A vibrational spectroscopic study of the phosphate mineral whiteite CaMn++Mg2Al2(PO4)(4)(OH)(2).8(H2O)

作者：Frost Ray L^*; Scholz Ricardo; Lopez Andres; Xi Yunfei

来源：Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy , 2014, 124: 243-248.

DOI：10.1016/j.saa.2014.01.053

• Whiteite
• Jahnsite
• Phosphate
• Hydroxyl
• Raman spectroscopy
• Infrared

Vibrational spectroscopy enables subtle details of the molecular structure of whiteite to be determined. Single crystals of a pure phase from a Brazilian pegmatite were used. The infrared and Raman spectroscopy were applied to compare the molecular structure of whiteite with that of other phosphate minerals. The Raman spectrum of whiteite shows an intense band at 972 cm(-1) assigned to the nu(1) PO43- symmetric stretching vibrations. The low intensity Raman bands at 1076 and 1173 cm(-1) are assigned to the nu(3) PO43- antisymmetric stretching modes. The Raman bands at 1266, 1334 and 1368 cm(-1) are assigned to AIOH deformation modes. The infrared band at 967 cm(-1) is ascribed to the PO43- nu(1) symmetric stretching vibrational mode. The infrared bands at 1024, 1072, 1089 and 1126 cm(-1) are attributed to the PO43- nu 3 antisymmetric stretching vibrations. Raman bands at 553, 571 and 586 cm(-1) are assigned to the nu(4) out of plane bending modes of the PO43-, unit. Raman bands at 432, 457, 479 and 500 cm(-1) are attributed to the nu 2 PO4 and H2PO4 bending modes. In the 2600 to 3800 cm(-1) spectral range, Raman bands for whiteite are found 3426, 3496 and 3552 cm(-1) are assigned to AIOH stretching vibrations. Broad infrared bands are also found at 3186 cm(-1). Raman bands at 2939 and 3220 cm(-1) are assigned to water stretching vibrations. Raman spectroscopy complimented with infrared spectroscopy has enabled aspects of the structure of whiteite to be ascertained and compared with that of other phosphate minerals.

• 出版日期2014-4-24