Please use this identifier to cite or link to this item: http://www.repositorio.ufop.br/handle/123456789/6190
Title: SEM, EDX and vibrational spectroscopic study of the phosphate mineral ushkovite MgFe2 3+(PO4)2(OH)2 8H2O – implications of the molecular structure.
Authors: López, Andrés
Cipriano, Ricardo Augusto Scholz
Frost, Ray Leslie
Belotti, Fernanda Maria
Keywords: Ushkovite
Phosphate
Hydroxyl
Raman spectroscopy
Issue Date: 2015
Citation: LOPÉZ, A. et al. SEM, EDX and vibrational spectroscopic study of the phosphate mineral ushkovite MgFe2 3+(PO4)2(OH)2 8H2O – implications of the molecular structure. Journal of Molecular Structure, v. 1081, p. 329-333, 2015. Disponível em: <http://www.sciencedirect.com/science/article/pii/S0022286014010199>. Acesso em: 08 set. 2015.
Abstract: The mineral ushkovite has been analyzed using a combination of electron microscopy with EDX and vibrational spectroscopy. Chemical analysis shows the mineral contains P, Mg with very minor Fe. Thus, the formula of the studied ushkovite is Mg3 2+(PO4)2 8H2O. The Raman spectrum shows an intense band at 953 cm 1 assigned to the m1 symmetric stretching mode. In the infrared spectra complexity exists with multiple antisymmetric stretching vibrations observed, due to the reduced tetrahedral symmetry. This loss of degeneracy is also reflected in the bending modes. Strong infrared bands around 827 cm 1 are attributed to water librational modes. The Raman spectra of the hydroxyl-stretching region are complex with overlapping broad bands. Hydroxyl stretching vibrations are identified at 2881, 2998, 3107, 3203, 3284 and 3457 cm 1. The wavenumber band at 3457 cm 1 is attributed to the presence of FeOH groups. This complexity is reflected in the water HOH bending modes where a strong infrared band centered around 1653 cm 1 is found. Such a band reflects the strong hydrogen bonding of the water molecules to the phosphate anions in adjacent layers. Spectra show three distinct OH bending bands from strongly hydrogen-bonded, weakly hydrogen bonded water and non-hydrogen bonded water. Vibrational spectroscopy enhances our knowledge of the molecular structure of ushkovite.
URI: http://www.repositorio.ufop.br/handle/123456789/6190
metadata.dc.identifier.doi: https://doi.org/10.1016/j.molstruc.2014.10.017
ISSN: 0022-2860
metadata.dc.rights.license: O periódico Journal of Molecular Structure concede permissão para depósito deste artigo no Repositório Institucional da UFOP. Número da licença: 3727590557783.
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