Raman spectroscopic study of the antimonate mineral bottinoite Ni[Sb 2 (OH) 12 ]·6H 2 O and in comparison with brandholzite Mg[Sb 5+ 2 (OH) 12 ]·6H 2 O

Raman spectroscopy was used to study the mineral bottinoite and a comparison with the Raman spectra of brandholzite was made. An intense sharp Raman band at 618 cm −1 is attributed to the SbO symmetric stretching mode. The low intensity band at 735 cm −1 is ascribed to the SbO antisymmetric stretching vibration. Low intensity Raman bands were found at 501, 516 and 578 cm −1 . Four Raman bands observed at 1045, 1080, 1111 and 1163 cm −1 are assigned to δ SbOH deformation modes. A complex pattern resulting from the overlapping band of the water and hydroxyl units is observed. Raman bands are observed at 3223, 3228, 3368, 3291, 3458 and 3510 cm −1 . The first two Raman bands are assigned to water stretching vibrations. The two higher wavenumber Raman bands observed at 3466 and 3552 cm −1 and two infrared bands at 3434 and 3565 cm −1 are assigned to the stretching vibrations of the hydroxyl units. Observed Raman and infrared bands are connected with OH···O hydrogen bonds and their lengths 2.72, 2.79, 2.86, 2.88 and 3.0 Å (Raman) and 2.73, 2.83 and 3.07 Å (infrared). Copyright © 2010 John Wiley & Sons, Ltd.