A Raman spectroscopic study of the uranyl phosphate mineral parsonsite

The mineral parsonsite, with samples from The Ranger Uranium Mine, Australia, and the La Faye Mine, Grury, Saone‐et‐Loire, Burgundy, France, has been characterised by Raman spectroscopy at 298 and 77 K and complemented with infrared spectroscopy. Two Raman bands close to 807 and 796 cm −1 are attributed to the ν 1 (UO 2 ) 2+ symmetric stretching modes, while two bands close to 953 or 945 cm −1 and 863–873 cm −1 are assigned to the ν 3 (UO 2 ) 2+ anti‐symmetric stretching vibrations. Four or five bands (953, 926, 910, 883 cm −1 ) are observed in the infrared spectrum in this region. Bands at 965–967 and 972 cm −1 are assigned to the ν 1 (PO 4 ) 3− symmetric stretching modes and bands that are observed in the 987 to 1078 cm −1 region to the ν 3 (PO 4 ) 3− anti‐symmetric stretching modes. Bands at 465, 439, 406, 394 cm −1 (298 K) and 466, 442, 405, 395 cm −1 (77 K) are assigned to the split, doubly degenerate ν 2 (PO 4 ) −3 bending vibrations. Bands of very low intensity at 609, 595, 591, 582, 560 and 540 cm −1 are attributed to the split, triply degenerate ν 4 (PO 4 ) −3 bending modes. Bands observed at wavenumbers lower than 300 cm −1 are connected with the split ν 2 (δ) (UO 2 ) 2+ bending, ν(UO ligand ), δ(UO ligand ) and lattice vibrations. UO bond lengths in uranyl were calculated from the Raman and infrared spectra, which are in agreement with those from the available X‐ray single crystal structure analysis of parsonsite. A short comment is given on the water content and the possibility of a hydrogen‐bonding network in the parsonsite crystal structure. Copyright © 2006 John Wiley & Sons, Ltd.