An infrared and Raman spectroscopic study of the uranyl micas.
Vibrational spectroscopy using a combination of infrared and Raman spectroscopy has been used to study the uranyl micas also known as the autunite minerals, of general formula M(UO2)2(XO4)2.8-12H2O where M may be Ba, Ca, Cu, Fe2+, Mg, Mn2+ or 1/2(HAl) and X is As or P. Included in these minerals are autunite, metautunite, torbernite, meta-torbernite, meta-zeunerite, saléeite and sabugalite. Compared with the results of infrared spectroscopy, Raman microscopy shows excellent band separation enabling the separation and identification of bands attributed to (UO2)2+ units, PO4 and AsO4 units. Common to all spectra were bands at around 900 and 818 cm(-1), attributed to the antisymmetric and symmetric stretching vibrations of the (UO2)2+ units. Water in autunites is in a highly structured arrangement in the interlayer of the uranyl micas. Water molecules are differentiated according to the strength of the hydrogen bonds formed between the water and the adjacent uranyl-phosphate or uranyl-arsenate surfaces and the hydration sphere of the interlayer cation.
Frost
Ray L
RL
Inorganic Materials Research Program, School of Physical and Chemical Sciences, Queensland University of Technology, G.P.O. Box 2434, Brisbane, Qld 4001, Australia. r.frost@qut.edu.au
D000538:Aluminum Silicates / Q000737:chemistry*; D008903:Minerals / Q000737:chemistry; D015394:Molecular Structure; D013055:Spectrophotometry, Infrared; D013059:Spectrum Analysis, Raman; D017974:Uranium Compounds / Q000737:chemistry*
D000538:Aluminum Silicates; D008903:Minerals; D017974:Uranium Compounds; C011934:mica