Vibrational spectroscopic characterization of the phosphate mineral kulanite Ba(Fe(2+),Mn(2+),Mg)2(Al,Fe(3+))2(PO4)3(OH)3.
The mineral kulanite BaFe2Al2(PO4)3(OH)3, a barium iron aluminum phosphate, has been studied by using a combination of electron microscopy and vibrational spectroscopy. Scanning electron microscopy with EDX shows the mineral is homogenous with no other phases present. The Raman spectrum is dominated by an intense band at 1022cm(-1) assigned to the PO4(3-)ν1 symmetric stretching mode. Low intensity Raman bands at 1076, 1110, 1146, 1182cm(-1) are attributed to the PO4(3-)ν3 antisymmetric stretching vibrations. The infrared spectrum shows a complex spectral profile with overlapping bands. Multiple phosphate bending vibrations supports the concept of a reduction in symmetry of the phosphate anion. Raman spectrum at 3211, 3513 and 3533cm(-1) are assigned to the stretching vibrations of the OH units. Vibrational spectroscopy enables aspects on the molecular structure of kulanite to be assessed.
A vibrational spectroscopic study of the phosphate mineral churchite (REE)(PO(4))⋅2H(2)O.
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 984cm(-1) assigned to the ν1(PO4(3-)) symmetric stretching mode. A lower intensity band observed at around 1067cm(-1) is attributed to the ν3(PO4(3-)) antisymmetric stretching mode. The (PO4(3-)) bending modes are observed at 497cm(-1) (ν2) and 565cm(-1)(ν4). Raman bands at 649 and 681cm(-1) are assigned to water librational modes. Vibrational spectroscopy enables aspects of the structure of churchite to be ascertained.
Thorium in monazite sand; separation and determination by precipitation from homogeneous solution
A new method is described which consists of three steps: (1) decomposition of the monazite sand with perchloric acid; (2) separation of thorium and the rare earths by hydrolysis of methyl-oxalate in acid solution; and (3) separation of thorium from the rare earths by hydrolysis of urea in the presence of formic acid. The authors consider the method to be accurate and rapid.