Spectroscopic characterisation of the LDH mineral quintinite Mg4Al2(OH)12CO3·3H2O

• We have studied the natural hydrotalcite quintinite MgAl2(OH)16(CO3)·4H2O.
• Raman and infrared spectroscopy coupled with SEM and EDX have been applied.
• Chemical analysis gave Mg and Al with minor amounts of Fe.
• Hydrogen bond distances were calculated.

Raman and infrared spectroscopy coupled with scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX) have been applied to study the natural hydrotalcite quintinite Mg4Al2(OH)12[CO3]·3H2O. SEM shows the mineral to be a homogenous phase. Quintinite is composed of Mg and Al as the major elements with minor amounts of Fe. Two Raman bands at 1046 and 1062 cm are assigned to the ν1 symmetric stretching modes of the carbonate anion. Thermal treatment shifts these bands to higher wavenumbers indicating a change in the carbonate bonding. Hydrogen bond distances are calculated using a Libowitzky-type empirical function and varied between 2.61 and 3.00 Å. Stronger hydrogen bonds were formed by water units as compared to the hydroxyl units.

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