EM - Escola de Minas
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/6
Notícias
A Escola de Minas de Ouro Preto foi fundada pelo cientista Claude Henri Gorceix e inaugurada em 12 de outubro de 1876.
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4 resultados
Resultados da Pesquisa
Item SEM, EDX and Raman and infrared spectroscopic study of brianyoungite Zn3(CO3,SO4)(OH)4 from Esperanza Mine, Laurion District, Greece.(2015) Frost, Ray Leslie; López, Andrés; Wang, Lina; Cipriano, Ricardo Augusto Scholz; Sampaio, Ney PinheiroThe mineral brianyoungite, a carbonate–sulphate of zinc, has been studied by scanning electron microscopy (SEM) with chemical analysis using energy dispersive spectroscopy (EDX) and Raman and infrared spectroscopy. Multiple carbonate stretching modes are observed and support the concept of non-equivalent carbonate units in the brianyoungite structure. Intense Raman band at 1056 cm_1 with shoulder band at 1038 cm_1 is assigned to the CO32_ m1 symmetric stretching mode. Two intense Raman bands at 973 and 984 cm_1 are assigned to the symmetric stretching modes of the SO4 2_ anion. The observation of two bands supports the concept of the non-equivalence of sulphate units in the brianyoungite structure. Raman bands at 704 and 736 cm_1 are assigned to the CO32_ m4 bending modes and Raman bands at 507, 528, 609 and 638 cm_1 are assigned to the CO32_ m2 bending modes. Multiple Raman and infrared bands in the OH stretching region are observed, proving the existence of water and hydroxyl units in different molecular environments in the structure of brianyoungite. Vibrational spectroscopy enhances our knowledge of the molecular structure of brianyoungite.Item Scanning electron microscopy with energy dispersive spectroscopy and Raman and infrared spectroscopic study of tilleyite Ca5Si2O7(CO3)2-Y.(2015) Frost, Ray Leslie; López, Andrés; Cipriano, Ricardo Augusto Scholz; Oliveira, Fernando A. N. deThe mineral tilleyite-Y, a carbonate-silicate of calcium, has been studied by scanning electron microscopy with chemical analysis using energy dispersive spectroscopy (EDX) and Raman and infrared spectroscopy. Multiple carbonate stretching modes are observed and support the concept of non-equivalent carbonate units in the tilleyite structure. Multiple Raman and infrared bands in the OH stretching region are observed, proving the existence of water in different molecular environments in the structure of tilleyite. Vibrational spectroscopy offers new information on the mineral tilleyite.Item Raman and infrared spectroscopic study of kamphaugite-(Y).(2015) Frost, Ray Leslie; López, Andrés; Cipriano, Ricardo Augusto ScholzWe have studied the carbonate mineral kamphaugite-(Y)(CaY(CO3)2(OH) H2O), a mineral which contains yttrium and specific rare earth elements. Chemical analysis shows the presence of Ca, Y and C. Back scattering SEM appears to indicate a single pure phase. The vibrational spectroscopy of kamphaugite-(Y) was obtained using a combination of Raman and infrared spectroscopy. Two distinct Raman bands observed at 1078 and 1088 cm 1 provide evidence for the non-equivalence of the carbonate anion in the kamphaugite-(Y) structure. Such a concept is supported by the number of bands assigned to the carbonate antisymmetric stretching mode. Multiple bands in the m4 region offers further support for the nonequivalence of carbonate anions in the structure. Vibrational spectroscopy enables aspects of the structure of the mineral kamphaugite-(Y) to be assessed.Item Vibrational spectroscopic study of poldervaartite CaCa[SiO3(OH)(OH)].(2015) Frost, Ray Leslie; López, Andrés; Cipriano, Ricardo Augusto Scholz; Lima, Rosa Malena FernandesWe have studied the mineral poldervaartite CaCa[SiO3(OH)(OH)] which forms a series with its manganese analogue olmiite CaMn[SiO3(OH)](OH) using a range of techniques including scanning electron microscopy, thermogravimetric analysis, Raman and infrared spectroscopy. Chemical analysis shows the mineral is reasonably pure and contains only calcium and manganese with low amounts of Al and F. Thermogravimetric analysis proves the mineral decomposes at 485 _C with a mass loss of 7.6% compared with the theoretical mass loss of 7.7%. A strong Raman band at 852 cm_1 is assigned to the SiO stretching vibration of the SiO3(OH) units. Two Raman bands at 914 and 953 cm_1 are attributed to the antisymmetric vibrations. Intense prominent peaks observed at 3487, 3502, 3509, 3521 and 3547 cm_1 are assigned to the OH stretching vibration of the SiO3(OH) units. The observation of multiple OH bands supports the concept of the non-equivalence of the OH units. Vibrational spectroscopy enables a detailed assessment of the molecular structure of poldervaartite