FT-Raman and FT-IR spectroscopic study of synthetic Mg/Zn/Al-hydrotalcites

Synthetic Mg/Zn/Al-hydrotalcites with atomic ratios of 6: 0: 2, 4: 2: 2, 2: 4: 2 and 0: 6: 2 were characterized by FT-Raman and FT-IR spectroscopy. 'Al-OH' IR translation modes are observed at 419,427,559,616 and 771 cm(-1) with two corresponding Raman bands at 465-477 and 547-553 cm(-1). 'Mg-OH' IR translation modes are found at 412,559 and 616 cm(-1) with equivalent Raman bands at 464-477 and 547-553 cm(-1). The 'Zn-OH' IR translation mode is found at 445 cm(-1) and the Raman modes around 450 and 495 cm-1. The CO32- group is identified by the nu(1)(IR) at 1112 cm(-1) and a doublet in the Raman around 1045-1055 and 1060 cm(-1). nu(2)(IR) is observed at 874 cm(-1). nu(3)(IR) is a doublet at 1359 and 1381 cm(-1). nu(4) is observed in both the IR and Raman spectra around 670 and 695-715 cm(-1), respectively. In the OH deformation region, a doublet is observed for'Al-OH'at 955 and 1033 cm(-1) in the IR spectra. The 'Zn-OH' IR deformation mode is observed at 1462 cm(-1). H2O is characterized by a bending mode at 1632 cm(-1) and an H-bonded interlayer H2O mode at 3266 cm(-1) with a Raman band between 3244 and 3271 cm(-1). The OH stretching region is characterized by three bands in the Raman spectra around 3355-3360,3440-3455 and 3535-3580 cm(-1). One band is observed in the IR spectra at 3471 cm(-1). Copyright (C) 2004 John Wiley Sons, Ltd.