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 A vibrational spectroscopic study of the silicate mineral normandite – NaCa(Mn2+,Fe2+)(Ti,Nb,Zr)Si2O7(O,F)2.(2015) Frost, Ray Leslie; López, Andrés; Theiss, Frederick L.; Cipriano, Ricardo Augusto Scholz; Romano, Antônio WilsonWe have studied the mineral normandite using a combination of scanning electron microscopy with energy dispersive spectroscopy and vibrational spectroscopy. The mineral normandite NaCa(Mn2+,Fe2+)(Ti,Nb,Zr)Si2O7(O,F)2 is a crystalline sodium calcium silicate which contains rare earth elements. Chemical analysis shows the mineral contains a range of elements including Na, Mn2+, Ca, Fe2+ and the rare earth element niobium. No Raman bands are observed above 1100 cm 1. The mineral is characterised by Raman bands observed at 724, 748, 782 and 813 cm 1. Infrared bands are broad; nevertheless bands may be resolved at 723, 860, 910, 958, 933, 1057 and 1073 cm 1. Intense Raman bands at 454, 477 and 513 cm 1 are attributed to OSiO bending modes. No Raman bands are observed in the hydroxyl stretching region, but low intensity infrared bands are observed at 3191 and 3450 cm 1. This observation brings into question the true formula of the mineral.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.