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Keywords:

  • hydrotalcite synthesis;
  • hydrocalumite;
  • Raman spectroscopy;
  • layered double hydroxide

Abstract

We have successfully synthesised hydrotalcites (HTs) containing calcium, which are naturally occurring minerals. Insight into the unique structure of HTs has been obtained using a combination of X-ray diffraction (XRD) as well as infrared and Raman spectroscopies. Calcium-containing hydrotalcites (Ca-HTs) of the formula Ca4Al2(CO3)(OH)12·4H2O (2:1 Ca-HT) to Ca8Al2(CO3)(OH)20· 4H2O (4:1 Ca-HT) have been successfully synthesised and characterised by XRD and Raman spectroscopy. XRD has shown that 3:1 calcium HTs have the largest interlayer distance. Raman spectroscopy complemented with selected infrared data has been used to characterise the synthesised Ca-HTs. The Raman bands observed at around 1086 and 1077 cm−1 were attributed to the ν1 symmetric stretching modes of the (CO32−) units of calcite and carbonate intercalated into the HT interlayer. The corresponding ν3 CO32− antisymmetric stretching modes are found at around 1410 and 1475 cm−1. Copyright © 2010 John Wiley & Sons, Ltd.