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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2 resultados
Resultados da Pesquisa
Item Vibrational spectroscopy of the borate mineral tunellite SrB6O9(OH)2 3(H2O) - implications for the molecular structure.(2014) Frost, Ray Leslie; López, Andrés; Cipriano, Ricardo Augusto Scholz; Xi, YunfeiTunellite is a strontium borate mineral with formula: SrB6O9(OH)2_3(H2O) and occurs as colorless crystals in the monoclinic pyramidal crystal system. An intense Raman band at 994 cm_1 was assigned to the BO stretching vibration of the B2O3 units. Raman bands at 1043, 1063, 1082 and 1113 cm_1 are attributed to the in-plane bending vibrations of trigonal boron. Sharp Raman bands observed at 464, 480, 523, 568 and 639 cm_1 are simply defined as trigonal and tetrahedral borate bending modes. The Raman spectrum clearly shows intense Raman bands at 3567 and 3614 cm_1, attributed to OH units. The molecular structure of a natural tunellite has been assessed by using vibrational spectroscopy.Item Characterization of the sulphate mineral amarantite - using infrared, Raman spectroscopy and thermogravimetry.(2013) Frost, Ray Leslie; López, Andrés; Cipriano, Ricardo Augusto Scholz; Xi, Yunfei; Silveira, Aléssio Jordan da; Lima, Rosa Malena FernandesThe mineral amarantite Fe3þ 2 (SO4)O _ 7H2O has been studied using a combination of techniques including thermogravimetry, electron probe analyses and vibrational spectroscopy. Thermal analysis shows decomposition steps at 77.63, 192.2, 550 and 641.4 _C. The Raman spectrum of amarantite is dominated by an intense band at 1017 cm_1 assigned to the SO2_ 4 m1 symmetric stretching mode. Raman bands at 1039, 1054, 1098, 1131, 1195 and 1233 cm_1 are attributed to the SO2_ 4 m3 antisymmetric stretching modes. Very intense Raman band is observed at 409 cm_1 with shoulder bands at 399, 451 and 491 cm_1 are assigned to the m2 bending modes. A series of low intensity Raman bands are found at 543, 602, 622 and 650 cm_1 are assigned to the m4 bending modes. A very sharp Raman band at 3529 cm_1 is assigned to the stretching vibration of OH units. A series of Raman bands observed at 3025, 3089, 3227, 3340, 3401 and 3480 cm_1 are assigned to water bands. Vibrational spectroscopy enables aspects of the molecular structure of the mineral amarantite to be ascertained.