A vibrational spectroscopic study of the phosphate mineral churchite (REE)(PO4)⋅2H2O

Vibrational spectroscopy has been used to study the rare earth mineral churchite of formula (REE)(PO4)⋅2H2O. The mineral contains a range of rare earth metals including yttrium depending on the locality. The Raman spectra of churchite-(REE) are characterized by an intense sharp band at 984 cm−1 assigned to the ν1 ( PO 4 3 - ) symmetric stretching mode. A lower intensity band observed at around 1067 cm−1 is attributed to the ν3 ( PO 4 3 - ) antisymmetric stretching mode. The ( PO 4 3 - ) bending modes are observed at 497 cm−1 (ν2) and 565 cm−1(ν4). Raman bands at 649 and 681 cm−1 are assigned to water librational modes. Vibrational spectroscopy enables aspects of the structure of churchite to be ascertained.