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Your search keyword '"Perez-Rodriguez, J.L."' showing total 97 results
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97 results on '"Perez-Rodriguez, J.L."'

35. Mossbauer spectroscopy investigation of ground and acid-treated vermiculite.

Author

Maqueda C., 3rd Mid-European clay conference Opatija, Croatia 18-23 Sep. 2006, Lerf A., Morillo E., Perez-Rodriguez J.L., Santas Romero A., Wagner F.E., Maqueda C., 3rd Mid-European clay conference Opatija, Croatia 18-23 Sep. 2006, Lerf A., Morillo E., Perez-Rodriguez J.L., Santas Romero A., and Wagner F.E.

Abstract

The spectra obtained for the starting materials can be interpreted by the superposition of three quadrupole doublets assigned to one octahedral Fe3+ and two Fe2+ sites. After grinding for 4 minutes the spectra retained the normal features and the Fe2+/ Fe3+ ratio remained almost unchanged, although XRD data showed a severe attack on the vermiculite structure. This indicates that the particle size and the long-range order were strongly affected by grinding while the local ordering was not greatly affected. Treatment of unground vermiculite samples containing 7. 50% Fe as Fe2O3 with 1M HCI resulted in almost 50% of the Fe being lost to solution. The Mossbauer spectrum was still very similar to the typical spectra of vermiculites, but there was a slight decrease in the Fe2+ content. A sample ground for 4 minutes and treated with 0.25 M HCl still showed the typical vermiculite Mossbauer spectrum with an Fe2+/Fe3+ ratio similar to the untreated sample. Samples ground for 2 or 4 minutes and treated with 1M HCI were completely orange and only Fe3+ remained., The spectra obtained for the starting materials can be interpreted by the superposition of three quadrupole doublets assigned to one octahedral Fe3+ and two Fe2+ sites. After grinding for 4 minutes the spectra retained the normal features and the Fe2+/ Fe3+ ratio remained almost unchanged, although XRD data showed a severe attack on the vermiculite structure. This indicates that the particle size and the long-range order were strongly affected by grinding while the local ordering was not greatly affected. Treatment of unground vermiculite samples containing 7. 50% Fe as Fe2O3 with 1M HCI resulted in almost 50% of the Fe being lost to solution. The Mossbauer spectrum was still very similar to the typical spectra of vermiculites, but there was a slight decrease in the Fe2+ content. A sample ground for 4 minutes and treated with 0.25 M HCl still showed the typical vermiculite Mossbauer spectrum with an Fe2+/Fe3+ ratio similar to the untreated sample. Samples ground for 2 or 4 minutes and treated with 1M HCI were completely orange and only Fe3+ remained.

Published
2006

36. Mineralogical Characterization of the Polychrome in Cultural Heritage Artifacts (Antiquity to Date) from Southern Spain Using Micro-Raman Spectroscopy and Complementary Techniques.

Author

Perez-Rodriguez, J.L. and Duran, A.

Subjects
*MINERALOGY, *COLOR in architecture, *CULTURAL property, *PIGMENTS, *ANTIQUITIES, *RAMAN spectroscopy
Abstract

This work reports on the use of micro-Raman spectroscopy for the characterization of materials used for producing the polychrome in cultural heritage artifacts from southern Spain. The micro-Raman technique was applied for the characterization of several types of artworks or for cross-sections from these works, which were produced along different historical epochs. This technique was demonstrated to be valuable for the characterization of compounds, which were all detected within the artworks studied. The identification of all of these compounds by micro-Raman was confirmed by other complementary techniques, such as micro-X-ray diffraction and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy. [ABSTRACT FROM AUTHOR]

Published
2014
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38. Natural Earth Pigments From Roman and Arabic Wall Paintings Revealed by Spectroscopic Techniques.

Author

Garofano, I., Duran, A., Perez-Rodriguez, J.L., and Robador, M.D.

Subjects
PIGMENTS, RAMAN spectroscopy, FOURIER transform infrared spectroscopy, ULTRAVIOLET radiation, ROMAN painting, SPECTRUM analysis, EARTH (Planet)
Abstract

Full identification of pigments used in wall paintings by Romans and Arabs that were recently discovered was achieved by the combined application of several spectroscopy methods. Identification of pigments was provided by the use of micro-Raman and FT-IR spectroscopy, while UV-Visible spectroscopy and chromatic studies permitted the authors to identify slight variations of hue attributed to mixtures of pigments. Natural earths and minerals were detected as the main pigments employed by both civilizations, although some differences were found between them. Red ochre, vermilion, yellow ochre, Egyptian blue, green earth, calcite, carbon, and possibly ivory blacks were identified in the Roman paintings. Only hematite and calcite were observed in the Arabic fragments. [ABSTRACT FROM PUBLISHER]

Published
2011
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39. Old and Modern Pigments Identification from a 14th Century Sculpture by Micro-Raman.

Author

Franquelo, M.L., Duran, A., Arquillo, D., and Perez-Rodriguez, J.L.

Subjects
FOURTEENTH century, RAMAN spectroscopy, POLYCHROMY, PIGMENTS, MICROSCOPY, CHRYSELEPHANTINE sculpture, CROSS-sectional method
Abstract

The chromatic characterization of the external part of the sculpture showed homogeneity values in the majority of the colored zones. The optical microscopy study showed different layers in the painting cross-sections. The complex polychromy was attributed to several restoration processes carried out along the time. The composition of the different layers of painting cross-sections was studied using the micro-Raman technique. The micro-Raman technique was very useful in characterizing some pigments that are difficult to determine by other experimental techniques. The study showed the presence of several pigments that had been applied in ancient and recent times. [ABSTRACT FROM PUBLISHER]

Published
2011
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