An infrared and Raman spectroscopic study of the uranyl micas

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• 作者：Frost ; Ray L.
• 关键词：Autunite ; Metautunite ; Arsenate ; Phosphate ; Vanadate ; Raman spectroscopy
• 刊名：Spectrochimica Acta Part A ; Molecular and Biomolecular Spectroscopy
• 出版年：2004
• 期刊代码：99_13861425
• 类别：ch
• 出版时间：June, 2004
• 卷：60
• 期：7
• 页码：1469-1480
• 文件大小：595 K

摘要

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 818cm⁻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.