A vibrational spectroscopic study of the anhydrous phosphate mineral sidorenkite Na3Mn(PO4)(CO3).

Resumo
Sidorenkite is a very rare low-temperature hydrothermal mineral, formed very late in the crystallization of hyperagpaitic pegmatites in a differentiated alkalic massif (Mt. Alluaiv, Kola Peninsula, Russia). Sidorenkite Na3Mn(PO4)(CO3) is a phosphate–carbonate of sodium and manganese. Such a formula with two oxyanions lends itself to vibrational spectroscopy. The sharp Raman band at 959 cm 1 and 1012 cm 1 are assigned to the PO43 stretching modes, whilst the Raman bands at 1044 cm 1 and 1074 cm 1 are attributed to the CO32 stretching modes. It is noted that no Raman bands at around 800 cm 1 for sidorenkite were observed. The infrared spectrum of sidorenkite shows a quite intense band at 868 cm 1 with other resolved component bands at 850 and 862 cm 1. These bands are ascribed to the CO32 out-of-plane bend (m2) bending mode. The series of Raman bands at 622, 635, 645 and 704 cm 1 are assigned to the m4 phosphate bending modes. The observation of multiple bands supports the concept of a reduction in symmetry of the carbonate anion from D3h or even C2v.
Descrição
Palavras-chave
Sidorenkite, Phosphate, Raman spectroscopy, Infrared spectroscopy
Citação
FROST, R. L. et al. A vibrational spectroscopic study of the anhydrous phosphate mineral sidorenkite Na3Mn(PO4)(CO3). Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy, v. 137, p. 930-934, 2015. Disponível em: <http://www.sciencedirect.com/science/article/pii/S1386142514012207>. Acesso em: 08 set. 2015.