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 phosphate mineral vantasselite Al4(PO4)3(OH)3 9H2O.(2015) Frost, Ray Leslie; Cipriano, Ricardo Augusto Scholz; Belotti, Fernanda Maria; López, Andrés; Theiss, Frederick L.We have studied the phosphate mineral vantasselite Al4(PO4)3(OH)3 9H2O using a combination of SEM with EDX and Raman and infrared spectroscopy. Qualitative chemical analysis shows Al, Fe and P. Raman bands at 1013 and 1027 cm 1 are assigned to the PO43 m1 symmetric stretching mode. The observation of two bands suggests the non-equivalence of the phosphate units in the vantasselite structure. Raman bands at 1051, 1076 and 1090 cm 1 are attributed to the PO43 m3 antisymmetric stretching vibration. A comparison is made with the spectroscopy of wardite. Strong infrared bands at 1044, 1078, 1092, 1112, 1133, 1180 and 1210 cm 1 are attributed to the PO4 3 m3 antisymmetric stretching mode. Some of these bands may be due to dAl2OH deformation modes. Vibrational spectroscopy offers a mechanism for the study of the molecular structure of vantasselite.Item A vibrational spectroscopic study of the silicate mineral lomonosovite Na5Ti2(Si2O7)(PO4)O2.(2014) Frost, Ray Leslie; López, Andrés; Theiss, Frederick L.; Graça, Leonardo Martins; Cipriano, Ricardo Augusto ScholzThe mineral lomonosovite has been studied using a combination of scanning electron microscopy with energy dispersive X-ray analysis and vibrational spectroscopy. Qualitative chemical analysis gave Si, P, Na and Ti as the as major elements with small amounts of Mn, Ca, Fe and Al. The mineral lomonosovite has a formula Na5Ti2(Si2O7)(PO4)O2. Raman bands observed at 909, 925 and 939 cm^-1 are associated with phosphate units. Raman bands found at 975, 999, 1070, 1080 and 1084 cm^-1 are attributed to siloxane stretching vibrations. The observation of multiple bands in both the phosphate stretching and bending regions supports the concept that the symmetry of the phosphate anion in the structure of lomonosovite is significantly reduced. Infrared spectroscopy identifies bands in the water stretching and bending regions, thus suggesting that water is involved with the structure of lomonosovite either through adsorption on the surface or by bonding to the phosphate units.