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Raman spectrum of decrespignyite [(Y,REE) 4 Cu(CO 3 ) 4 Cl(OH) 5 ·2H 2 O] and its relation with those of other halogenated carbonates including bastnasite, hydroxybastnasite, parisite and northupite
Author(s) -
Frost Ray L.,
Palmer Sara J.
Publication year - 2011
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.2959
Subject(s) - raman spectroscopy , analytical chemistry (journal) , chemistry , infrared , carbonate , infrared spectroscopy , nuclear magnetic resonance , materials science , mineralogy , optics , physics , organic chemistry , chromatography
Raman spectroscopy complemented with infrared spectroscopy has been used to study the rare‐earth‐based mineral decrespignyite [(Y,REE) 4 Cu(CO 3 ) 4 Cl(OH) 5 · 2H 2 O] and the spectrum compared with the Raman spectra of a series of selected natural halogenated carbonates from different origins including bastnasite, parisite and northupite. The Raman spectrum of decrespignyite displays three bands at 1056, 1070 and 1088 cm −1 attributed to the CO 3 2− symmetric stretching vibration. The observation of three symmetric stretching vibrations is very unusual. The position of the CO 3 2− symmetric stretching vibration varies with the mineral composition. The Raman spectrum of decrespignyite shows bands at 1391, 1414, 1489 and 1547 cm −1 , whereas the Raman spectra of bastnasite, parisite and northupite show a single band at 1433, 1420 and 1554 cm −1 , respectively, assigned to the ν 3 (CO 3 ) 2− antisymmetric stretching mode. The observation of additional Raman bands for the ν 3 modes for some halogenated carbonates is significant in that it shows distortion of the carbonate anion in the mineral structure. Four Raman bands are observed at 791, 815, 837 and 849 cm −1 , which are assigned to the (CO 3 ) 2− ν 2 bending modes. Raman bands are observed for decrespignyite at 694, 718 and 746 cm −1 and are assigned to the (CO 3 ) 2− ν 4 bending modes. Raman bands are observed for the carbonate ν 4 in‐phase bending modes at 722 cm −1 for bastnasite, 736 and 684 cm −1 for parisite and 714 cm −1 for northupite. Multiple bands are observed in the OH stretching region for decrespignyite, bastnasite and parisite, indicating the presence of water and OH units in the mineral structure. Copyright © 2011 John Wiley & Sons, Ltd.