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

详细信息    查看全文

• 作者：Ray L. Frost^a ; ^{r.frost@qut.edu.au" class="auth_mail} ; Ricardo Scholz^b ; André ; s Ló ; pez^a ; Yunfei Xi^a
• 关键词：Whiteite ; Jahnsite ; Phosphate ; Hydroxyl ; Raman spectroscopy ; Infrared
• 刊名：Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
• 出版年：24 April, 2014
• 年：2014
• 卷：124
• 期：Complete
• 页码：243-248
• 全文大小：957 K

文摘

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^鈭? assigned to the 谓₁ symmetric stretching vibrations. The low intensity Raman bands at 1076 and 1173 cm^鈭? are assigned to the 谓₃ antisymmetric stretching modes. The Raman bands at 1266, 1334 and 1368 cm^鈭? are assigned to AlOH deformation modes. The infrared band at 967 cm^鈭? is ascribed to the 谓₁ symmetric stretching vibrational mode. The infrared bands at 1024, 1072, 1089 and 1126 cm^鈭? are attributed to the 谓₃ antisymmetric stretching vibrations. Raman bands at 553, 571 and 586 cm^鈭? are assigned to the 谓₄ out of plane bending modes of the unit. Raman bands at 432, 457, 479 and 500 cm^鈭? are attributed to the 谓₂ PO₄ and H₂PO₄ bending modes. In the 2600 to 3800 cm^鈭? spectral range, Raman bands for whiteite are found 3426, 3496 and 3552 cm^鈭? are assigned to AlOH stretching vibrations. Broad infrared bands are also found at 3186 cm^鈭?. Raman bands at 2939 and 3220 cm^鈭? 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.