Structural characterization of rondorfite, calcium silica chlorine mineral containing magnesium in tetrahedral position [MgO₄]^6?, with the aid of the vibrational spectroscopies and fluorescence

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• 作者：M. Dulski^a ; ^{mdulski@us.edu.pl} ; A. Bulou^b ; ^{Alain.Bulou@univ-lemans.fr} ; K.M. Marzec^c ; ^{marzec@chemia.uj.edu.pl} ; E.V. Galuskin^d ; ^{evgeny.galuskin@us.edu.pl} ; R. Wrzalik^a ; ^{roman.wrzalik@us.edu.pl}
• 关键词：Rondorfite ; Magnesiosilicate pentamer ; [MgO4]6&minus ; coordination ; Infrared and Raman spectroscopy ; Fluorescence
• 刊名：Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
• 出版年：2013
• 出版时间：15 January, 2013
• 年：2013
• 卷：101
• 期：Complete
• 页码：382-388
• 全文大小：1551 K

文摘

Raman and infrared spectra of rondorfite Ca₈Mg(SiO₄)₄Cl₂, a calcium chlorosilica mineral containing magnesium in tetrahedral position, has been studied in terms of spectra-structure relations. Raman spectra have been measured at different excited laser lines: 780 nm, 532 nm, 488 nm and 457 nm. This mineral is characterized by a single sharp intense Raman band at 863 cm^?1 assigned to the ¦Í₁ [SiO₄]^4? (A_g) symmetric stretching mode in the magnesiosilicate pentamer. Due to symmetry restriction the other Raman bands have a small intensity. Two Raman bands observed at 564 cm^?1 and 526 cm^?1 are associated simultaneously with ¦Í₄ [MgO₄]^6? and ¦Í₄ [SiO₄]^4? symmetric and antisymmetric modes where magnesium occurs in the tetrahedral configuration. The weak bands at 422 cm^?1 and 386 cm^?1 are associated with the ¦Í₂ bending mode of CaO₆ in octahedral configuration, respectively. Moreover the infrared spectrum shows very weak bands associated with the hydroxyl group and/or water molecule. Additionally, the strong fluorescence phenomenon was observed and related to the presence of chlorine atoms, magnesium Mg²⁺ ions in atypical configuration or point defects.