Raman spectroscopy of gallium-based hydrotalcites of formula Mg6Ga2(CO3)(OH)16· 4H2O

✍ Scribed by Ray L. Frost; Sara J. Palmer; Laure-Marie Grand

• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 321 KB
• Volume: 41
• Category: Article
• ISSN: 0377-0486
• DOI: 10.1002/jrs.2508

✦ Synopsis

Abstract

Insight into the unique structure of hydrotalcites has been obtained using Raman spectroscopy. Gallium‐containing hydrotalcites of formula Mg~4~Ga~2~(CO~3~)(OH)~12~· 4H~2~O (2:1 Ga‐HT) to Mg~8~Ga~2~(CO~3~)(OH)~20~· 4H~2~O (4:1 Ga‐HT) have been successfully synthesized and characterized by X‐ray diffraction and Raman spectroscopy. The d(003) spacing varied from 7.83 Å for the 2:1 hydrotalcite to 8.15 Å for the 3:1 gallium‐containing hydrotalcite. Raman spectroscopy complemented with selected infrared data has been used to characterize the synthesized gallium‐containing hydrotalcites of formula Mg~6~Ga~2~(CO~3~)(OH)~16~· 4H~2~O. Raman bands observed at around 1046, 1048 and 1058 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 1346, 1378, 1446, 1464 and 1494 cm^−1^. The splitting of this mode indicates that the carbonate anion is in a perturbed state. Raman bands observed at 710 and 717 cm^−1^ assigned to the ν~4~ (CO~3~^2−^) modes support the concept of multiple carbonate species in the interlayer. Copyright © 2009 John Wiley & Sons, Ltd.