Synthesis and Raman spectroscopy of indium‐based hydrotalcites of formula Mg 6 In 2 (CO 3 )(OH) 16 · 4H 2 O

Insight into the unique structure of layered double hydroxides has been obtained using a combination of X‐ray diffraction and Raman spectroscopy. Indium‐containing hydrotalcites of formula Mg 4 In 2 (CO 3 )(OH) 12 · 4H 2 O [2:1 In‐LDH (layered double hydroxides)] through to Mg 8 In 2 (CO 3 )(OH) 18 · 4H 2 O (4:1 In‐LDH) with variation in the Mg : In ratio have been successfully synthesized. The d (003) spacing varied from 7.83 Å for the 2:1 LDH to 8.15 Å for the 3:1 indium‐containing layered double hydroxide. Raman spectroscopy complemented with selected infrared data has been used to characterize the synthesized indium‐containing layered double hydroxides of formula Mg 6 In 2 (CO 3 )(OH) 16 · 4H 2 O. Raman bands observed at around 1058, 1075 and 1115 cm −1 are attributed to the symmetric stretching modes of the CO 3 2− units. Multiple ν 3 CO 3 2− antisymmetric stretching modes are found at around 1348, 1373, 1429 and 1488 cm −1 in the infrared spectra. The splitting of this mode indicates that the carbonate anion is in a perturbed state. Raman bands observed at 690 and 700 cm −1 assigned to the ν 4 CO 3 2− modes support the concept of multiple carbonate species in the interlayer. Copyright © 2010 John Wiley & Sons, Ltd.