O estudo mostrou que a produtividade oceânica ao largo da costa ocidental Portuguesa é maior durante as fases frias do Estádio 5 e durante os Estádios Glaciares 4 e 6, sugerindo uma maior disponibilidade de nutrientes durante esses períodos. Os dados de d13C, variações da granulometria e parâmetros magnéticos, sugerem correntes de fundo mais fortes durante os períodos frios, concordantes com uma maior contribuição das correntes de fundo austrais na margem Este do Atlântico Norte. Os nossos dados sugerem uma ligação entre a variação da produtividade oceânica e a circulação termohalina.
- Cultural Heritage analysis using Synchrotron Radiation: case studies in Ceramics, Glasses, and Lithologic MaterialsPublication . Veiga, JP; Coutinho, ML; Figueiredo, Elin; Silva, TeresaABSTRACT: Synchrotron radiaton is a powerful tool for non‐destructve analysis of materials in cultural heritage research. It has revolutonized our ability to understand the compositon, structure, and history of cultural heritage objects, leading to significant advances in fields such as archaeology, art conservation, and materials science. Dedicated beamlines for cultural heritage research are available at synchrotron facilites around the world, such as the European Synchrotron Radiation Facility (ESRF), SOLEIL synchrotron, and ALBA synchrotron, providing specialized support and instrumentation for high‐resolution analysis of cultural heritage objects using various techniques, such as X‐ray absorption spectroscopy, X‐ray fluorescence, X‐ray diffraction, and X‐ray imaging.
- Análise expedita de U e de razões Zr/Rb em solos e relação com a componente geológica na região de Nisa-Castelo de Vide, PortugalPublication . Prazeres, Cátia; Batista, Maria Joao; Silva, Teresa; Figueiredo, M. Ondina
- ARQUEOLIT: an open access lithotheque in Portugal [Resumo]Publication . Jordão, Patrícia; Soares, Sofia; Silva, Teresa
- Structural and Optical Characterization of Mechanochemically Synthesized CuSbS2† [Abstract]Publication . Esperto, Luís; Figueira, Isabel; Mascarenhas, João; Silva, Teresa; Correia, J.B.; Neves, FilipeABSTRACT: The present work describes experimental studies related to the characterization of CuSbS2 directly synthesized after 2 h of mechanochemical synthesis (MCS) at 340 rpm, starting from mixtures of elemental powders. X-ray diffraction (XRD) and UV-VIS-NIR spectroscopy were carried out to analyze the crystal structure, degree of crystallinity, crystallite size and optical properties of the mechanochemically synthesized CuSbS2 powders. Rietveld refinement was carried out using Diffrac. TOPAS (Bruker AXS). Thermal stability of the synthesized materials was evaluated by the vacuum thermal heat treatment of the mechanochemically synthesized CuSbS2 powders at 350 °C for 24 h. Furthermore, the CuSbS2 powders were also analyzed by field-emission scanning electron microscopy (FE-SEM), laser diffraction, and differential thermal analysis.
- Tomografia de neutrões aplicada a azulejos do séc. XVII - visualização para caracterização, diagnóstico e optimização de técnicas de conservaçãoPublication . Pereira, M. A. Stanojev; Prudêncio, Maria Isabel; Marques, J. G.; Figueiredo, M. Ondina; Dias, M. I.; Silva, Teresa; Esteves, L.; Burbidge, Christopher Ian; Trindade, M. J.; Albuquerque, Maria Beatriz
- Indium-carrier minerals in polymetallic sulphide ore deposits : a crystal chemical insight into an indium binding state supported by X-ray absorption spectroscopy dataPublication . Figueiredo, M. Ondina; Silva, Teresa; de Oliveira, Daniel Pipa Soares; Rosa, Diogo