title: Structural characterization of rondorfite, calcium silica chlorine mineral containing magnesium in tetrahedral position [MgO4]6-, with the aid of the vibrational spectroscopies and fluorescence.
abstract: 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 ν1 [SiO4]4- (Ag) 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 ν4 [MgO4]6- and ν4 [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 ν2 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.
authors.affiliation: A.Chelkowski Institute of Physics, University of Silesia, ul. Uniwersytecka 4, 40-007 Katowice, Poland. mdulski@us.edu.pl
authors.forename: M
authors.initials: M
authors.lastname: Dulski
authors.forename: A
authors.initials: A
authors.lastname: Bulou
authors.forename: K M
authors.initials: KM
authors.lastname: Marzec
authors.forename: E V
authors.initials: EV
authors.lastname: Galuskin
authors.forename: R
authors.initials: R
authors.lastname: Wrzalik
mesh_terms: D002118:Calcium / Q000737:chemistry*; D002713:Chlorine / Q000737:chemistry*; D005453:Fluorescence; D017633:Magnesium Silicates / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013059:Spectrum Analysis, Raman
chemical_list: D017633:Magnesium Silicates; D002713:Chlorine; D002118:Calcium