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 Infrared and Raman spectroscopic characterization of the borate mineral hydroboracite CaMg[B3O4(OH)3]2 3H2O – implications for the molecular structure.(2014) Frost, Ray Leslie; Cipriano, Ricardo Augusto Scholz; López, Andrés; Xi, Yunfei; Graça, Leonardo MartinsWe have studied the mineral hydroboracite CaMg[B3O4(OH)3]2 3H2O using electron microscopy and vibrational spectroscopy. Both tetrahedral and trigonal boron units are observed. The nominal resolution of the Raman spectrometer is of the order of 2 cm^-1 and as such is sufficient enough to identify separate bands for the stretching bands of the two boron isotopes. The Raman band at 1039 cm^-1 is assigned to BO stretching vibration. Raman bands at 1144, 1157, 1229, 1318 cm^-1 are attributed to the BOH in-plane bending modes. Raman bands at 825 and 925 cm^-1 are attributed to the antisymmetric stretching modes of tetrahedral boron. The sharp Raman peak at 925 cm^-1 is from the 11-B component such a mode, then it should have a smaller 10-B satellite near (1.03) x (925) = 952 cm^-1, and indeed a small peak at 955 is observed. Four sharp Raman bands observed at 3371, 3507, 3563 and 3632 cm^-1 are attributed to the stretching vibrations of hydroxyl units. The broad Raman bands at 3076, 3138, 3255, 3384 and 3551 cm^-1 are assigned to water stretching vibrations. Infrared bands at 3367, 3505, 3559 and 3631 cm^-1 are assigned to the stretching vibration of the hydroxyl units. Broad infrared bands at 3072 and 3254 cm^-1 are assigned to water stretching vibrations. Infrared bands at 1318, 1349, 1371, 1383 cm^-1 are assigned to the antisymmetric stretching vibrations of trigonal boron.Item A vibrational spectroscopic study of the borate mineral takedaite Ca3(BO3)2.(2014) Frost, Ray Leslie; López, Andrés; Xi, Yunfei; Graça, Leonardo Martins; Cipriano, Ricardo Augusto ScholzWe have studied the mineral takedaite Ca3(BO3)2, a borate mineral of calcium using SEM with EDX and vibrational spectroscopy. Chemical analysis shows a homogeneous phase, composed of Ca. Boron was not detected. A very intense Raman band at 1087 cm^-1 is assigned to the BO stretching vibration of BO3 units. Additional Raman bands may be due to isotopic splitting. In the infrared spectrum, bands at 1218 cm^-1 and at 1163, 1262 and 1295 cm^-1 are assigned to the trigonal borate stretching modes. Raman bands at 712 and 715 cm^-1 are assigned to the in-plane bending modes of the BO3 units. Vibrational spectroscopy enables aspects of the molecular structure of takedaite to be assessed.